DWU

aneuploidy

Abnormal number of chromosomes. - down syndrome extra #21 chromosome - due to NONDISJUNCTION -

phases of menstrual cycle

menstrual phase, proliferative phase, secretory phase - corpus luteum produces PROGESTEsterone which allows the endometrium to be receptive to implantation of the blastocyst

chordates have a

notochord that is lost

chief cells

secrete pepsinogen

xylem - contains what 2 types of cells

tracheids and vessel members conducts water and minerals from soil makes annual growth rings to record plant age

acetyl coa

a high-energy fuel molecule for the citric acid cycle

Founder effect

a special type of genetic drift and states that when a group of emigrating individuals settle in a new location, these individuals would have a much smaller gene pool than their original population.

Amyloids

are abnormal, aggregates of proteins that can lead to severe fatal diseases. They are not digested

What do juxtaglomerular cells release when blood pressure is low? A. Renin B. Calcitonin C. Angiotensin I D. Parathyroid hormone E. Aldosterone CHECKEXHIBIT

are special cells located in the afferent arteriole near the glomerulus and can detect changes in blood pressure and sodium levels. When blood pressure or sodium levels are low, they release an enzyme called renin.

umbilical vein

carries oxygenated, nutrient-rich blood from the placental to the fetus, while the umbilical artery carry deoxygenated, nutrient-depleted blood from the fetus to the placenta

Glucocorticoids

cortisol

what are the components of aeromaticity?

cyclic/ring, all sp2 carbons, 4n+2 (aromatic) (ie - 6 pi electrons) vs. 4 pi electrons (anti-aromatic)

Associative learning

involves learning that two things are connected to each other.

as BP increases,

VP decreases

LH stimulates ____ to produce what 2 hormones

corpus luteum progesterone and estrogen - allows blood vessels to grow - uterline lining prepares for egg implantation for fertilization

darwin lacked an understanding of

genetics

Bayesian mimicry

occurs when a harmless animal mimics the coloring of a dangerous animal.

parietal cells

secrete HCl and intrinsic factor B-12 absorption

For which element is this the condensed electron configuration? [Ne] 3s23p2 A. N B. Ne C. Mg D. Si E. Ge CHECKEXHIBIT

si

Amino acids are formed by

are never chemically digested. Instead they are formed from the breakdown/cleavage of proteins performed by the pepsin enzyme in your stomach, and also by trypsin and chymotrypsin in the small intestine.

Spatial learning

is associating a response with a specific location.

Melanin

is generated by melanocytes in the stratum basale, not the granulosum.

All of the following species are members of the phylum mollusca EXCEPT one. Which one is the EXCEPTION? A. Clam B. Squid C. Octopus D. Snail E. Lobster CHECKEXHIBIT

Lobsters are crustacea in the phylum arthropoda. [E] is the answer. The phylum mollusca includes clams, snails, slugs, squids, octopi, cephalopods, and gastropods. Answer choices [A], [B], [C], and [D] are incorrect. Topic:Diversity of Life

Alpha particles are composed of ____ making them the same as a ____ atom.

2 protons and 2 neutrons, making them the same as a He atom.

Which of the carbocations is most likely to rearrange?

A 1,2-methyl shift on molecule [B] leads to formation of a tertiary carbocation. Because the resulting tertiary carbocation is more stable than the original secondary carbocation, this rearrangement is favorable and will occur. In contrast, the possible rearrangements of [A] result in secondary carbocations; because the original molecule is already a secondary carbocation, these rearrangements provide no added stability to the molecule and are therefore unlikely. The same is also true of option [C].

To where does urine immediately flow from the nephron tubules? A. Collecting duct B. Renal pelvis C. Ureter D. Bladder E. Urethra CHECKEXHIBIT

After filtration, reabsorption, and secretion in the nephrons, the filtrate (urine) of all the different nephrons flow into the collecting duct. Choice [A] is correct. Urine pathway: collecting duct → renal pelvis → ureter → bladder → urethra and exit Topic:Anatomy and Physiology

To where does urine immediately flow from the nephron? A. Collecting duct B. Renal pelvis C. Ureter D. Bladder E. Urethra

After filtration, secretion and reabsorption in the nephrons, the filtrate (urine) of all the different nephrons flow into the collecting duct.

secondary alcohol reacts with H3PO4 and H3O+ to afford....?

Alcohols reacted with aqueous acid (H3O+, H3PO4/H2SO4 in H2O) undergo "acid-catalyzed dehydration", or in other words, an elimination reaction! The "dehydration" comes from the fact the alcohol is dehydrated by eliminating H2O, leaving behind the most-substituted alkene possible (Zaitsev). 2-methyl-3-hexene is a minor product of the reaction (non-Zaitsev or Hoffmann). Primary alcohols use an E2 mechanism. Conversely, secondary and tertiary alcohols use an E1 mechanism (meaning carbocation rearrangements are possible).

Which of the following descriptions accurately describes alkali metals? A. Can have multiple oxidation states B. Often form brightly-colored compounds C. Series of non-metal elements that are highly electronegative D. Tend to donate their electrons in reactions E. The least reactive of all known elements CHECKEXHIBIT

Alkali metals only have an oxidation state of +1. [A] is incorrect. Transition metals form brightly-colored compounds. [B] is incorrect. Alkali metals are not electronegative. [C] is incorrect. Noble gases are the least reactive elements. [E] is incorrect. Alkali metals are in Group 1 of the periodic table. They tend to donate their one valence electron in reactions to achieve a full outer shell.

Which of the following descriptions accurately describes alkali metals? A. Can have multiple oxidation states B. Often form brightly-colored compounds C. Series of non-metal elements that are highly electronegative D. Tend to donate their electrons in reactions E. The least reactive of all known elements CHECKEXHIBIT

Alkali metals only have an oxidation state of +1. [A] is incorrect. Transition metals form brightly-colored compounds. [B] is incorrect. Alkali metals are not electronegative. [C] is incorrect. Noble gases are the least reactive elements. [E] is incorrect. Alkali metals are in Group 1 of the periodic table. They tend to donate their one valence electron in reactions to achieve a full outer shell. [D] is the answer. Topic:Periodic Trends

All of the following describe alpha decay EXCEPT one. Which one is the EXCEPTION? A. Likely for a large nuclei B. Reduces mass number C. Represented by 42He D. Species loses neutrons E. Species loses electrons CHECKEXHIBIT

Alpha decay occurs when a nucleus emits an alpha particle. Alpha particles are composed of 2 protons and 2 neutrons, making them the same as a He atom. Thus, you will often see alpha particles written as: 4He2 or 4 a 2 Because the atom's nucleus is giving away two protons and two neutrons, the atom's atomic number (number of protons) will decrease by two and its mass number (number of protons + neutrons) will decrease by four. The number of electrons of the species does not change in an alpha decay. From the answer choices, the only answer that does not describe alpha decay is choice [E]. Thus, [E] is the correct answer. Topic:Nuclear Reactions

What does an electrolytic cell require? A. Heat B. Pressure C. Light D. Power source E. Mixing CHECKEXHIBIT

An electrolytic cell has an endothermic chemical reaction. The reaction is not spontaneous so a power source is required. Energy is stored in an electrochemical cell. That energy can be released when the cell is allowed to run in a galvanic mode. All of the answers are not requirements of an electrolytic cell except a power source,

Which electron configuration represents an atom in an excited state? A. 1s22s22p5 B. 1s22s22p53s1 C. 1s22s22p63s1 D. 1s22s22p63s2 E. 1s22s22p63s23p1 Correct An electron is normally in its g

An electron is normally in its ground state, the lowest energy state available. We know that in the ground state, the atoms will go in the following order: 1s22s22p63s23p64s23d104p65s24d105p66s24f14 and so on... In an excited state, however, the atom's electrons are not all in the lowest possible energy level so they deviate from the order shown above. All of the answer choices follow this format except [B]. Thus, [B] is the correct answer. Topic:Atomic and Electronic Structure I have a question about this explanation I have feedback about this explanationWhich electron configuration represents an atom in an excited state? A. 1s22s22p5 B. 1s22s22p53s1 C. 1s22s22p63s1 D. 1s22s22p63s2 E. 1s22s22p63s23p1 Correct An electron is normally in its g

All of the following electron configurations are for an atom in its ground state EXCEPT one. Which one is the EXCEPTION? A. [Ar] 4s1 B. [Ar] 4s13d3 C. [Ar] 4s13d5 D. [Ar] 4s13d10 E. [Ar] 4s23d3 Incorrect

An electron is normally in its ground state, the lowest energy state available. We know that in the ground state, the atoms will go in the following order: 1s22s22p63s23p64s23d104p65s24d105p66s24f14 and so on... The question is asking for the exception, so we are looking for the atom that does not follow this format. We can automatically eliminate [A] and [E] because they follow the ground state format shown above. We are left with [B], [C], and [D]. Looking at the remaining answer choices carefully, notice that [C] and [D] are common exceptions in electron configuration. [C] is the electron configuration for chromium (Cr) and [D] is the electron configuration for Copper (Cu). This leaves us with [B] as the correct answer. Topic:Atomic and Electronic Structure

reverse transcriptase

An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis. RNA = temp DNA = synthesized

Pepsin

An enzyme present in gastric juice that begins the hydrolysis of proteins

endonuclease

An enzyme that cleaves its nucleic acid substrate at internal sites in the nucleotide sequence.

Which of the following is an immediate effect of increased blood pH? A. Increased formation of myoglobin B. Decreased formation of reduced hemoglobin C. Increased production of 2,3-BPG D. Decreased production of carbonic anhydrase E. Increased formation of carbaminohemoglobin

An increase in blood pH is a result of a decrease in the concentration of protons (H+). Thus, there will be fewer protons available to form reduced hemoglobin (H+Hb) Increased blood pH does not affect the formation of myoglobin, carbonic anhydrase, 2,3-BPG, or carbaminohemoglobin.

what are the rules for assigning oxidation numbers?

As a reminder, here are the rules for assigning oxidation number: The oxidation number of an atom in its elemental form is zero (e.g. N2, Ag). The oxidation number of a monatomic ion is equal to its charge (e.g. Ca2+ has an oxidation number of +2). The sum of oxidation numbers in a molecule or formula is zero. The sum of oxidation numbers in a polyatomic ion is equal to the charge of the ion. The oxidation number of Group IA is +1 in all of its compounds. Group IIA has an oxidation number of +2 in all of its compounds. Hydrogen has an oxidation number of +1 if combined with nonmetals and -1 if combined with a metal and boron. Fluorine has an oxidation number of -1 in all of its compounds. Oxygen has an oxidation number of -2 in all of its compounds except in peroxide (-1) and when combined with F (e.g. in OF2, because F has an oxidation number of -1 in all of its compounds, it follows that O has an oxidation number of +2). Halogens have an oxidation number of -1 if combined with metals, nonmetals (except O), and other halogens lower in the group.

At what point does the graph of 4x + 5y = 20 cross the y-axis? A. (2, 0) B. (4, 0) C. (0, 0) D. (0, 2) E. (0, 4) CHECKEXHIBIT

As the y-axis is located where x = 0**** whenever we plug in 0 for x, we can solve for the point where an equation would cross the y-axis. Plugging in 0 for x in the given equation, 4x + 5y = 20 4(0) + 5y = 20 5y = 20 y = 4 Thus, when x = 0, y = 4. Or the graph will cross the y-axis at (0, 4), making the correct answer [E].

Assign the correct IUPAC name for the following molecule including R/S designation(s) at any and all stereocenters:

At our left stereocenter Br is the highest priority group. The second highest priority group is the C on the right of the stereocenter (the other chiral carbon). Third is the methyl above the stereocenter, and last is the H on the wedge bond. Tracing from 1 to 2 to 3 leads us in a counterclockwise circle, making this stereocenter S originally, until we realize our H is on a wedge; therefore we switch the configuration to the opposite of what we found, making this stereocenter R. At the right stereocenter Br is the highest priority group. The second highest priority group is the C on the left of the stereocenter (the other chiral carbon). Third is the ethyl on the dash bond, and last is the H on the wedge bond. Tracing from 1 to 2 to 3 leads us in a clockwise circle, making this stereocenter R originally, until we realize our H is on a wedge; we then switch the configuration to the opposite of what we found, making this stereocenter S. To name this structure, we first number the longest carbon chain giving the carbons bound to substituents (the two Br's) the lowest numbers possible. Numbering from left to right satisfies this criterion and gives us a parent chain that is 5 carbons long (pentane). This numbering scheme puts our stereocenters at carbons 2 and 3; we put those numbers in parentheses followed immediately by the R/S configuration at that carbon. The parentheses come first, followed by the name of the substituents and parent chain in usual fashion: (2R,3S)-2,3-dibromopentane.

Which of the below elements has the largest atomic radius? A. Mg B. Al C. Si D. P E. S CHECKEXHIBIT

Atomic radius increases to the left and down the periodic table. Mg is the farthest to the left.

All of the following are the effects of an increase in atrial natriuretic peptide EXCEPT one. Which one is the EXCEPTION? A. Increase glomerular filtration rate B. Increase thirst C. Reduce blood volume D. Reduce blood pressure E. Decrease sodium reabsorption CHECKEXHIBIT

Atrial natriuretic peptide (ANP) is made by atrial cells in the heart. It is secreted in order to reduce blood volume and pressure in response to intense stretching of the atria. ANP also increases glomerular filtration rate and sodium excretion, decreases sodium reabsorption, and inhibits renin and the renin-angiotensin-aldosterone system.

All of the following are the effects of an increase in atrial natriuretic peptide EXCEPT one. Which one is the EXCEPTION? A. Increase glomerular filtration rate B. Increase thirst C. Reduce blood volume D. Reduce blood pressure E. Decrease sodium reabsorption CHECKEXHIBIT

Atrial natriuretic peptide (ANP) is made by atrial cells in the heart. It is secreted in order to reduce blood volume and pressure in response to intense stretching of the atria. ANP also increases glomerular filtration rate and sodium excretion, decreases sodium reabsorption, and inhibits renin and the renin-angiotensin-aldosterone system. ANP does not increase thirst, making Choice [B] the exception and the correct answer. Topic:Anatomy and Physiology

All the following are true about viruses EXCEPT one. Which one is the EXCEPTION? A. They can switch between lysogenic and lytic cycles B. They can pick up a phospholipid envelope from a host cell membrane C. They are involved in bacterial transformation D. They can exist as both DNA and RNA viruses E. Their coats are made up of capsomeres Correct

Bacterial transformation refers to the process by which bacterial cells take up extracellular DNA from their environment. Bacterial transduction, on the other hand, relies on viruses to transfer DNA between bacterial cells. We are looking for the exception, so Choice [C] is our correct answer. Choices [A], [B], [D], and [E] are true statements about viruses, so they are incorrect.

Heptane and toluene boil at 100 ºC and 110 ºC, respectively. Equimolar amounts of the two were mixed. At what temperature will the resulting solution boil? A. 100 ºC B. 105 ºC C. 110 ºC D. 115 ºC E. 120 ºC CHECKEXHIBIT

Boiling point is defined as the temperature at which the vapor pressure equals the atmospheric pressure. Since the vapor pressure of the solution is somewhere in between the vapor pressure of the pure liquids, we should expect the boiling point of the solution to be in between the boiling points of the pure liquids. Thus, [B] is the correct answer. Note: If equimolar amounts were not mixed (ie. more of one of the solutions) the boiling point of the solution will be closer to the boiling point of the component with the higher mole fraction.

Which diatomic species has the strongest bond? A. H2 B. N2 C. O2 D. F2 E. Cl2 CHECKEXHIBIT

Bond strength increases with increasing number of bonds: triple bonds are stronger than double bonds, which in turn are stronger than single bonds. To solve this question, figure out the number of bonds in each answer choice and determine which one has the greatest number of bonds. The bond in H2 is a single bond: H-H The bond in N2 is a triple bond: N≡N The bond in O2 is a double bond: O=O The bond in F2 is a single bond: F-F. The bond in Cl2 is a single bond: Cl-Cl. N2 has the greatest number of bonds, and thus, has the strongest bond.

data analysis strategy

By looking at the chart, it is easily seen that there are between 30-35 seniors on the team and between 10-15 juniors on the team. We cannot read the values directly off the graph, so we must analyze the statements that are given to us. Statement (1) tells us that the number of seniors on the team is divisible by 3. Since the number of players must be a whole integer and the only whole integer divisible by 3 in the 30-35 range is 33, we know that the number of seniors on the team must be 33; this means that statement (1) alone is sufficient. Statement (2) tells us that there are 3 times as many seniors on the team than juniors. This means that multiplying the number of juniors by 3 has to give us a whole integer number that falls between 30-35. The only number that does this is 11, since 11 x 3 = 33. Thus, statement (2) alone is sufficient. Since both statements (1) and (2) are sufficient by themselves, the correct answer is [D].

Which of the following is an example of a polysaccharide carbohydrate correctly paired with its function? A. Glucose; produces ATP in eukaryotic cellsB. Glycogen; stores energy in plant cellsC. Cellulose; provides structure for plant cellsD. Chitin; stores energy in animal cellsE. Starch; provides structure for arthropods

Cellulose is indeed a polysaccharide carbohydrate that provides structural support for walls of plant cells and wood. Choice [A] is incorrect because glucose is a monosaccharide, not a polysaccharide. However, it is true that one of the functions of glucose is to produce ATP in eukaryotic cells via the process of cellular respiration. All the other choices are incorrect because they match a polysaccharide to the incorrect function. Choice [B] is incorrect because glycogen functions to store energy in animal cells, not in plants cells. Starch is the polysaccharide that stores energy in plant cells. This helps eliminate choice [E]. Starch is not a structural molecule. Chitin is the molecule that provides structure for arthropods (and fungal cell walls). This helps eliminate choice [D]. Chitin is a structural molecule, it does not store energy.

Cholecystokinin

Cholecystokinin is a hormone released by the lining of the duodenum in the small intestine in response to the detection of proteins/fats. This leads to slowing of gastric emptying, initiating pancreatic enzyme release and stimulating the gallbladder to release bile. It does not trigger the production of intestinal mucus, which makes choice [C] the correct answer.

ll the following are roles and functions of cholesterol EXCEPT one. Which one is the EXCEPTION? A. Steroid precursor B. Membrane rigidity C. Bile acid precursor D. Vitamin D synthesis E. Glucose storage CHECKEXHIBIT

Cholesterol has four hydrocarbon rings, making it a great precursor molecule to steroids, bile acid, and vitamin D. Cholesterol is also amphipathic, allowing it to interact with the phospholipid bilayer and affect membrane rigidity. We are looking for the exception, so choice [E] is correct because cholesterol does not function in glucose storage.

All the following are roles and functions of cholesterol EXCEPT one. Which one is the EXCEPTION? A. Steroid precursor B. Membrane rigidity C. Bile acid precursor D. Vitamin D synthesis E. Glucose storage CHECKEXHIBIT

Cholesterol has four hydrocarbon rings, making it a great precursor molecule to steroids, bile acid, and vitamin D. Cholesterol is also amphipathic, allowing it to interact with the phospholipid bilayer and affect membrane rigidity. We are looking for the exception, so choice [E] is correct because cholesterol does not function in glucose storage. Choices [A], [B], [C], and [D] are incorrect. Topic:Molecules and Fundamentals of Biology

All of the following are a result of coevolution EXCEPT one. Which one is the EXCEPTION? A. Camouflage B. Aposematic coloration C. Batesian mimicry D. Mullarian mimicry E. Homoplasy CHECKEXHIBIT

Coevolution describes when two species impart selective pressures on each other and results in the evolution of both species. All the following except for homoplasy are results of coevolution. Choice [E] is the correct answer. Homoplasy, a.k.a. convergent evolution, describes when two distinct clades develop very similar characteristics despite not sharing any common ancestors. Camouflage allows animals to avoid visual detection by matching their appearance with the environment. Aposematic coloration (warning coloration) is a vibrant, bright coloration of poisonous animals that warns predators of their poison. Batesian mimicry occurs when a harmless animal mimics the coloring of a dangerous animal. Mullerian mimicry occurs when different poisonous species that share a common predator evolve to resemble each other so that it is easier for the predator to learn to avoid these species.

Cells regulate lipid content of their membrane in response to both external and internal changes. If temperature is reduced, a cell will respond by

Cold temperatures will cause cell membranes to become more rigid. The cell will respond to this by trying to make its membrane less rigid (or more fluid). This immediately eliminates answer choices [D] and [E]. Increasing membrane fluidity involves increasing the amount of unsaturated fatty acids. Remember, unsaturated fatty acid tails have double bonds which bend the structure of the tails. These 'bends' or 'kinks' prevent the molecules from packing closely together, making the entire membrane more fluid. Increasing the amount of unsaturated fatty acids will increase membrane fluidity. This eliminates answer choices [C]. Choice [B] is incorrect because saturated fatty acids will decrease the membrane fluidity, not increase it. Remember, saturated fatty acids do not have double bonds. This means that they do not have those 'bends' or 'kinks' (saturated is straight), which allow them to pack closely together and make the membrane more rigid. Increasing the amount of such molecules will decrease membrane fluidity. This leaves us with answer choice [A]. Key Takeaways: Unsaturated fatty acids cause more fluidity because of their bent structures. Saturated fatty acids do not have double bonds and are able to pack closely together, resulting in rigidity.

Which of the following is a key difference between prokaryotic transcription and eukaryotic transcription? A. Prokaryotes use RNA Polymerase; eukaryotes use DNA Polymerase B. Transcription occurs in the cytosol for prokaryotes; transcription occurs in the nucleus for eukaryotes C. Prokaryotic polymerases need specific transcription factors; eukaryotic polymerases can directly bind to DNA D. Prokaryotes uses rho-independent termination; eukaryotes uses rho-dependent termination E. Prokaryotes utilize a 5' cap; eukaryotes do not

Correct Prokaryotes lack a nucleus and other membrane-bound organelles, so they perform transcription in the cytosol. Eukaryotes perform transcription in the nucleus. Choice [B] is our correct answer. Choice [A] is incorrect because transcription always requires RNA polymerase. Choice [C] is incorrect because eukaryotic polymerases require specific transcription factors while prokaryotic polymerases can directly bind to DNA. Choice [D] is incorrect because only prokaryotes perform rho-independent and rho-dependent termination. Choice [E] is incorrect because eukaryotic mRNA undergoes processing and adds a 5' cap, not prokaryotic mRNA. Topic: Molecular GeneticsI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Which of the following solutes would decrease water's freezing point by the greatest amount, per mole of solute added? A. NaCl B. Ba(OH)2 C. Cl2 D. Al(NO3)3 E. Li2S CHECKEXHIBIT

Each solute will dissociate into a different number of ions when dissolved in water. Let's take a look at each solute: NaCl dissolves into two things: Na+ and Cl- Ba(OH)2 dissolves into three things: Ba2+ and 2 OH- Cl2 dissolves into two things: 2 Cl- Al(NO3)3 dissolves into four things: Al3+ and 3 NO3- Li2S dissolves into three things: 2 Li+ and S2- The formula for freezing point depression is: ΔTF = -(KF · m · i) Where ΔT is the temperature change, KF is the constant for the solution, m is the molality, and "i" is the van't Hoff factor. A higher van't Hoff factor has a directly proportional increased effect on temperature change, and thus, [D] must be the correct answer since it has the largest van't Hoff factor, which depresses the freezing point the most, giving us the lowest freezing point. Topic:Chemical Solutions

Which of the following was present in Earth's primordial atmosphere? A. Inorganic compounds B. Organic compounds C. Oxygen D. Condensed gases E. Polymers CHECKEXHIBIT

Earth's primordial atmosphere mostly consisted of inorganic compounds including methane (CH4), ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), hydrogen gas (H2), nitrogen gas (N2), water (H2O), hydrogen sulfide (HS). Choice [A] is correct. The rest of the answers are incorrect; no organic compounds, oxygen, condensed gases or polymers were found. Topic:Evolution

Which of the following will decrease the solubility of AgBr? Increasing pH Adding CuBr Decreasing the temperature A. I only B. III only C. I and II only D. II and III only E. I, II, and III CHECKEXHIBIT

Find the balanced chemical equation: AgBr (s) → Ag+ (aq) + Br- (aq) An increase in pH increases the basicity, increasing the concentration of OH- ions. AgOH forms a solid precipitate. This precipitate decreases the concentration of Ag+ ions, shifting the reaction right, and increasing the solubility of AgBr. I is incorrect. CuBr dissolves into Cu+ and Br- ions. Increasing the concentration of Br- shifts the equilibrium left, and decreasing the solubility of AgBr. II is correct. A decrease in temperature will decrease the solubility of AgBr. III is correct. [D] is the answer. Topic:Chemical Equilibria

What is the concentration of Fe2+ at equilibrium if the Ksp of FeS equals 6.0 x 10-19 in an aqueous solution of pure water?

Find the balanced chemical equation: FeS (s)àFe2+ (aq) + S2- (aq) Find the equilibrium expression: Ksp = [Fe2+][S2-] Solve: 6.0 x 10-19 = [Fe2+][S2-] 6.0 x 10-19 = x2 x = sqrt(6.0 x 10-19)

Diasteroisomers

First we check that the two compounds have the same chemical formula. In this case, both molecules have the chemical formula: C6H12O. We next ask whether they have the same connectivity or bonding pattern. The molecule on the left has a carbon bound to a hydroxyl group and the carbon immediately to its right is bound to a methyl substituent; this matches the connectivity of the right molecule. Now we move on to asking whether or not these molecules have different 3D shapes caused by chiral centers, cis/trans, or E/Z isomerism. The molecule on the left is in a cis configuration (as both substituents are coming up off the ring), but the molecule on the right is in a trans configuration (as one substituent is coming up off the ring and the other is going down)! Thus we move on to our last question: are these molecules non-superimposable mirror images of one another? If we draw the mirror-image of the molecule on the left, it would look like this: No amount of flipping will make this match up with the molecule on the right, meaning these molecules are not enantiomers and must be diastereomers. Topic:Stereochemistry I have a question about this explanation I have feedback about this explanation

what are constitutional isomers?

First we check that the two compounds have the same chemical formula. In this case, both molecules have the chemical formula: C6H12O. We next ask whether they have the same connectivity or bonding pattern. The molecule on the left has a carbon bound to a hydroxyl group and the carbon immediately to its right is bound to a methyl substituent. The molecule on the right also has a carbon bound to a hydroxyl group, however, the carbon immediately to its right is not bound to a methyl substituent. These represent differences in bonding patterns or connectivity, meaning these molecules are constitutional (or structural) isomers. * constitutional - think connectivity *

Are the following molecules isomers of each other? If so, what kind of isomers? A. Yes; diastereomers B. Yes; constitutional isomers C. No D. Yes; cis/trans isomers E. Yes; Enantiomers CHECKEXHIBIT

First we check that the two compounds have the same chemical formula. In this case, both molecules have the chemical formula: C6H12O. We next ask whether they have the same connectivity or bonding pattern. The molecule on the left has a carbon bound to a hydroxyl group and the carbon immediately to its right is bound to a methyl substituent. The molecule on the right also has a carbon bound to a hydroxyl group, however, the carbon immediately to its right is not bound to a methyl substituent. These represent differences in bonding patterns or connectivity, meaning these molecules are constitutional (or structural) isomers. Topic:Stereochemistry

recognizing diastereomer vs. enantiomer

First we check that the two compounds have the same chemical formula. In this case, both molecules have the chemical formula: C6H12O. We next ask whether they have the same connectivity or bonding pattern. The molecule on the left has a carbon bound to a hydroxyl group and the carbon immediately to its right is bound to a methyl substituent; this matches the connectivity of the right molecule. Now we move on to asking whether or not these molecules have different 3D shapes caused by chiral centers, cis/trans, or E/Z isomerism. The molecule on the left is in a cis configuration (as both substituents are coming up off the ring), but the molecule on the right is in a trans configuration (as one substituent is coming up off the ring and the other is going down)! Thus we move on to our last question: are these molecules non-superimposable mirror images of one another? If we draw the mirror-image of the molecule on the left, it would look like this:

Are the following molecules isomers of each other? If so, what kind of isomers?

First we check that the two compounds have the same chemical formula. In this case, both molecules have the chemical formula: C6H12O. We next ask whether they have the same connectivity or bonding pattern. The molecule on the left has a carbon bound to a hydroxyl group and the carbon immediately to its right is bound to a methyl substituent; this matches the connectivity of the right molecule. Now we move on to asking whether or not these molecules have different 3D shapes caused by chiral centers, cis/trans, or E/Z isomerism. The molecule on the left is in a cis configuration (as both substituents are coming up off the ring), but the molecule on the right is in a trans configuration (as one substituent is coming up off the ring and the other is going down)! Thus we move on to our last question: are these molecules non-superimposable mirror images of one another? If we draw the mirror-image of the molecule on the left, it would look like this: No amount of flipping will make this match up with the molecule on the right, meaning these molecules are not enantiomers and must be diastereomers.

If f(7x) = x2 + 15x - 16, then what is f(42) equal to?

First, as the equation is equal to f(7x), f(42) = f(7x), 42 = 7x, 6 = x Then, plugging in 6 for all the x's in the equation, f(42) = x2 + 15x - 16 f(42) = (6)2 + 15(6) - 16 f(42) = 36 + 90 - 16 = 110.

how to find whether the starting number should be left or right (naming organic compounds)

First, find the longest contiguous carbon chain; in this instance, the longest chain is 8 carbons long (octane) found by simply counting straight across the molecule. To find whether we should number starting from the left or the right, we compare the locations of the substituents and pick the lowest combination of numbers. From the left we have substituents at carbons 3, 5, and 6; from the right we get 3, 4, and 6. Thus, we number from the right. Putting our substituents in alphabetical order (remember the prefix "iso" is used in alphabetization while the prefix "di" is not) we get 3,6-diethyl-4-isopropyloctane. Topic: NomenclatureI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Below is the unbalanced chemical equation for the decomposition of Ni2O3. From left to right, what are the coefficients in the balanced chemical equation? __Ni2O3 → __Ni + __O2 A. 2, 4, 3 B. 2, 4, 8 C. 3, 2, 7 D. 3, 5, 8 E. 4, 6, 4 CHECKEXHIBIT

First, recognize that you will need a coefficient of 2 in front of the Ni2O3 to have an even number of oxygens necessary to balance the right side. That results in 4 Ni and 6 O on the left side. A coefficient of 4 in front of Ni and 3 in front of O2 on the right balance the equation. 2 Ni2O3 → 4 Ni + 3 O2

Which of the following is a flat bone? A. Skull B. Kneecap C. Pelvis D. Femur E. Vertebrae CHECKEXHIBIT

Flat bones are like Oreos in which the cortical bone acts as the hard outer structure and the cancellous bone act as the inside filling. Examples of flat bones include the sternum and the bones forming the skull. Choice [A] is correct. Choice B is incorrect; the kneecap is an example of sesamoid bones, bones that are embedded within tendons to increase muscle leverage and power. Choice C and E are incorrect; the pelvis and the vertebrae forming the spine are examples of irregular bones. Choice D is incorrect; the femur is an example of long bones.

Arrange the ions of these compounds according to their oxidation states from least to greatest. LiCl, CaCO3

Following the rules for oxidation number, we can determine the oxidation number of each ion: Li is found in Group IA of the periodic table, so it has a +1 oxidation number To counter the +1 oxidation number of Li, Cl must have a -1 oxidation number Ca is found in Group IIA of the periodic table, so it has a +2 oxidation number To counter the +2 oxidation number of Ca, CO3 must have a -2 oxidation number all together (this is also a common ion that you should remember) Arranging the oxidation numbers from least to greatest, we have: CO3, Cl, Li, Ca. Thus, [A] is the correct answer.

protonation vs deprotonation

For any amino acid: If the pH of the solution is LOWER than the pKa of the functional group, the functional group will be protonated. If the pH of the solution is HIGHER than the pKa of the functional group, the functional group will be deprotonated. Nitrogen is positively charged when protonated and neutral when deprotonated. Oxygen is neutral when protonated and negatively charged when deprotonated. Our amine, carboxylic acid, and R group all have a pKa value lower than the given pH of 13, thus we can expect all of them to be in their deprotonated forms. Thus, the amine will be deprotonated (-NH2), having a neutral charge. Both carboxylic acid groups will be deprotonated (-COO-). Choice [A] is the only form of aspartic acid where all three groups are deprotonated! Note: The deprotonated form of an amine has 3 total bonds and the protonated form has 4 bonds. Topic:Acids and Bases

A bird launches into flight from a point on the ground. After 4 seconds, the bird has flown 20 feet relative to its initial spot on the ground. If the bird can fly 4 feet per second horizontally, how fast can the bird fly vertically?

From this problem, we have to assume that the bird is flying diagonally upwards. With that being said, if the bird flies 4 ft/s horizontally, after 4 seconds the bird would have gone 16 feet. We can now use the Pythagorean theorem to solve how far the bird flies vertically. Using 20 as the hypotenuse, x^2 + 16^2 = 20^2 x^2 + 256 = 400 x^2 =144 x = 12 The bird traveled vertically 12 ft after 4 seconds. Since the question asks for the speed of the bird, 12 ft / 4 seconds would give us a speed of 3 ft/s, making the correct answer [B]. draw the shape -- use Pythag. theorem

Which term best describes the process of non-random migration? A. Natural selection B. Gene flow C. Genetic drift D. Founder effect E. Bottleneck effect

Gene flow is the process of moving alleles between populations through individual's migration. It best describes the process of non-random migration, as individuals choose where they migrate to. Choice [B] is the correct answer. Natural selection describes the non-random process of selection, or where alleles become more or less common as a result of the individual's interactions with the environment. On the other hand, genetic drift is the random increase or decrease of allele frequencies. Both do not describe non-random migration, so choices [A] and [C] are incorrect. Founder effect is a special type of genetic drift and states that when a group of emigrating individuals settle in a new location, these individuals would have a much smaller gene pool than their original population. The bottleneck effect is similar in that it describes an event that kills off most of the population, leaving behind a much smaller population and gene pool. Both do not describe non-random migration, so choices [D] and [E] are incorrect.

In what region of the chromosome does genetic recombination occurs?

Genetic recombination involves exchange of genetic material between sister chromatids of homologous chromosomes during synapsis. Physically, these regions of crossover are called chiasmata, so choice [A] is our correct answer. Choice [B] is incorrect because centromeres are chromosomal regions that link sister chromatids together. Choice [C] is incorrect because kinetochores are proteins that assemble at centromeres for spindle attachment during cell division. Choice [D] is incorrect because the synaptonemal complex is a group of proteins that temporarily forms between homologous chromosomes during synapsis. Choice [E] is incorrect because the centrosome is an organelle that assists with mitotic spindle formation. Topic:Cell Division I have a question about this explanation I have feedback about this explanation

If equal amounts of hydrogen and oxygen are placed in a porous container and are allowed to escape, which gas will escape faster and how much faster? A. Hydrogen, 3 times faster B. Hydrogen, 4 times faster C. Hydrogen, 7 times faster D. Oxygen, 3 times faster E. Oxygen, 7 times faster CHECKEXHIBIT

Graham's Law of Effusion states: r1/r2 = sqrt(M1/M2) The LOWER the molar mass, the HIGHER the rate of effusion. Hydrogen gas will escape at a rate 4 times greater than oxygen gas.

Among the following aqueous solutions, which represents the correct order of increasing osmotic pressure? 0.20 M NaCl 0.20 M CaCl2 0.20 M glucose A. I < II < III B. I < III < II C. II < I < III D. III < I < II E. III < II < I CHECKEXHIBIT

Here is the equation for osmotic pressure: ∏ = iMRT All of the aqueous solutions have the same concentration, so the only difference is the Van't Hoff Factor (i). The Van't Hoff Factor is equal to the number of ions the species can dissolve into. Let's look at the van't hoff factor (i) for each aqueous solution: NaCl -> Na+ and Cl-; the i of NaCl is 2 CaCl2 -> Ca2+ and 2Cl-; the i of CaCl2 is 3 glucose cannot dissolve further; the i of glucose is 1 Thus, [D] is the correct answer.

Diels-Alder Reaction requires:

Here our diene is on the right and our dienophile is on the left. In typical Diels-Alder fashion, the dienophile attacks the diene forming a six-membered ring with a double bond between the two interior carbons of the diene (as seen in answer [A] and [C]). Our new six-membered ring will have two methyl substituents on one side (one on each of the alkene carbons) and the five-membered ring structure on the other side, giving [A] as the correct answer.

epoxide addition to aklyne then opened in basic conditions...

Here we are opening an epoxide under basic conditions (notice that the addition of acid does not occur until the second step of the reaction; thus the attack and opening of the epoxide occurs under basic conditions). Our strong nucleophile (the alkyne organolithium) will attack the epoxide at the less substituted carbon. Therefore, the epoxide O should end up bound to a secondary carbon and should also not be bound to the same carbon as the alkyne. In the second step, acid is added to protonate the negatively charged oxygen. [D] is the only answer that fits these criteria. Topic:Alcohols Ethers Epoxides

epoxide: basic opening?

Here we are opening an epoxide with a strong nucleophile (CH3O-) under basic conditions. Our strong nucleophile wants to attack the least substituted of the epoxide carbons; thus our CH3O- attacks the primary carbon rather than the tertiary. The electrons from the previous bond between that primary carbon and the epoxide oxygen go out onto the oxygen, giving it a negative charge. In the last step, the negatively charged O grabs an H from the solvent, giving structure [A] as the final product.

A molecule that contains a ketone and an ester + NaBH4 in a methanol solvent.... we'd expect to see in products ??

Here we are reacting a molecule containing a ketone and an ester with the reducing agent NaBH4 in methanol solvent. NaBH4 and LiAlH4 are sources of H- and use those hydride ions to reduce carbonyls to alcohols; however, recall that NaBH4 can only reduce aldehydes or ketones. It is not strong enough to reduce esters, amides or carboxylic acids. Thus we would expect NaBH4 to reduce the ketone to a secondary alcohol, but leave the ester alone, as seen in [B].

Farmer John has an enclosure with an area of 400 square foot. The width of the rectangular enclosure is 9 feet greater than the length. What is the perimeter of the enclosure? A. 68 B. 72 C. 80 D. 82 E. 96 CHECKEXHIBIT

Here we can set up equations to quickly tackle this problem. Using the l = length, w = width, p = perimeter and a = area, we can create an equation for the area and for the perimeter. l*w = a 2l + 2w = p Substituting what the problem has given us, a = 400 and w = l + 9, we get: l * (l + 9) = 400 l2+ 9l = 400 l2 + 9l - 400 = 0 (l - 16)(l + 25) = 0 As we can see here l = -25 or l = 16. Since we can't have a negative value for length we will work with l = 16 ft, which makes w = 25 ft. Plugging that into the perimeter equation, 2(16) + 2(25) = p 82 = p We see that the perimeter would then be 82 ft, making our final answer [D]. FAQ: How do you know to get the factors -16 and 25? A: Remember to factor any equation, we need two numbers to add to the middle term and multiply to the last. For this problem we need 25 - 16 to get the term 9 and we need 25 * -16 to get the term -400. If you are struggling with thinking of coming up with these terms, you can always quickly jot down number for a factor tree. That way you can quickly see your possible factors, as well as factors which will have a difference of 9 to use for this problem.

what happens when you react a methyl ketone with I2 and -OH? what are these reagents

Here we react a methyl ketone with I2 and -OH. You should recognize these reagents as haloform reagents. In the first step the -OH deprotonates one of the three alpha hydrogens from the methyl group, creating an enolate intermediate. This enolate attacks and binds to an I from I2. These first two steps occur two more times each until you have formed this intermediate: Another -OH now attacks the carbonyl, forming a tetrahedral intermediate. Upon collapse of the intermediate and reformation of the carbonyl, CI3- is kicked off as the leaving group. The 3 I's help to stabilize the carbanion until it deprotonates the carboxylic acid to form a carboxylate. The negatively charged O of the carboxylate associates with the positively charged Na ion to form the products shown in [B]. Topic:Alpha Substitution Reactions of Carbonyls

Higher intermolecular forces leads to

Higher boiling point Higher heat of vaporization Higher viscosity Higher surface tension Lower vapor pressure

Which of the following processes breaks the peptide bonds within a protein? A. Hydrolysis B. Condensation C. Combustion D. Aminoacyltransferase E. Hydrogenation CHECKEXHIBIT

Hydrolysis reactions involve adding water to a covalent bond, splitting the covalent bond apart. Peptide bonds undergo this process when broken apart, so choice [A] is correct. Choice [B] is incorrect because condensation involves removing water to form a covalent bond. Choice [C] is incorrect because combustion describes the reaction of a hydrocarbon with oxygen to form carbon dioxide and water. Choice [D] is incorrect because aminoacyltransferase helps with peptide bond formation. Choice [E] is incorrect because hydrogenation typically describes the addition of hydrogen atoms to a molecule. Topic:Molecules and Fundamentals of Biology

Which of the following occurs as a result of hyperventilation? A. Alveolar acidosis B. Respiratory alkalosis C. Metabolic acidosis D. Thoracic alkalosis E. Cardiac acidosis CHECKEXHIBIT

Hyperventilation refers to when rapid breathing occurs, consequently depleting the amount of carbon dioxide in the blood. Because an abundance of carbon dioxide contributes to higher concentrations of [H+], the decrease of carbon dioxide will cause respiratory alkalosis. Choice [B] is correct. Choices [A], [C] and [E] can be eliminated because they are refer to acidosis, not alkalosis. Thoracic alkalosis is not an actual abnormal condition, nor does hyperventilation affect the thoracic region of the body. Choice [D] is incorrect.

If 42x+7 = 163x+2, then which of the following is equal to x? A. -2/3 B. -1/2 C. 2/3 D. 3/4 E. 2

If 42x+7 = 163x+2, then which of the following is equal to x? A. -2/3 B. -1/2 C. 2/3 D. 3/4 E. 2 Incorrect To tackle this problem, we first use the power rule of exponents to get equivalent bases. 42x+7 = 163x+2 42x+7 = (42)3x+2 42x+7 = 46x+4 Now that the bases are equivalent, we can set the exponent terms equal to each other and solve for x. 2x + 7 = 6x + 4 7 = 4x + 4 3 = 4x ¾ = x Thus, the answer to this problem would be [D]. Topic: AlgebraI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Ben can mow a lawn in 3 hours. If Ben and Jake can mow the lawn together in 2 hours, how long does it take for Jake to mow the lawn alone? A. 2 hours B. 3 hours C. 5 hours D. 6 hours E. 7 hours CHECKEXHIBIT

If Ben can mow 1 lawn in 3 hours then he can mow ⅓ of a lawn in 1 hour. In 2 hours, Ben would be able to mow ⅔ of a lawn. That means there would be ⅓ of a lawn for Jake to mow in 2 hours. If Jake mows ⅓ of a lawn in 2 hours, then Jake would take 6 hours to mow 1 lawn. Thus the answer would be [D].

Consider the following reaction: LiBr (aq) ⇌ Li+1 (aq) + Br-1 (aq) Which of the following would occur if NaBr were added to the mixture of LiBr? A. The amount of LiBr will stay the same B. The amount of Na+1 will increase C. The amount of Br-1 will increase D. The amount of Na+1 will decrease E. The amount of LiBr will increase

If NaBr were added, it would dissociate into its ions: NaBr (s) ⇌ Na+1 (aq) + Br-1 (aq) This would increase the concentration of Br- in this reaction: LiBr (aq) ⇌ Li+1 (aq) + Br-1 (aq) According to the common ion effect and Le Chatelier's Principle, the reaction would shift left to reestablish equilibrium. The amount of Li+ and Br- would both decrease, while LiBr would increase.

Tom can paint a wall in 6 hours, while Patrick can paint the same wall in 3 hours. If Tom paints the wall for 2 hours, how much time will it take for Patrick to finish painting the wall? A. 1 hour B. 1.5 hours C. 2 hours D. 2.5 hours E. 3 hours CHECKEXHIBIT

If Tom can paint the entire wall in 6 hours and he paints for 2 hours, he has painted ⅓ of the wall. This leaves ⅔ of the wall to be painted. If Patrick paints the entire wall in 3 hours, he paints ⅓ of the wall each hour. Since there are ⅔ of the wall remaining to be painted, it will take him 2 hours to paint the remainder. Topic:Applied Mathematics

All of the following taxonomic groups are eukaryotic EXCEPT one? Which one is the EXCEPTION? A. Archaea B. Protista C. Fungi D. Plantae E. Animalia CHECKEXHIBIT

If a taxonomic group is not eukaryotic, then it must be prokaryotic. There are two groups that are prokaryotic: eubacteria and archaea. Therefore the correct answer choice is [A]. The rest of the answer choices all are eukaryotic groups, or organisms whose cells contain membrane bound nuclei and organelles, and are incorrect. Protists are a kingdom of eukaryotic organisms that are not fungi, plants or animals, but include fungus-, plant-, and animal-like protists. Some examples of protists include dinoflagellates, diatoms, euglenoids, and protozoa. Fungi are heterotrophic saprophytes that feed on dead and decaying matter. Some examples of fungi include yeast and molds. Plantae or plants are autotrophic eukaryotes that conduct photosynthesis. Animalia or animals are diploid, multicellular eukaryotes that are heterotrophic aerobes; they cannot make their own food and depend on oxygen.

If an angle is six more than two times its supplement, what is the measure of this angle? A. 50 degrees B. 66 degrees C. 112 degrees D. 122 degrees E. 147 degrees CHECKEXHIBIT

If an angle is six more than two times its supplement, what is the measure of this angle? A. 50 degrees B. 66 degrees C. 112 degrees D. 122 degrees E. 147 degrees Incorrect Supplementary angles are angles that when added up, equal 180 degrees. We can set up a system of equations to solve for the supplements. X can represent the larger angle while y can represent the smaller of the two. x + y = 180 x = 2y + 6 Plugging in the second equation into the first will let us solve for y, we can then use the known y value to solve for x and answer the question. (2y + 6) + y = 180 3y = 174 y = 58 x + 58 = 180 x = 122 The angle which is 6 more than 2 times its supplement would thus, be 122 degrees. So the correct answer would be [B]. Topic: AlgebraI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

There are 34 students in anatomy class and 37 students in physics class. If there are 48 students in total, how many students are in both classes? A. 20 B. 21 C. 22 D. 23 E. 24 CHECKEXHIBIT

If none of the students were in the same class, there would be 37 + 34 = 71 total students. However, we are told that there are only 48 students in total, which means there must be some students that are included in both classes. We can find the number of students that are the same in both classes by subtracting the actual number of students from the number of students that we would expect if none of them were enrolled in both classes. 71 - 48 = 23 students who are enrolled in both classes. Option [D] is correct.

Alpha substitution reaction of carbonyls

If we could put a leaving group alpha to the carbonyl and then attack the alpha carbon with HN(CH3)2, we could displace the leaving group and form our desired product. We can replace alpha hydrogens with halogens (good leaving groups) one of two ways: acid or base-catalyzed alpha halogenation. Base-catalyzed alpha halogenation will replace all alpha hydrogens with a halogen. Acid-catalyzed alpha halogenation will only replace one alpha hydrogen with a halogen. We only want to place one halogen on our molecule as there are no excess halogens in our final product. The reagents in [D] react our molecule with Br2 and TFA (an acid), adding one Br in place of one alpha hydrogen. Next we attack the alpha carbon with HN(CH3)2, kicking off Br- and forming our desired product.

starting aldehyde with ? to make nitrogen containing product

If we could put a leaving group alpha to the carbonyl and then attack the alpha carbon with HN(CH3)2, we could displace the leaving group and form our desired product. We can replace alpha hydrogens with halogens (good leaving groups) one of two ways: acid or base-catalyzed alpha halogenation. Base-catalyzed alpha halogenation will replace all alpha hydrogens with a halogen. Acid-catalyzed alpha halogenation will only replace one alpha hydrogen with a halogen. We only want to place one halogen on our molecule as there are no excess halogens in our final product. The reagents in [D] react our molecule with Br2 and TFA (an acid), adding one Br in place of one alpha hydrogen. Next we attack the alpha carbon with HN(CH3)2, kicking off Br- and forming our desired product.

how to go from cyclohexanone to cyclohexene

If we could put a leaving group alpha to the carbonyl and then perform an elimination reaction removing an H and kicking off the leaving group, we could form our desired product. We can replace alpha hydrogens with halogens (good leaving groups) one of two ways: acid or base-catalyzed. Base-catalyzed alpha halogenation will replace all alpha hydrogens with a halogen. Acid-catalyzed alpha halogenation will only replace one alpha hydrogen with a halogen. We only want to place one halogen on our molecule as there are no excess halogens in our final product. The reagents in [B] react our molecule with Br2 and TFA (an acid), adding one Br in place of one alpha hydrogen. Next we treat our molecule with a strong base (EtO-), removing an H from the beta carbon, pushing electrons in to form the alkene, and kicking off the Br.

how to make an alkene on a ring with carbonyl

If we could put a leaving group alpha to the carbonyl and then perform an elimination reaction removing an H and kicking off the leaving group, we could form our desired product. We can replace alpha hydrogens with halogens (good leaving groups) one of two ways: acid or base-catalyzed. Base-catalyzed alpha halogenation will replace all alpha hydrogens with a halogen. Acid-catalyzed alpha halogenation will only replace one alpha hydrogen with a halogen. We only want to place one halogen on our molecule as there are no excess halogens in our final product. The reagents in [B] react our molecule with Br2 and TFA (an acid), adding one Br in place of one alpha hydrogen. Next we treat our molecule with a strong base (EtO-), removing an H from the beta carbon, pushing electrons in to form the alkene, and kicking off the Br. Topic:Alpha Substitution Reactions of Carbonyls

In the molecule below, how many Gauche interactions can be observed at the C2-C3 bond?

If we take the molecule given in the question and convert it to its Newman Projection, we should see the following: Whenever two substituents larger than hydrogen are adjacent to each other in a staggered conformation, they experience a Gauche interaction. Seeing as we have four methyl groups all adjacent to each other, we should observe three Gauche interactions.

David gives 20 of his marbles away to one of his friends, and gives ¼ of the remaining marbles to another friend. If he's left with 75 marbles at the end, how many marbles did he have initially? A. 100 B. 120 C. 140 D. 160 E. 180

If we work backwards we can quickly get the answer to this problem. David gives away ¼ of his marbles and is left with 75, thus, that would be ¾ of his previous amount of marbles. 75/3 = 25, so 25 is ¼, and he would have previously had 100 marbles. The first statement says he gives 20 marbles away and then is left with 100. That means he would originally have 120 marbles. The answer would then be

David gives 20 of his marbles away to one of his friends, and gives ¼ of the remaining marbles to another friend. If he's left with 75 marbles at the end, how many marbles did he have initially? A. 100 B. 120 C. 140 D. 160 E. 180 CHECKEXHIBIT

If we work backwards we can quickly get the answer to this problem. David gives away ¼ of his marbles and is left with 75, thus, that would be ¾ of his previous amount of marbles. 75/3 = 25, so 25 is ¼, and he would have previously had 100 marbles. The first statement says he gives 20 marbles away and then is left with 100. That means he would originally have 120 marbles. The answer would then be [B].

Find the empirical formula of a compound that is 36% carbon, 16% hydrogen, and 48% oxygen by mass. A. C2H12O2 B. C2H13O4 C. C2H15O3 D. C3H15O4 E. C3H16O3 CHECKEXHIBIT

If you have 100 g of the compound, there is 36 g C, 16 g H, and 48 g O. Convert each into moles. 36g C * 1 molC/12 g C) = 3 mol C 16 g H * 1 mol H/ 1 g H = 16 mol H 48 g O * (1 mol O/16 g O) = 3mol O That gives the molecular formula C3H16O3, which is also the empirical formula because it cannot be simplified

IgG antibodies

IgG antibodies are the most abundant antibodies found in circulation and can trigger opsonization. Choice [C] is incorrect. They are the only antibody that can cross the placenta to give the fetus passive immunity.

Which of the following correctly matches the cell cycle phase with its corresponding process? A. Prophase - genome replication B. Metaphase - chromosomes are pulled to the opposite, polar ends by spindle fibers C. Anaphase - chromosome numbers double D. Telophase - chromosomes line up at midpoint E. Interphase - chromatin condenses into chromosomes CHECKEXHIBIT

In anaphase of mitosis, sister chromatids are pulled apart and then considered to be individual chromosomes. Since each original chromosome has two sister chromatids, the chromosome number doubles during anaphase. Choice [C] is our correct answer. Choice [A] is incorrect because genome replication occurs during the S phase of interphase. Choice [B] is incorrect because chromosomes are pulled to opposite ends of the cell during anaphase. Choice [D] is incorrect because chromosomes line up at the midpoint of the cell during metaphase. Choice [E] is incorrect because chromatin condenses into chromosomes during prophase. Topic:Cell Division

Which statement best describes the overall steps of the Electron Transport Chain in animal cells?

In animal cells the electron transport chain (commonly referred to as the ETC) is instrumental in cellular respiration. During the ETC, the two energy carriers, NADH and FADH2, are oxidized. Their electrons are transferred to the cytochromes embedded in the intermembrane of the mitochondria. As the electrons "jump" along the ETC, hydrogen ions are pumped out of the matrix into the intermembrane space. As a result of the hydrogen ion gradient (an electrochemical gradient), the hydrogen ions move through the ATP synthase out of the intermembrane space back into the matrix, thereby making ATP for the cell. The only answer option that details this process accurately is [A]. Note: NADPH, is an energy carrier in photosynthesis. You can think that the "P" is for plants to help remember, but it is really for phosphorus.

The number of laptops sold in a given month is normally distributed with a mean of 1,200 laptops and a standard deviation of 200 laptops. For a random month, what is the probability that 1,600 or less laptops were sold? A. 50% B. 68% C. 84.5% D. 97.5% E. 99.7% CHECKEXHIBIT

In order to answer this question, we need to be familiar with the 68-95-99.7 rule of normal distributions. This rule is as follows: If a data set is normally distributed, 68% of the data lies within one standard deviation above and below the mean of the data set, 95% of the data lies between two standard deviations above and below the mean, and 99.7% of the data lies between three standard deviations above and below the mean. See the illustration below: Source: https://commons.wikimedia.org/wiki/File:Empirical_Rule.PNG We know the mean (µ) number of laptops sold is 1200 and we know the standard deviation (σ) of the laptops sold is 200. To find the probability that less than 1600 laptops were sold, we need to account for all the area under the curve left of the line that is at µ + 2σ. We know that 95% of the data lies within 2 standard deviations of the mean. However, we must also account for the area of the left tail of the distribution that lies further than µ - 2σ. Since the total area under the curve is 1, and there is only 5% unaccounted for, the area of this left tail must be 2.5%. We add this to the 95% to get a total of 97.5%.

According to a survey, the average number of textbooks a given student has is normally distributed with a mean of 5 and a standard deviation of 1. If a student is chosen at random, what is the probability that this student has more than 6 textbooks? A. 2.5% B. 5% C. 16% D. 32% E. 50%

In order to answer this question, we need to be familiar with the 68-95-99.7 rule of normal distributions. Recall that the mean is represented by µ and the standard deviation is represented by σ. This rule is as follows: If a data set is normally distributed, 68% of the data lies within one standard deviation above and below the mean of the data set (µ +/- σ), 95% of the data lies between two standard deviations above and below the mean (µ +/- 2σ), and 99.7% of the data lies between three standard deviations above and below the mean (µ +/- 3σ). Since there is a 68% chance of students having between 4 and 6 text books, there is a 32% of students having more than 6 textbooks or less than 4 textbooks. Due to the symmetry of the normal curve, we can say that 16% lies above 6 textbooks and 16% lies below 4 textbooks, therefore option [C] is the correct answer.

According to a survey, the average number of textbooks a given student has is normally distributed with a mean of 5 and a standard deviation of 1. If a student is chosen at random, what is the probability that this student has more than 6 textbooks? A. 2.5% B. 5% C. 16% D. 32% E. 50% CHECKEXHIBIT

In order to answer this question, we need to be familiar with the 68-95-99.7 rule of normal distributions. Recall that the mean is represented by µ and the standard deviation is represented by σ. This rule is as follows: If a data set is normally distributed, 68% of the data lies within one standard deviation above and below the mean of the data set (µ +/- σ), 95% of the data lies between two standard deviations above and below the mean (µ +/- 2σ), and 99.7% of the data lies between three standard deviations above and below the mean (µ +/- 3σ). Since there is a 68% chance of students having between 4 and 6 text books, there is a 32% of students having more than 6 textbooks or less than 4 textbooks. Due to the symmetry of the normal curve, we can say that 16% lies above 6 textbooks and 16% lies below 4 textbooks, therefore option [C] is the correct answer.

What is the rate law for the following reaction? A. Rate = k [CH3CH2CHBrCH3][OH-] B. Rate = k [CH3CH2CHBrCH3][OH-]2 C. Rate = k [OH-] D. Rate = k [CH3CH2CHBrCH3]2[OH-] E. Rate = k [CH3CH2CHBrCH3] CHECKEXHIBIT

In order to correctly predict the rate law for the reaction, we must determine whether this reaction will proceed via an SN1 or SN2 mechanism. First we ask, "Is the carbon bonded to the leaving group primary, secondary or tertiary?" It is secondary, meaning the reaction could go either SN1 or SN2. Next we ask, "Is our nucleophile strong or weak?" Because our nucleophile has a negative charge, we say it is strong and thus will not wait around for a carbocation to form; it will attack quickly in SN2 fashion. SN2 reactions have rate laws that include the concentration of both the electrophile and the nucleophile, eliminating answers [C] and [E]. There are no coefficients in the chemical formula of the reaction, so there should be no powers in our rate law, making [A] the correct answer.

Consider the pie chart below. There are 82 total employees in the company. How many employees work in operations? There are seven times as many employees who work in sales as operations There are 36 total employees who work in operations and manufacturing A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statement (1) and (2) TOGETHER are NOT sufficient. CHECKEXHIBITIncorrect

Incorrect In order to solve this problem, we need information about at least three of the values on the pie chart. Since this is the case, we can immediately disregard answer choices [A], [B], and [D]. Now all we must do is determine if the two statements together give us enough information. Statement (2) lets us know that there are 36 employees that work in operations and manufacturing. Let w = sales, x = marketing, y = manufacturing, and z = operations. Writing an expression for statement (2) gives us: y + z = 36 Statement (1) tells us that there are 7 times as many employees working in sales than operations. Writing an expression for statement (1) gives us: z = 7w We are able to write 2 equations, but the system of equations has 3 variables, which means we are unable to solve for any of the variables. Thus, the correct answer is [E]: Statement (1) and (2) TOGETHER are NOT sufficient.

for real values of x QA: 4x^3 + 16x^2 + 24x/ x^2 + 4x + 6 QB: 4x - 1

Incorrect We need to simplify quantity A so that we can more easily compare it to quantity B. Since every term in the numerator contains an x, we can factor an x out of the polynomial. Since every term in the numerator is also divisible by 4, we can also factor out a 4. Since both the numerator and the denominator contain the exact same term, their value is equal to 1. We are left with: By comparing this simplified expression to quantity B, we can see that quantity B will always be 1 less than quantity A. This means that quantity A will always be greater than quantity B. Choice [A] is the correct answer.

A mouse is shocked with an extremely bright light. Afterwards, the mouse is fearful of entering bright areas of a room. Which of the following best describes this behavior? A. Insight B. Reflex C. Habituation D. Instinct E. Sensitization CHECKEXHIBIT

Insight is a form of associative learning. It involves learning in a new situation where no reinforcement is required. The mouse associates bright light with pain, making it fearful of new, bright, areas. [A] is the answer. A reflex is an involuntary response to a stimulus. [B] is incorrect. In habituation, behavioral response decreases from repetitive meaningless stimulus. [C] is incorrect. Instincts are innate behaviors without thought, like bird migration. [D] is incorrect. In sensitization, as stimulus occurs more often, behavioral response increases. [E] is incorrect. Topic:Animal Behavior

hich of the following is isoelectronic with Ne? A. O- B. F- C. Na- D. Ca2+ E. Cr2+ CHECKEXHIBIT

Isoelectric series are groups of elements with the same number of electrons. F has 9 electrons, and F-, an ion with an additional negative charge, has 10 electrons, the same as Ne. [B] is the answer. Topic:Periodic Trends

sprio compounds named

LOW - HIFirst, we find our parent chain name by counting the total number of carbons in the molecule (in this case the total number is ten so our parent chain will be decane). Next, we count the number of carbons on each side of the spiro carbon (the carbon where the two rings intersect). This molecule has 5 carbons on the left of the spiro carbon and 4 on the right. We then place the numbers of carbons from LOWEST TO HIGHEST inside the brackets, separated by a period. Lastly, add the prefix "spiro" before the brackets and the parent chain name after the brackets to get the final answer. Topic:Nomenclature

AWESOME! x and y are two distinct positive integers and their product is equal to 16. What is the value of y? y is greater than x y is an even integer A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statement (1) and (2) TOGETHER are NOT sufficient. CHECKEXHIBIT

Let us begin by factoring 16 to find the possible values of x and y. These factors are 1, 2, 4, 8, and 16. Since x and y must be distinct, we can eliminate 4 from this list, since it must be multiplied by itself to equal 16. We are left with 1, 2, 8, and 16 as possible values of x and y. Statement (1) tells us that y is greater than x. This means that y must be either 8 or 16 (2 x 8 = 16 and 1 x 16 = 16). Since we are left with two possible values of y and we are not given more information, statement (1) by itself is not sufficient. Statement (2) tells us that y is an even integer. All the possible values of y are already even, so this information does not help us. This means that statement (2) by itself is insufficient. Since statement (1) by itself is insufficient and statement (2) tells us no new information, the correct answer is [E]; Statement (1) and (2) TOGETHER are NOT sufficient. Topic:Data Analysis, Interpretation, and Sufficiency

The even numbers on a regular die are painted yellow. On a second regular die, the numbers that are three less than a perfect square are painted yellow. If both dice are thrown, what is the chance that both come up yellow? A. 1/12 B. 1/6 C. 1/4 D. 1/3 E. 1/2 CHECKEXHIBIT

Let us first determine the probability of coming up yellow for each individual die. On the first die, all the even numbers are painted yellow. Since a regular die has the numbers 1-6, three of the sides will be painted yellow, since 2,4, and 6 are even numbers. Rolling this single die would give us a chance of 3/6 or ½ of coming up yellow. On the second die, the numbers that are three less than a perfect square are painted yellow. Recall that a perfect square is any number that has a square root that is a whole integer. We can easily find the lowest of these by squaring numbers, starting at 1. 12 = 1 22 = 4 32 = 9 We now need to consider values that are three less than these numbers that might appear on a die. 1 - 3 = -2 4 - 3 = 1 9 - 3 = 6 Only 2 of these values (1 and 6) appear on a standard die. Thus, the probability of rolling a yellow on the second die is 2/6, or ⅓. Since we now have the probabilities of rolling a yellow for each individual die, we can multiply the probabilities together to find the probability of both dice coming up yellow. 1/2 * 1/3 = 1/6 Option [B] is the correct answer.

for X > 0 and X < 145 QA: 1 quarter of 75 percent of x QB: three quarters of 20 percent of x

Let us first rewrite the quantities given to us as mathematical expressions. Quantity A (0.25)(0.75)(x) Quantity B (0.75)(0.20)(x) We can easily see that both expressions have the terms (0.75) and (x) in common. This allows us to disregard these terms, leaving us with: Quantity A (0.25) Quantity B (0.20) Since 0.25 is greater than 0.20, quantity A is greater than quantity B; choice [A] is the correct answer. Topic:Quantitative Comparison

y = 3x + 5 / 24 QA: 8y-1 QB: x

Let's solve the given equation for x, so that we can easily compare quantity B to quantity A. Regardless of whether y is a positive or negative value, quantity B will always subtract 5/3 (1.66) from 8y while quantity A will only subtract 1, meaning that quantity A will always be greater than quantity B. Option [A] is the correct answer. Because Quantity A is greater than quantity B, the correct answer is [A].

All of the following species are members of the phylum mollusca EXCEPT one. Which one is the EXCEPTION? A. Clam B. Squid C. Octopus D. Snail E. Lobster

Lobsters are crustacea in the phylum arthropoda. [E] is the answer. The phylum mollusca includes clams, snails, slugs, squids, octopi, cephalopods, and gastropods. Answer choices [A], [B], [C], and [D] are incorrect.

What best describes the following reaction? 235U → 141Ba + 92Kr + energy

Looking at the reaction, we can see that it involves a single reactant breaking into two products in addition to energy. This is known as a nuclear decay reaction, also known as nuclear fission. Thus, [A] is the correct answer. Let's take a look at why the other answers are incorrect: A nuclear capture reaction, otherwise known as nuclear fusion, involves the combining of two or more reactants to make a single product and energy. There is only one reactant in the above reaction so we can eliminate choice [B]. Beta decay converts a neutron to a proton and emits an electron. The atomic number increases (1 more proton) but atomic mass stays the same. This has nothing to do with the above reaction so choice [C] is incorrect. In an electron capture reaction, the inner shell electron is drawn into the nucleus and combines with a proton, forming a neutron. The mass number stays the same whereas the atomic number decreases by 1 (like positron emission). This is not shown in the above reaction so we can also eliminate choice [D]. In a gamma decay reaction, a nucleus in an excited state releases a photon. This does not change atomic mass or atomic number, but takes the nucleus from a high energy state to a low energy state. The above reaction has nothing to do with gamma decay. Therefore, we can eliminate choice [E] and conclude that [A] is the correct answer.

What best describes the following reaction? 235U → 141Ba + 92Kr + energy A. Fission B. Fusion C. Beta decay D. Electron capture E. Gamma decay CHECKEXHIBIT

Looking at the reaction, we can see that it involves a single reactant breaking into two products in addition to energy. This is known as a nuclear decay reaction, also known as nuclear fission. Thus, [A] is the correct answer. Let's take a look at why the other answers are incorrect: A nuclear capture reaction, otherwise known as nuclear fusion, involves the combining of two or more reactants to make a single product and energy. There is only one reactant in the above reaction so we can eliminate choice [B]. Beta decay converts a neutron to a proton and emits an electron. The atomic number increases (1 more proton) but atomic mass stays the same. This has nothing to do with the above reaction so choice [C] is incorrect. In an electron capture reaction, the inner shell electron is drawn into the nucleus and combines with a proton, forming a neutron. The mass number stays the same whereas the atomic number decreases by 1 (like positron emission). This is not shown in the above reaction so we can also eliminate choice [D]. In a gamma decay reaction, a nucleus in an excited state releases a photon. This does not change atomic mass or atomic number, but takes the nucleus from a high energy state to a low energy state. The above reaction has nothing to do with gamma decay. Therefore, we can eliminate choice [E] and conclude that [A] is the correct answer. Topic:Nuclear Reactions

All of the following statements about low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs) are correct EXCEPT ONE. Which one is the EXCEPTION? A. LDLs have low protein density while HDLs have high protein density B. LDLs decrease glucose breakdown while HDLs increase glucose breakdown C. LDLs are considered unhealthy while HDLs are considered healthy D. LDLs deliver cholesterol to tissues while HDLs deliver cholesterol to the liver E. LDLs are not involved in bile production while HDLs stimulate bile production CHECKEXHIBIT

Low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs) are responsible for transporting hydrophobic fat molecules around the body. They have no role in regulating glucose breakdown, so choice [B] is the exception and thus the correct answer. This problem can also be done through a process-of-elimination. LDLs have a low density of proteins and HDLs have a high density of proteins. Choice [A] is true and can be eliminated. LDLs are considered unhealthy because they deliver cholesterol to peripheral tissues through the bloodstream, which can cause clogged blood vessels and lead to serious medical risks such as heart attacks. On the other hand, HDLs are considered healthy because they take cholesterol away from the peripheral tissues and deliver it to the liver, where it is used to make bile. Therefore choices [C], [D]. and [E] can all be eliminated. Topic:Cellular Energy I have a question about this explanation I have feedback about this explanation

All of the following is found within a cell membrane EXCEPT for one. Which one is the EXCEPTION? A. Phospholipids B. Cholesterol C. Proteins D. Lumen E. Glycolipids CHECKEXHIBIT

Lumen in biology refers to the "inside space" of a referenced structure, such as the thylakoid lumen within the thylakoids of chloroplasts. Since lumen will not be found in a cell membrane and we are looking for the exception, choice [D] is correct. Choice [A] is incorrect because phospholipids make up the phospholipid bilayer of cell membranes. Choice [B] is incorrect because cholesterol is present in the cell membrane to affect membrane rigidity. Choice [C] is incorrect because membrane proteins are found dispersed throughout the cell membrane. Choice [E] is incorrect because glycolipids are found in all eukaryotic cellular membranes, extending into the extracellular environment. Topic:Cells and Organelles

What cell type in the epidermis mediates light touch sensation? A. Corneocytes B. Keratinocytes C. Langerhans cells D. Merkel cells E. Melanocytes CHECKEXHIBIT

Merkel cells, housed in the stratum basale, are specialized mechanoreceptors cells that can respond to light touch sensations (which makes them extremely abundant in fingertips). Choice [D] is correct. Corneocytes, found in the stratum corneum (most superficial epidermal layer), are basically dead, fully differentiated keratinocytes that provide protection against infection, dehydration and physical harm. It is not involved in touch sensation; choice [A] is incorrect. Keratinocytes are the main cells of the epidermis that divide and differentiate as they migrate from the deeper to more superficial layers. They do not mediate light touch sensation, so Choice [B] is incorrect. Langerhan cells, contained mostly in the stratum spinosum, are the dendritic cells of the epidermis and are important in the communication between the innate and adaptive immune systems. They are not involved in mediating light touch sensation; Choice [C] is incorrect. Melanocytes, housed in the stratum basale, produce melanin that is responsible for pigmentation and protection from UV radiation. It is not involved in touch sensation; Choice [E] is incorrect.

What is the main purpose of having MHC I on cells? A. To assist with phagocytosis B. To distinguish self from foreign cells C. To stimulate histamine release D. To act as an immunosuppressant E. To induce immune memory activation CHECKEXHIBIT

Our immune system distinguishes between self and non-self cells through the major histocompatibility complex (MHC) found on the surface of cells. Every nucleated body cells bear MHC I molecules on their cell surface, and every genetically-unique individual will have their own unique set of uniform MHC I molecules. Choice [B] is the correct answer. Choice [A] is incorrect; the complement system assists with phagocytosis, not MHC I. Choice [C] is incorrect; MHC I cannot stimulate histamine release. Antibodies and the inflammatory response can stimulate basophils and mast cells to release histamine. Choice [D] is incorrect; MHC I is not an immunosuppressant. Choice [E] is incorrect; immune memory activation is a key feature of memory B cells and memory T cells, not MHC I. They activate as a quick and effective immune response when encountering pathogens that have invaded before.

what reagents would you use to transform an alkyl halide to have an alcohol group in place of halide?

Our starting material is an alkyl halide so our first reagent must be one that reacts with alkyl halides. Choices [A] and [D] are both reagents that react exclusively with alkenes and alkynes; they will not work as our first steps and are incorrect answer choices. We are now left with Choices [B], [C] and [E]. Choice [C] uses aqueous acid as the first step. This could substitute the Br for an OH, however, the second step of oxymercuration will not react with an alcohol. Choice [C] is not the correct answer. With Choices [B] and [E] left, both have strong base as the first step which react with alkyl halides to create alkenes via elimination. Choice [E] reacts the resulting alkene with BH3, H2O2/NaOH as the second step, creating the less substituted alcohol. Choice [B] reacts the resulting alkene with Hg(OAc)2/H2O, NaBH4 as the second step, creating the more substituted alcohol. Choice [B] gives us the correct answer; the question shows the more substituted alcohol as the final product.

From where is oxytocin released? A. Thyroid gland B. Parathyroid C. Hypothalamus D. Anterior pituitary E. Posterior pituitary CHECKEXHIBIT

Oxytocin is produced by the hypothalamus and released by the posterior pituitary gland. Choice [E] is the correct answer and Choice [C] is eliminated. Choices [A] and [B] are incorrect; The thyroid gland creates and secretes 3 hormones: T3, T4 (T3 and T4 increases basal metabolism), and calcitonin (decreases blood calcium levels) while the parathyroid gland secretes parathyroid hormone (PTH - increases blood calcium levels). Choice [D] is incorrect; the anterior pituitary gland releases several hormones that are either tropic or direct. Hormones it produces can be remembered with the acronym FLAT PiG. "FLAT" hormones are tropic hormones, while "PiG" hormones are direct hormones. Tropic hormones (target/act on other endocrine glands) F - Follicle Stimulating Hormone (FSH) L - Luteinizing Hromone (LH) A - Adrenocorticotropic Hormone (ACTH) T - Thyroid Stimulating Hormone (TSH) Direct hormones (stimulate other organs directly) P - Prolactin i - ignore! G - Growth Hormone (GH)

Real Gas Equation Corrections

P+(n^2*a/V)(V-nb)=nRT when a and b are zero, it is the ideal gas law. a represent attractive forces and b represents size of particle). - an2/V2 Corrects for Intermolecular forces - nb corrects for repulsions (volume)

Which of the following is the most direct effect of removing peripheral chemoreceptors? A. Unregulated breathing B. Weakened blood brain barrier C. Increased heart rate D. Lowered blood oxygen concentration E. Decreased blood proton levels CHECKEXHIBIT

Peripheral chemoreceptors are located in 'bodies' that surround the aortic arch and carotid arteries, and detect changes in the concentration of oxygen, carbon dioxide, and protons in arterial blood. Based upon the detected concentrations, they send signals back to the medulla oblongata to regulate breathing. Thus, if peripheral chemoreceptors were removed we would have unregulated breathing. Choice [A] is correct. Choice [B] is incorrect; peripheral chemoreceptors are not protected by the blood brain barrier, thus removing them will not affect the blood brain barrier. (Mnemonic: peripheral chemoreceptors are in the peripheral nervous system). While unregulated breathing may lower blood oxygen concentration and decrease proton levels temporarily, it is not the most direct effect of removing peripheral chemoreceptors, as unregulated breathing may also lead to higher blood oxygen concentrations or higher proton levels. Choices [D] and [E] are incorrect. Removing peripheral chemoreceptors will not affect heart rate. Choice [C] is incorrect.

All of the following are shared characteristics between phospholipids and glycolipids EXCEPT for one. Which of the following is the EXCEPTION? A. Fatty acid chainsB. Carbohydrate groupC. Polar head groupD. Amphipathic propertiesE. Commonly found in the cellular membrane

Phospholipids and glycolipids are very similar except for the one major difference in that phospholipids contain a phosphate group (which the R group is attached to) while glycolipids contain a carbohydrate group. Remember that "glyco-" stands for sugar, which is a carbohydrate. This will help you remember that glycolipids contain carbohydrate groups, rather than phosphate groups. Therefore the correct answer is answer choice [B]. Both phospholipids and glycolipids contain hydrophobic tails (non-polar fatty acid chains) and hydrophilic heads (polar head groups), which give them amphipathic properties. This eliminates choices [A], [C], and [D]. Their amphipathic properties are the biggest reason why both phospholipids and glycolipids are commonly found in plasma membranes. Phospholipids make up the phospholipid bilayer that we commonly associate with plasma membranes. Glycolipids are embedded in the plasma membrane and mainly serve as recognition sites for cell-cell interactions. This eliminates choice [E]. Key Takeaways: 'Glyco' indicates a carbohydrate group and 'phospho' indicates a phosphate group. Plasma membranes are phospholipid bilayers.

CAM plants prevent photorespiration through which of the following phenomena? A. Spatial isolation B. Behavioral isolation C. Temporal isolation D. Chemical isolation E. Mechanical isolation CHECKEXHIBIT

Photorespiration occurs when the enzyme RuBisCo binds to oxygen instead of carbon dioxide and causes the cell to perform oxygen fixation, which wastes the cell's resources. CAM plants can prevent photorespiration from happening through timing, or temporal isolation. Answer choice [C] is correct. During the day CAM plants close their stomata to prevent transpiration and gases from entering the leaf (thus preventing photorespiration from occurring). At night they open their stomata to convert carbon dioxide to malate to be stored for future use. In contrast, C4 plants use spatial isolation to prevent photorespiration; the carbon dioxide is sent to a different location where oxygen cannot compete with it for RuBisCO. Choice [A] is incorrect. The rest of the answer choices are all evolutionary isolation mechanisms used in species to identify proper mates within their own species and are not involved in restricting photorespiration. Behavioral isolation is an evolutionary mechanism that helps members of the same species find suitable mates through mating rituals or other behaviors. Chemical isolation involves having chemical barriers that prevent gametes fertilized by other species from forming. Mechanical isolation is where male and female genitalia are not compatible between two different species. Choices [B], [D], and [E] can all be eliminated. Topic:Photosynthesis

In which area of the leaf does most photosynthesis occur? A. Stomata B. Cuticle C. Epidermis D. Palisade mesophyll E. Spongy mesophyll CHECKEXHIBIT

Photosynthesis is the process in which solar energy is converted to chemical energy. Both stages of photosynthesis occur in a plant's chloroplasts. Inside a leaf, the palisade mesophyll cells contain the most chloroplasts and conduct the most photosynthesis; thus the correct answer is [D]. While the spongy mesophyll cells does conduct some photosynthesis, they have fewer chloroplasts and do not receive as much light because they are found at the bottom of a leaf. Towards the bottom of the leaf, stomata can also be found. They are pores that function as the site of atmospheric gas exchange, not photosynthesis. Therefore Choice [A] and [E] are incorrect. Choice [C] is incorrect because epidermis tissue surrounds roots, stems, leaves, flowers, fruits and seeds and serves as protection from the outside environment. No photosynthesis is done at the epidermis. Finally, answer choice [B] can be eliminated because the cuticle is the waxy layer that covers a leaf to reduce water loss and is not a site of photosynthesis.

what makes the greatest resonance contributer?

Pictured below is the correct resonance structure for the molecule posed in the question: The lone pair on the carbon attacks the carbon of the carbonyl; this causes the oxygen originally giving one of its lone pairs to carbon, to take it back. As this oxygen takes back its lone pair, it now has three lone pairs! Oxygen with 1 bond and 3 lone pairs acquires a negative charge. This matches Choice [C]. The best way to sniff out incorrect resonance structures is to pay attention to: Charge! Resonance structures must all maintain the same overall formal charge. Atoms must maintain their proper formal charge. Octet! Atoms cannot have more than 4 bonds. Structure! Molecular formula and location of the atoms must be constant between resonance structures. If either change, you no longer have the same molecule and this cannot be a valid resonance structure. Choice [A] is incorrect as Oxygen with 1 bond and 3 lone pairs should have a -1 charge, not a +1 charge. The overall charge of the molecule is +1; this does not match the original molecule which has an overall formal charge of -1. Choice [B] is incorrect as the center carbon has violated the octet rule. Carbon can only have 4 bonds, not 5! Choice [D] is incorrect as the molecule has an overall formal charge of -2. Since the overall charge of the molecule is -2; this does not match the original molecule which has an overall formal charge of -1. Topic:Bonding and Molecular Geometry

Which of the following is a pluripotent stem cell? A. Zygote B. Blastomere of the morula C. Inner cell mass cells D. Hematopoietic cell E. Spore CHECKEXHIBIT

Pluripotent stem cells are stem cells that can differentiate into any of the three germ layers and give rise to any cell type, but can't develop extraembryonic tissue. An example of a pluripotent stem cell are inner cell mass cells. Choice [C] is the correct answer. A zygote and the blastomere of the morula are examples of totipotent cells, single cells that has the potential to become an entire organism. Choices [A] and [B] are incorrect. A hematopoietic cell (divides into many different types of blood cells) is an example of a multipotent cell, a cell that can give rise to only some of the three germ layers. Choice [D] is incorrect. Finally a spore is a reproductive cell used in many plants, algae, fungi and protozoa. They are not stem cells and therefore choice [E] is incorrect.

Which of the following is a key difference between prokaryotic transcription and eukaryotic transcription? A. Prokaryotes use RNA Polymerase; eukaryotes use DNA Polymerase B. Transcription occurs in the cytosol for prokaryotes; transcription occurs in the nucleus for eukaryotes C. Prokaryotic polymerases need specific transcription factors; eukaryotic polymerases can directly bind to DNA D. Prokaryotes uses rho-independent termination; eukaryotes uses rho-dependent termination E. Prokaryotes utilize a 5' cap; eukaryotes do not CHECKEXHIBIT

Prokaryotes lack a nucleus and other membrane-bound organelles, so they perform transcription in the cytosol. Eukaryotes perform transcription in the nucleus. Choice [B] is our correct answer. Choice [A] is incorrect because transcription always requires RNA polymerase. Choice [C] is incorrect because eukaryotic polymerases require specific transcription factors while prokaryotic polymerases can directly bind to DNA. Choice [D] is incorrect because only prokaryotes perform rho-independent and rho-dependent termination. Choice [E] is incorrect because eukaryotic mRNA undergoes processing and adds a 5' cap, not prokaryotic mRNA.

Which of the red-colored hydrogen atoms below is most acidic? A. Proton A B. Proton B C. Proton C D. Proton D E. All protons have equal acidity Incorrect Proton A looks like it is bonded to a carbon that is sp3-hybridized but the conjugate base is actually sp2-hybridized in addition to being aromatic and stabilized by resonance. None of the other molecules have a resonance-stabilized, aromatic conjugate base so they are all less acidic. Topic: Acids and BasesI have a question about this explanationI have feedback about this explanation Which of the red-colored hydrogen atoms below is most acidic? A. Proton A B. Proton B C. Proton C D. Proton D E. All protons have equal acidity Incorrect

Proton A looks like it is bonded to a carbon that is sp3-hybridized but the conjugate base is actually sp2-hybridized in addition to being aromatic and stabilized by resonance. None of the other molecules have a resonance-stabilized, aromatic conjugate base so they are all less acidic. Topic: Acids and BasesI have a question about this explanationI have feedback about this explanation

All of the following are characteristics of RNA EXCEPT one. Which one is the EXCEPTION? A. Contains uracilB. Less stable than DNAC. Contains phosphodiester bondsD. Usually forms a double helixE. Contains ribose sugar

RNA and DNA are similar in that they are both polymers of nucleotides. Nucleotides in both RNA and DNA are connected by phosphodiester bonds.This eliminates choice [C].Now for the differences.RNA contains uracil instead of thymine, which is found in DNA. This eliminates choice [A].RNA is composed of nucleotides that contain ribose sugar, which contains an extra hydroxyl group at the 2' carbon. DNA is composed of deoxyribose sugar, which does not contain the 2' hydroxyl group. The extra hydroxyl group in the ribose sugar makes RNA less stable than DNA because RNA is more likely to participate in chemical reactions.This eliminates choices [B] and [E].Lastly, RNA is usually single stranded and therefore does not normally exist in a double helix structure. The double helix is characteristic of DNA.

Which of the following is the best definition of a boiling point? A. The temperature at which the vapor pressure of the liquid equals one atmosphere of pressure. B. The temperature at which the liquid vaporizes. C. The temperature at which the surrounding pressure becomes greater than the vapor pressure of the liquid. D. The temperature at which the vapor pressure of the liquid equals the surrounding pressure. E. The pressure at which a liquid can no longer vaporize. CHECKEXHIBIT

Recall that a liquid boils when the pressure exerted by the liquid molecules toward the atmosphere (called the liquid's vapor pressure) equals or exceeds the pressure exerted by the atmosphere pressing down upon the liquid. Topic:IM Forces and Lab Techniques

orgo KMnO4, H20 + benzene = ? product

Recall that as long as the benzyl carbon has at least one bond to H, then treatment with KMnO4, H2O will yield benzoic acid as the product, regardless of the identity of the rest of the alkyl substituent. What makes this reaction unique is the presence of two benzyl carbons, both of which have at least one bond to H. Thus we convert each benzyl carbon into a -COOH and neglect the rest of the alkyl chain, forming product

One aromatic ring attached to another ring reacts with KMNO4 + H20 to make...?

Recall that as long as the benzyl carbon has at least one bond to H, then treatment with KMnO4, H2O will yield benzoic acid as the product, regardless of the identity of the rest of the alkyl substituent. What makes this reaction unique is the presence of two benzyl carbons, both of which have at least one bond to H. Thus we convert each benzyl carbon into a -COOH and neglect the rest of the alkyl chain, forming product [D].

The following compounds all have similar molecular weights. Which compound would have the LOWEST boiling point?

Recall that boiling points increase as the strength of intermolecular forces increase. Options [A], [B], [C], and [D] all have at least one covalent bond between hydrogen and O or N; these molecules are all capable of forming hydrogen bonds. [E], on the other hand, lacks a covalent bond between hydrogen and oxygen, meaning it is incapable of forming hydrogen bonds. Due to the electronegativity difference between oxygen and carbon, [E] has a dipole and will have dipole-dipole intermolecular forces. However, these forces are significantly weaker than hydrogen bonding, giving [E] the lowest boiling point out of these molecules.

What acts as the oxidizing agent in the following reaction? Ag+ (ag) + Mn (s) + H2O (l) → Ag (s) + Mn2+ (aq) + H2O (l) A. Ag+ B. Mn2+ C. H+ D. H- E. O2- CHECKEXHIBIT

Recall that losing electrons is oxidation (LEO) while gaining electrons is reduction (GER). Our equation shows Ag+ (aq) becoming Ag (s). Notice that Ag's charge goes from +1 to 0, meaning it must have gained electrons and become reduced. Our equation also shows Mn (s) becoming Mn2+ (aq). Notice that Mn's charge goes from 0 to 2+, meaning it must have lost electrons and become oxidized. An oxidizing agent is a species that oxidizes another species and is itself reduced. Ag+ is thus our oxidizing agent, as it goes from having an oxidation number of +1 on the left to 0 on the right; it is being reduced. Thus, [A] is the correct answer.

What acts as the oxidizing agent in the following reaction? Ag+ (ag) + Mn (s) + H2O (l) → Ag (s) + Mn2+ (aq) + H2O (l) A. Ag+ B. Mn2+ C. H+ D. H- E. O2- CHECKEXHIBIT

Recall that losing electrons is oxidation (LEO) while gaining electrons is reduction (GER). Our equation shows Ag+ (aq) becoming Ag (s). Notice that Ag's charge goes from +1 to 0, meaning it must have gained electrons and become reduced. Our equation also shows Mn (s) becoming Mn2+ (aq). Notice that Mn's charge goes from 0 to 2+, meaning it must have lost electrons and become oxidized. An oxidizing agent is a species that oxidizes another species and is itself reduced. Ag+ is thus our oxidizing agent, as it goes from having an oxidation number of +1 on the left to 0 on the right; it is being reduced. Thus, [A] is the correct answer. Topic:Electrochemistry and Oxidation Reduction Reactions

What are the two functions of the enzyme RuBisCO during the Calvin cycle? A. Reduce PGA and bind CO2 B. Reduce PGA and bind O2 C. Carboxylate RuBP and bind CO2 D. Carboxylate RuBP and bind O2 E. Bind CO2 and bind O2 CHECKEXHIBIT

RuBisCo or RuBP carboxylase/oxygenase is an essential enzyme that catalyzes carbon fixation in the Calvin Cycle. It does this by binding CO2 and carboxylating RuBP to form PGA. Looking at the answer choices, choice [C] is correct. We can automatically eliminate choices [A] and [B] because RuBisCo creates PGA, not reduce it. While RuBisCO does bind to oxygen, the question specifically asks for its function during the Calvin cycle. Binding oxygen does not happen in the Calvin Cycle but rather in photorespiration. Choice [B] can be eliminated again using this reasoning along with choice [D] and [E]. Topic:Photosynthesis

what is the pacemaker of the heart

SA node - entrance of the right atrium delivers electrical impulses at regular intervals that allow heart to beat atrial contraction - pushed blood into the ventricles

Fungi are responsible for decomposing fallen trees in an ecosystem. Which term best describes the role of the fungi? A. Scavenger B. Detritivore C. Autotroph D. Saprophyte E. Anaerobe CHECKEXHIBIT

Saprophytes are decomposers that consume dead or decaying organic material. [D] is the answer. Scavengers are carnivores or herbivores that decompose other dead animals or plants. [A] is incorrect. Detrivores are worms or slugs that consume detritus, exposing more organic material for decomposers. [B] is incorrect. Autotrophs can make their own food. [C] is incorrect. Anaerobes perform anaerobic respiration. [E] is incorrect.

What is the main function of Schwann cells? A. Produce nutrients for nuclei in the spinal cord B. Provide blood supply to glial cells C. Secrete cerebrospinal fluid for the brain D. Contributes to the blood brain barrier E. Form myelin sheath in neurons CHECKEXHIBIT

Schwann cells are part of the peripheral nervous system and form the myelin sheath, the fatty insulation of the axon, in neurons. Answer Choice [E] is correct. Oligodendrocytes perform the same function in the central nervous system. Astrocytes (CNS) and satellite cells (PNS) both provide blood supply to their respective system's neurons. Astrocytes also provide nutrients to CNS neurons, including neurons in the spinal cord, and contribute to the blood-brain-barrier. Choices [A], [B] and [D] are incorrect. Ependymal cells create the cerebrospinal fluid for the brain. Choice [C] is incorrect. Topic:Anatomy and Physiology

can secondary alcohols be oxidized to aldehyde or CA ? AS A RULE OF THUMB, secondary alcohols can be oxidized up to ____?

Secondary alcohols can NEVER be oxidized to an aldehyde or carboxylic acid... rule -- 2ndary alcohols oxidized up to KETONES

An organic apple costs $1.60 more than a regular apple. If the cost of a regular apple and an organic apple together is 280% of the cost of a regular apple, how much does an organic apple cost? A. $1.80 B. $2.00 C. $2.80 D. $3.60 E. $4.00 CHECKEXHIBIT

Setting up a system of equations would let us solve for the cost of an organic apple. Using RA as regular apple and OA as organic apple, RA + 1.60 = OA RA + OA = 2.8 RA Plugging in the OA from the first equation into the second, RA + (RA + 1.60) = 2.8 RA 2 RA + 1.60 = 2.8 RA 1.60 = 0.8 RA 2 = RA Since an organic apple costs $1.60 more than a regular apple, the organic apple would cost $3.60. The final answer would then be [D].

What is the value of x? x2 - 2x -15 = 0 (x - 5)(x + 3) = 0 A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statement (1) and (2) TOGETHER are NOT sufficient. CHECKEXHIBIT

Since we must have at least 2 equations in order to solve for x, we immediately know that either statement by itself is insufficient. This eliminates choices [A], [B], and [D]. All we must do now is determine whether or not both statements together are sufficient. If we factor statement (1), we get: x2 - 2x - 15 = (x - 5)(x + 3) A quick glance confirms that this is the exact same equation as that in statement (2). Since statement (1) and statement (2) do not give us different equations, we are unable to solve for x. Thus, [E] is the correct answer; statement (1) and (2) TOGETHER are NOT sufficient. FAQ: I am able to determine from each statement that x = 5 or x = -3, so shouldn't each statement be sufficient by themselves? A: If each statement were to be sufficient by themselves, then they would have to give a result to only one x value. However, both statement 1 and 2 say that x can be either -3 or 5, but we don't know exactly which one. For the scope of the DAT, there has to be a solid one answer for the statements to be sufficient.

secondary alcohol reacts with (Na2Cr2O7) / H2SO4 and H20 .... ? What is the product of the following reaction? A. butanal B. 2-butanone C. butanoic acid D. butane E. butyl butanoate

Sodium dichromate (Na2Cr2O7) is an extremely strong oxidizing agent and will oxidize primary and secondary alcohols as well as aldehydes. As a rule of thumb, secondary alcohols can only be oxidized up to ketones. Out of all the answer choices, only Choice [B] is a ketone. Secondary alcohols can never be oxidized to an aldehyde or carboxylic acid, eliminating Choices [A] and [C]. Sodium dichromate does not result in the formation of alkanes or esters, eliminating Choices [D] and [E]. Chromium trioxide (CrO3) can be used in place of sodium dichromate (Na2Cr2O7); they will produce the exact same products.

Which of the following substances will be more soluble in hexane than in water?

Solubility depends on the similarity of intermolecular forces of attraction. Remember that "like dissolves like", i.e. polar substances dissolve in polar solvents; nonpolar substances dissolve in nonpolar solvents. Hexane is nonpolar while water is polar. Therefore, we should expect nonpolar substances to be more soluble in hexane than in water. Molecules I (octane) and III (toluene) are nonpolar as they are purely hydrocarbons (C and H). Molecule II (acetic acid) contains a polar carboxylic acid group; because of its polar character in cannot be miscible in hexane and will only be soluble in polar solvents. Thus, the nonpolar character of molecule I (octane) and III (toluene) dictate they must be more soluble in hexane than in water.

which is more soluble in hexane than water

Solubility depends on the similarity of intermolecular forces of attraction. Remember that "like dissolves like", i.e. polar substances dissolve in polar solvents; nonpolar substances dissolve in nonpolar solvents. Hexane is nonpolar while water is polar. Therefore, we should expect nonpolar substances to be more soluble in hexane than in water. Molecules I (octane) and III (toluene) are nonpolar as they are purely hydrocarbons (C and H). Molecule II (acetic acid) contains a polar carboxylic acid group; because of its polar character in cannot be miscible in hexane and will only be soluble in polar solvents. Thus, the nonpolar character of molecule I (octane) and III (toluene) dictate they must be more soluble in hexane than in water.

Given the following chemical equation, which of the following is true for H2 going in the forward direction? H2 (g) + O2 (g) → 2H2O (l)

Start off by assigning oxidation numbers (ON) to all atoms in the reaction to determine which substance is oxidized or reduced. H2 (g) + O2 (g) → 2H2O (l) Reactants: H: 0 O: 0 Products: H: +1 O: -2 The ON of H increased from 0 to +1, therefore H2 was oxidized. On the other hand, the ON of O decreased from 0 to -2, therefore O2 was reduced. Looking at the forward reaction, O2 oxidizes H2, and H2 reduces O2. Therefore, H2 is the reducing agent (as it is oxidized). [A], [B], and [E] are incorrect. The salt bridge serves as a source of unreactive cations and ions, which flow back-and-forth to counterbalance charges as they build up in the anode and cathode chambers. For this problem, we should remember the mnemonic "RED CAT" and "AN OX". This means that the reduction reaction occurs at the cathode and the oxidation reaction occurs at the anode in a voltaic cell. As H2 participates in the reaction and is present at the anode, it would not compose the salt bridge. Thus, we can eliminate choice [D] leaving us with [C] as the correct answer.

Given the following chemical equation, which of the following is true for H2 going in the forward direction? H2 (g) + O2 (g) → 2H2O (l) A. Gets reduced B. Oxidizing agent C. Present at the anode D. Composes the salt bridge E. Decreases in oxidation number CHECKEXHIBIT

Start off by assigning oxidation numbers (ON) to all atoms in the reaction to determine which substance is oxidized or reduced. H2 (g) + O2 (g) → 2H2O (l) Reactants: H: 0 O: 0 Products: H: +1 O: -2 The ON of H increased from 0 to +1, therefore H2 was oxidized. On the other hand, the ON of O decreased from 0 to -2, therefore O2 was reduced. Looking at the forward reaction, O2 oxidizes H2, and H2 reduces O2. Therefore, H2 is the reducing agent (as it is oxidized). [A], [B], and [E] are incorrect. The salt bridge serves as a source of unreactive cations and ions, which flow back-and-forth to counterbalance charges as they build up in the anode and cathode chambers. For this problem, we should remember the mnemonic "RED CAT" and "AN OX". This means that the reduction reaction occurs at the cathode and the oxidation reaction occurs at the anode in a voltaic cell. As H2 participates in the reaction and is present at the anode, it would not compose the salt bridge. Thus, we can eliminate choice [D] leaving us with [C] as the correct answer. Topic:Electrochemistry and Oxidation Reduction Reactions

What is the outermost extraembryonic layer? A. Amnion B. Allantois C. Yolk sac D. Gray crescent E. Chorion CHECKEXHIBIT

Structures outside of the embryo provide protection and nourishment to the fetus. The chorion is the outermost layer, containing the fetal half of the placenta. [E] is the answer. The amnion is the innermost layer, which secretes amniotic fluid. [A] is incorrect. The allantois is inside of the chorion, storing waste for removal. [B] is incorrect. The yolk sac is inside of the chorion, and contains yolk. [C] is incorrect. The gray crescent is part of the frog embryo. It is opposite to the site of sperm entry. [D] is incorrect.

For an ideal gas under constant volume, if the temperature is doubled, the pressure would:

Temperature and pressure are directly related. If temperature is doubled, pressure is doubled.

Which of the sets of pink-colored hydrogen atoms in this pair of molecules is more positively charged (and hence, will appear further to the left in 1H-NMR)? I. II. A. Hydrogen in molecule I B. Hydrogen in molecule II C. Too similar to distinguish between the two CHECKEXHIBIT

The carbon in molecule II is adjacent to an oxygen, which is more electronegative than carbon, while the carbon in molecule I is bound only to carbons. The oxygen sucks electron density toward itself and away from the carbon and its associated hydrogens in molecule II, leaving those hydrogens more positively charged than the hydrogens in molecule I. Thus the hydrogens in molecule II will appear further to the left in a 1H-NMR spectrum.

All of the following statements are supported by the central dogma of genetics regarding the flow of genetic information EXCEPT for one. Which one is the EXCEPTION? A. The genetic information of DNA can be used to synthesize RNA.B. The genetic information of RNA can be used to synthesize proteins.C. The genetic information of DNA can be used to synthesize DNA.D. The genetic information of a protein can be used to synthesize RNA.E. Proteins can be used to assist in the processing of other proteins.

The central dogma of genetics states that information flows from DNA → RNA → proteins. DNA is used to synthesize RNA in the process of transcription. This eliminates choice [A]. The genetic information of an RNA molecule is used to synthesize a polypeptide chain in the process of translation, which is then used to synthesize proteins. This eliminates choice [B]. The genetic information of a DNA strand can be used to synthesize a complementary DNA strand that runs antiparallel to it. This can be seen in the process of DNA replication. This eliminates choice [C]. Proteins contribute to the molecular machinery that processes other proteins. Besides the various protein enzymes used in transcription and translation, chaperonin proteins are example of specialized protein that assist in protein processing. Chaperonins help newly synthesized proteins to correctly fold, and configure. This eliminates choice [E]. By process of elimination, this leaves us with choice [D] as the correct answer. Biological information cannot be transferred backwards from protein to protein or protein to nucleic acid. Proteins can help with the processing and development of a protein, but ultimately cannot code for it. Key Takeaways: The central dogma of genetics states that information flows from DNA → RNA → proteins. Biological information cannot be transferred backwards from protein to protein or protein to nucleic acid. Proteins can help with the processing and development of a protein, but ultimately cannot code for it.

Which of the following is an important function of the complement system? A. MHC binding B. Antigen presentation C. Heparin release D. Opsonization E. Interferon amplification CHECKEXHIBIT

The complement system comprises of a system of approximately 'side-kick' 30 proteins that aid immune cells in battling pathogens more effectively. They can improve the 'eating' ability of phagocytosing cells by binding complement protein C3b to antigens and tagging them for phagocytosis through a process called opsonization. Choice [D] is correct. Our immune system distinguishes between self and non-self cells through the major histocompatibility complex (MHC) found on the surface of cells. MHC I molecules are found on all nucleated cells, but only antigen-presenting cells such as macrophages and dendritic cells contain MHC II. They act as a bridge between innate and adaptive response by presenting antigens bound to MHC II for recognition by the lymphocytes part of the adaptive response such as T cells. MHC and APCs are not a part of the complement system, so choices [A] and [B] is incorrect. Heparin, a type of anticoagulant, is released by granules in basophils, which is not part of the complement system. Choice [C] is incorrect. Interferons are secreted by virus-infected cells to warn nearby non-infected cells and play no part in the complement system. Choice [E] is incorrect.

How many hydrogen bonds would be present in the following double-stranded DNA molecule? ACCGTGATGC TGGCACTACG

The complementary bases on separate, antiparallel strands of DNA (and RNA) are held together by hydrogen bonds. Adenine and thymine pair together via 2 hydrogen bonds while cytosine and guanine pair together via 3 hydrogen bonds. In the given DNA molecule, there are 4 A-T pairs and 6 C-G pairs. (4 AT pairs * 2 hydrogen bonds) + (6 CG pairs * 3 hydrogen bonds) = 26 total hydrogen bonds. Key Takeaways: Adenine and thymine pair together via 2 hydrogen bonds while cytosine and guanine pair together via 3 hydrogen bonds.

how to find the cojugate acid?

The conjugate acid of any base can be found by simply adding one proton (only one H) to the base and increasing its charge by +1. In this case, the base is the amine group, NH2. Its conjugate acid is NH3+. FAQ: Why cant the proton be added to OH (choice C)? Great question! So, an H can be added to the OH. However, the NH2 is more basic than the OH. Thus, the NH2 will get protonated first. By definition, a "conjugate acid" is the molecule formed when we add ONE (and only one) H+ equivalent to our base, not two or more. So, you might ask: why is the NH2 more basic than the OH? Well, an N is less electronegative (further to the left on the periodic table) than an O. Thus, an N is more willing to share electrons than an O (barring any extraneous variables), which makes an N more basic than an O, if all other factors are the same, which they are, in this case. Hence, the NH2 is more basic than the OH. Topic:Acids and Bases I have a question about this explanation I have feedback about this explanation

If a fully charged phone battery allows Brian to talk for 3 hours, how long can Brian talk with a 15% charged phone battery? A. 15 minutes B. 19 minutes C. 22 minutes D. 27 minutes E. 42 minutes CHECKEXHIBIT

The correct answer is [D]. We can solve this problem by comparing ratios. Making the fully charged phone equal 100, we know that with the phone at 100% battery, Brian can talk for 3 hours, or 100/3. We can then say, if the phone was a 15% battery, Brian can talk for x hours, or 15/x. We can then set up the equation: 100/3 = 15/x, and solve for x 100x = 45 x = 0.45 This means Brian can talk for 0.45 hours. Since the answer choices are in minutes, we just multiply that by 60 to get 27 minutes. FAQ: Q: Can we just use 180 minutes instead of 3 hours while comparing ratios? A: Yes, just make sure to convert from hours to minutes correctly and know that x will then be in minutes.

Find f(g(x)): f(x) = x^2 + 3 F(g) = x + 2

The correct answer to this problem is [E]. To tackle this problem, first think of f(x). If x equals a number, we plug in that number for x and solve for f. We do the same thing in this case, g(x) equals an equation, and we plug that into wherever we see a "x" in the function f(x). Thus, f(g(x)) = (x + 2)2 + 3 = (x +2)(x + 2) + 3 = (x2 + 4x + 4) + 3 = x2 + 4x = 7

Find f(g(x)): f(x) = x^2 + 3 f(g) = X^2 + 2

The correct answer to this problem is [E]. To tackle this problem, first think of f(x). If x equals a number, we plug in that number for x and solve for f. We do the same thing in this case, g(x) equals an equation, and we plug that into wherever we see a "x" in the function f(x). Thus, f(g(x)) = (x + 2)2 + 3 = (x +2)(x + 2) + 3 = (x2 + 4x + 4) + 3 = x2 + 4x = 7 Topic:Algebra

QA: 98,000 * 10^-3 QB: 0.98 * 10^2

The easiest way to compare quantities A and B is to simply solve them by moving the decimal points accordingly. Quantity A = 98,000 * 10-3 = 98 Quantity B = 0.98 * 102 = 98 Since the quantities result in the same value, they are equal. Option [C] is the correct answer. Because Quantity A is equal to Quantity B, the correct answer is [C].

Which of the following has a non zero enthalpy of formation? A. Hg (l) B. Cl2 (l) C. N2 (g) D. H2 (g) E. C (graphite) CHECKEXHIBIT

The enthalpy of formation is the ΔH of a chemical reaction forming one mole of a single substance from its parent elements in their standard states. Any element in its standard state has an enthalpy of formation value of 0 kJ/mol. Here is a periodic table labeled with standard states: Choice [B] is the only answer choice that is not in its standard state. Cl2 is a gas at standard state (not a liquid), thus, will have a non zero enthalpy of formation. [B] is the correct answer. Topic:Thermodynamics and Thermochemistry

Which of the following substances is chemically digested by salivary amylase? A. Amino acids B. Triglycerides C. Amyloids D. Vitamins E. Starches CHECKEXHIBIT

The enzyme salivary amylase is contained within saliva, and begins the chemical digestion of carbohydrates in the mouth. Of the following answer choices, only starches fall under this category. Choice [E] is correct. Amino acids are never chemically digested. Instead they are formed from the breakdown/cleavage of proteins performed by the pepsin enzyme in your stomach, and also by trypsin and chymotrypsin in the small intestine. Choice [A] is incorrect. Bile (NOT an enzyme!!) mechanically breaks down fats into smaller fat droplets, while the pancreatic lipase digests the emulsified fats into glycerol and fatty acids. Choice [B] is incorrect. Amyloids are abnormal, aggregates of proteins that can lead to severe fatal diseases. They are not digested and choice [C] is incorrect. Large intestine bacteria produce vitamin B and K while the absorption of vitamins takes place in the small intestine. Choice [D] is incorrect.

The extracellular matrix provides mechanical support in the area between animal cells. Which of the following structural proteins is found in the highest proportion within the extracellular matrix? A. Collagen B. Proteoglycan C. Fibronectin D. Laminin E. Keratin CHECKEXHIBIT

The extracellular matrix (ECM) between animal cells is mainly made up of collagen, a protein secreted by fibroblasts that gives tissues strength and rigidity. Choice [A] is our correct answer. Choices [B], [C], and [D] are incorrect because even though these proteins are found in the ECM, they are not the most common. Choice [E] is incorrect because keratin is a type of intermediate filament contained within the cell. Topic:Cells and Organelles

Where in a nephron is the filtrate most concentrated? A. Distal convoluted tubule B. Bowman's capsule C. Bottom of the descending limb D. Top of the descending limb E. Top of the ascending limb CHECKEXHIBIT

The filtrate is most concentrated at the bottom of the descending limb. Choice [C] is correct. The descending limb has a high permeability to water and low permeability to solutes. Thus when the filtrate travels down, water from the filtrate rushes out and absorbed back into blood capillaries running parallel to the loop of Henle. The solute stays; so as the water is removed from the filtrate, the filtrate becomes increasingly more concentrated and is most concentrated at the bottom of the descending limb.

In a soccer game, there are ten players on the field. How many different teams of six can be chosen? A. 10! B. 6! C. 210 D. 140 E. 4! CHECKEXHIBIT

The first thing that we should do in solving problems like this is determining if order is important. This is so that we can determine if the scenario is asking for combinations or permutations. If I select 6 players for the team, the order in which I draw the players does not matter since it is the overall team that is important. Whether a player is drawn first or sixth, the player will still be on the team. As this is the case, we know the question is asking for combinations and we can now use the combination equation to determine how many different teams of six can be chosen.

How many different combinations of letters can you make from the letters of the word "ANATOMY" ? A. 360 combinations B. 840 combinations C. 1,244 combinations D. 2,520 combinations E. 5,040 combinations CHECKEXHIBIT

The first thing we have to realize is that since the letter A is repeated in this word, there will be some combinations that are actually the same because of the duplicates. We must adjust for these duplicate combinations by using the following formula: #different combinations = max # combinations without repears / (a1!)(a2!).... Each term in the denominator represents the number of repeated entries for each letter that is repeated. Since there are 7 letters in the word 'anatomy', there are 7! Possible combinations assuming no repeats. There is only one repeated letter in the word (the letter A), and it is repeated twice, so the correction should be 2!. Plugging these values into our formula gives us: # of different combinations = 7!/2! 7*6*5*4*3*2*1 / 2*1

slow block to polyspermy

The formation of the fertilization envelope and other changes in an egg's surface that prevent fusion of the egg with more than one sperm. The slow block begins about 1 minute after fertilization. cortical granules in teh egg fuse with plasma membrane = sperm-proor membrane rxns harden the vitelline layer - prevent sperm to enter = slow block

heat curve: T vs head added (flat line) - looks like up flat up flat up

The graph provided is a heat curve. A heat curve is a diagram that shows how a substance changes from a solid to a liquid to a gas, as the temperature is raised. The slope of segments AB and CD can be used to determine the heat capacities of the solid and the liquid, respectively. Choices [A] and [B] can be eliminated. Melting, or fusion, refers to the change of a substance from the solid phase to the liquid phase. Segment BC represents the heat required to completely convert a substance from a solid to a liquid. Choices [D] and [E] can be eliminated. Segments DE represents the heat required to completely vaporize the substance. Thus, [C] is the correct answer.

A 100 g apple is combusted in a bomb calorimeter. The temperature increased by 20ºC. The heat capacity of the bomb calorimeter is 20.0 kJ/ºC. How much energy is obtained from this apple?

The heat of a reaction in a bomb calorimeter is given by: qrxn = -C x ∆T where C is the heat capacity of the bomb calorimeter and ΔT is the change in temperature. So, for the reaction given: qrxn = -20.0 kJ/ºC x (20 ºC) = -400 kJ. This means that 400 kJ of heat is released (the negative sign indicates that heat is released) for 100 grams of food, or 4 kJ of heat per gram.

A 100 g apple is combusted in a bomb calorimeter. The temperature increased by 20ºC. The heat capacity of the bomb calorimeter is 20.0 kJ/ºC. How much energy is obtained from this apple? A. 4 kJ B. 40 kJ C. 100 kJ D. 400 kJ E. 800 kJ CHECKEXHIBIT

The heat of a reaction in a bomb calorimeter is given by: qrxn = -C x ∆T where C is the heat capacity of the bomb calorimeter and ΔT is the change in temperature. So, for the reaction given: qrxn = -20.0 kJ/ºC x (20 ºC) = -400 kJ. This means that 400 kJ of heat is released (the negative sign indicates that heat is released) for 100 grams of food, or 4 kJ of heat per gram. Thus, [D] is the correct answer. Topic:Thermodynamics and Thermochemistry

All of the following statements describing the law of independent assortment are correct EXCEPT one. Which one is the EXCEPTION? A. Homologous chromosomes line up independently in meiosis I B. Independent assortment only occurs in meiosis C. Genes that are linked are likely to be inherited together D. The separation pattern of chromosomes is completely random E. Genetic variability is increased during this process CHECKEXHIBIT`

The law of independent assortment states that in meiosis, homologous chromosomes line up at the metaphase plate independently of one another, which makes the separation of maternal and paternal alleles during anaphase I random. Choices [A], [B] and [D] can be eliminated. The random separation of the alleles contributes to genetic variability, eliminating choice [E]. Although choice [C], genes that are linked are likely to be inherited together is a correct statement, it does not correctly describe the law of independent assortment and is therefore the exception.

Which of the following is a main function of the liver? A. Salt absorption B. Acid neutralization C. Vitamin production D. Erythrocyte destruction E. Chymotrypsin secretion CHECKEXHIBIT

The liver plays an important role in cleaning, detoxifying, and maintaining a healthy bloodstream. One way it contributes to its role is through erythrocyte destruction (though most RBC destruction is done in the spleen) - destroying old or useless RBCs.

The best way to sniff out incorrect resonance structures is to pay attention to what 3 things?

The lone pair on the carbon attacks the carbon of the carbonyl; this causes the oxygen originally giving one of its lone pairs to carbon, to take it back. As this oxygen takes back its lone pair, it now has three lone pairs! Oxygen with 1 bond and 3 lone pairs acquires a negative charge. This matches Choice [C]. The best way to sniff out incorrect resonance structures is to pay attention to: Charge! Resonance structures must all maintain the same overall formal charge. Atoms must maintain their proper formal charge. Octet! Atoms cannot have more than 4 bonds. Structure! Molecular formula and location of the atoms must be constant between resonance structures. If either change, you no longer have the same molecule and this cannot be a valid resonance structure. Choice [A] is incorrect as Oxygen with 1 bond and 3 lone pairs should have a -1 charge, not a +1 charge. The overall charge of the molecule is +1; this does not match the original molecule which has an overall formal charge of -1. Choice [B] is incorrect as the center carbon has violated the octet rule. Carbon can only have 4 bonds, not 5! Choice [D] is incorrect as the molecule has an overall formal charge of -2. Since the overall charge of the molecule is -2; this does not match the original molecule which has an overall formal charge of -1.

What occurs in the luteal phase of the menstrual cycle? A. Follicle develops into the corpus luteum B. Cilia sweeps egg into the oviduct C. Follicle stimulating hormone peaks D. Luteinizing hormone peaks E. Menstruation ends CHECKEXHIBIT

The luteal phase occurs after ovulation and involves the development of the corpus luteum from the follicle. Choice [A] is correct. During ovulation, the release of the egg from the follicle, the cilia of the fimbriae (fingerlike projections) sweep the ovulated egg to the uterus through the oviduct (fallopian tube). This does not occur in the luteal phase so choice [B] is incorrect. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) peak during ovulation, not the luteal phase. Choices [C] and [D] are incorrect. Menstruation ends halfway into the follicular phase, not the luteal phase. Choice [E] is incorrect. Below is a chart depicting the stages of menstruation, hormone levels, ovarian histology, and endometrial histology.

What is a possible ml value for the valence electron in Ca+? A. -2 B. -1 C. 0 D. 1 E. 2 CHECKEXHIBIT

The magnetic quantum number ml describes the spatial orientation of the subshell. The first step in determining the ml value for Ca+ is to locate it on the Periodic Table. The Periodic Table is organized in terms of blocks. The block in which an element resides tell you the orbital in which its outermost electrons are located. Ca+ is found on period 4, group 2 of the Periodic Table, which is located in the s block. This means that its outermost electrons are located in a s orbital. The second step is to determine the azimuthal quantum number, l, that describes the orbital in which an electron is located. The azimuthal quantum number, l, can take the possible values: l = 0 → the s orbital l = 1 → the p orbital l = 2 → the d orbital l = 3 → the f orbital Because Ca+ has its outermost electrons in a s orbital, l = 0. The s orbital can only hold two electrons. . As a result: l = 0 → ml = 0 [C] is the correct answer. Topic:Atomic and Electronic Structure

directing group

The nitro group on our starting molecule is an electron withdrawing group and meta director, meaning Cl should only be added meta to the NO2 (eliminating [A] and [B]). [C] and [D] both have Cl added meta to the NO2, but will this reaction be slower or faster than the chlorination of benzene? NO2 being an electron withdrawing group is said to deactivate the ring, making it less reactive. Thus this reaction will occur slower than if we were chlorinating benzene itself. Topic:Aromatic Compounds

oxidation rules

The oxidation number of an atom in its elemental form is zero (e.g. N2, Ag). The oxidation number of a monatomic ion is equal to its charge (e.g. Ca2+ has an oxidation number of +2). The sum of oxidation numbers in a molecule or formula is zero. The sum of oxidation numbers in a polyatomic ion is equal to the charge of the ion. The oxidation number of Group IA is +1 in all of its compounds. Group IIA has an oxidation number of +2 in all of its compounds. Hydrogen has an oxidation number of +1 if combined with nonmetals and -1 if combined with a metal and boron. Fluorine has an oxidation number of -1 in all of its compounds. Oxygen has an oxidation number of -2 in all of its compounds except in peroxide (-1) and when combined with F (e.g. in OF2, because F has an oxidation number of -1 in all of its compounds, it follows that O has an oxidation number of +2). Halogens have an oxidation number of -1 if combined with metals, nonmetals (except O), and other halogens lower in the group.

The following are the rules for assigning oxidation number:

The oxidation number of an atom in its elemental form is zero (e.g. N2, Ag). The oxidation number of a monatomic ion is equal to its charge (e.g. Ca2+ has an oxidation number of +2). The sum of oxidation numbers in a molecule or formula is zero. The sum of oxidation numbers in a polyatomic ion is equal to the charge of the ion. The oxidation number of Group IA is +1 in all of its compounds. Group IIA has an oxidation number of +2 in all of its compounds. Hydrogen has an oxidation number of +1 if combined with nonmetals and -1 if combined with a metal and boron. Fluorine has an oxidation number of -1 in all of its compounds. Oxygen has an oxidation number of -2 in all of its compounds except in peroxide (-1) and when combined with F (e.g. in OF2, because F has an oxidation number of -1 in all of its compounds, it follows that O has an oxidation number of +2). Halogens have an oxidation number of -1 if combined with metals, nonmetals (except O), and other halogens lower in the group.

All of the following processes are performed by the pancreas EXCEPT one. Which one is the EXCEPTION? A. Neutralization of acid B. Digestion of starches C. Breakdown of fats D. Secretion of zymogens E. Release of bile CHECKEXHIBIT

The pancreas secretes pancreatic amylases to break down starches, pancreatic lipase to break down fats, zymogens such as trypsinogen and chymotrypsinogen, and bicarbonate ions to neutralize stomach acid flowing into the small intestine. It is not responsible for the release of bile; this is done by the gallbladder.

All of the following processes are performed by the pancreas EXCEPT one. Which one is the EXCEPTION? A. Neutralization of acid B. Digestion of starches C. Breakdown of fats D. Secretion of zymogens E. Release of bile CHECKEXHIBIT

The pancreas secretes pancreatic amylases to break down starches, pancreatic lipase to break down fats, zymogens such as trypsinogen and chymotrypsinogen, and bicarbonate ions to neutralize stomach acid flowing into the small intestine. It is not responsible for the release of bile; this is done by the liver. Choice [E] is the exception and the correct answer.

Which of the following is correctly paired? A. Alpha cells - insulin B. Beta cells - glucagon C. Delta cells - cortisol D. Parafollicular cells - calcitonin E. Corpus luteum - follicle stimulating hormone

The parafollicular cells of the thyroid secretes calcitonin, which decreases blood calcium levels. Choice [D] is correct. Alpha cells secrete glucagon, beta cells secrete insulin, and delta cells secrete somatostatin. None of those are correctly matched so choices [A], [B] and [C] are incorrect. LH stimulates ovulation during the menstrual cycle, and ovulation leaves behind a structure called corpus luteum in the ovary. Corpus luteum then produces female sex hormones progesterone and estrogen. Topic:Anatomy and Physiology

Which of the following is correctly paired? A. Alpha cells - insulin B. Beta cells - glucagon C. Delta cells - cortisol D. Parafollicular cells - calcitonin E. Corpus luteum - follicle stimulating hormone CHECKEXHIBIT

The parafollicular cells of the thyroid secretes calcitonin, which decreases blood calcium levels. Choice [D] is correct. Alpha cells secrete glucagon, beta cells secrete insulin, and delta cells secrete somatostatin. None of those are correctly matched so choices [A], [B] and [C] are incorrect. LH stimulates ovulation during the menstrual cycle, and ovulation leaves behind a structure called corpus luteum in the ovary. Corpus luteum then produces female sex hormones progesterone and estrogen. Topic:Anatomy and Physiology

What process involves the fusion of two hyphae into a single cell with two haploid nuclei? A. Plasmogamy B. Karyogamy C. Cytokinesis D. Binary Fission E. Budding CHECKEXHIBIT

The process in which two hyphae of a mycelium fuse to form a single fused cell with two haploid nuclei (pronuclei) is known as plasmogamy. Choice [A] is correct. Karyogamy is the process after plasmogamy in which the pronuclei's two nuclei eventually fuse into a single diploid nuclei. Choice [B] is incorrect. Cytokinesis is the process in which a cell splits into two, which is the opposite of fusion. Choice [C] is incorrect. Binary fission is when a cell grows, replicates its genome, and divides into two genetically identical cells. It does not refer to the fusion of two hyphae, therefore choice [D] is incorrect. Budding is an asexual process where a new organism grows out of an old organism and become separated when the new organism develops fully. Choice [E] is incorrect.

All of the following molecules are directly produced during glycolysis EXCEPT ONE. Which one is the EXCEPTION? A. ATP B. G3P C. NADH D. FADH2 E. Pyruvate CHECKEXHIBIT

The question is asking for the exception, so we are looking for a molecule that is not directly produced during glycolysis. Here, answer choice [D] FADH2 is the correct answer as it is not a product of glycolysis. Instead, FADH2 is produced in the Krebs cycle when the four-carbon intermediate passes its electrons to FAD and FAD undergoes a reduction to FADH2. We can also solve this problem through process-of-elimination. Glycolysis is a metabolic process in which a glucose molecule is converted to two pyruvate molecules. This eliminates answer choice [E]. One of its intermediates is G3P or glyceraldehyde-3-phosphate, the 3-carbon molecule precursor to pyruvate. This eliminates choice [B]. The net energetic products of glycolysis are two ATP and two NADH molecules, which eliminates choices [A] and [C], leaving [D] as the correct answer. Topic:Cellular Energy I have a question about this explanation I have feedback about this explanation

In a school, the ratio of male to female students is 3:4. In the same school, the ratio of students to teachers is 12:1. If there are 72 male students in the school, how many teachers are there? A. 7 teachers B. 12 teachers C. 14 teachers D. 18 teachers E. 24 teachers CHECKEXHIBIT

The ratio of male students to female students is 3:4. As there are 72 male students, 72/3 = 24, thus the multiplication factor is 24 (a multiplication factor is something to get from the original simplified ratio to the current ratio that we are working with). If we multiply the ratio of female students by the multiplication factor, we get 24 x 4 = 96 female students in the school. The total number of students is then, 72 + 96 = 168 students. Finally, as there is 1 teacher for 12 students, if we divide the total students by 12, we get 168/12 = 14 teachers in the school. Thus the answer is [C]. Topic:Algebra

Which of the following contributes to the secondary structure of a protein?

The secondary structure of a protein is the 3D shape that forms from its hydrogen bonding between amino and carboxyl groups of adjacent amino acids. Secondary structures include the alpha helix and beta sheet. Therefore choice [B] is the correct answer. The tertiary structure of a protein is the 3D structure that forms from interactions between the R-groups of amino acids. These interactions include hydrogen bonding, ionic bonding, hydrophobic effect, disulfide bonds, and Van der Waals forces (also known as electrostatic interactions). This definition eliminates answer choices [A], [C], and [E]. Choice [D] is incorrect because metallic bonding is not present in any level of protein structure. Note: hydrogen bonding occurs in both secondary and tertiary structures. After hydrogen bonding in secondary structure has formed, further hydrogen bonding between R groups of amino acids then contribute to a protein's tertiary structure. The major distinguishment between hydrogen bonding in secondary and tertiary structure is that secondary structure involves interactions between the amino and carboxyl groups of adjacent amino acids, while tertiary structure involves interactions between the R groups of amino acids (that do not have to be adjacent). Key Takeaways: Hydrogen bonding between amino and carboxyl groups of adjacent amino acids contributes to secondary structure. Common secondary protein structures include alpha helices and beta-pleated sheets.

What product would you obtain if you reacted cyclohexanone with H+ and two equivalents of CH3CH2OH?

The shortest way to answer this question is to recall that when aldehydes and ketones are reacted with acid and two equivalents of alcohol, the carbonyl carbon becomes a ketal (a carbon bound to two OR groups). Here we treat a ketone with an acid and alcohol, forming the corresponding ketal, [D].

Which of the following represents a start codon? A. AUG B. UAA C. UAG D. UGA E. GAU CHECKEXHIBIT

The start codon you should memorize is AUG, which codes for methionine. The start codon signals the initiation of translation. Choice [A] is our correct answer. UAA, UAG, and UGA are stop codons, which terminate translation. Choices [B], [C], and [D] are incorrect.

Which of the following represents a start codon? A. AUG B. UAA C. UAG D. UGA E. GAU CHECKEXHIBIT

The start codon you should memorize is AUG, which codes for methionine. The start codon signals the initiation of translation. Choice [A] is our correct answer. UAA, UAG, and UGA are stop codons, which terminate translation. Choices [B], [C], and [D] are incorrect. Choice [E] is incorrect because GAU is not a start codon. Topic:Molecular Genetics

What is the purpose of the stratum granulosom? A. Strength B. Immunity C. Melanin synthesis D. Water barrier E. Fat storage CHECKEXHIBIT

The stratum granulosum is a layer composed mainly of keratinocytes that secrete lamellar bodies, which form a hydrophobic membrane. These lamellar bodies help create a water barrier.

Of the different structures that make up the cytoskeleton in eukaryotic cells, which of the following has the largest diameter? A. Actin B. Nuclear lamins C. Microtubules D. Contractile rings E. Keratin CHECKEXHIBIT

The three cytoskeletal components are microfilaments, intermediate filaments, and microtubules. Microtubules have the largest diameter out of the three, so choice [C] is the correct answer. Choice [A] is incorrect because actin makes up microfilaments, which are the smallest cytoskeletal component in terms of diameter. Choice [B] is incorrect because the nuclear lamins are a type of intermediate filament, which have a diameter between the other cytoskeletal components. Choice [D] is incorrect because contractile rings are formed from microfilaments, the smallest cytoskeletal component. Choice [E] is incorrect because keratin is made of intermediate filaments, the medium sized cytoskeletal component.

Which of the following actions would shift the following reaction to the left, given that it is currently at equilibrium? Na2SO4 (s) ⇌ 2 Na+ (aq) + SO42- (aq) ΔHºrxn = -250.0 KJ A. Decreasing temperature B. Removal of Na+ C. Addition of Na2SO4 D. Removal of SO42- E. Increasing temperature CHECKEXHIBIT

The ΔH°rxn is negative, so the reaction is exothermic and heat can be treated as a product. Na2SO4 (s) ⇌ 2 Na+ (aq) + SO42- (aq) + heat If the temperature was decreased, the reaction would shift right. [A] is incorrect. If Na+ was removed, the reaction would shift right. [B] is incorrect. If Na2SO4 was added, no change would occur because solids are not included in the equilibrium equation. [C] is incorrect. If SO42- was removed, the reaction would shift right. [D] is incorrect. Increasing the temperature would shift the reaction left because heat is a product. [E] is the answer.

Four dice are rolled. What is the probability that all four dice come up with the same number?

There are six distinct ways to satisfy this - we could roll 1111, 2222, 3333, 4444, 5555, or 6666. We must take all of these possibilities into account. Let us first consider the probability of rolling a 1 four times in a row. Since the probability of rolling a 1 is ⅙, this would be: 1/6 * 1/6 * 1/6 * 1/6 = 1/1296 Since each of the six ways to satisfy this have the same probability, we can find the probability that all four dice come up with the same number by adding the probability we found to itself 6 times. This gives us: 6/1296 = 1/216 Alternatively, the probability of rolling any number 1-6 on the first roll is 1. Rolling that same number on die number 2 would have a probability of ⅙, and getting that same number on the third and fourth dice is also ⅙.

How many atoms are in a body-centered cubic unit cell? A. 1 B. 2 C. 3 D. 4 E. 5 CHECKEXHIBIT

There are three types of unit cells you need to know for the DAT: Simple cubic - 1 atom per unit cell Body-centered cubic - 2 atoms per unit cell Face-centered cubic - 4 atoms per unit cell This question specifically asks about body-centered cubic unit cells. Memorizing the 3 types of unit cells above, we can easily get to the correct answer, [B], as there are 2 atoms per unit cell in a body-centered cubic unit cell. [B] is the correct answer.

The mortality rate after contracting a certain disease is 60%. What is the chance that one in two people who contract the disease will survive?

There are two possible outcomes in this situation. The first possibility is that the first person lives the second person dies. The second possibility is that the first person dies and the second person lives. Since these outcomes are mutually exclusive, we add their probabilities together. p(½ people who attract disease survive) = p(person 1 dies, person 2 lives) + p(person 1 lives, person 2 dies) Since the mortality is 60%, we know that there is a 0.6 chance an infected person dies. This also lets us know that there is a 0.4 chance an infected person lives. p(½ people who attract disease survive) = (0.6*0.4) + (0.4*0.6) = (0.24) + (0.24) = 0.48 Since there is a 0.48 chance that ½ people who contract the disease survive, option [D] is the correct answer.

The mortality rate after contracting a certain disease is 60%. What is the chance that one in two people who contract the disease will survive? A. 0.12 B. 0.24 C. 0.36 D. 0.48 E. 0.60 CHECKEXHIBIT

There are two possible outcomes in this situation. The first possibility is that the first person lives the second person dies. The second possibility is that the first person dies and the second person lives. Since these outcomes are mutually exclusive, we add their probabilities together. p(½ people who attract disease survive) = p(person 1 dies, person 2 lives) + p(person 1 lives, person 2 dies) Since the mortality is 60%, we know that there is a 0.6 chance an infected person dies. This also lets us know that there is a 0.4 chance an infected person lives. p(½ people who attract disease survive) = (0.6*0.4) + (0.4*0.6) = (0.24) + (0.24) = 0.48 Since there is a 0.48 chance that ½ people who contract the disease survive, option [D] is the correct answer. Topic:Probability and Statistics

Which of the following Grignard reactions on an aldehyde or ketone could be used to synthesize 1-methylcyclohexanol?

This problem is most easily solved by realizing first that 1-methylcyclohexanol is a tertiary alcohol. Recall from the video that Grignard reagents will react with ketones to form tertiary alcohols and with aldehydes to form secondary alcohols. [A], [C] and [D] are all ketones and will yield tertiary alcohols, but which will yield 1-methylcyclohexanol? 1-methylcyclohexanol has 7 carbons; [A] has 8 carbons in its starting material and 1 will be added through the Grignard reagent, giving a total of 9 carbons. [C] has 3 carbons in its starting material and 6 will be added through the Grignard reagent, giving 9 carbons total carbons. [D] has 6 carbons in its starting material and 1 will be added through the Grignard reagent, giving 7 carbons total. Thus [D] is the correct answer.

Which of the following Grignard reactions on an aldehyde or ketone could be used to synthesize 1-methylcyclohexanol? A. B. C. D. CHECKEXHIBIT

This problem is most easily solved by realizing first that 1-methylcyclohexanol is a tertiary alcohol. Recall from the video that Grignard reagents will react with ketones to form tertiary alcohols and with aldehydes to form secondary alcohols. [A], [C] and [D] are all ketones and will yield tertiary alcohols, but which will yield 1-methylcyclohexanol? 1-methylcyclohexanol has 7 carbons; [A] has 8 carbons in its starting material and 1 will be added through the Grignard reagent, giving a total of 9 carbons. [C] has 3 carbons in its starting material and 6 will be added through the Grignard reagent, giving 9 carbons total carbons. [D] has 6 carbons in its starting material and 1 will be added through the Grignard reagent, giving 7 carbons total. Thus [D] is the correct answer.

Which of the following Grignard reactions on an aldehyde or ketone could be used to synthesize butan-2-ol?

This problem is most easily solved by realizing first that butan-2-ol is a secondary alcohol. Recall from the video that Grignard reagents will react with ketones to form tertiary alcohols and with aldehydes to form secondary alcohols. Both [B] and [D] are aldehydes and will yield secondary alcohols, but which will yield butan-2-ol? Butan-2-ol has 4 carbons; [B] has 2 carbons in its starting material and 2 will be added through the Grignard reagent, giving a total of four carbons. [D] has 3 carbons in its starting material and 2 will be added through the Grignard reagent, giving 5 total carbons. Thus [B] is the correct answer.

sublimation effect on enthalphy and entropy

This process consumes heat (increases enthalpy) and creates disorder (increases entropy).

Which electronic transition corresponds to emission of light with the longest wavelength? A. 1 → 2 B. 2 → 1 C. 4 → 3 D. 4 → 6 E. 5 → 4 CHECKEXHIBIT

This question requires the understanding of three concepts: Photons are only emitted from an atom when electrons fall in energy level. The differences between different energy levels (n) decreases as you increase in energy levels. As the wavelength of a photon decreases, the energy of that photon increases. From the start, we can eliminate [A] and [D] as they show an absorption of energy rather than an emission. We should then evaluate the relative differences in energy levels in the remaining three choices. Knowing the energy gap decreases as the levels increase, [E] has a smaller energy gap (5 to 4) than [B] (2 to 1) and [C] (4 to 3), meaning [E] will emit a photon with the lowest energy and thus the longest wavelength. [E] is the correct answer. Topic:Atomic and Electronic Structure

f(x) = x^2 + 5x - 14 Quantity A: smallest root of f(x) Quantity B: -8

This question requires us to solve for the roots of the given function. We can factor the function as follows: f(x) = (x + 7)(x - 2) We can now set each of the terms of the function equal to zero and solve for x to find the roots of f(x). 0 = (x + 7) x = -7 0 = (x - 2) x = 2 The smallest root of the roots is -7. Since -7 (quantity A) is greater than -8 (quantity B),

f(x) = x^2 + 5x - 14 QA: the smallest root of f(x) QB: -8

This question requires us to solve for the roots of the given function. We can factor the function as follows: f(x) = (x + 7)(x - 2) We can now set each of the terms of the function equal to zero and solve for x to find the roots of f(x). 0 = (x + 7) x = -7 0 = (x - 2) x = 2 The smallest root of the roots is -7. Since -7 (quantity A) is greater than -8 (quantity B), choice [A] is the correct answer. Topic:Quantitative Comparison

f(x) = -6x + 9 QA: root of the equation QB: 3

This question requires us to solve for the roots of the given function. We can factor the function as follows: f(x) = (x - 3)(x - 3) We can now set (x - 3) equal to zero and solve for x to find the root of f(x). 0 = (x - 3) x = 3 The root of the equation is 3, which is equal to quantity B. Since this is the case, quantity A is equal to quantity B and option [C] is the correct answer.

f(x) = x^2 - 6x + 9 QA: root of the equation QB: 3

This question requires us to solve for the roots of the given function. We can factor the function as follows: f(x) = (x - 3)(x - 3) We can now set (x - 3) equal to zero and solve for x to find the root of f(x). 0 = (x - 3) x = 3 The root of the equation is 3, which is equal to quantity B. Since this is the case, quantity A is equal to quantity B and option [C] is the correct answer.

What particle completes this reaction? 3718Ar → 3719K + ____ A. 10n B. 11p C. 0-1ß D. 11e E. 00γ CHECKEXHIBIT

To answer this question, we must balance the numbers on both sides. The mass number 37 stays the same on both sides of the equations, but the product has a larger atomic number. To balance the equation, we must add an electron to the right side. This is known as a beta particle or we can say the compound underwent beta decay. Beta decay is the process that converts a neutron to a proton and electron.

3 IN A ROW For which value of q would the following system of linear equations have no solution? qx + 2y = 12 4x + y = 7 A. 6 B. 7 C. 8 D. 9 E. 10 CHECKEXHIBIT

To be able to eliminate the y term and solve for x, we can first double the second equation, then subtract the second equation from the first. qx + 2y = 12 - (8x + 2y = 14) = qx - 8x = -2 The equation gives us possible solutions for x. If we plug in the answer choices, we see that any of the answer choices gives up a number for x, except for 8. When we plug in 8, we get 0 = -2, which is not possible. This means that when q = 8, there is no solution for x, or no solution for the system of linear equations. The answer is therefore [C]. Topic:Algebra

How many stereoisomers of this molecule are possible?

To find the maximum number of stereoisomers a molecule can have, remember this formula: Number of stereoisomers = 2n, where "n" is the number of chiral centers. The molecule given has 4 chiral carbons (indicated by the * below) and does not have a plane of symmetry, so it has 24 or 16 stereoisomers.

Samantha's pie stand has a quota of 30 visitors per day over a span of seven days. If on the seventh day, 18 people visited her stand, then what was the average number of visitors per day for the past 6 days? A. 30 B. 31 C. 32 D. 33 E. 34 CHECKEXHIBIT

To solve this problem, we can set up the general equation to solve for averages. x+x+x+x+x+x+18/7 = avg In this case, we can plug in the value for the weekly quota of 30 visitors for the average. We can also replace one of the x values with 18. From there we will be able to solve for the rest of the x's, under the assumption that they are all the same.

If a sphere has a surface area of 201, what would be its radius to the nearest whole number? A. 4 B. 5 C. 6 D. 7 E. 8 CHECKEXHIBIT

To solve this problem, we should start with the formula for the surface area of a sphere: A = 4πr2 Since the surface area of the sphere is given in the question, we can set 201 as the surface area, and solve for the radius. 201 = 4πr2 50.25 = πr2 16 = r2 4 = r Since the radius of the sphere is 4, the correct answer is [A].

Calculate the percent yield of CN2OH4(s) (60g/mol) given that 30.0g of CN2OH4(s) was produced when 34.0g of NH3(g) (17.0g/mol) was reacted with excess carbon dioxide according to the following balanced reaction: 2 NH3(g) + CO2(g) → CN2OH4(s) + H2O(l) A. 40.0% B. 42.5% C. 44.5% D. 50.0% E. 55.9% CHECKEXHIBIT

Use dimensional analysis to solve this problem: If we have 34 g of NH3 and NH3 has a molecular mass of 17 g/mol, we have 2 moles of NH3. We can then use the mole ratios and the masses to get the theoretical yield. 2mol NH3 * (1 mol CN2OH4/2 mol NH3) (60 g CH2OH4/1 molCH2OH4) = 60 g CN2OH4 Calculate percent yield: 30 g CN2OH4 produced / 60 g CN2OH4 expected = 50% yield [D] is the correct answer. Topic:Stoichiometry

Calculate the percent yield of CN2OH4(s) (60g/mol) given that 30.0g of CN2OH4(s) was produced when 34.0g of NH3(g) (17.0g/mol) was reacted with excess carbon dioxide according to the following balanced reaction: 2 NH3(g) + CO2(g) → CN2OH4(s) + H2O(l) A. 40.0% B. 42.5% C. 44.5% D. 50.0% E. 55.9%

Use dimensional analysis to solve this problem: 2 mol NH# * (1 mol CN2OH4/2mol NH3) * (60 g CN2OH4/ 1 mol CN2OH4) = 60 g CN2OH4 If we have 34 g of NH3 and NH3 has a molecular mass of 17 g/mol, we have 2 moles of NH3. We can then use the mole ratios and the masses to get the theoretical yield. Calculate percent yield: 30 g CN2OH4 produced / 60 g CN2OH4 expected = 50% yield

A container with a pressure of 6 atm occupies a volume of 18.6 L at 273 K. How many moles of gas are present in the container? A. B. C. D. E. CHECKEXHIBIT

Use the Ideal Gas Law: PV = nRT (6 atm)(18.6 L) = n (0.082 L*atm/mol*K)(273 K) so n = 6*18.6/ (0.082 L*atm/mol*K)(273 K)

While riding his bike, Mike travels 16 miles at 40 miles per hour, then he rides additional 8 miles at a certain velocity. If Mike's average velocity for the entire trip is 20 miles per hour, then what was his velocity during his 8-miles trip? A. 5 mph B. 10 mph C. 15 mph D. 20 mph E. 25 mph CHECKEXHIBIT

Using the equation v = d/t, we can set the total distance traveled divided by the total travel time to get his average velocity for the entire trip. For the 16 mile strip, using v = d/t we can solve for t by: 40 = 16/t 40t = 16 t = 0.4 hours Now thinking about the whole trip, we can use x for the amount of time that the 8-mile portion took. 20 = (16 + 8) / (0.4 + x) 20(0.4 + x) = 24 8 + 20x = 24 20x = 16 x = 0.8 hours Since we know the 8 mile part of the trip took 0.8 hours, we can solve for his speed. v = 8/ 0.8 v = 10 miles per hour His speed was 10 miles per hour during the 8 mile trip, thus, the answer would be [B].

Which of the following valves controls blood flow between the right atrium and right ventricle?

Valves that control the blood flow (and prevent backflow) in the heart are known as Atrioventricular valves. Of the two, the tricuspid valve serves as the valve between the right atrium and right ventricle. The right atrium of the heart accepts deoxygenated blood returning from the body and pumps it through the tricuspid valve and into the right ventricle. Choice [B] is correct. Recall the mnemonic: The Right AV valve = Tricuspid valve.

The vapor pressure of substance A is 5 atm greater than substance B. Which of the following is true? A. A has a lower boiling point B. A has a higher heat of vaporization C. B has weaker intermolecular forces D. B has lower surface tension E. The vapor above a solution of A and B will have more substance B CHECKEXHIBIT

Vapor pressure is the upward pressure exerted by a substance on the atmosphere. Vapor pressure is inversely related to boiling point. If the vapor pressure of a substance increases, then its boiling point must decrease. Since substance A has a greater vapor pressure than substance B, then substance A must have a lower boiling point than substance B. Thus, [A] is the correct answer.

The reaction CO2 + H2O → H2CO3 is first order overall. What are the units of k? A. M2s-2 B. M1s-1 C. s-1 D. M-1s-1 E. M-2s-1 CHECKEXHIBIT

We are told that the reaction is first order overall. When figuring out the overall order of the rate law, we add up the exponents. For example: Rate = k[A]m[B]n The overall order of the rate law above is m+n. It works the same with the units of k. Let's add up the exponents and take the absolute value to get the reaction order for each answer choice: Answer choice [A]: M2s-2 = 2 + (-2) = 0 (zero order overall) Answer choice [B]: M1s-1 = 1 + (-1) = 0 (zero order overall) Answer choice [C]: s-1 = -1 (first order overall) Answer choice [D]: M-1s-1 = (-1) + (-1) = -2 (second order overall) Answer choice [E]: M-2s-1 = (-2) + (-1) = -3 (third order overall) The only answer choice that is first order overall is choice [C]. Thus, [C] is the correct answer with units of k being s-1.

x is a prime number and is a factor of 18. What is x? x is a one-digit number x is divisible by 2

We can begin by finding each of the factors of 18. They are 1,2,3,6,9, and 18. Of these, only 2 and 3 are prime numbers. Recall that a prime number is any whole integer that is divisible only by itself and 1. Statement (1) tells us that x is a one-digit number. Since both 2 and 3 are one-digit numbers, this statement does not help us; statement (1) alone is insufficient. Statement (2) tells us that x is divisible by 2. 2 is divisible by 2, but 3 is not. This means that x=2. Thus, statement (2) by itself is sufficient. Thus, [B] is the correct answer; Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

x is a prime number and is a factor of 18. What is x? x is a one-digit number x is divisible by 2 A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statement (1) and (2) TOGETHER are NOT sufficient. CHECKEXHIBIT

We can begin by finding each of the factors of 18. They are 1,2,3,6,9, and 18. Of these, only 2 and 3 are prime numbers. Recall that a prime number is any whole integer that is divisible only by itself and 1. Statement (1) tells us that x is a one-digit number. Since both 2 and 3 are one-digit numbers, this statement does not help us; statement (1) alone is insufficient. Statement (2) tells us that x is divisible by 2. 2 is divisible by 2, but 3 is not. This means that x=2. Thus, statement (2) by itself is sufficient. Thus, [B] is the correct answer; Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

If [(x + y) (d + e)] / 3 is equal to 24 and d + e = 8, then which of the following is equivalent to 5x + 5y?

We can easily eliminate a variable from the first expression by plugging 8 in for (d + e). This gives us x+y*8/3 = 34 We can simplify this by dividing 24 by (8/3) to give us x + y = 9 We are asked to find 5x + 5y. Since each term in this expression is multiplied by 5, we can simplify to yield 5(x+y) Since we know the value of (x+y), we can plug it in to determine the correct answer. 5(9) = 45

which ringed molecule will be more acidic?

We can gauge the acidity of a molecule based on the stability of the resulting conjugate base. These two molecules give the conjugate bases below: Which is more stable? Notice that both molecules meet the first two criteria of aromaticity: both are cyclic with all carbons being sp2 hybridized. The left conjugate base has 6 pi electrons which is a solution to the 4n+2 equation; thus the left conjugate base is aromatic and very stable. The right intermediate has 4 pi electrons which is not a possible solution to the 4n+2 equation making it anti-aromatic and very unstable. Thus the cyclopentadiene (left molecule) will be more acidic as its conjugate base is a very stable aromatic compound.

what does the wittig reaction do?

We can replace the oxygen of a carbonyl with an alkyl group through use of the Wittig reagent. [A] shows the necessary reagents to complete the desired reaction; we simply replace the O with whatever carbanion group is bound to the P in the Wittig reagent.

what are diastereomers

We can see that these molecules have identical connectivity, meaning they are not structural isomers but some sort of stereoisomers. To determine what kind of stereoisomers, we first find the R/S configuration of each stereocenter. The molecule on the left has 2 stereocenters with configurations of S and R (from left to right). The molecule on the right has 2 stereocenters with configurations of S and S (from left to right). Because their R/S configurations differ at at least one, but not all stereocenters, these molecules are diastereomers.

diastereomers....

We can see that these molecules have identical connectivity, meaning they are not structural isomers but some sort of stereoisomers. To determine what kind of stereoisomers, we first find the R/S configuration of each stereocenter. The molecule on the left has 2 stereocenters with configurations of S and R (from left to right). The molecule on the right has 2 stereocenters with configurations of S and S (from left to right). Because their R/S configurations differ at at least one, but not all stereocenters, these molecules are diastereomers.

Johnny has 4 toys that are worth $6 each and x number of toys that are worth $12 each. How many toys in total does Johnny have if the total value of his toys is $120? A. 8 B. 12 C. 16 D. 20 E. 24 CHECKEXHIBIT

We can set up an equation to quickly tackle this problem. Using x as the number of toys Johnny has that are worth $12: 4 * 6 + x * 12 = 120 24 + 12x = 120 12x = 96 x = 8 Johnny has 8 toys that are worth $12, but as the problem states, we are looking for the total number of Johnny's toys. The 8 $12 toys plus the 4, $6 toys, would give us a total of 12 toys. Thus, the answer would be [B]. don't forget that the questions asks for TOTAL amount of toys... avoid trap

Johnny has 4 toys that are worth $6 each and x number of toys that are worth $12 each. How many toys in total does Johnny have if the total value of his toys is $120? A. 8 B. 12 C. 16 D. 20 E. 24 CHECKEXHIBIT

We can set up an equation to quickly tackle this problem. Using x as the number of toys Johnny has that are worth $12: 4 * 6 + x * 12 = 120 24 + 12x = 120 12x = 96 x = 8 Johnny has 8 toys that are worth $12, but as the problem states, we are looking for the total number of Johnny's toys. The 8 $12 toys plus the 4, $6 toys, would give us a total of 12 toys. Thus, the answer would be [B]. Topic:Algebra

If a fully charged phone battery allows Brian to talk for 3 hours, how long can Brian talk with a 15% charged phone battery? A. 15 minutes B. 19 minutes C. 22 minutes D. 27 minutes E. 42 minutes

We can solve this problem by comparing ratios. Making the fully charged phone equal 100, we know that with the phone at 100% battery, Brian can talk for 3 hours, or 100/3. We can then say, if the phone was a 15% battery, Brian can talk for x hours, or 15/x. We can then set up the equation: 100/3 = 15/x, and solve for x 100x = 45 x = 0.45 This means Brian can talk for 0.45 hours. Since the answer choices are in minutes, we just multiply that by 60 to get 27 minutes.

Jenny and Lisa can file 980 papers in 5 hours. If Jenny can file 82 papers an hour, how many papers can Lisa file in an hour? A. 102 B. 114 C. 123 D. 132 E. 144 CHECKEXHIBIT

We can solve this problem by using a classic rate equation. First we find how many hours it takes for Jenny to file all 980 papers, and then we can plug our values in and solve. 1/hours it takes Jenny + 1/hours it takes Lisa = 1/hours it takes both 1/11.95 + 1/x = 1/5 Solving for x gives us 8.6. We then divide 980 by 8.6 to give us Lisa's filing rate, which is 114 papers/hour. FAQ: How did you get 11.95 hours? A: If it takes Jenny an hour to file 82 papers, this means she takes 11.95 hours to file 980 papers: 980 / 82 = 11.95 hours

how to form anti-mark from alkene?

We want to add an H to the less substituted carbon of an alkene and an OH to the more substituted carbon of an alkene. We have two options: we could treat the starting material with H3O+ or with the reagents in [D]. In either case, the H will add to the less substituted carbon, forming a tertiary carbocation intermediate. The H2O then attacks that carbocation. Following deprotonation, we get the correct final product. [A] would give the anti-Markovnikov product, adding OH to the less substituted carbon. [B] and [E] would both add two hydroxyl groups to the alkene. [C] would add an OCH3 rather than an OH.

What is the formal charge on the nitrogen atom in NH4+?

What is the formal charge on the nitrogen atom in NH4+? A. 0 B. 1 C. 2 D. 3 E. 4 Incorrect To calculate the formal charge of an atom in a molecule, draw a complete Lewis structure of the molecule including all bonding and nonbonding electron pairs. Here is the complete Lewis structure of NH4+: Then use the following formula (from Dr. Mike's 3.4 General Chemistry video): Formal Charge = (valence electrons) - (dots) - (bonds) Nitrogen has 5 valence electrons, no dots, and 4 bonds. Thus, to calculate the formal charge on the nitrogen, we write: Formal Charge = (5) - (0) - (4) = 1 The nitrogen atom has a formal charge of 1. [B] is the correct answer. Topic: Molecular Structure and GeometryI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Rank the following leaving groups in order of increasing reactivity:

What this question is really asking is, "Which of the given leaving groups is most stable after it leaves?" To help us get a better sense of what we are dealing with, let's rewrite each leaving group as it would be after it leaves. If done correctly, each leaving group should have gained a negative charge. Which of these negatively charged molecules is most stable? We know that Br- is very stable on its own. Leaving group V also appears quite stable as its negative charge can resonate throughout its oxygens. I, III, and IV on the other hand are all poorer leaving groups. Leaving group I gives a negatively charged oxygen with no resonance stabilization, III gives a negatively charged fluorine and IV gives a negatively charged nitrogen. The stability of these three molecules can be sorted out by comparing their relative electronegativities. Because N is the least electronegative of the three, it is the least stable. O is the next least electronegative, and F is the most electronegative and therefore is the most stable. Thus, our three least reactive groups should be ranked IV < I < III in the correct answer choice. Pro-tip: It is difficult to say whether II or V is more reactive, but only one answer choice has IV < I < III, so we don't need to make a determination regarding II and V. Thus [A] is the correct answer. Topic:Alcohols Ethers Epoxides

what happens when you react alkane with br2 and hv?

When reacting alkanes with Br2 and hv (or heat, or peroxide), we simply add ONE Br to the most substituted carbon on the molecule that has an H bound to it. This occurs because this reaction proceeds through a radical intermediate, and more substituted carbons form more stable radical intermediates. This molecule is made up of secondary and primary carbons with one tertiary carbon; thus we place the Br on the tertiary carbon to get the correct answer, [C]. Topic:Free Radical Halogenation and Diels Alder

klinefelter syndrome

XXY or XXXY - sterile, feminine males

thioacetal compound (ring with 2 S's) followed by acid catalysis (HgCl2/H3O+) yields what?

a ketone

Which of the following particles has the greatest mass? A. Gamma particle B. Alpha particle C. Beta particle D. Proton E. Electron

alpha (helium)

Crystallization

also referred to as freezing

fusion

also referred to as melting

antigen

an antibody generating foreign macromolecule include bacteria, fungi, viruses, protozoa, parasites (worms)

Keratinocytes

are the main cells of the epidermis that divide and differentiate as they migrate from the deeper to more superficial layers. They do not mediate light touch sensation,

Gas Density Formula

d = P(MW)/RT = M/V MW - molar volume V - STP (22.4)

red tides are caused by

dinoflagellates (not red algae) produce toxic chemicals

Solids are more soluble at ______ temperatures

higher (melting sugar in coffee)

Nitrogen fixing bacteria

in the root nodules of legumes fix atmospheric nitrogen (N₂) into ammonia (NH₃) and ammonium (NH₄⁺). Choice [A] is incorrect.

more electrons (anions) _____ size

increases more e- = larger atoms

electron affinity trend

increases UP and to the RIGHT

ionization energy trend

increases UP and to the RIGHT

why do atoms get smaller as you go across a period from left to right?

increasing Zeff effective nuclear charge means the size decreases incr. #p+ = incr. Zeff = decr. size

Mollecular solids show ____ bonding, properties, EX

intermolecular forces soft, low melting point, non-conductive H2O, CO2

the nitro group on benzene is what type of directing group?

meta... EWG

metallic solids show ____ bonding, properties, EX

metallic bonding variable hardness, MP, conductive Fe, Mg

phase diagram of water has a ___ slope solid-liquid line

negative slope solid-liquid line density ice < liquid increase P = melt ice (opposite of normal) water is denser as a liquid than a solid (solid - ice --> floats)

simple cubic cell (# atoms per cell, location)

1 atom per unit cell atoms at CORNERS of cell

1 cm^3

1 mL = 1cc

At STP, 1 mole of gas occupies...

22.4 L R = 0.0821 L*atm/mol*k 1 atm 273 K

simplify: 4log10(3) - 2log10(9)

4log10(3) - 2log10(9) = log10(34) - log10(92) = log10(34/92) = log10(81/81) = log10(1) = 0

simplify: 9^4 - 3^8

9^4 - (32)^4 = 94 - (9)4 = 0

voltaic/galvanic cell vs. electrolytic cell (E inputs/spontaneity)?

A SPONTANEOUS reacting electrochemical cell w/o energy input required = VOLTAIC/GALVANIC CELL A NON-SPONTANEOUS reacting electrochemical cell = ELECTROLYTIC cell, and requires the input of ENERGY

coagulase

A bacterial enzyme that causes blood plasma to clot coagulates fibrinogen

chiral carbon

A carbon atom attached to four different atoms or groups of atoms.

What is the effect on Km (Michaelis constant) and Vmax if a catalyst and non-competitive inhibitor are added? A. Km and Vmax both decrease B. Km increases and Vmax decreases C. Km decreases and Vmax stays the same D. Km stays the same and Vmax increases E. Km stays the same and Vmax decreases

A catalyst will decrease Km because the greater enzyme's ability to function, the less substrate is needed for the reaction to reach maximum reaction velocity. A non-competitive inhibitor will decrease Vm because these inhibitors cannot be outcompeted by adding more substrate, lowering the overall maximum reaction velocity. Note that if we only added a non-competitive inhibitor, Km stays the same and Vmax decreases. The effect of the catalyst is to lower Km. Therefore choice [A] is our correct answer.

What is the effect on Km (Michaelis constant) and Vmax if a catalyst and non-competitive inhibitor are added? A. Km and Vmax both decrease B. Km increases and Vmax decreases C. Km decreases and Vmax stays the same D. Km stays the same and Vmax increases E. Km stays the same and Vmax decreases CHECKEXHIBIT

A catalyst will decrease Km because the greater enzyme's ability to function, the less substrate is needed for the reaction to reach maximum reaction velocity. A non-competitive inhibitor will decrease Vm because these inhibitors cannot be outcompeted by adding more substrate, lowering the overall maximum reaction velocity. Note that if we only added a non-competitive inhibitor, Km stays the same and Vmax decreases. The effect of the catalyst is to lower Km. Therefore choice [A] is our correct answer. Choices [B], [C], [D], and [E] are incorrect. FAQ: I thought Km stays the same for non-competitive inhibitor? A: If we only add a non-competitive inhibitor, the Km would stay the same and the Vmax will decrease. This is absolutely correct! However, in this question, notice that we also have added a catalyst along with the non-competitive inhibitor, which has the effect of lowering Km.

ketone structure?

A ketone functional group is composed of a carbon doubly bonded to oxygen and bonded to two other carbons and has the general structure

When a horse and donkey reproduce, they produce a mule, which lives to adulthood, but cannot reproduce. What form of reproductive isolation is this? A. Behavioral isolation B. Gamete isolation C. Hybrid mortality D. Hybrid sterility E. Hybrid F2 breakdown CHECKEXHIBIT

A mule is a classic example of hybrid sterility, which defines when a hybrid zygote is sterile and cannot reproduce. Choice [D] is therefore the correct answer. Behavioral isolation occurs when different species do not perform the right type of mating rituals, hence preventing mating. Choice [A] is incorrect. Gamete isolation occurs when gametes from different species do not recognize and thus cannot fertilize each other. Choice [B] is incorrect. Hybrid mortality is when a hybrid zygote dies before reaching a reproductive age. Choice [C] is incorrect. Hybrid F2 breakdown refers to when the second generation of hybrids suffer from decreased fitness. Choice [E] is incorrect. Behavioral and gamete isolation are examples of prezygotic isolation, while hybrid mortality, hybrid sterility, and hybrid F2 breakdown are examples of postzygotic isolation.

Which of the following is true regarding voltaic cells? A. Oxidation is at the cathode B. Electrons flow from the anode to the cathode C. A non-spontaneous reaction D. Requires the input of energy E. The anode is positive CHECKEXHIBIT

A spontaneously reacting electrochemical cell is known as a voltaic or galvanic cell. A non-spontaneous reacting electrochemical cell is known as an electrolytic cell, and requires the input of energy. A major difference between a voltaic cell and a galvanic cell is that in an electrolytic cell the anode is positive and cathode is negative, while in a galvanic cell the anode is negative and the cathode is positive. Therefore, choices [C], [D], and [E] can be eliminated. Using the mnemonic "AN OX" and "RED CAT", we can remember that OXidation occurs at the ANode, and REDuction occurs at the CAThode in an electrochemical cell. Choice [A] can also be eliminated. Regardless of the charges on the anode and cathode, the flow of the electrons always goes from anode to cathode. Thus, [B] is the correct answer.

Which of the following is a state function? A. Enthalpy B. Heat C. Work D. Exothermic E. Endothermic CHECKEXHIBIT

A state function is a property whose value does not depend on the path taken to reach that particular value, but only on the initial and final values. An analogy is a trip from New York to California. It doesn't matter whether you drove through Canada, or flew direct, all that matters with the destination is that you arrive in California. In this example, destination is a state function. Alternatively, a path function (non-state function) is one in which the process matters. Path functions depend on the transition or change of the state. Think about the trip from New York to California. The amount of work that trip takes certainly depends on the route taken. If you decide to fly from New York to Canada, before heading to California, you're going to require a lot more work than if you fly direct. Heat and work are examples of path (non-state) functions. Thus, choices [B] and [C] can be eliminated. The terms exothermic and endothermic have nothing to do with state function or path function. Thus, choices [D] and [E] can be eliminated. For the change in enthalpy of a reaction, enthalpy does not depend on how we got from reactants to products; it only depends on the initial and final values of the reaction's enthalpy. Thus, [A] is the correct answer. Topic:Thermodynamics and Thermochemistry

Homoplasy

a.k.a. convergent evolution, describes when two distinct clades develop very similar characteristics despite not sharing any common ancestors.

lysosomes pH

acidic

fast block to polyspermy

acrosomal reaction - electrical response occurs to change the membrane potential to prevent polyspermy

Renin

activates angiotensinogen into Angiotensin I - renin is released by juxtaglomerular cells when BP is low

cowper's bulbourethral glands

add more thick mucous material to the semen

for mutually exclusive probabilities we _____ their probabilities?

add together

Reacting an alkene with HBr and peroxide will lead to...

addition of H and Br across the alkene in anti-Markovnikov fashion... we expect: H adding to the more substituted carbon of the alkene and Br adding to the less substituted carbon of the alkene; this is the definition of anti-Markovnikov addition

Fragmentation

aka regeneration, describes when a piece of an organism that broke off regenerates into a completely new organism.

Mineralocorticoids

aldosterone

how does aldosterone affect Na/K in kidneys/ BP/ BV

aldosterone affects sodium reabsorption + potassium secretion in kidneys collecting duct raises BP raises BV

what does the adrenal cortex make

aldosterone and cortisol

_____ is a mineralocorticoid isolated form the adrenal ____

aldosterone; adrenal cortex

Which reaction type occurs with the following? tertiary halide, strong base, and heat

E2

transduction

DNA transfer by a virus

Observational learning

is learning by watching another animal perform the same behavior.

The stratum spinosum

is responsible for skin's strength and immunity communication due to its high prevalence of desmosomes and Langerhan cells (dendritic cells of the epidermis).

The bond dissociation energy

is the energy required to break a bond (an endothermic process).To calculate the bond dissociation energy, add up the Hbond for molecule

Fat storage

is the main function of the hypodermis not the epidermis.

Hybrid mortality

is when a hybrid zygote dies before reaching a reproductive age.

Enantiomers

isomers that are mirror images of each other

if an element has an EVEN # e-

it's EITHER dia or paramagnetic (use diagram to discern)

what does low ionization energy mean

it's easy to remove an electron

if an element has an ODD # e-

it's paramagnetic

coelentrates

jellyfish, sea anemones, corals carnivores tenticles to capture prey stinging cells - nematocysts These animals have body walls made up of two layers of cells and a central, saclike digestive system. They exhibit radial symmetry.

solid and gas solubility rules

↑ temperature = ↑ solid solubility ↑ pressure, ↓ temperature = ↑ gas solubility solids are most soluble at high temperature while gases are most soluble at low temperature and high pressure.

aldosterone stimulates what (bp/bp/kidney ?)

kidney cells to REABSORB sodium ions and water from the filtrate/ rise in blood volume and blood pressure

atoms get _____ as you go down and to the left

larger

Larger, charged molecules have _____ lattice energies

larger LA with larger charge

shorter bond distance (smaller ions)

larger lattice energy

_____ gases effuse more quickly than ___ gases

lighter ... heavier

Arthropod examples

lobster, crab, shrimp, spider, insects (grasshoppers) jointed legs, exoskeletons, open CS, bilateral insects with head thorax abdomen spiracles and tracheal tubes = RS largest animal phylum

gases behave most ideally under ___ pressures and ___ temperatures

low pressure, high temperatures

1. the VOLUME or size of each individual gas molecule is insignificant is most accurate at

low pressures

which group has O2 is a good oxidizing agent, but O3 is even better, likes to react with metals to form metal oxides

oxygen group

phloem

sieve tubes transports sugars and solutes

name 3 cubic unit cells

simple body-centered face centered

Aufbau Principle

electron filling from LOW to HI energy orbitals auf, i've fallen and i need to get up (from lo to hi)

postzygotic isolation

hybrid mortality, hybrid sterility, and hybrid F2 breakdown

what reaction uses this reagent: 1. B2H6, THF/ 2) H2O2, OH-

hydroboration reaction

what AA is used in euks for initiation during protein synth

methionine, not N-formyl methionine

Molality equation

moles of solute/kg of solvent

Molarity equation

moles of solute/liters of solution liters of solution = solvent + solute

Solubility Rules: what IS soluble?

most group 1 metal cations NO3- nitrate ClO4- perchlorate C2H3O2- acetate NH4+ ammonium

# of nuclei in skeletal muscle

multinucleate voluntary striated doesn't undergo mitosis normally thick myosin filaments that side past thin actin protein filaments

covalent network show ____ bonding, properties, EX

network of coalent bonds hard, high melting point, non-conductive, C (diamond, graphite), SiO2 (quartz)

which element is the highest electron affinity?

chlorine

Calcitonin

released by parafollicular cells in the thyroid.

Aldosterone

released by the adrenal cortex

electromagnetic spectrum LO E (long wavelength) --> Hi E (short wavelength) mnonic

roman men invented very unusual x-ray guns

solid to gas

sublimation

parthenogenesis

unfertilized birth

Bile

(NOT an enzyme!!) mechanically breaks down fats into smaller fat droplets, while the pancreatic lipase digests the emulsified fats into glycerol and fatty acids.

Aposematic coloration

(warning coloration) is a vibrant, bright coloration of poisonous animals that warns predators of their poison.

how many nucleotides to make one amino acid

3 ex: proline = CCU

face centered cubic cell (# atoms per cell, location)

4 atoms per unit cell atoms at corners and face centers of unit cell

1 atm =

760 torr = 760 mmHg

What is a benzylic carbon?

Carbon in a benzene ring

what is the largest element

Francium

pancreas

involved in chymotrypsin secretion

Critical point on phase diagram

Point on the boiling/condensing line that marks where a substance will only exist as a gas if it continues

We are trying to create a final product containing a secondary alcohol

Recall that both NaBH4 and LiAlH4 will reduce ketones to secondary alcohols. Only option [D] has a ketone being reduced by NaBH4 or LiAlH4, and thus only [D] would give the desired product. The second step is simply an acid quench to protonate the O- that results from hydride attack.

Angela drives 25 miles at 25 mph, then 45 miles at 60 mph. What is her average speed for the whole trip? A. 32 mph B. 40 mph C. 42.5 mph D. 50 mph E. 52.5 mph CHECKEXHIBIT

The average speed for Angela's trip can be calculated by dividing the total distance she travelled by the total time she travelled. We can divide Angela's distance by her speed to find her total time. 25 miles/ 25 mi/hour = 1 hour 45 miles/ 60 miles/hr = 0.75 hours Her total time would be 1.75 hours. We can now divide her total distance by her total time to find her average speed for the trip. 70 miles / 1.75 hours = 40 miles/hour

Dalton's Law of Partial Pressures

States that the total pressure of a mixture of gases is equal to the sum of the pressures of all the gases in the mixture Ptotal = Pa + Pb + ....

Cu electron configuration

[Ar] 4s1 3d10

polarity refers to the

unequal sharing of electrons

tetrahedral bond angle

109.5

molecular chaperones

A protein that helps other proteins fold or refold from a partially denatured state.

Anode Oxidation Reduction Cathode

AN OX RED CAT

Solubility Rules: what ISN'T soluble?

Ag+, Pb2+, S2-, OH-, Hg2+, CO32-, PO43- are insoluble

bond length formula

BL = atomic radius1 + atomic radius2

prezygotic isolation

Behavioral and gamete isolation

Kelvin =

Celsius + 273

The presence of electronegative atoms such as chlorine typically makes for polar molecules. All of the following molecules are polar EXCEPT for one. Which one is the EXCEPTION? A. CH3Cl B. CH2Cl2 C. CCl4 D. CH3CH2Cl E. CH3CHCl2 CHECKEXHIBIT

Do not be fooled; while all of these compounds contain an electronegative chlorine, they are not all polar. Polar molecules have dipole moments. Dipole moments are created by the unequal sharing of electrons in polar bonds (bonds between atoms of different electronegativities). Not all molecules containing polar atoms are overall polar molecules; we also must consider the shape of the molecules. All the molecules given have a polar C-Cl bond, but in CCl4, these bonds are arranged in such a way that the dipoles cancel each other, resulting in a net zero dipole moment. This is because in CCl4, electron density is equally dispersed as we have a chlorine pulling on carbon in all four directions. In the other four molecules, notice how electron density is not equally dispersed; these all have a chlorine unequally pulling electron density away from carbon. As a result, these are all polar compounds and have a dipole moment as evidenced by the crossed arrow. Hence, Choice [C] is our correct answer as CCl4 does not have a dipole moment and is thus overall nonpolar.

Photoelectric effect equation

Einstein's equation relating the energy of a photon, the work function of a metal and the maximum kinetic energy of any emitted photoelectrons: hf = Φ + KEmax KE electron ejected = Ephoton - work function

Tropic hormones (target/act on other endocrine glands) FLAT

F - Follicle Stimulating Hormone (FSH) L - Luteinizing Hromone (LH) A - Adrenocorticotropic Hormone (ACTH) T - Thyroid Stimulating Hormone (TSH)

Grignard reagents will react with ketones to form _______ alcohols and with aldehydes to form _____ alcohols.

Grignard reagents will react with ketones to form tertiary alcohols and with aldehydes to form secondary alcohols.

HIGHER Intermolecular forces leads to BP heat of vaporization viscosity surface tensions vapor pressure

HIGHER BP - requires more E to break bonds HIGHER heat of vaporization HIGHER viscosity HIGHER surface tensions LOWER vapor pressure

How are vapor pressure and boiling point related?

INVERSE relation hi VP, lo BP lo BP, hi VP

X<0 Quantity A: |(x+12)^3/ e^4x | Quantity B: 22x

Initially, this looks like a complicated problem, but it becomes much simpler if we think in terms of positive and negative values. Let's examine quantity A. X can represent any value less than 0. This means that no matter what value we plug in for x, we will be left with a number that is not 0. The absolute value function tells us that this number will be either 0 or positive. Now let's examine quantity B. We know that x must be a negative number since its value has to be less than 0. If we multiply a negative number by 22 (a positive number), the result will always be a negative number. Since quantity A will always be 0 or positive and quantity B will always be negative, we know that quantity A is greater than quantity B. Choice [A] is the correct answer.

What is the pOH of a 10.1 x 10-6 M solution of NaOH? A. log (10.1) B. ln 1/10.1e-8 C. -log (10.1 x 10-6) D. 14 - 10.1 CHECKEXHIBIT`

NaOH is a strong base and will dissociate completely. A 10.1 x 10-6 M solution of NaOH will dissociate into 10.1 x 10-6 M of Na+ and 10.1 x 10-6 M of OH-. NaOH ↔ Na+ + OH- Convert from [OH] to pOH. pOH = -log[OH-] pOH = -log[10.1 x 10-6] [C] is the answer. Topic:Acid Base Equilibria and Titrations

how does PTH effect osteoclastic activity vs. calcitonin

PTH - stimulates osteoclastic activity calcitonin - decreases osteoclastic activity/tones down blood calcium

Ideal Gas Law

PV=nRT

Which mating term is correctly matched with its meaning? A. Polygamy, one partner at a time B. Polygyny, one female with multiple males C. Polyandry, one male with multiple females D. Monogamy, mate once per lifetime E. Iteroparity, mate many times per lifetime CHECKEXHIBIT

Polygamy is many partners at once. [A] is incorrect. Polygyny is one male with multiple female partners. [B] is incorrect. Polyandry is one female with multiple male partners. [C] is incorrect. Monogamy is one partner at once. [D] is incorrect. Iteroparity is mating many times per lifetime. [E] is the answer.

large intestine

Salt absorption and vitamin production are main functions of the

what happens to blood after passing through the right AV valve (tricuspid) into the right ventricle?

The right ventricle then pumps the deoxygenated blood through the pulmonary semilunar valve and into the pulmonary arteries. When the left atrium contracts after accepting oxygenated blood returning from the lungs via the pulmonary veins, the blood flows through the mitral valve, or the bicuspid valve, into the left ventricle. The left ventricle then pumps the oxygenated blood through the aortic semilunar valve and into the aorta for circulation around the entire body.

electronegativity trend

UP and to the RIGHT (F is most EN)

what is the pathway of urine?

Urine pathway: → collecting duct → renal pelvis → ureter → bladder → urethra and exit

Large intestine

bacteria produce vitamin B and K while the absorption of vitamins takes place in the small intestine.

Autotrophs

can make their own food.

gas to solid

deposition

Ectoderm layer becomes

hair, eyes, teeth, skin, NS, eye lens

as lattice energy increases melting point

increases

hydrogen bonding

intermolecular H bonds with either N, O, or F

dipole-dipole

intermolecular between polar molecules

golgi bodies

membrane bound sacs that package glycoproteins

spermatogenesis occurs in teh

seminiferous tubules of the testes

colorblindness and hemophilia

sex linked diseases colorblindness - a recessive x-linked disorder in which an individual cannot distinguish between certain colors

Solubility Rules: what trumps what

solubles trump insolubles

Diastereomers

stereoisomers that are not mirror images

genetic drift

the random increase or decrease of allele frequencies. Both do not describe non-random migration

formal charge formula

valance electrons - dots - bonds

formal charge =

valence electrons - electrons - bonds

liquid to gas

vaporization

what are the hormones of the posterior pituitary (where are they made)

vasopressin and oxytocin - made in hypothalamus

# chemical shifts = ?

# chemically unique carbons

log10(1) = ?

0

what are the 3 ideal gas assumptions

1. the VOLUME or size of each individual gas molecule is insignificant 2. gas molecules collisions with each other are perfectly elastic (no IM forces) 3. the average kinetic energy of a gas depends only on the system's temperature

If an angle is six more than two times its supplement, what is the measure of this angle? A. 50 degrees B. 66 degrees C. 112 degrees D. 122 degrees E. 147 degrees CHECKEXHIBIT

122!

body centered cubic cell (# atoms per cell, location)

2 atoms per cell atoms at corners + body center of unit cell

aromatic pi electrons in 4n+2 rule include

2, 5, 10, 14, 18

If the ratio between the sixth and fifth terms of an arithmetic sequence is 23/19, and the sequence is increasing with a common difference of 4, what is the first number of the sequence? A. 2 B. 3 C. 4 D. 5 E. 6 CHECKEXHIBIT

3

turner syndrome

45 chromosomes, lacking X chromosome, sterile, no ovaries,

How many hydrogen atoms are present in 46 grams of CH3CH2OH? A. 7.2 x 1023 B. 1.9 x 1024 C. 3.6 x 1024 D. 3.8 x 1024 E. 4.8 x 1025 CHECKEXHIBIT

46 g CH3CH2OH * (1 mol CH3Ch2OH/46 g CH3CH2OH) * (6 mol H / 1 mol CH3CH2OH) * (6.02 x 1023/1 mol H) = 3.6 X10 24

A lower/higher pKb corresponds to a lower pKa. pKa + pKb = 14 A lower/higher corresponds to a higher Ka. pKa = -log[Ka]

A HIGHER pKb corresponds to a lower pKa. pKa + pKb = 14 A LOWER pKa corresponds to a higher Ka. pKa = -log[Ka]

Quantity A: 4log10(3) - 2log10(9) Quantity B: 9^4 - 3^8

A. Quantity A is greater. B. Quantity B is greater. C. The two quantities are equal. D. The relationship cannot be determined from the information given. Incorrect We can simplify Quantity A as follows: 4log10(3) - 2log10(9) = log10(34) - log10(92) = log10(34/92) = log10(81/81) = log10(1) = 0 We can simplify Quantity B using properties of exponents: 94 - 38 = 94 - (32)4 = 94 - (9)4 = 0 Because Quantity A is equal to Quantity B, the correct answer would be [C]. Topic: Quantitative ComparisonI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

in proks, the initiation step of protein synthesis places the initiator codon of the mRNA, usually ___ and ____- at the proper site on the ribosome

AUG; f-Met-t-RNA

small intestine and pancreas

Acid neutralization is performed by the small intestine and pancreas (small intestine produces secretin -> stimulates pancreas to secrete basic bicarbonate ions) in order to neutralize the gastric acid just entering the duodenum.

markovnikov product forms what type of product?

Addition of HX (X = Cl, Br etc.) to an alkene is a Markovnikov reaction, meaning the most substituted product will be our major product. As we add Cl to the most substituted carbon in the product, doing so does not form a chiral center. Our product is completely achiral so only one product will form. This problem could easily have had a different answer. By removing one of the left-hand methyl groups, we would have gotten enantiomers as our answer. prop-2-ene ---HCL---> 5050/racemic mixture Remember that the addition of HX to alkene uses a planar (flat) cationic intermediate; the incoming nucleophile can attack from the front or the rear of the molecule, this is why we must consider the possibility of chiral centers in the product.

what is the equilibrium constant expression? What happens to coefficients?

All aqueous or gaseous compounds are included in the equilibrium constant expression: Keq = [products]/[reacctants] COEFFICIENTS in the balanced equation are denoted as POWERS in the equilibrium constant expression The even numbers on a regular die are painted yellow. On a second regular die, the numbers that are three less than a perfect square are painted yellow. If both dice are thrown, what is the chance that both come up yellow? A. 1/12 B. 1/6 C. 1/4 D. 1/3 E. 1/2 CHECKEXHIBIT

If the complement of an angle and the supplement of the same angle summed together equals 122 degrees, find the angle. A. 58 degrees B. 67 degrees C. 71 degrees D. 74 degrees E. 82 degrees CHECKEXHIBIT

An angle plus its complement is equal to 90 degrees, while an angle plus its supplement is equal to 180 degrees. With this in mind, we can set up and solve an equation. (90 - x) + (180 - x) = 122 270 - 2x = 122 -2x = -148 x = 74 degrees

AN OX RED CAT

Anode Oxidation Reduction Cathode

What are the two Bronsted-Lowry acids in the following equilibrium? H2SO4 + H2O ⇌ HSO4- + H3O+

Bronsted-Lowry acids are H+ donors. H2SO4 donates a H+ in the forward direction. H3O+ donates a H+ in the reverse reaction.

What are the two Bronsted-Lowry acids in the following equilibrium? H2SO4 + H2O ⇌ HSO4- + H3O+ A. H2SO4 and HSO4- B. H2SO4 and H3O+ C. HSO4- and H3O+ D. HSO4- and H2O E. H2O and H3O+ CHECKEXHIBIT

Bronsted-Lowry acids are H+ donors. H2SO4 donates a H+ in the forward direction. H3O+ donates a H+ in the reverse reaction. [B] is the answer. Topic:Acid Base Equilibria and Titrations

Which of the following descriptions is correct regarding chlorine and sodium? A. Chlorine is a metal and sodium is a nonmetal B. Chlorine is less electronegative than sodium C. Chlorine has a smaller atomic radius than sodium D. Chlorine has a lower ionization energy than sodium E. Chlorine less readily forms π bonds than sodium CHECKEXHIBIT

Chlorine is a halogen and nonmetal. Sodium is an alkali metal. [A] is incorrect. Electronegativity and ionization energy increase to the top right of the periodic table. [B] and [D] are incorrect. Chloride and sodium are not capable of forming pi bonds. [E] is incorrect Atomic radius decreases to the top right of the periodic table. Chlorine is smaller than sodium.

what does the adrenal medulla make

Epinephrine (adrenaline) and norepinephrine (noradrenaline)

how to name organic spiro compounds

First, we find our parent chain name by counting the total number of carbons in the molecule (in this case the total number is ten so our parent chain will be decane). Next, we count the number of carbons on each side of the spiro carbon (the carbon where the two rings intersect). This molecule has 5 carbons on the left of the spiro carbon and 4 on the right. We then place the numbers of carbons from LOWEST TO HIGHEST inside the brackets, separated by a period. Lastly, add the prefix "spiro" before the brackets and the parent chain name after the brackets to get the final answer.

Which of the sets of pink-colored hydrogen atoms in this pair of molecules is more positively charged (and hence, will appear further to the left in 1H-NMR)? A) - unconjugated ring B) - conjugated ring

Hydrogens bound to aromatic rings appear roughly between 6 - 8 ppm in 1H-NMR spectra, while hydrogens bound to sp3-hybridized carbons are much further upfield (to the right), appearing between 1 - 5 ppm.

IgA antibodies

IgA antibodies are most abundant in body secretions (breastmilk, tears, saliva) and functions to stop pathogens externally. They can also give a newborn passive immunity through breastfeeding.

Given x, y, and z, where the ratio of x:y = 3:8, and the ratio of x:z = 9:11, what is the ratio of y:z? A. 8:11 B. 8:13 C. 11:24 D. 24:11 E. 24:17 CHECKEXHIBIT

In order to compare y to z, we must first manipulate our ratios so that our x values are the same. We can do this by multiplying x:y by 3. x:y = 3*(3:8) = 9:24 x:z = 9:11 Since the x values are the same for each ratio, we know that they are on the same scale and we can now directly compare y to z. y:z = 24:11

Which interaction gives ionic compounds their relatively high melting points?

Ionic solids are made from a network of interlacing ionic bonds. The attractions between ions in these solids are ion-ion attractions. These ion-ion attractions are very strong and are responsible for ionic compounds' relatively high melting points

Which of the following is isoelectronic with Ne? A. O- B. F- C. Na- D. Ca2+ E. Cr2+ CHECKEXHIBIT

Isoelectric series are groups of elements with the same number of electrons. F has 9 electrons, and F-, an ion with an additional negative charge, has 10 electrons, the same as Ne.

3x + 5 > 12 QA: 2 QB: x

Let's solve the inequality for x, so we can easily compare quantity B to quantity A. x (quantity B) must always be greater than 7/3. Since 7/3 is greater than 2 (quantity A), quantity B will always be greater than quantity A.

Tunicates

Members of the subphylum Urochordata, sessile marine chordates that lack a backbone.

What cell type in the epidermis mediates light touch sensation? A. Corneocytes B. Keratinocytes C. Langerhans cells D. Merkel cells E. Melanocytes CHECKEXHIBIT

Merkel cells, housed in the stratum basale, are specialized mechanoreceptors cells that can respond to light touch sensations (which makes them extremely abundant in fingertips).

Treatment of benzene with HNO3/H2SO4 results in addition of an ___ in what directing position?

NO2 group (nitration). The -COOH group is a carboxylic acid and a meta director, thus the NO2 would preferentially attach to the meta position.

ketone and an ester with the reducing agent NaBH4 in methanol solvent.

NaBH4 and LiAlH4 are sources of H- and use those hydride ions to reduce carbonyls to alcohols; however, recall that NaBH4 can only reduce aldehydes or ketones. It is not strong enough to reduce esters, amides or carboxylic acids. Thus we would expect NaBH4 to reduce the ketone to a secondary alcohol, but leave the ester alone

Which phase change is correctly paired with its opposite? A. Crystallization, deposition B. Fusion, condensation C. Fusion, crystallization D. Sublimination, vaporization E. Triple point, critical point CHECKEXHIBIT

Note: Crystallization is also referred to as freezing and fusion is also referred to as melting. From the given phase change pairs, the only pair that have phase changes occurring in opposite direction is answer choice [C].

A strong infrared (IR) absorption band between 1750 and 1700 indicates which of the following functional groups?

Peaks in the 1700-1750 region are characteristic of carbonyls.

Π bonds are formed by which of the following orbitals?

Pi bonds are always formed by the "side by side"/parallel overlap of unhybridized p-orbitals! Sigma bonds are always formed by the direct overlap of orbitals and orbital hybridization (s and p-orbitals together).

Where is the bundle of His located in the heart? A. Papillary muscles B. Chordae tendineae C. Interventricular septum D. Right atrium E. Left atrium CHECKEXHIBIT

The bundle of His is located in the interventricular septum, which separates the two ventricles. Choice [C] is correct. Papillary muscles are attached to AV valves via stringy tendons called chordae tendineae. The bundle of His is not located on either of these, and choices [A] and [B] are incorrect. The right and left atrium are places in which deoxygenated and oxygenated blood (respectively) fill up and flow, and are not where the bundle of His is located. Choice [D] and [E] are incorrect.

vapor pressure depression

The decrease in the vapor pressure of a liquid caused by the presence of dissolved solute; a colligative property.

habituation

behavioral response decreases from repetitive meaningless stimulus.

As long as the benzyl carbon has at least one bond to H, then treatment with KMnO4, H2O will yield ____ as the product?

benzoic acid as the product

what makes insulin

beta cells in pancreas

endoderm becomes

bladder lining, digestive and respiratory tracts, liver, pancreas, gall bladder

How many hydrogen atoms are present in 46 grams of CH3CH2OH? A. 7.2 x 1023 B. 1.9 x 1024 C. 3.6 x 1024 D. 3.8 x 1024 E. 4.8 x 1025 CHECKEXHIBIT

compound to mol/g to mol H atom/compound to avogadro #/ 1 mol H atom

gas to liquid

condensation

Saphrophytes

decomposers

bottleneck effect

describes an event that kills off most of the population, leaving behind a much smaller population and gene pool. Both do not describe non-random migration

ll of the following microscopy techniques can be used to observe a living cell EXCEPT one. Which one is the EXCEPTION? A. Compound microscopy B. Electron microscopy C. Dark field microscopy D. Confocal laser scanning microscopy E. Phase contrast microscopy CHECKEXHIBIT

electron

an element in what state has an enthalpy of formation = 0?

elements in their standard states

ATP allows _____ reactions to become ____

endergonic; exergonic

catecholamine examples - released during ___ response

epinephrine, norepinephrine, dopamine sympathetic NS response

describe fungi

eukaryotic heterotrophs secrete digest. enzymes / reabsorb soluble products made of hyphae filaments - multiple hyphae = mycelium reproduce asex/sex saprophytic - breaking down dead orgs haploid state predominates - alternate between dip/hap have cell walls more similar to human cells than bacterial cell

what kind of reaction is electron affinity?

exothermic rxn

Non-disjunction

failure of homologous chromosomes to separate - 47 chromosomes

How many possible stereoisomers are there of the following molecule?

first determine # stereocenters... then use 2n formula to determine # stereoisomers. To begin, recall that the number of possible stereoisomers of a certain molecule can be calculated using the equation 2n, where n = the number of stereocenters in the molecule. The molecule in question has 2 stereocenters: one on the left (C bound to CH3, Br, H, and a C bound to the rest of the molecule) and one on the right (C bound to CH3, Cl, OH and a carbon bound to the rest of the molecule). Thus we can say the number of possible stereoisomers = 22 = 4.

the number of possible stereoisomers

for n chiral centers, there are 2^n possible stereoisomers

Which of the following fetal adaptations allows direct transfer of blood between the right and left atria?

foramen ovale is a hole in which slightly oxygenated blood can travel directly from the right atrium to the left atrium.

Corneocytes

found in the stratum corneum (most superficial epidermal layer), are basically dead, fully differentiated keratinocytes that provide protection against infection, dehydration and physical harm. It is not involved in touch sensation;

solid to liquid

fusion

Cl2 Standard State

gas - not liquid

Melanocytes

housed in the stratum basale, produce melanin that is responsible for pigmentation and protection from UV radiation. It is not involved in touch sensation;

electronegativity

how thirsty an atom is for electrons

ion-dipole forces

intermolecular forces between ions and polar substances NaCl

Typsin

intestinal enzyme that breaks peptide bonds; produces amino acids breaks proteins

ionic solids show ____ bonding, properties, EX

ionic bonding hard, high melting point, brittle, non-conductive NaCl, MgO

grashoppers do not have a ____ chromosome/ females and males are instead

male - X female - XX

spermatozoa

matured in coiled tube - epididymis

do osteoblasts/clasts carry out mitosis?

no - they secrete collagen/ build bone

Can viruses contain both DNA and RNA?

no, they can only contain one nucleic acid can have spherical/rod capsid

meso compounds

optically active and do NOT rotate the place of polarized light

Osmosis equation

pi = iMRT

which has a non-zero net dipole movement is looking for the molecule that's...

polar polarity = imbalance of electrons

Oxytocin

produced by the hypothalamus and released by the posterior pituitary gland

what happens if LH decreases (case of no fertilization)

progesterone levels fall uterine wall tissue breaks down menstruation begins

oocyte dev is halted at what stage of meiosis until a female reaches puberty

prophase I

sea stars are what symmetry

radial

what steps to problem solve neuman projection and asked to find chirality and naming?

redraw the molecule in linear form from the neuman projection - which are in front? back? which carbons have 4 unique attachment s= chiral. backbone = ending

NaBH4 is a ____ agent

reducing

Budding

refers to when an outgrowth (a bud) forms on an organism and separates to form a new organism.

# of nuclei in smooth muscle

single nucleated urinary bladder walls, digestive system, uterus, blood vessels involuntary nonstriated actin and mysoin - not organized into sarcomeres

# of nuclei in cardiac muscle

single nucleus striations intercalated discs involuntary

mesoderm

skeleton, muscles, gonads, kidney, CS

Bryophytes

small and short nonvascular plants (e.g. mosses, hornworts and liverworts) that grow horizontally to be near the water and nutrient source due to their lack of roots. contain rhizoids, small hair-like projections, which help in water absorption and provide minor anchorage. They also use spores as their main dispersal unit.

Amphioxus

small marine animals - invertebrates- doesn't lose notochord

smaller charged ions have ____ lattice energies

smaller

what 2 muscle types are mononucleated?

smooth muscle cardiac muscle SC - 1

morula

solid ball of cells divide to form hollow ball = blastula morula --> blastula --> gastrula

what is another word for miscible?

soluble

spiro naming vs bicyclo naming

spiro: [small ring #: big ring #] bicyclo: [big ring #: small ring #]

leydig cells secrete

testosterone that allows germ cells to mature into sperm cells

binary fission

the DNA of a unicellular organism is replicated and the two DNA molecules migrate to opposite sides. A septum appears in the middle and splits to create two separate cells.

ionization energy

the amount of energy to REMOVE/ionize an electron from an atom

freezing point depression

the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

electron affinity

the energy GIVEN OFF when an atom gains an e-

Henry's Law

the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid PA = kH[A]

Vapor pressure- inversely related to ___

the upward pressure exerted by a substance on the atmosphere. Vapor pressure is inversely related to boiling point. If the vapor pressure of a substance increases, then its boiling point must decrease. Since substance A has a greater vapor pressure than substance B, then substance A must have a lower boiling point than substance B.

never place a double bond at a bridgehead carbon unless

there are at least 8 carbons making up the ring (proper p orbital overlap/reduced strain)

which group has form colorful compounds due to the way their d-orbitals behave

transition metals

vas deferens

transports sperm to teh urethra then out the penis

The central atom of a molecule has one double bond, two single bonds, and zero lone pairs. What is the molecular geometry of this molecule? A. Trigonal bipyramidal B. Tetrahedral C. Trigonal pyramidal D. Trigonal planar E. Bent CHECKEXHIBIT

trig planar

Swern reaction

turns primary alcohols into aldehydes turns secondary alcohols into ketones

when I hear PARAmagnetic I think.....

unpaired attracted to magnets (with unpaired e-) element with ODD number of electrons

Hydroboration

water is added across a double bond -anti-markonikov -syn addition BH3 adds to the LESS substituted carbon H atom adds to MORE substituted carbon

amide linkages require a ____ molecule for hydrolysis

water molecule

a strong acid has a strong/weak CB?

weak

Hyperventilation causes ____

when rapid breathing occurs, consequently depleting the amount of carbon dioxide in the blood. Because an abundance of carbon dioxide contributes to higher concentrations of [H+], the decrease of carbon dioxide will cause respiratory alkalosis.

boiling point

when the vapor pressure is equal to or exceeds atmospheric pressure

The absolute value function tells us that this number will be either ___or ____.

zero or positive

How many chemical shifts will be present in the 13C NMR spectrum of 2,3-dimethylheptane? A. 4 B. 5 C. 6 D. 7 E. 8 CHECKEXHIBIT

From drawing out the structure of 2,3-dimethylheptane, we can find all the chemically unique carbons present and how many shifts will occur. By drawing a straight line across the molecule, we can determine the number of chemical shifts. The two methyl groups marked "1" are exactly the same, counting as just one unique shift. Every other carbon is chemically unique and will register in a 13C NMR spectrum. We will see a total of eight unique shifts. # chemical shifts = # chemically unique carbons

Which of the following is insoluble in water? A. AgCl B. HClO4 C. KOH D. NaCl E. NaNO3 CHECKEXHIBIT

Here are the general rules of solubility of ionic compounds in water: Most Group 1 metal cations, NO3-, ClO3-, C2H3O2-, and NH4+ salts are soluble. Most Ag+, Pb2+ S2-, OH-, Hg22+, CO32-, and PO43- salts are insoluble. The solubles generally trump the insolubles. Following the rules of solubility, you'll notice that choice [A] contains Ag+, which is insoluble in water. Thus, [A] is the correct answer.

reduction of a ketone to an alcohol

Ketones (and aldehydes) are reduced to the corresponding alcohol (secondary alcohol for ketones, primary alcohols for aldehyde) upon treatment with sodium borohydride (NaBH4). NaBH4 does not oxidize ketones up to carboxylic acids as it is a reducing agent, removing Choice [A]. For Choice [C], NaBH4 is not capable of fully removing a carbonyl group nor adding an extra carbon. Choice [D] could have been the correct answer had we used a Wittig Reagent instead but NaBH4 is a reducing agent and would never give us an alkene as a product; it always produces an alcohol. Choice [E] is not possible as NaBH4 does not produce esters nor is there any way to produce an ester from a ketone in one step.

What type of microtubule shortens during anaphase to pull centromeres apart? A. Kinetochore microtubules B. Centrosomes C. Astral microtubules D. Polar microtubules E. Centrioles CHECKEXHIBIT

Kinetochore microtubules attach to the kinetochores of the chromosomes during metaphase, and shorten during anaphase to pull them apart at their centromeres. Choice [A] is our correct answer. Choice [B] is incorrect because centrosomes are organelles that help with mitotic spindle formation. Choice [C] is incorrect because astral microtubules emanate out from centrosomes and function to orient the spindle apparatus. Choice [D] is incorrect because polar microtubules extend from centrosomes to push them towards opposite ends of the cell. Choice [E] is incorrect because centrioles are the components that make up centrosomes.

If f(x) = x + 2 and g(x) = x2, what is f(g(f(x)))?

This is another nesting equation problem. We tackle this like every other and solve for the inside portion of the equation first. Plugging in f(x) for all x in g(x) we get: f(x) = x + 2, g(f(x)) = (x + 2)2 Now plugging in g(f(x)) for all x in f(x) we get: g(f(x)) = (x + 2)2, f(x) = ((x + 2)2) + 2 The answer would then be [D].

What is the molecular formula of a compound composed of 1.01g hydrogen and 16.00g oxygen, given that its molecular weight is 34g/mol? A. H2O2 B. H3O3 C. H3O4 D. H4O5 E. H4O6 CHECKEXHIBIT

There is one mole of hydrogen in 1.01 g H (1.01 g/mol). There is one mole of oxygen in 16.00 g O (16 g/mol). The empirical formula must be HO. The molecular weight of HO is 17 g, so there must be two moles of HO for a molecular weight of 34 g/mol. The molecular formula is H2O2. [A] is the correct answer. Topic:Stoichiometry

How many different kinds of carbon atoms are there in the following molecule (in other words, how many different signals would be seen in this molecule's 13C-NMR spectrum)?

This particular molecule has 5 carbon atoms. We need to decipher whether or not they are equivalent. The carbon on the far right is bound to 3 H's and is alpha (or next to) a carbonyl. The carbonyl carbon is quite clearly different from the carbon on the right as it has no bonds to hydrogen; it instead has two bonds to carbon and a double bond with oxygen. So far our non-equivalent carbon count is up to 2. Moving to the carbon on the left of the carbonyl, we see that it is bound to 2 methyls, one hydrogen, and is next to a carbonyl. We have not encountered a carbon with that description yet, making this carbon unique and moving our non-equivalent carbon count up to 3. Both methyl groups coming off this carbon are identical: they are bound to 3 H's and the same carbon. Although they are identical to one another, they are unique from the rest of the carbons we have encountered so far. Thus we add one more carbon to our non-equivalent carbon count for a final answer of 4.

If the conjugate acid of a molecule has a pKa of 1.2, what would you expect the molecule to be?

The pKa of the conjugate acid is given. A low pKa corresponds to a high Ka and a strong acid. pKa = -log[Ka] A strong acid has a weak conjugate base.

If the conjugate acid of a molecule has a pKa of 1.2, what would you expect the molecule to be? A. Strongly acidic B. Weakly acidic C. Neutral D. Weakly basic E. Strongly basic CHECKEXHIBIT

The pKa of the conjugate acid is given. A low pKa corresponds to a high Ka and a strong acid. pKa = -log[Ka] A strong acid has a weak conjugate base. [D] is the answer. Topic:Acid Base Equilibria and Titrations

How many moles of MgO are in 5 L of 0.2M solution? A. 0.5 B. 1 C. 1.5 D. 2 E. 2.5 CHECKEXHIBIT

The question is asking for moles of MgO so we have to rearrange the equation to: molarity = mol/liter Moles of solute = (Molarity)(Liters of solution) The molarity and liters of solution are given in the question. Plug in these values: Moles of solute = (0.2)(5) = 1 mole

What is an oxidizing agent?

a species that oxidizes another species and is itself reduced.

adrenal cortex

helps us with long-term stresses.

What particle completes this reaction? 3718Ar → 3719K + ____

To answer this question, we must balance the numbers on both sides. The mass number 37 stays the same on both sides of the equations, but the product has a larger atomic number. To balance the equation, we must add an electron to the right side. This is known as a beta particle or we can say the compound underwent beta decay. Beta decay is the process that converts a neutron to a proton and electron.

What percent of 23/100 is 391/10000? A. 3% B. 9% C. 17% D. 25% E. 33%

To quickly solve this problem, we should multiply the 23/100 by 100/100 to get 2300/10000. Then, 391/2300 = 0.17, or 17%. Thus, the answer is [C].

What percent of 23/100 is 391/10000? A. 3% B. 9% C. 17% D. 25% E. 33% CHECKEXHIBIT

To quickly solve this problem, we should multiply the 23/100 by 100/100 to get 2300/10000. Then, 391/2300 = 0.17, or 17%. Thus, the answer is [C]. Topic:Algebra

4 bags of bananas and 7 bags of coconuts weigh 31 kg. If two bags of bananas and one bag of coconuts weigh 8 kg, how much does one bag of bananas weigh? A. 2.5 kg B. 3.0 kg C. 3.4 kg D. 4.0 kg E. 4.4 kg CHECKEXHIBIT

We are given enough information here to set up a system of equations, which we can then solve. Let x represent the weight of a bag of bananas and y represent the weight of a bag of coconuts. 4x + 7y = 31kg 2x + 1y = 8kg Let's solve the second equation for y y = 8 - 2x We can plug this into the first equation to solve for x, the weight of a bag of bananas. 4x + 7(8 - 2x) = 31 -10x = -25 x = 2.5 kg

for x > 0 QA: | sqrt(81x) | QB: | sqrt(16x) + 5sqrt(x) |

We can arrive at this conclusion by simplifying quantity B: | sqrt(16x) + 5sqrt(x) | = | 4sqrt(x) + 5sqrt(x) | = | 9sqrt(x) | can be rewritten as --> | sqrt(81x) | Since quantity B simplifies to the exact same value as quantity A, the two quantities are equal; the correct answer is [C].

Factor the equation x2 - 8x - 20.

When factoring an equation with a squared term that has a coefficient of 1, a good place to start is to determine the factors of "c" value (the number without an x). The factors of 20 in this case would be 1, 20, 2, 10, 4, or 5. Out of these numbers, we need to pick 2 that will somehow, add or subtract to -8 (or the number with only one x). We can see that 2 - 10 = 8. Since we are subtracting the 10, that will be shown as subtraction in the equation. So when we throw in 10 and 2 in to the factored equation, we should get (x - 10)(x + 2).

what is the pathway of urine?

Urine pathway: collecting duct → renal pelvis → ureter → bladder → urethra and exit

A container holds 30.0 mL of carbon at 10° C and a pressure of 736 mm Hg. What will be its volume if the temperature increases by 10° C?

Use a variation of the combined gas law: (V1)/(T1) = (V2)/(T2) (30.0 mL)/(283 K) = (V2)/(293 K) V2 = (30.0 mL)(293 K)/(283 K)

A container holds 30.0 mL of carbon at 10° C and a pressure of 736 mm Hg. What will be its volume if the temperature increases by 10° C?

Use a variation of the combined gas law: (V1)/(T1) = (V2)/(T2) (30.0 mL)/(283 K) = (V2)/(293 K) V2 = (30.0 mL)(293 K)/(283 K) [D] is the correct answer. Topic:Gases I have a question about this explanation I have feedback about this explanation

which group has low ionization Es, react explosively with water, form ionic compounds

alkali metals

which group has low ionization energies, don't react as violently with water

alkaline earth metals

when I hear DIAmagnetic I think.....

all paired slightly repelled by magnets because it has all paired e- element with EVEN number of electrons

ductus venosus

allows oxygenated blood coming from the umbilical vein to flow into the inferior vena cava and mix with deoxygenated blood

ductus arteriosus

allows the deoxygenated blood to flow out the pulmonary artery and into the descending aorta.

Detrivores

are worms or slugs that consume detritus, exposing more organic material for decomposers.

sensitization

as stimulus occurs more often, behavioral response increases.

Langerhan cells,

contained mostly in the stratum spinosum, are the dendritic cells of the epidermis and are important in the communication between the innate and adaptive immune systems. They are not involved in mediating light touch sensation;

Nitrifying bacteria

convert ammonia and ammonium into nitrites (NO₂⁻) and nitrites into nitrates (NO₃⁻). Choices [B] and [C] are incorrect.

Denitrifying bacteria

converts any unused nitrates that were not absorbed by plant roots back into N₂, atmospheric nitrogen. Choice [E] is the correct answer.

liquid to solid

crystallization

london dispersion forces (van der waals)

intermolecular between all molecules TEMPORARY dipole, includes polar and nonpolar molecules the greater the weight, the greater the london dispersion forces

What are mineralocorticoids?

involved with water and salt balance

successive ionization energies.... what happens once you remove all valance electrons

ionization energy increases a lot

The enthalpy of formation

is the ΔH of a chemical reaction forming one mole of a single substance from its parent elements in their standard states. Any element in its standard state has an enthalpy of formation value of 0 kJ/mol.

why is the NH2 more basic than OH?

less en/ more willing to share e- = more basic Well, an N is less electronegative (further to the left on the periodic table) than an O. Thus, an N is more willing to share electrons than an O (barring any extraneous variables), which makes an N more basic than an O, if all other factors are the same, which they are, in this case. Hence, the NH2 is more basic than the OH.

an electron donating group like OCH3 pushes electron density back towards benzene --> CB is less stable which means the parent acid is less ____

less stable CB means the parent acid is less acidic The molecule on the right is not more acidic than the one on the left. This molecule has the less stable conjugate base because -OCH3 group is an electron donating group that can push electron density back towards benzene, making the conjugate base less stable. The molecule on the left does not have this problem and is thus the more acidic of the two.

a less stable conjugate base means the parent molecule is more or less acidic?

more stable CB = more acidic parent acid

Bredt's Rule

never place a double bond at a bridgehead carbon, unless at least 8 carbons make up the ring. under 8 carbons gives a ring with a double bond that causes too much strain, and p orbitals can't properly overlap A stable bridged bicyclic compound cannot have a double bond at a bridgehead position unless one of the rings contains at least eight carbon atoms

which group has inert (unreactie gases)

noble gases - have full octets

C2H5OH/ H2O are not ___ in eachother

not miscible

Sexual reproduction

occurs when an egg is fertilized, not unfertilized

Mullerian mimicry

occurs when different poisonous species that share a common predator evolve to resemble each other so that it is easier for the predator to learn to avoid these species.

Behavioral isolation

occurs when different species do not perform the right type of mating rituals, hence preventing mating.

Gamete isolation

occurs when gametes from different species do not recognize and thus cannot fertilize each other.

PCC reagent in orgo....

oxidizes primary alcohols to aldehydes

what's the relationship between PKa anbd PKb?

the higher the PKb, the lower the PKa

Which of the following has a non zero enthalpy of formation?

the only answer choice that is not in its standard state. Cl2 is a gas at standard state (not a liquid), thus, will have a non zero enthalpy of formation.

3d orbitals are higher than the 4s UNTIL....

the orbitals are filled.... then the 4s is higher than 3d

Gene flow

the process of moving alleles between populations through individual's migration. It best describes the process of non-random migration, as individuals choose where they migrate to.`

what 2 things make a molecule polar?

to be polar, a molecule needs to have two things: 1. polar bonds (eN difference) 2. asymmetry In other words, there needs to be a difference in electronegativity between the bonded elements, and the shape of the molecule must be such that the dipoles of each individual bond do not cancel each other out.

Which of the following is paramagnetic? A. He B. Be C. Ne D. Ca E. Br Incorrect

A paramagnetic substance is an element that has unpaired electrons. To solve this question, figure out the number of electrons in the last subshell of each answer and determine which one has at least one unpaired electron (or is paramagnetic). He has 2 electrons in its 1s orbital, so every electron is paired up. It is thus diamagnetic. Be has 2 electrons in its 2s orbital, so every electron is paired up. It is thus diamagnetic. Ne has 6 electrons in its 2p orbital, so every electron is paired up. It is thus diamagnetic. Ca has 2 electrons in its 4s orbital, so every electron is paired up. It is thus diamagnetic. Br has 5 electrons in its 4p orbital, so not every electron is paired up. It is thus paramagnetic. [E] is the correct answer. Topic: Atomic and Electronic StructureI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Corpus Lutenum - breaks down into the ____ _____ if no fertilization occurs

A structure formed by a follicle that shed its ovum. breaks down into the corpus albicans if no fertilization occurs stimulated by LH to produce progesterone and estrogen - allow for blood vessels to grow/ uterine lining to prepare for implantation of the egg to be fert

diatoms

A unicellular photosynthetic alga with a unique glassy cell wall containing silica yellow/brown

Which of the following is an immediate effect of increased blood pH? A. Increased formation of myoglobin B. Decreased formation of reduced hemoglobin C. Increased production of 2,3-BPG D. Decreased production of carbonic anhydrase E. Increased formation of carbaminohemoglobin Incorrect An increase in blood pH is a result of a decrease in

An increase in blood pH is a result of a decrease in the concentration of protons (H+). Thus, there will be fewer protons available to form reduced hemoglobin (H+Hb). Choice [B] is correct. Increased blood pH does not affect the formation of myoglobin, carbonic anhydrase, 2,3-BPG, or carbaminohemoglobin. Choices [A], [C], [D], and [E] are incorrect.

All of the following are characteristics of antibodies EXCEPT one. Which one is the EXCEPTION? - activate the compliment system - trigger the release of histamine - initiate opsonization of pathogens - mediate an allergic response - attract immune cells to periphery

Antibodies or immunoglobulins are released by plasma cells to tag and neutralize antigens. Although they perform a lot of different functions, antibodies do not attract immune cells to periphery. This is done through rally signalling during the inflammatory response, in which histamine is secreted to dilate nearby capillaries (increasing blood flow) and make capillary walls more permeable and recruit immune cells to the site of injury.

At what point does the graph of 4x + 5y = 20 cross the y-axis? A. (2, 0) B. (4, 0) C. (0, 0) D. (0, 2) E. (0, 4) CHECKEXHIBIT

As the y-axis is located where x = 0, whenever we plug in 0 for x, we can solve for the point where an equation would cross the y-axis. Plugging in 0 for x in the given equation, 4x + 5y = 20 4(0) + 5y = 20 5y = 20 y = 4 Thus, when x = 0, y = 4. Or the graph will cross the y-axis at (0, 4), making the correct answer [E]. Topic:Algebra

All of the following are examples of associative learning EXCEPT one. Which one is the EXCEPTION? A. Spatial learning B. Fixed action patterns C. Observational learning D. Classical conditioning E. Operant conditioning CHECKEXHIBIT

Associative learning involves learning that two things are connected to each other. Spatial learning is associating a response with a specific location. Observational learning is learning by watching another animal perform the same behavior. Classical conditioning involves pairing a neutral stimulus with an unconditioned stimulus so that the neutral stimulus ends up eliciting a physiological response. Operant conditioning is when an animal learns to associate one of its behaviors with either a reward or a punishment. [A], [C], [D], and [E] are incorrect. A fixed action pattern is an innate behavior initiated by a specific stimulus. It is not a learned behavior; therefore; [B] is the answer. Topic:Animal Behavior

All of the following statements about cholecystokinin are correct EXCEPT one. Which one is the EXCEPTION? A. Slows down gastric emptying B. Released by duodenal cells C. Triggers production of intestinal mucus D. Initiates pancreatic enzyme release E. Stimulates release of bile CHECKEXHIBIT

Cholecystokinin is a hormone released by the lining of the duodenum in the small intestine in response to the detection of proteins/fats. This leads to slowing of gastric emptying, initiating pancreatic enzyme release and stimulating the gallbladder to release bile. It does not trigger the production of intestinal mucus, which makes choice [C] the correct answer.

Claisen condensation reactions occur between ________ _______?

Claisen condensation reactions occur between two esters. In the first step, our methoxide steals the alpha hydrogen on our starting material forming an enolate. This enolate then attacks the carbonyl carbon of another identical ester molecule, forming a tetrahedral intermediate. Upon collapse of the tetrahedral intermediate, -OCH3 is kicked off as a leaving group and the carbonyl reforms as a ketone. This gives us our final β-keto ester product, [E]. Note: make sure to check that your product has the proper number of carbons. Because our starting material has 4 carbons, our product should have 8 carbons (as it requires two molecules of our starting material to come together). Topic:Alpha Substitution Reactions of Carbonyls

Among the following, which represents the correct order of decreasing electronegativity? A. Fr > Cs > Rb > K B. F > O > N > C C. Li > Be > B > C D. Pb > Sn > Ge > Si E. K > Ca > Sc > Ti

Electronegativity decreases from the top right to the bottom left of the periodic table. [B] is the correct answer which follows this trend.

how to count non bonding electrons

Every lone pair can be considered as two "non-bonding electrons". Whenever we are counting the number of non-bonding electrons, we must assume every atom has a full octet, unless they are hydrogen or are charged. The oxygens in this molecule each have 2 bonds, so they must have 2 lone pairs or 4 non-bonding electrons each to satisfy their octet. The fluorine in this molecule has just one bond, so it must have 3 lone pairs or 6 non-bonding electrons to fill its octet. Lastly, the nitrogen in this molecule has three bonds, so it must have 1 lone pair or 2 non-bonding electrons to fill its octet. Hence, this molecule contains 20 nonbonding electrons, making Choice [E] the correct answer. Notice the question asks for the number of nonbonding electrons (20), not the number of lone pairs (10), making Choice [A] incorrect. Topic:Bonding and Molecular Geometry

By which process will a Cl- ion cross through the cell membrane? A. Simple diffusion B. Osmosis C. Facilitated transport D. Countercurrent exchange E. Pinocytosis CHECKEXHIBIT

Facilitated transport describes how large, hydrophilic molecules such as Cl- are transported across the cell membrane using a channel or carrier protein. Therefore choice [C] is our correct answer. Choice [A] is incorrect because only small, uncharged, nonpolar molecules can cross the cell membrane through simple diffusion. Choice [B] is incorrect because osmosis refers to the simple diffusion of water. Choice [D] is incorrect because countercurrent exchange refers to having two fluids flow in different directions, allowing some sort of exchange to occur between them such as oxygen or heat exchange. Choice [E] is incorrect because pinocytosis refers to cellular drinking of dissolved extracellular materials.

By which process will a Cl- ion cross through the cell membrane? A. Simple diffusion B. Osmosis C. Facilitated transport D. Countercurrent exchange E. Pinocytosis CHECKEXHIBIT

Facilitated transport describes how large, hydrophilic molecules such as Cl- are transported across the cell membrane using a channel or carrier protein. Therefore choice [C] is our correct answer. Choice [A] is incorrect because only small, uncharged, nonpolar molecules can cross the cell membrane through simple diffusion. Choice [B] is incorrect because osmosis refers to the simple diffusion of water. Choice [D] is incorrect because countercurrent exchange refers to having two fluids flow in different directions, allowing some sort of exchange to occur between them such as oxygen or heat exchange. Choice [E] is incorrect because pinocytosis refers to cellular drinking of dissolved extracellular materials. Topic:Cells and Organelles

IgM antibodies

IgM antibodies is a pentamer that is first to be produced in response to an antigen and activates the complement system.

5 classes of antibodies to know for the DAT Mnemonic: Me And Eve Don't Go

IgM, IgA, IgE, IgD, IgG (Ig stands for immunoglobulin)

Which of the following would be the strongest acid? Which would be the weakest? H2Se H2O H2Te H2S A. H2Se, H2Te B. H2O, H2Te C. H2Te, H2O D. H2S, H2Se CHECKEXHIBIT

For atoms in the same group, atomic size increases as we go down the periodic table. As atomic size increases, acidity increases as well. With increased atomic size, the bond length to hydrogen increases as well, making this bond easier to break. Te has the largest atomic size so H2Te will be the strongest acid. O has the smallest atomic size so H2O will be the weakest acid. Topic:Acids and Bases

Find f(g(h(x))): f(x) = 4x g(x) = 2(x + 3) h(x) = x2 A. 4x2 + 24 B. 2x + x2 + 12 C. 6x + 12 D. 8x2 + 24 E. 12x2 + 18 CHECKEXHIBIT

For nested equation problems like this, work from the inside out. First, we will determine what g(h(x)) is by substituting h(x) in for x in the g(x) formula. g(h(x)) = 2(x2 + 3) We will now take the expression we have just reached and substitute it for x in the f(x) equation to solve f(g(h(x))): f(g(h(x))) = 4(2(x2 + 3)) = 4(2x2 + 6) = 8x2 + 24 Answer choice [D] is correct. Topic:Algebra

H-NMR Spectroscopy - which is more Positive/further to the left - aromatic ring Hydrogens or Sp3 H?

Hydrogens bound to aromatic rings appear roughly between 6 - 8 ppm in 1H-NMR spectra, while hydrogens bound to sp3-hybridized carbons are much further upfield (to the right), appearing between 1 - 5 ppm.

IgE antibodies

IgE antibodies are found on basophils and mast cells and can bind and trigger the release of histamine to mediate an allergic response when there is an allergen.

Which compound is polar? A. CO2 B. SiO2 C. BH3 D. CH4 E. H2O CHECKEXHIBIT

In order for a compound to be polar, a molecule needs to have two things: polar bonds and asymmetry. In other words, there needs to be a difference in electronegativity between the bonded elements, and the shape of the molecule must be such that the dipoles of each individual bond do not cancel each other out. [A], [B], and [E] all have polar bonds, but [C] and [D] do not. [A] and [B] are both symmetrical, meaning that they are nonpolar despite having polar bonds. Only [E] has polar bonds and asymmetry, making it polar. [E] is the correct answer. Topic:Molecular Structure and Geometry

X < 0 and X < 145 Quantity A: one quarter of 75% of x Quantity B: 3 quarters of 20% of x

Let us first rewrite the quantities given to us as mathematical expressions. Quantity A (0.25)(0.75)(x) Quantity B (0.75)(0.20)(x) We can easily see that both expressions have the terms (0.75) and (x) in common. This allows us to disregard these terms, leaving us with: Quantity A (0.25) Quantity B (0.20) Since 0.25 is greater than 0.20, quantity A is greater than quantity B; choice [A] is the correct answer.

what does the PCC reagent do?

PCC oxidizes primary alcohols to aldehydes, giving [A] as the final product.

phosphoenolpyruvate

PEP - high energy molecule delta G -15 Kcal/mole

Which of the following are possible blood types for a child with a blood type AB father and blood type AO mother? A. Type A, B B. Type AB, O C. Type A, B, O D. Type A, B, AB E. Type A, B, AB, O CHECKEXHIBIT

Remember that blood types are an example of codominance, or both A and B alleles that are contributed are expressed and seen. Also remember that there are two genes being contributed by both parents, with one of those genes being either A/B and the other being the recessive O gene. Draw a Punnett square to easily visualize the possibilities:If a blood type AB father and type AO mother have a child, their child can either be Type A, Type B, or Type AB. Choice [D] is correct.

If you extracted cyclohexane with water and toluene, in which layer would the cyclohexane end up? A. Water B. Toluene C. There would be equal amounts of cyclohexane in both water and toluene D. It would form a racemic mixture CHECKEXHIBIT

Remember that like dissolves like. Nonpolar molecules prefer nonpolar solvents while polar molecules prefer polar solvents. Because cyclohexane is nonpolar, it will prefer being in the nonpolar solvent: toluene.

What is true for steroid hormones? A. Produced in the smooth ER B. Initiate second messenger response C. Bind to cell surface receptors D. Use indirect stimulation E. Initiate quick acting responses CHECKEXHIBIT

Steroid hormones are 4-ring structures that belong in the same family as lipids and are synthesized in the smooth ER. Choice [A] is the correct answer. (memorization tip: oil is greasy and slippery, hence smooth) Choice [B] is incorrect; steroids skip the secondary messenger and go directly into the nucleus to affect transcription/translation activity. Choice [C] is incorrect; steroids can diffuse through the membrane and directly bind to receptors floating in the cytoplasm or receptors on the nucleus. Choice [D] is incorrect; steroids are direct stimulators. Choice [E] is incorrect; steroids are relatively more slow acting than peptide hormones.

What will increase Ecell, given the following equation? H2 (g) + F2 (g) → 2HF (aq) Eºcell = 0.9 A. Increase Q B. Increase temperature C. Decrease [H2] D. Decrease [F2] E. Decrease [HF] CHECKEXHIBIT

The Nernst Equation relates the reduction potential of an electrochemical reaction to the standard electrode potential, n, and Q. Ecell = standard E(^degree)cell - 0.592/n * log(Q) Answer option [A] is incorrect: As Q increases, Ecell decreases. Answer option [B] is incorrect: Temperature is not related to the Nernst Equation and thus, increasing temperatures will not increase Ecell. We can also use Le Chatelier's principle to predict the effect of concentration changes to the cell potential. Any change that favors the forward reaction will increase the cell potential. Answer option [C] is incorrect: Decreasing the concentration of H2 would shift the equilibrium to the left, thus decreasing Ecell. Answer option [D] is incorrect: Decreasing the concentration of F2 would shift the equilibrium to the left, thus decreasing Ecell. The only answer option that accurately describes the effect of changing concentrations is answer option [E]. As the concentration of HF decreases, Ecell increases. Thus, [E] is the correct answer. Topic:Electrochemistry and Oxidation Reduction Reaction

Which part of an electrocardiogram represents atrial depolarization? A. Q wave B. R wave C. S wave D. P wave E. T wave CHECKEXHIBIT

The P wave, the first small 'up-wave', represents both atria depolarizing. Therefore choice [D] is correct. The Q wave represents depolarization through the interventricular septum (initiates ventricular depolarization), not the atria depolarizing. Choice [A] is incorrect. The R wave represents depolarization through both ventricles, not the atria. Choice [B] is incorrect. The S wave represents the completion of the ventricular depolarization. Choice [C] is incorrect. The T wave represents ventricular repolarization. Choice [E] is incorrect.

All of the following statements describing the law of independent assortment are correct EXCEPT one. Which one is the EXCEPTION? A. Homologous chromosomes line up independently in meiosis I B. Independent assortment only occurs in meiosis C. Genes that are linked are likely to be inherited together D. The separation pattern of chromosomes is completely random E. Genetic variability is increased during this process CHECKEXHIBIT

The law of independent assortment states that in meiosis, homologous chromosomes line up at the metaphase plate independently of one another, which makes the separation of maternal and paternal alleles during anaphase I random. Choices [A], [B] and [D] can be eliminated. The random separation of the alleles contributes to genetic variability, eliminating choice [E]. Although choice [C], genes that are linked are likely to be inherited together is a correct statement, it does not correctly describe the law of independent assortment and is therefore the exception. Topic:Heredity

Which of the following is referred to as a cluster of genes typically inherited together? A. Genotype B. Phenotype C. Haplotype D. Epistasis E. Pleiotropy CHECKEXHIBIT

`When a group of genes are located very close together on a chromosome, they tend to be inherited together. These groups of genes are known as haplotypes. Choice [C] is correct. A genotype is the actual DNA sequence for a given allele while a phenotype is the observable trait that results from the genotype. Both are thus not clusters of genes; Choice [A] and [B] incorrect. Epistasis is the interaction between genes in which one gene can affect the expression of another gene. It does not refer to a cluster of genes; Choice [D] is incorrect. Pleiotropy occurs when a gene can be expressed in many different phenotypes. It does not refer to a cluster of genes; Choice [E] is incorrect.

All of the following describe alpha decay EXCEPT one. Which one is the EXCEPTION? A. Likely for a large nuclei B. Reduces mass number C. Represented by 42He D. Species loses neutrons E. Species loses electrons CHECKEXHIBIT

alpha decay occurs when a nucleus emits an alpha particle. Alpha particles are composed of 2 protons and 2 neutrons, making them the same as a He atom. Thus, you will often see alpha particles written as: Because the atom's nucleus is giving away two protons and two neutrons, the atom's atomic number (number of protons) will decrease by two and its mass number (number of protons + neutrons) will decrease by four. The number of electrons of the species does not change in an alpha decay. From the answer choices, the only answer that does not describe alpha decay is choice [E]. Thus, [E] is the correct answer.

formulas for quantitative electrolytic cell calculations: (grams and moles) 2 equations

amp*sec*MW/ n*F = grams product amps*sec/n*F = moles product If you want to solve for grams, use the top formula. If you want to solve for moles, just remove the molecular weight to get the second formula. (amps) = amperes, or the current (seconds) = the amount of time the reaction took place in seconds (MW) = molecular weight of the product (n) = moles of electrons in the reaction (F) = Faraday constant In this question, we are solving for the number of moles of Ag. Because we are looking for moles, we use the second formula and do not need the MW of Ag. We are already given the amp, seconds, and Faraday constant. The only remaining variable that we need is n (moles of electrons in the reaction). To find n, we must determine the change in oxidation state of Ag in this reaction. Ag goes from a +1 to a 0 oxidation state, indicating that 1 electron was moved in the reaction, therefore we will use 1 mole of electrons in the equation. Plugging in our numbers

to extract an acid, you need a _____ solution

basic (ie pH 10) the higher pH can deprotonate the acid and bring it from the ether layer into the aqueous layer

salivary amylase

contained within saliva, and begins the chemical digestion of carbohydrates in the mouth. Of the following answer choices, only starches fall under this category

Process for drawing Lewis structures

count number fo electrons required per atom identify the central atom start by drawing single bonds to connecting atoms lay down all the remaining electrons until the octets are filled/run out of electrons

thyroid gland

creates and secretes 3 hormones: T3, T4 (T3 and T4 increases basal metabolism), and calcitonin (decreases blood calcium levels)

EWGs on rings ____ ring rxns

deactivate... make slower

less electrons (cations) _____ size

decreases

Atomic radius

decreases across a period and increases down a group

Parthenogenesis

describes the development of an unfertilized egg into a viable organism

Natural selection

describes the non-random process of selection, or where alleles become more or less common as a result of the individual's interactions with the environment.

Annelid examples

earthworms, leeches true coeloms (body cavities) closed CS nephridia - excretory ganglia - nerve cluster

1. (CH3)2CHLi, Et2O, 2. H3O

eliminate also based on incorrect number of final carbons Realize that our first reactant, (CH3)2CHLi, is NOT LDA but an organolithium. In the first step, the CH of our organolithium attacks the carbonyl carbon, kicking a lone pair of electrons up onto the oxygen. In the second step, we protonate the oxygen, forming product

protists are ___otic classified according to ____

eukaryotic; locomotion

what does HWE state and assumptions?

genotype and phenotype stability can be achieved in a population law examines POPUlation gene pools (not individual) assuming these things, there shouldn't be a change in the population gene pool: large pop random mating no net migration no mutation no NS

gases are less soluble at ____ temperatures

higher more energy helps them escape the liquid

gases are more soluble at _____ pressures

higher more pressure forces gas into the liquid

why do atoms get larger going down a group?

higher energy (n) shell = larger size

ionic charge

how many electrons an atom must gain or lose to FORM OCTET ie +1, atom needs to lose 1 e-; -1, atom needs to gain one more e-

oocyte

immature egg cell in an ovary that may undergo meiotic division to form an ovum.

name 4 INTERmolecular forces STRONGEST to WEAKEST

ion-dipole hydrogen bonding dipole-dipole london dispersion

what makes glucagon

pancreatic alpha cells

Anaerobes

perform anaerobic respiration.

anterior pituitary gland

releases several hormones that are either tropic or direct. Hormones it produces can be remembered with the acronym FLAT PiG. "FLAT" hormones are tropic hormones, while "PiG" hormones are direct hormones.

adrenal medulla

responsible for fighting against short-term stresses (fight or flight response)

2 associated angles with trigonal bipyramidal

90 120

boyles law

P1V1=P2V2

CO2 on a molecule can look like

an ester

the more negatively charged the compound the more _____

basic it is

Which of the following accurately describes the phylum that is bilateral, pseudocoelomate, and can reproduce parthenogenetically?

Nematoda (Round worms, hook worms) and Rotifera (Rotifers) represent the phylums that are pseudocoelomate. Of the two, both have bilateral symmetry but only Rotifera can reproduce parthenogenetically. Therefore the correct answer choice is [C]. Cnidaria (hydra, jellyfish) only contains two germ layers and thus cannot be classified based on coelom. They are also radial in body symmetry and do not reproduce parthenogenetically. Choice [A] is eliminated. Mollusca (clam, snail, octopus) are bilateral, but they are coelomate and do not reproduce parthenogenetically. Choice [D] is eliminated. Echinodermata (starfish, sea urchin) are bilateral in larvae stage, but radial in adult stage. They are also coelomate and do not reproduce parthenogenetically. Choice [E] is eliminated. For questions about the phylums, it's always a good idea to memorize the mnemonic below: DAT Mnemonic: Privileged Children Play Nicely Rapidly And Maturely, Arthur Ensures Cooperation Porifera Cnidaria Platyhelminthes Nematoda Rotifera Annelida Mollusca Arthropoda Echinodermata Chordata

Which of the following enzymes is responsible for accepting electrons during the final step of non-cyclic photophosphorylation? A. NADP+ reductase B. RuBisCo C. PEP carboxylase D. ATP synthase E. Photosystem I CHECKEXHIBIT

Non-cyclic photophosphorylation describes the entirety of the light dependent reactions which excites electrons released from water and passes them down an electron transport chain. At the end of the electrons journey, they are passed to the final enzyme called NADP+ reductase, which reduces NADP+ to NADPH. Therefore answer choice [A] is correct. While both ATP synthase and Photosystem I are involved in non-cyclic photophosphorylation, they are only intermediate steps of the process and not the final enzymes that accept the electrons. Choice [D] and [E] can be eliminated. RuBisCo is a very common enzyme that is utilized in the Calvin cycle but not in light dependent reactions. Choice [B] is incorrect. PEP carboxylase is used in C4 photosynthesis, and is involved in fixing CO2 into a three-carbon molecule called PEP in a process called the PEP carboxylase reaction. It has no role in non-cyclic photophosphorylation, therefore choice [C] can be eliminated.

If you extracted cyclohexane with water and toluene, in which layer would the cyclohexane end up

Nonpolar molecules prefer nonpolar solvents while polar molecules prefer polar solvents. Because cyclohexane is nonpolar, it will prefer being in the nonpolar solvent: toluene

liquid oxygen (O2) is _____ while liquid nitrogen (N2) is _____

O2 --> paramagnetic N2 --> diamagnetic

acidity increases with

atomic size

(C2H5)2O solvent is

ether layer

Combines Gas Law

P1V1/T1 = P2V2/T2

lattice energy

the energy required to completely separate an ionic compound's cations from anions

Which of the following indicates a highly efficient enzyme? A. High KmB. Low VmaxC. High specificity constantD. Present in its apoenzyme stateE. Exhibits competitive inhibition

(Note: @ timestamp 2:01 - Km stays the same in noncompetitive inhibition.) Answer: C An enzyme's specificity constant indicates how efficiently an enzyme binds a substrate and converts it to a product. A high specificity constant indicates a highly efficient enzyme. Therefore the correct answer is [C]. A high Km indicates a low binding affinity of the enzyme and the substrate. A low binding affinity means that the enzyme cannot bind to the substrate, and therefore catalyze the reaction as easily. Km (Michaelis constant) has an inverse relationship with binding affinity. This eliminates choices [A] and [E]. Choice [E] is incorrect because competitive inhibition raises Km. Choice [B] is incorrect because Vmax is the maximum velocity at which an enzyme can carry out a reaction. A low Vmax value indicates a slow enzyme. Choice [D] is incorrect because an apoenzyme is an enzyme without its cofactor (a non-protein molecule that assists the enzyme in carrying out the reaction). An enzyme will work more efficiently in its holoenzyme state (the enzyme and its cofactor). Key Takeaways: Specificity constants indicate how efficiently an enzyme both binds a substrate and converts it to a productHigh specificity constant = efficient enzymeLow specificity constant = inefficient enzyme

we want to reduce an ester to a primary alcohol

1. H+, 2. OHCH2CH2OH, 2. LiAlH4 3. H3O+ That can be done through use of the hydride source LiAlH4 (recall that NaBH4 is not strong enough to reduce esters so it can only reduce aldehydes and ketones). However, we cannot simply add LiAlH4 as in [C] because the LiAlH4 will non-selectively reduce both carbonyl groups in our molecule. How can we reduce the ester but leave the ketone untouched? We first convert the ketone into a protecting group (a ketal) which does not react with LAH.

4 steps to generate a net ionic equation?

1. balance equation 2. use solubility rules to label everything as s, l, g, or aq 3. cut all the aq's in 1/2 separating their cations from their anions 4. cancel out all the species that are exactly the same on both sides (these are spectator ions)

process for comparing 2 organic molecules and analyzing if they're isomers... 4 questions...

1. do they have the same chemical formula? 2. do they have the same connectivity/bonding pattern? 3. are the 3D shapes different due to chiral centers, cis/trans, or E/Z isomerism? 4. if mirror images: ENANT. if NOT mirror images: DIAST.

`Tawny and Camela take 24 minutes to paint the entire wall together. If Tawny can paint a wall in 30 minutes, how fast can Camela paint the same wall? A. 30 B. 60 C. 90 D. 120 E. 150 CHECKEXHIBIT

1/time it takes Tammy + 1/time it takes Camela = 1/ time it takes both of them 1/30 minutes + 1/ X minutes = 1/24 minutes Solving for x gives us 120, which is the number of minutes that it takes Camela to paint the wall.

The National Institute of Science and Technology reviewed several commercially available clocks to determine the number of seconds they lost per year. They found that this data followed a Gaussian distribution with a mean of 400 seconds lost per year and a standard deviation of 50 seconds. What percentage of clocks lose less than 300 seconds per year? A. 0.3% B. 2.5% C. 5% D. 16% E. 32% CHECKEXHIBIT

A Gaussian distribution is also known as a normal distribution. That means that 68% of the data will fall within +/- 1 standard deviation (SD), 95% will fall within +/- 2 standard deviations, and 99.7% will fall +/- 3 standard deviations. In the figure below is a SD The problem states that the mean time lost is 400 seconds and that 1 SD is 50 seconds. With that being said, 300 seconds is 2 SD's below the mean. Looking as the figure, we can see that the mean minus two SD's leaves us with only 2.5%. That means only 2.5% of clocks would lose less than 300 seconds every year, making our final answer [B].

The conjugate acid of which of the following bases will have the highest Ka? A. PO43- (pKb = 1.62) B. C2H5NH2 (pKb = 3.13) C. CN- (pKb = 4.69) D. ClO- (pKb = 6.47) E. CH3COO- (pKb = 9.25) CHECKEXHIBIT

A higher pKb corresponds to a lower pKa. pKa + pKb = 14 A lower pKa corresponds to a higher Ka. pKa = -log[Ka] CH3COO- has the largest pKb.

When a horse and donkey reproduce, they produce a mule, which lives to adulthood, but cannot reproduce. What form of reproductive isolation is this?

A mule is a classic example of hybrid sterility, which defines when a hybrid zygote is sterile and cannot reproduce

dip in kinetics reaxtion graph represents....?

A reaction intermediate is a short-lived (transient) molecule that forms in a multistep reaction. It is a different, separate existing molecule that is unique from the reactants and the products.

Which of the following is true regarding voltaic cells? A. Oxidation is at the cathode B. Electrons flow from the anode to the cathode C. A non-spontaneous reaction D. Requires the input of energy E. The anode is positive CHECKEXHIBIT

A spontaneously reacting electrochemical cell is known as a voltaic or galvanic cell. A non-spontaneous reacting electrochemical cell is known as an electrolytic cell, and requires the input of energy. A major difference between a galvanic cell and an electrolytic cell is that in a galvanic cell the anode is negative and the cathode is positive, while in an electrolytic cell the anode is positive and cathode is negative. Therefore, choices [C], [D], and [E] can be eliminated. Using the mnemonic "AN OX" and "RED CAT", we can remember that OXidation occurs at the ANode, and REDuction occurs at the CAThode in an electrochemical cell. Choice [A] can also be eliminated. Regardless of the charges on the anode and cathode, the flow of the electrons always goes from anode to cathode. Thus, [B] is the correct answer. Topic:Electrochemistry and Oxidation Reduction Reactions

What does the adrenal gland regulate? A. Metabolism B. Puberty C. Digestion D. Water retention E. Stress

Adrenal glands are known to help us cope with stress

gastrula

An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.

colligative properties depend on WHAT

COLLIGATIVE = CONCENTRATION OF SOLUTE properties that depend on the CONCENTRATION of solute particles but not on their identity

As you move down and to the left on the periodic table: A. Atomic radius decreases and electronegativity decreases B. Atomic radius decreases and electronegativity increases C. Atomic radius does not change but electronegativity increases D. Atomic radius increases and electronegativity increases E. Atomic radius increases and electronegativity decreases CHECKEXHIBIT

Atomic radius increases down and to the left of the periodic table because of added electron shells and a decrease in protons. Electronegativity decreases down and to the left of the periodic table because it is harder to remove an electron from a full shell close to the nucleus.

Beta decay is the process that converts a ____

Beta decay is the process that converts a neutron to a proton and electron.

In which part of the cell does beta-oxidation of fatty acids take place? A. Cytoplasm B. Smooth ER C. Mitochondrial matrix D. Nucleolus E. Lysosomes CHECKEXHIBIT

Beta-oxidation is the process of creating ATP from fatty acids (The product of beta-oxidation is acetyl-CoA, which will directly enter the Krebs cycle) and occurs in the mitochondrial matrix. Thus the correct answer is [C]. Choice [A] is incorrect; glycolysis instead takes place in the cytoplasm. Choice [B] is incorrect; the smooth ER is the site of fat and steroid synthesis, not beta-oxidation. Choice [D] is incorrect; the nucleolus is the dense region within the nucleus responsible for rRNA production, not beta-oxidation. Choice [E] is incorrect; lysosomes function to break down substances, not perform beta-oxidation. Topic:Cellular Energy I have a question about this explanation I have feedback about this explanation

During an action stroke, where does calcium bind after being released from the sarcoplasmic reticulum? A. Actin B. H-zone C. Troponin D. Myosin E. M-line

Calcium is released from the sarcoplasmic reticulum into the sarcoplasma, where it binds to troponin-C. Choice [C] is correct. Calcium binding to troponin triggers a conformational change in troponin, causing it to pull tropomyosin away from the actin filaments to allow the myosin filaments to bind and perform the rest of the contraction. Choices [A] and [D] are incorrect. The H-zone defines the part of the sarcomere where we only have myosin, not where calcium binds. Choice [B] is incorrect. (Mnemonic: H is a thick letter, so the H-zone is the region of thick filaments - myosin). On the other hand, the M-line represents the midpoint of each sarcomere. Choice [E] is incorrect. Topic:Anatomy and Physiology

amphioxus and tunicates

Chordates that are not vertebrates - do NOT lose their notocord

mnemonic below to easily remember the different epidermal layers Come Let's Get Some Beers

Corneum Lucidum Granulosum Spinosum Basale

Arrange the following gases in order of decreasing density at STP, assuming ideal behavior. Carbon Monoxide, CO Hydrogen, H2 Oxygen, O2 A. III > II > I B. II > I > III C. II > III > I D. I > II > III E. III > I > II CHECKEXHIBIT

Density = Pressure* molarmass / R*Temp Density depends on molar mass. The higher the molar mass, the higher the density. CO = 28 g/mol H2 = 2 g/mol O2 = 32 g/mol

a straight line (decreasing) kinetics graph represents what order rnx?

Different reaction orders have characteristic data points, producing a straight line. The three characteristic plots you should know for the DAT are zero, first, and second order rates. If the reaction is first order, a plot of ln[x] (natural logarithm) vs time will produce a straight line with the slope = -k (like shown in the given graph). Thus, [B] is the correct answer.

How many sigma (σ) and pi (π) bonds are there in the molecule? H3C nitrile carbonyl H3c

Each single bond in a molecule indicates one sigma bond. Double bonds are made up of one sigma bond and one pi bond. Triple bonds are made up of one sigma bond and two pi bonds. In our molecule here, we see that we have single, double, and triple bonds. Do not forget to draw out your hydrogens! There are two methyl groups on the left and right sides respectively, so there are six more H bonds we need to draw in. Let's now count our bonds: 3 C-C single bonds, 1 C-C triple bond, 1 C=O double bond, and 6 C-H single bonds. This brings us to a total of 11 sigma bonds and 3 pi bonds, thus option [A] is our correct answer.

counting sigma and pi bonds`

Each single bond in a molecule indicates one sigma bond. Double bonds are made up of one sigma bond and one pi bond. Triple bonds are made up of one sigma bond and two pi bonds. In our molecule here, we see that we have single, double, and triple bonds. Do not forget to draw out your hydrogens! There are two methyl groups on the left and right sides respectively, so there are six more H bonds we need to draw in. Let's now count our bonds: 3 C-C single bonds, 1 C-C triple bond, 1 C=O double bond, and 6 C-H single bonds. This brings us to a total of 11 sigma bonds and 3 pi bonds, thus option [A] is our correct answer. Topic:Bonding and Molecular Geometry I have a question about this explanation I have feedback about this explanation

Which of the following was present in Earth's primordial atmosphere?

Earth's primordial atmosphere mostly consisted of inorganic compounds including methane (CH4), ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), hydrogen gas (H2), nitrogen gas (N2), water (H2O), hydrogen sulfide (HS). Choice [A] is correct.

Which of the following has a negative ∆Srxn? A. Freezing B. Sublimation C. Vaporization D. Fusion E. Pressure decreasing CHECKEXHIBIT

Entropy describes the fact that the universe favors disorder over order. The entropy of a system increases as the disorder of the system increases (when molecules are more separated and disordered, or more moles/molecules are produced). Entropy decreases (ΔS < 0) with an increase in pressure. Answer choice [E] is the opposite with a decrease in pressure resulting in a positive entropy. Thus, choice [E] can be eliminated. Generally speaking, all the phase changes going from solid to liquid to gas result in an increase in entropy, as atoms are held less rigidly at each phase. Because they are more free to move about, they are in a state of greater disorder or greater entropy (ruling out answers [B], [C], and [D]). On the other hand, phase changes going in the reverse direction (gas to liquid or liquid to solid) are associated with a decrease in the entropy of the system. Take freezing, for example: molecules of liquid water become more ordered by coming together to form solid ice. This increase in order is the same as a decrease in entropy, so answer choice [A] is correct. Topic:Thermodynamics and Thermochemistry

In an ecological community, deer and bison compete for small shrubs as a food source. A sudden growth in the deer population causes depletion of food for the bison. This is an example of: A. Interference competition B. Antagonism competition C. Exploitation competition D. Apparent competition E. Intraspecific competition CHECKEXHIBIT

Exploitation competition occurs when resources are depleted. The deer depleted food for the bison. [C] is the answer. Interference competition occurs when two individuals directly compete through aggression, for example. [A] is incorrect. Antagonism competition is not a form of competition. [B] is incorrect. Apparent competition occurs when one predator preys on two species. [D] is incorrect. Intraspecific competition occurs between members of the same species. [E] is incorrect.

In an ecological community, deer and bison compete for small shrubs as a food source. A sudden growth in the deer population causes depletion of food for the bison. This is an example of: A. Interference competition B. Antagonism competition C. Exploitation competition D. Apparent competition E. Intraspecific competition

Exploitation competition occurs when resources are depleted. The deer depleted food for the bison. [C] is the answer. Interference competition occurs when two individuals directly compete through aggression, for example. [A] is incorrect. Antagonism competition is not a form of competition. [B] is incorrect. Apparent competition occurs when one predator preys on two species. [D] is incorrect. Intraspecific competition occurs between members of the same species. [E] is incorrect. Topic:Ecology

Which set of reagents is best for preparing (Z)-4-methyl-2-hexene from 4-methyl-2-hexyne? A. H2, Pd/C B. Na/NH3 C. H2NNH2, NaOH D. Zn(Hg) / HCl E. H2, Lindlar's catalyst (Pd/CaCO3) CHECKEXHIBIT

First, let's draw out our starting material, 4-methyl-2-hexyne, and our product, (Z)-4-methyl-2-hexene. Here is the reaction we want to have occur: We want to convert an alkyne into a cis or Z alkene. The reagents the DAT uses for this transformation are H2 with Lindlar's catalyst (option [E]).

Michael is twice as old as his sister. How old is Michael? Michael was four times as old as his sister two years ago Michael's sister will be 8 years old in five years A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statement (1) and (2) TOGETHER are NOT sufficient.

From the question, we know that Michael is twice as old as his sister. Let m represent Michael's age and s represent his sister's age: m = 2s Statement (1) tells us that Michael was four times as old as his sister was 2 years ago. We can express this as: m - 2 = 4(s - 2) Since we have two distinct equations and two variables to solve for, we are able to solve for the values of both m and s. This means that statement (1) alone gives us enough information to solve for Michael's age. Statement (2) tells us that Michael's sister will be 8 years old in five years. We can express this as: s + 5 = 8 Solving for s tells us the age of Michael's sister, and we can easily use this to solve for Michael's age using the first equation we wrote. This means that statement (2) alone gives us sufficient information. Since both statements alone give us sufficient information, the correct answer is [D].

Which of the following organs is necessary for gluconeogenesis in the Cori cycle? A. Liver B. Pancreas C. Thymus D. Kidneys E. Thyroid gland CHECKEXHIBIT

Gluconeogenesis creates new glucose from different types of fuel sources. In the Cori cycle, lactate is recycled back into glucose. Lactate is transported to hepatocytes to be oxidized back into pyruvate, and then pyruvate is converted to glucose through gluconeogenesis. Hepatocytes are liver cells, therefore the correct answer is [A]. Choice [B] is incorrect; the pancreas is involved in regulating the glucose level in our body and secreting digestive enzymes, not gluconeogenesis. Choice [C] is incorrect; the thymus plays an important role in developing T cells, not gluconeogenesis. Choice [D] is incorrect; the kidney functions to filter waste and excess water out of the blood and has no involvement in gluconeogenesis. Choice [E] is incorrect; the thyroid gland is responsible for regulating calcium levels and metabolism and has no involvement in gluconeogenesis. Topic:Cellular Energy

When two monosaccharides join to form a disaccharide, a glycosidic bond links them together. Which of following processes accomplishes the formation of a glycosidic linkage? A. HydrolysisB. AminoacyltransferaseC. DehydrationD. Amide-bond formationE. Saturation

Glycosidic linkages are formed through the process of dehydration. Carbohydrates have some variation of the chemical composition CHO, often seen as a carbon ring with OH groups and H's sticking out of it. To form a bond between two carbohydrates, you must remove an OH from one carbohydrate and an H from another. This forms a glycosidic linkage and produces a molecule of H2O as a byproduct. Because a water molecule is taken away from the carbohydrate molecules, this process is called dehydration. Choice [A] is incorrect because hydrolysis is the process that breaks glycosidic linkages. Hydrolysis is the opposite reaction of dehydration, which is the process that forms glycosidic linkages. Choice [B] is incorrect because aminoacyltransferases is a group of enzymes used in transferring amino groups. This reaction does not have anything to do with glycosidic linkage formation. Choice [D] is incorrect because an amide-bond is formed to join amino acids together, during the formation of peptides. It joins the carbonyl group of one amino acid and the amine group of the adjacent amino acid. This reaction does not have anything to do with glycosidic linkage formation. Choice [E] is incorrect because saturation is the term for the amount of double bonds present in a fatty acid. A hydrogenation reaction will add hydrogen to a molecule to remove double bonds. This concept does not have anything to do with glycosidic linkage formation. Key Takeaways: Glycosidic linkages are formed through the process of dehydration - OH from one carbohydrate and H from adjacent carbohydrate (H2O).

If H2O has a pKA of 15.7 and acetic acid has a pKA of 4.75, which is a stronger base, hydroxide (OH-) or acetate (C2H3O2-)? A. H2O B. OH- C. acetic acid D. C2H3O2- CHECKEXHIBIT

H2O is the weaker acid as evidenced by its high pKA, thus it will have the stronger conjugate base in OH-. All in all, a weaker acid results in a stronger conjugate base.

what are the 5 hormones of the anterior pituitary

HGH LH FSH TSH Prolactin

Hund's Rule

HUN, DON'T pair electrons unless you have to!

In what part of the integumentary system are hair follicles' erector pili muscles? A. Epidermis B. Dermis C. Glands D. Hypodermis E. Connective tissue

Hair follicles and their erector pili muscles are contained in the dermis. These muscles function to erect hair ("goosebumps") and play roles in temperature regulation and scaring off predators in some mammals. Choice

standard states of elements: Hg, Cl2, N2, H2, graphite

Hg - liquid Cl2 - gas N2 - gas H2 - gas graphite -

what 2 elements are liquids in standard states?

Hg and Br

How many electrons are transferred in the following equation? Zn (s) → ZnSO4 (s) A. 1 B. 2 C. 3 D. 4 E. 5 CHECKEXHIBIT

How many electrons are transferred in the following equation? Zn (s) → ZnSO4 (s) A. 1 B. 2 C. 3 D. 4 E. 5 Incorrect On the DAT, you won't be expected to fully balance out entire redox equations, simply because it takes too much time. Instead, you'll be asked to do a part of a balance redox equation. If we find the oxidation states of zinc in the reactant phase and in the product phase, we can find the amount of electrons that were transferred in this half-reaction. We can immediately see that the oxidation state of zinc in the reactant is 0 following the rules of assigning oxidation numbers. As a reminder, here are the rules for assigning oxidation number: The oxidation number of an atom in its elemental form is zero (e.g. N2, Ag). The oxidation number of a monatomic ion is equal to its charge (e.g. Ca2+ has an oxidation number of +2). The sum of oxidation numbers in a molecule or formula is zero. The sum of oxidation numbers in a polyatomic ion is equal to the charge of the ion. The oxidation number of Group IA is +1 in all of its compounds. Group IIA has an oxidation number of +2 in all of its compounds. Hydrogen has an oxidation number of +1 if combined with nonmetals and -1 if combined with a metal and boron. Fluorine has an oxidation number of -1 in all of its compounds. Oxygen has an oxidation number of -2 in all of its compounds except in peroxide (-1) and when combined with F (e.g. in OF2, because F has an oxidation number of -1 in all of its compounds, it follows that O has an oxidation number of +2). Halogens have an oxidation number of -1 if combined with metals, nonmetals (except O), and other halogens lower in the group. The key to figuring out the oxidation state of zinc on the product side is recalling your polyatomic ions. SO4 is a polyatomic ion with an oxidation number of -2. Since we only have 1 mole of sulfate ion, the overall negative charge on this molecule is -2 and therefore, in order for the overall charge to be zero, the oxidation number of zinc must be +2. The difference between zinc on the reactant side versus product side is 2 electrons. Thus, [B] is the correct answer. Topic: Electrochemistry and Oxidation Reduction ReactionsI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

Draw trans-1,2-dibromocyclohexane in a chair conformation.

In this question, we are trying to find the correct molecule for trans-1,2-dibromocyclohexane: Choice [A] has both bonds to Br pointing down; this is cis-1,2-dibromocyclohexane. Choice [C] is cis-1,4-dibromocyclohexane. Both bonds to Br are pointing up so this is "cis", not "trans". Choice [D] is trans-1,4-dibromocyclohexane. Choice [B] is trans-1,2-dibromocyclohexane. One Br is pointing up and other is pointing down. This is trans-1,2-dibromocyclohexane!

The mean and standard deviation of a set of numbers is given by x and y, respectively. If all of the numbers are subtracted by 2, how do x and y change? A. both decrease B. both stay the same C. x decreases, y stays the same D. x decreases, y increases E. x stays the same, y decreases CHECKEXHIBIT

In a data set, the mean is the average of all of the numbers that compose the set that is found by summing the numbers and dividing the total by the number of values in the data set. If all of the numbers are subtracted by 2, the mean will decrease by exactly 2 as well. The standard deviation measures the average of how far each data point lies from the mean within the data set. Since every value in the data set is subtracted by 2, the entire data set shifts by the exact same amount and the standard deviation remains unaffected. The average distance of each point from the mean stays the same. Since the mean is represented by x and the standard deviation is represented by y, option [C] is the correct answer. Topic:Probability and Statistics

OCH# grop on tri-carbon... reacts with HCl over heat

In the first step of this reaction, the O gets protonated by our strong acid, HCl. This leaves the HOCH3 with a positive charge, making it a good leaving group. The HOCH3 leaves, leaving behind a tertiary carbocation. Now the Cl- can come and attack the carbocation, forming [B] as the final product. Note this reaction occurred in SN1 fashion.

example sn1

In this reaction, we substitute a Cl for -OH ; this is a substitution reaction. This eliminates Choice [A] which is an addition reaction and Choices [D] and [E] which are both elimination reactions. This leaves us between Choices [B] and [C]. We must decide whether this reaction when through an SN1 or an SN2 route. The leaving group is a secondary halide, which can favor either SN1 or SN2. Water is a weak nucleophile, so this discourages SN2, since it cannot displace the leaving group and attack all in one step. Notice, the substitution reaction takes place at a chiral center and we are doing substitution via SN1. We will get a 50/50 racemic mix of enantiomers as our products.

If [(x + y) (d + e)] / 3 is equal to 24 and d + e = 8, then which of the following is equivalent to 5x + 5y? A. 40 B. 45 C. 50 D. 55 E. 60

Incorrect We can easily eliminate a variable from the first expression by plugging 8 in for (d + e). This gives us We can simplify this by dividing 24 by (8/3) to give us x + y = 9 We are asked to find 5x + 5y. Since each term in this expression is multiplied by 5, we can simplify to yield 5(x+y) Since we know the value of (x+y), we can plug it in to determine the correct answer. 5(9) = 45 Option [B] is the correct answer. Topic: AlgebraI have a question about this explanationI have feedback about this explanation NEXTEXHIBIT

All of the following are a result of high intermolecular forces EXCEPT one. Which one is the EXCEPTION? A. Low vapor pressure B. Low viscosity C. High boiling point D. High heat of vaporization E. High surface tension CHECKEXHIBIT

Intermolecular forces are the forces that attract molecules to each other. The stronger the intermolecular forces, the more intensely molecules are attracted to each other and hence, "stick" together. Higher intermolecular forces leads to: Higher boiling point Higher heat of vaporization Higher viscosity Higher surface tension Lower vapor pressure The question is asking for the exception, so we are looking for an effect that doesn't occur from higher intermolecular forces. Higher intermolecular forces leads to all of the answer choices except lower viscosity.

Place the following elements in order of increasing ionization energy: Li, N, B, F A. B, N, Li, F B. F, N, B, Li C. F, B, N, Li D. N, B, F, Li E. Li, B, N, F CHECKEXHIBIT

Ionization energy increases from the bottom left to the top right of the periodic table. [E] is the answer that follows this trend.

Michael pays $60 for an order of 800 markers. If 25% of the markers get lost in shipping, how much should Michael charge per marker to make a 150% profit? A. $0.10 B. $0.18 C. $0.22 D. $0.25 E. $0.30 CHECKEXHIBIT

Let's first calculate the amount that Michael has to make in order to make 150% profit. If he made 150% profit on his initial cost of $60, he would make an additional $90 dollars ($60 would give him 100% profit and another $30 would give him another 50% profit for a total of 150% profit). This means he must make $150 total. Now let's find the number of markers that Michael receives by multiplying his order of 800 markers by .75 (75%). This tells us that Michael only receives 600 markers. Since we know how many markers Michael received and how much money he needs to make, we can do simple division do find out how much he must sell each marker for. $150 / 600 markers = $0.25 per marker FAQ: Isn't 150% of 60 just 90? Why do we add it to $60? A: 150% profit of $60 is indeed $90. However, the question is asking how much he should charge per marker to make a 150% profit. This means he must also factor in cost. If he wants to make up the initial $60 he accrued in cost, then he must add that to the $90 profit he intends to make, which results in $150.

All of the following is found within a cell membrane EXCEPT for one. Which one is the EXCEPTION? A. Phospholipids B. Cholesterol C. Proteins D. Lumen E. Glycolipids CHECKEXHIBIT

Lumen in biology refers to the "inside space" of a referenced structure, such as the thylakoid lumen within the thylakoids of chloroplasts. Since lumen will not be found in a cell membrane and we are looking for the exception, choice [D] is correct. Choice [A] is incorrect because phospholipids make up the phospholipid bilayer of cell membranes. Choice [B] is incorrect because cholesterol is present in the cell membrane to affect membrane rigidity. Choice [C] is incorrect because membrane proteins are found dispersed throughout the cell membrane. Choice [E] is incorrect because glycolipids are found in all eukaryotic cellular membranes, extending into the extracellular environment.

a molecule is MORE ACIDIC with..

MORE STABLE CB. We can gauge the acidity of a molecule based on the stability of the resulting conjugate base.

What is the pOH of a 10.1 x 10-8 M solution of NaOH?

NaOH is a strong base and will dissociate completely. A 10.1 x 10-8 M solution of NaOH will dissociate into 10.1 x 10-8 M of Na+ and 10.1 x 10-8 M of OH-. NaOH ↔ Na+ + OH- Convert from [OH] to pOH. pOH = -log[OH-] pOH = -log[10.1 x 10-8]

Which of the following accurately describes the phylum that is bilateral, pseudocoelomate, and can reproduce parthenogenetically? A. Cnidaria B. Nematoda C. Rotifera D. Mollusca E. Echinodermata CHECKEXHIBIT

Nematoda (Round worms, hook worms) and Rotifera (Rotifers) represent the phylums that are pseudocoelomate. Of the two, both have bilateral symmetry but only Rotifera can reproduce parthenogenetically. Therefore the correct answer choice is [C]. Cnidaria (hydra, jellyfish) only contains two germ layers and thus cannot be classified based on coelom. They are also radial in body symmetry and do not reproduce parthenogenetically. Choice [A] is eliminated. Mollusca (clam, snail, octopus) are bilateral, but they are coelomate and do not reproduce parthenogenetically. Choice [D] is eliminated. Echinodermata (starfish, sea urchin) are bilateral in larvae stage, but radial in adult stage. They are also coelomate and do not reproduce parthenogenetically. Choice [E] is eliminated. For questions about the phylums, it's always a good idea to memorize the mnemonic below: DAT Mnemonic: Privileged Children Play Nicely Rapidly And Maturely, Arthur Ensures Cooperation Porifera Cnidaria Platyhelminthes Nematoda Rotifera Annelida Mollusca Arthropoda Echinodermata Chordata Topic:Diversity of Life I have a question about this explanation I have feedback about this explanation

assimilation

Nitrates are taken up by plant roots in a process called assimilation, which denitrifying bacteria plays no role in. Choice [D] is incorrect.

Which of the following enzymes is responsible for accepting electrons during the final step of non-cyclic photophosphorylation?

Non-cyclic photophosphorylation describes the entirety of the light dependent reactions which excites electrons released from water and passes them down an electron transport chain. At the end of the electrons journey, they are passed to the final enzyme called NADP+ reductase, which reduces NADP+ to NADPH. Therefore answer choice [A] is correct. While both ATP synthase and Photosystem I are involved in non-cyclic photophosphorylation, they are only intermediate steps of the process and not the final enzymes that accept the electrons. Choice [D] and [E] can be eliminated. RuBisCo is a very common enzyme that is utilized in the Calvin cycle but not in light dependent reactions. Choice [B] is incorrect. PEP carboxylase is used in C4 photosynthesis, and is involved in fixing CO2 into a three-carbon molecule called PEP in a process called the PEP carboxylase reaction. It has no role in non-cyclic photophosphorylation, therefore choice [C] can be eliminated. Topic:Photosynthesis

Which of the following names best describes clusters of rod shaped bacteria? A. Streptococcus B. Streptobacillus C. Staphylococcus D. Staphylobacillus E. Spirochetes

Notice that the bacteria have certain naming conventions, which can be used to determine bacterial shapes. Strep- bacteria typically grow and attach together in a chain while staph- bacteria are found in clusters. Coccus bacteria have a spherical shape while bacillus bacteria have a rod-like shape. Using these naming conventions above, we find that choices [A], [B], and [C] are incorrect. Our correct answer is choice [D]. Choice [E] is incorrect because spirochetes are spiral shaped bacteria.

Which of the following plant hormones ends seed dormancy and stimulates fruit production? A. Abscisic acid B. Gibberellins C. Cytokinins D. Auxins E. Ethylene CHECKEXHIBIT

Of the five plant hormones you must remember for the DAT, Gibberellins affects stem and shoot elongation, flowering, and also seed dormancy and stimulating fruit production. Choice [B] is correct. *remember auxins are responsible for plant tropisms! (phototropism, gravitropism and thigmotropism)

If osmotic pressure increases on one side of a U-shaped tube, what will happen to the solution on the other side of the tube? A. Density increases B. Solubility increases C. Temperature increases D. Height increases E. Concentration increases CHECKEXHIBIT

Osmotic pressure is the pressure that must be applied to prevent net movement of water from lower concentration to higher concentration. From the above diagram, as osmotic pressure increases (P1 ) is applied on the left side of the U-shaped tube, the height of the right side increases. Thus, [D] is the correct answer.

Direct hormones (stimulate other organs directly) PiG

P - Prolactin i - ignore! G - Growth Hormone (GH)

Π bonds are formed by which of the following orbitals? A. Two p-orbitals B. Two s-orbitals C. One s- and one p-orbital D. All of the above

Pi bonds are always formed by the "side by side"/parallel overlap of unhybridized p-orbitals! Sigma bonds are always formed by the direct overlap of orbitals and orbital hybridization (s and p-orbitals together).

Which of the following is a pluripotent stem cell? A. Zygote B. Blastomere of the morula C. Inner cell mass cells D. Hematopoietic cell E. Spore Incorrect

Pluripotent stem cells are stem cells that can differentiate into any of the three germ layers and give rise to any cell type, but can't develop extraembryonic tissue. An example of a pluripotent stem cell are inner cell mass cells. Choice [C] is the correct answer. A zygote and the blastomere of the morula are examples of totipotent cells, single cells that has the potential to become an entire organism. Choices [A] and [B] are incorrect. A hematopoietic cell (divides into many different types of blood cells) is an example of a multipotent cell, a cell that can give rise to only some of the three germ layers. Choice [D] is incorrect. Finally a spore is a reproductive cell used in many plants, algae, fungi and protozoa. They are not stem cells and therefore choice [E] is incorrect. Topic:Reproduction and Developmental Biology

All of the following steps are involved in the PCR process EXCEPT one. Which one is the EXCEPTION? A. Denaturation splits DNA into single strands B. Telomerase preserves the ends of DNA strands C. Temperature is lowered for primer annealing D. DNA primers hybridize to DNA strands E. Taq polymerase performs elongation of DNA CHECKEXHIBIT

Polymerase chain reaction (PCR) is used to amplify DNA fragments and involves three steps referred to as denaturation, primer annealing, and elongation. Denaturation splits DNA into single strands, primer annealing allows hybridization of DNA primers under low temperatures, and elongation uses Taq polymerase for synthesis of complementary DNA strands. Choices [A], [C], [D], and [E] are incorrect. On the other hand, telomerase is an enzyme that adds repetitive sequences to the ends of DNA strands during natural DNA replication and is not involved in PCR. Since we are looking for the exception, our correct answer is choice [B

Graham's Law of Effusion Equation

Rate1/Rate2=square root of (M2/M1)

Which of the following reactions represents a propagation step in the free radical bromination of propane? (what does propagation entail?)

Recall that a propagation step is any step that has at least one radical on both sides of the equation. Thus we should look for a step in which there is at least one radical on both sides of the equation.

Given a half life of 10 minutes and a sample of 60 g 178Au, how many grams remain after 30 minutes? A. 7.5 B. 15 C. 20 D. 30 E. 60 CHECKEXHIBIT

Recall that the amount of sample will halve with each passing half-life. 30 minutes is three half-lives. The sample will fall to half its value three times. Thus, to calculate the remaining grams after three half-lives, we write: 60 g * (1/2) * (1/2) * (1/2) = 7.5 g The correct answer is [A].

proton NMR signals

Remember that just as with 13C-NMR, if two different hydrogens are in exactly the same environment -that is, they have the EXACT same stuff all around them in all directions- then they are the "same kind of" (or "equivalent") hydrogens. The number of signals we see on our 1H-NMR spectrum will equal the number of non-equivalent (different) hydrogen atoms in our molecule. The hydrogens on the CH3 to the right of the carbonyl are unique from the other hydrogens in the molecule (they are bound to a carbon that is bound to a carbonyl carbon), though they are equivalent with one another. The H on the CH left of the carbonyl is unique as well (it is bound to a carbon that is bound to a carbonyl carbon and two methyl groups). The six H's coming off the methyl groups bound the CH are a third unique type of hydrogen, though they are equivalent with one another (they are all bound to a carbon that is bound to CH). Because there are three types of unique hydrogens in this molecule, we will three signals.

most stable cation?

Remember the trend for carbocation stability (from most stable to least stable): tertiary allylic > secondary allylic > tertiary > primary allylic > secondary > primary. Also recall that an allylic carbocation is one that is one bond away from a double bond; in other words, it is a resonance stabilized carbocation. The carbocation in [D] is bound to three other carbons, making it a tertiary carbocation. However, also notice that it is resonance stabilized by the adjacent double bond. Swinging the double bond down results in another tertiary carbocation at the top of the molecule. This tertiary allylic is the most stable type of carbocation, making it the correct answer. [A] is a primary allylic carbocation (if you draw the resonance structure you get a secondary carbocation). [B] is a tertiary carbocation; however, it lacks resonance stabilization, making it weaker than nearly all the other answers. [C] is a secondary allylic carbocation which is quite stable, but not as stable as [D]. [E] is a vinylic cation which is very unstable as it is not allylic like our other answer choices. It is the least stable out of all our answer choices as it is not stabilized by resonance.

Which of the following is true of ribozymes? A. Make a reaction more spontaneousB. Are chemically changed during a reactionC. Are composed of proteinsD. Require cofactorsE. Lowers activation energy

Ribozymes are RNA molecules that act as enzymes. The fact that they are RNA molecules eliminates answer choice [C]. The fact that they are enzymes eliminates answer choices [A] and [B] while leading us to the correct answer choice [E]. Enzymes act as catalysts for reactions by lowering the activation energy and accelerating the rate of reactions. They do not make a reaction more spontaneous (choice [A]) and do not change chemically during the reaction (choice [B]). Although they can undergo conformational/physical changes, enzymes will never change in chemical composition during a reaction. Enzymes are chemically constructed to bind specific substrates and to catalyze specific reactions. To change the chemical composition of an enzyme is to remove the enzyme's ability to do its job. Choice [D] is incorrect because there is no general rule that all ribozymes (or enzymes) require cofactors to function. Key Takeaways: Enzymes do NOT make a reaction more spontaneous. Enzymes do NOT change chemically during a reaction.

Sebum is released in all of the following locations EXCEPT one. Which is the EXCEPTION? A. Nose B. Back of hand C. Palm of hand D. Eyelid E. Elbow CHECKEXHIBIT

Sebum are the oily and waxy products of sebaceous glands, and function to lubricate and waterproof surrounding hair and skin. They are located everywhere EXCEPT the palms of the hands and soles of the feet. Choice [C] is the exception and the correct answer.

Two people leave from the same building. After 3 hours, they are 15 miles apart. If one walked due east at 3 miles per hour, how fast did the other walk due north? A. 2 mph B. 3 mph C. 4 mph D. 5 mph E. 6 mph CHECKEXHIBIT

Since due east and due north are at right angles from one another, we can solve this problem using the Pythagorean theorem. Since the two people are 15 miles apart at the end, we know that 15 miles must be the hypotenuse. We can easily find the length of one leg of the triangle by multiplying the rate given to us by the time. 3 mph * 3 hours = 9 miles We now use the Pythagorean theorem to find the length of the third leg. 92 + b2 = 152 b2 = 144 b = 12 Since this person walked 12 miles in the same time as the other person (3 hours), he must have walked 4 miles per hour.

What type of intermolecular force is most responsible for methanol's solubility in water? A. London dispersion forces B. Dipole-dipole C. Ion-dipole D. Hydrogen bonding E. Metallic bonding CHECKEXHIBIT

Solubility depends on the similarity of intermolecular forces of attraction: like dissolves like. As a result, polar substances dissolve in polar solvents, while nonpolar substances dissolve in nonpolar solvents. Looking at the image above, you can see that methanol contains an -OH group. This -OH group can form hydrogen bonds with water, making it soluble in water. Thus, [D] is the correct answer.

identical compounds

are meso = the same molecule Have the same R, S designations at every tetrahedral Stereogenic center

When the following equation is balanced using the smallest whole numbers, what is the coefficient in front of H2(g) on the reactant side of the reaction? CO(g) + H2(g) → C8H18(l) + H2O(l) A. 17 B. 18 C. 19 D. 20 E. 21 CHECKEXHIBIT

Starting with carbon, there are 8 carbons on the right side of the equation. Adding a coefficient of 8 in front of CO balances the carbons. Now that there are 8 oxygens on the left, adding a coefficient of 8 in front of H2O balances the oxygens. Given C8H18 and 8H2O, there are 34 hydrogens on the right. A coefficient of 17 in front of H2 on the left will balance the equation. 8CO(g) + 17H2(g) → C8H18(l) + 8H2O(l) On both sides of the equation there are now 8 carbons, 8 oxygens, and 34 hydrogens.

When the following equation is balanced using the smallest whole numbers, what is the coefficient in front of H2(g) on the reactant side of the reaction? CO(g) + H2(g) → C8H18(l) + H2O(l) A. 17 B. 18 C. 19 D. 20 E. 21 CHECKEXHIBIT

Starting with carbon, there are 8 carbons on the right side of the equation. Adding a coefficient of 8 in front of CO balances the carbons. Now that there are 8 oxygens on the left, adding a coefficient of 8 in front of H2O balances the oxygens. Given C8H18 and 8H2O, there are 34 hydrogens on the right. A coefficient of 17 in front of H2 on the left will balance the equation. 8CO(g) + 17H2(g) → C8H18(l) + 8H2O(l) On both sides of the equation there are now 8 carbons, 8 oxygens, and 34 hydrogens. [A] is the correct answer.

Consider the frequency table below. Solve for x. The median is 30 The mode is repeated x times

Statement (1) does not actually give us any information that we didn't already know from the chart. Since x appears in the same frequency both above and below 30 in the data set, any value of x could be inserted and the median would remain the same. Statement (1) is definitely not sufficient on its own. Statement (2) tells us that the value that is repeated the most is repeated x times. However, this only lets us know that x must be greater than or equal to 9; it tells us nothing else. Thus, statement (2) alone is insufficient. Since statement (2) is insufficient alone and statement (1) doesn't give us any new information, the correct answer is [E]; Statement (1) and (2) TOGETHER are NOT sufficient. Topic:Data Analysis, Interpretation, and Sufficiency

Glycosylation, sulfation and phosphorylation (of proteins) represent functions of which cell organelle?

The Golgi apparatus is an organelle which somewhat resembles a stack of pita bread or pancakes. Its purpose is to modify proteins that are manufactured by the endoplasmic reticulum. Within the Golgi are resident enzymes, which catalyze the cargo proteins. The modification processes are glycosylation - the adding or removing of sugars from the protein, sulfation - addition of sulfate groups and phosphorylation - adding phosphate groups.

Michael Reaction

The Michael reaction or Michael addition is the nucleophilic addition of a carbanion or another nucleophile to an α,β-unsaturated carbonyl compound containing an electron withdrawing group. It belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C-C bonds.

The specific heat capacity for a variety of substances is given in J/gºC. Which of the following has the lowest final temperature when the same amount of heat is added to 1g of each substance at the same starting temperature? A. 0.245 B. 0.489 C. 0.873 D. 0.983 E. 1.198

The amount of heat absorbed by a substance, q, is related to the change in temperature, ΔT, of the substance by the equation: q = M*C*deltaT where C is the specific heat capacity of the substance and m is the mass of the substance. We see from this equation that for a given amount of heat (q), temperature change (ΔT) decreases as heat capacity (C) increases. Thus the final temperature decreases with increasing C. Choice [E] has the largest heat capacity at 1.198 J/gºC, and therefore will have the lowest final temperature.

Factor the equation x2 - 8x - 20. A. (x+10)(x+2) B. (x+10)(x-2) C. (x-10)(x+2) D. (x-10)(x-2) E. (x-10)2 CHECKEXHIBIT

The answer to this problem is [C]. When factoring an equation with a squared term that has a coefficient of 1, a good place to start is to determine the factors of "c" value (the number without an x). The factors of 20 in this case would be 1, 20, 2, 10, 4, or 5. Out of these numbers, we need to pick 2 that will somehow, add or subtract to -8 (or the number with only one x). We can see that 2 - 10 = 8. Since we are subtracting the 10, that will be shown as subtraction in the equation. So when we throw in 10 and 2 in to the factored equation, we should get (x - 10)(x + 2). Topic:Algebra

What is the bond dissociation energy of CH4, in kJ?

The bond dissociation energy is the energy required to break a bond (an endothermic process). Here is the lewis structure for CH4: As you can see, CH4 has 4 C-H bonds. To calculate the bond dissociation energy, add up the Hbond for 4 C-H bonds: 400 kJ + 400 kJ + 400 kJ + 400 kJ = 1,600 kJ [D] is the correct answer.

How many electrons are transferred in the following equation? Zn (s) → ZnSO4 (s)

The key to figuring out the oxidation state of zinc on the product side is recalling your polyatomic ions. SO4 is a polyatomic ion with an oxidation number of -2. Since we only have 1 mole of sulfate ion, the overall negative charge on this molecule is -2 and therefore, in order for the overall charge to be zero, the oxidation number of zinc must be +2. The difference between zinc on the reactant side versus product side is 2 electrons. Thus, [B] is the correct answer.

the more _____ charged the compound, the more acidic it is

The more positively-charged the compound, the more acidic it is. Hence, the more negatively-charged the compound, the more basic it is. Thus, Choice [C] is the correct answer. Topic:Acids and Bases

How many protons, neutrons, and electrons are in 205Hg2+, respectively?

The number of protons in an element never changes, as that is what makes each element unique. Looking at the periodic table, we see that Hg has 80 protons. The 205 superscript is the mass number of our ion; the mass number is equal to [the number of protons in the ion] + [the number of neutrons]. Thus, to calculate the number of neutrons, we write: 205 = 80 + # of neutrons 205 - 80 = 125 = # of neutrons 125 = # of neutrons Lastly, we recall that neutral atoms have an equal number of protons and electrons. We add or remove electrons to give negative or positive charges to ions, respectively. Because our ion has a charge of 2+, we must have two more protons than electrons. Thus, we must have 78 electrons.

What product would you obtain if you reacted cyclohexanone with H+ and two equivalents of CH3CH2OH? A. B. C. D. CHECKEXHIBIT

The shortest way to answer this question is to recall that when aldehydes and ketones are reacted with acid and two equivalents of alcohol, the carbonyl carbon becomes a ketal (a carbon bound to two OR groups). Here we treat a ketone with an acid and alcohol, forming the corresponding ketal, [D].

Which compound will be the most soluble in H2O? A. O2 B. PCl5 C. CH4 D. CH2OH E. CH2Cl2 CHECKEXHIBIT

The solubility of a compound in a solvent depends on the "like dissolves like" principle. H2O is a polar compound. Therefore, whichever compound is polar and possesses the ability to hydrogen bond will be most soluble in H2O. A hydrogen bond forms between a positive hydrogen and a lone pair with very strong electronegativity. Remember the acronym FON: elements F, O, and N. CH2OH is the only compound that is polar and can hydrogen bond, so it will be the most soluble in H2O. [D] is the correct answer. Topic:Molecular Structure and Geometry

c = d^3 QA) 1/c QB) 1/d

The variable d can represent any real number. If d is a positive number, c must be a larger positive number. For example, if d=2, c=8. If we plug these numbers into our quantities, we see that quantity B is greater. If d is a negative number, c must be an even larger negative number. For example if d=-2, c=-8. If we plug these numbers into our quantities, we see that quantity A is greater. Since quantity A could be either larger or smaller than quantity B depending on if variable d is negative or positive, we are not able to determine the relationship between the quantities. Option [D] is the correct answer. Topic:Quantitative Comparison

In a garage, the ratio of tennis balls to baseballs is 3:7. In the same garage, the ratio of all balls to cones is 8:1. If there are 30 cones in the garage, how many tennis balls are in the garage? A. 60 B. 72 C. 84 D. 96 E. 110 CHECKEXHIBIT

To solve this problem, we should start with 30 cones. We know the ratio of total balls to cones is 8:1. If we multiply this by 30 cones, we would get a ratio of 240:30, or a total of 240 balls.The ratio of tennis balls to baseballs is 3:7, or for every 10 balls, 3 will be tennis balls, and 7 will be baseballs. As we have 240 balls, we can multiply the 3:7 ratio by 24 to get 72:168 which means there are 72 tennis balls in the garage. Thus the answer to this question is [B]. 1. find out how many total balls are in the garage. multiple the ball to cone ratio by 30 since we know the actual # cones = 30 in the garage). this gives 8:1*(30) = 240 balls : 30 cones. total 240 balls in garage. considering the other ratio: 3:7, which mean s for every total 10 balls (3+7) 3 are tennis and 7 are baseballs. we have a total of 240 balls. so multiply 3:7 ratio by 24 = 72:168 which means there are 72 tennis balls.

If the radius of a hemisphere is increased from 2 to 5, how much does the surface area increase, assuming that we are not considering the base of the hemisphere? A. 14𝛑 B. 26𝛑 C. 28𝛑 D. 32𝛑 E. 42𝛑 CHECKEXHIBIT

To solve this problem, we should start with the formula for the surface area of a sphere: A = 4πr2 Since the question asks about a hemisphere (half of a sphere), it means that the formula for the surface area of a hemisphere is simply half of that of a sphere: A = 2πr2 First, we can find the surface area of the hemisphere when the radius is 2: A = 2πr2 A = 2π(2)2 A = 8π Next, we can find the surface area of the hemisphere when the radius is increased to 5: A = 2πr2 A = 2π(5)2 A = 50π We can now subtract 8π from 50π to find out how much the surface area increased: 50π - 8π = 42π Thus, the correct answer is [E]. Topic:Algebra

Charles' Law

V1/T1=V2/T2

Avogadro's Law

V1/n1=V2/n2

for quantity x<0 y <0 A: x + y B: | x + y |

We must first realize that the values of x and y will always be negative numbers. With this in mind, we can look at each quantity. For quantity A, we are taking the sum of x and y. No matter which numbers we plug in for x and y, the answer will always be a negative number, because the sum of two negative numbers will always be negative. For quantity B, it is important to realize the function of the absolute value bars. Taking the absolute value of an expression takes the end result of the expression and turns it positive. No matter what negative values we plug into quantity B, the absolute value bars will turn the value positive. Since quantity A always results in a negative number and quantity B always results in a positive number, quantity B is greater than quantity A. The correct answer is [B].

Rank the following leaving groups in order of increasing reactivity:

What this question is really asking is, "Which of the given leaving groups is most stable after it leaves?" To help us get a better sense of what we are dealing with, let's rewrite each leaving group as it would be after it leaves. If done correctly, each leaving group should have gained a negative charge. Which of these negatively charged molecules is most stable? We know that Br- is very stable on its own. Leaving group V also appears quite stable as its negative charge can resonate throughout its oxygens. I, III, and IV on the other hand are all poorer leaving groups. Leaving group I gives a negatively charged oxygen with no resonance stabilization, III gives a negatively charged fluorine and IV gives a negatively charged nitrogen. The stability of these three molecules can be sorted out by comparing their relative electronegativities. Because N is the least electronegative of the three, it is the least stable. O is the next least electronegative, and F is the most electronegative and therefore is the most stable. Thus, our three least reactive groups should be ranked IV < I < III in the correct answer choice. Pro-tip: It is difficult to say whether II or V is more reactive, but only one answer choice has IV < I < III, so we don't need to make a determination regarding II and V.

Which of the following is referred to as a cluster of genes typically inherited together? A. Genotype B. Phenotype C. Haplotype D. Epistasis E. Pleiotropy CHECKEXHIBIT

When a group of genes are located very close together on a chromosome, they tend to be inherited together. These groups of genes are known as haplotypes. Choice [C] is correct. A genotype is the actual DNA sequence for a given allele while a phenotype is the observable trait that results from the genotype. Both are thus not clusters of genes; Choice [A] and [B] incorrect. Epistasis is the interaction between genes in which one gene can affect the expression of another gene. It does not refer to a cluster of genes; Choice [D] is incorrect. Pleiotropy occurs when a gene can be expressed in many different phenotypes. It does not refer to a cluster of genes; Choice [E] is incorrect.

Which of the following could you add to increase the solubility of CaBr2

Write the balanced chemical equation: CaBr2(s) ⇌ Ca2+(aq) + 2Br-(aq) Examine the ions that each compound will dissolve into. If KOH is added to the solution, Ca(OH)2 will precipitate out. This will decrease the concentration of Ca2+, shift the reaction right, and increase the solubility oh CaBr2.

Which of the following could you add to increase the solubility of CaBr2? A. HCl B. HBr C. H2SO4 D. NaNO3 E. KOH

Write the balanced chemical equation: CaBr2(s) ⇌ Ca2+(aq) + 2Br-(aq) Examine the ions that each compound will dissolve into. If KOH is added to the solution, Ca(OH)2 will precipitate out. This will decrease the concentration of Ca2+, shift the reaction right, and increase the solubility oh CaBr2. [E] is the answer. Topic:Acid Base Equilibria and Titrations

Identify each substance in the following reaction as an acid, a base, a conjugate base, or a conjugate acid.KOH (aq) + H2CO3 (aq) → KHCO3 (aq) + H2O (l) A. base, acid, conj. base, conj. acid B. acid, base, conj. base, conj. acid C. base, acid, conj. acid, conj. base D. acid, base, conj. acid, conj. base CHECKEXHIBIT

You can replace Group 1 metals with a negative charge so the overall reaction looks like this: -OH (aq) + H2CO3 (aq) → -HCO3 (aq) + H-O-H (l) -OH → H-O-H Thus, OH- is a base as it gained a proton to become H2O on the other side of the equation, which is the conjugate acid. H2CO3 → -HCO3 Thus, H2CO3 is an acid as it lost a proton to become -HCO3 on the other side of the equation, which is the conjugate base. Topic:Acids and Bases I have a question about this explanation I have feedback about this explanation

react a methyl ketone with I2 and -OH.

You should recognize these reagents as haloform reagents. In the first step the -OH deprotonates one of the three alpha hydrogens from the methyl group, creating an enolate intermediate. This enolate attacks and binds to an I from I2. These first two steps occur two more times each until you have formed this intermediate: (containing 3 iodines) Another -OH now attacks the carbonyl, forming a tetrahedral intermediate. Upon collapse of the intermediate and reformation of the carbonyl, CI3- is kicked off as the leaving group. The 3 I's help to stabilize the carbanion until it deprotonates the carboxylic acid to form a carboxylate. The negatively charged O of the carboxylate associates with the positively charged Na ion to form the products shown in [B].

Copper electron configuration

[Ar] 4s1 3d10

Chromium electron configuration

[Ar] 4s1 3d5

Cr electron configuration

[Ar] 4s1 3d5

Ag electron configuration

[Kr] 5s1 4d10

Mo electron configuration

[Kr] 5s1 4d5

Au electron configuration

[Xe] 4f14 5d10 6s1

Which of the following structures develops from the embryonic hindbrain? A. Cerebrum B. Thalamus C. Pineal gland D. Medulla oblongata E. Corpus callosum CHECKEXHIBIT

`The hindbrain develops into the metencephalon and the myelencephalon. The myelencephalon is the posterior region of the embryonic hindbrain that develops into the medulla oblongata. Choice [D] is correct. The metencephalon is the anterior region of the embryonic hindbrain that develops into the cerebellum. Choice [A] is incorrect. The embryonic forebrain develops into the thalamus and pineal gland from the diencephalon. Choices [B] and [C] are incorrect. The corpus callosum is the thick band of nerve fibers that connects the two sides of the brain together. It develops at the end of the first pregnancy trimester, and does not develop from the embryonic hindbrain nor any of the other embryonic brain regions. Choice [E] is incorrect.

What is standard deviation?

a computed measure of how much scores vary around the mean score

Scavengers

are carnivores or herbivores that decompose other dead animals or plants

Saprophytes

are decomposers that consume dead or decaying organic material.

Sodium dichromate (Na2Cr2O7) reagent on primary vs secondary alcohols. and/or Chromium trioxide (CrO3) can be used in place of sodium dichromate (Na2Cr2O7); they will produce the exact same products.

an extremely strong oxidizing agent and will oxidize primary and secondary alcohols as well as aldehydes. As a rule of thumb, secondary alcohols can only be oxidized up to ketones. Secondary alcohols can never be oxidized to an aldehyde or carboxylic acid, eliminating Choices [A] and [C]. Sodium dichromate does not result in the formation of alkanes or esters, eliminating Choices [D] and [E].

A fixed action pattern

an innate behavior initiated by a specific stimulus. It is not a learned behavior;

Which of the following names best describes clusters of rod shaped bacteria? A. Streptococcus B. Streptobacillus C. Staphylococcus D. Staphylobacillus E. Spirochetes

bacillus = rod Notice that the bacteria have certain naming conventions, which can be used to determine bacterial shapes. Strep- bacteria typically grow and attach together in a chain while staph- bacteria are found in clusters. Coccus bacteria have a spherical shape while bacillus bacteria have a rod-like shape. Using these naming conventions above, we find that choices [A], [B], and [C] are incorrect. Our correct answer is choice [D].

to gague the acidity of a molecule, look at its _______?

conjugate base stability if CB is very stable, parent acid = acidic

What is the role of denitrifying bacteria in the nitrogen cycle? A. Fix atmospheric nitrogen into ammonia and ammonium B. Convert ammonia and ammonium into nitrites C. Convert nitrites into nitrates D. Assist plants with nitrate uptake E. Convert nitrates into atmospheric nitrogen CHECKEXHIBIT

denitrifying bacteria converts any unused nitrates that were not absorbed by plant roots back into N₂, atmospheric nitrogen. Choice [E] is the correct answer. Nitrogen fixing bacteria in the root nodules of legumes fix atmospheric nitrogen (N₂) into ammonia (NH₃) and ammonium (NH₄⁺). Choice [A] is incorrect. Nitrifying bacteria then convert ammonia and ammonium into nitrites (NO₂⁻) and nitrites into nitrates (NO₃⁻). Choices [B] and [C] are incorrect. Nitrates are taken up by plant roots in a process called assimilation, which denitrifying bacteria plays no role in. Choice [D] is incorrect.

Coevolution

describes when two species impart selective pressures on each other and results in the evolution of both species

bond length

distance between the nuclei of 2 bonded atoms

gauche interaction

draw the Neuman projection first Whenever two substituents larger than hydrogen are adjacent to each other in a STAGGERED conformation, they experience a Gauche interaction. Seeing as we have four methyl groups all adjacent to each other, we should observe three Gauche interactions. The steric interaction that results when two groups in a Newman projection are separated by a dihedral angle of 60 degrees

G cells

gastrin which stimulate HCl production of parietal cells

what are enzymes

globular proteins lower activation energy don't arter delta H, delta G, or Keq feedback inhibition allows for a rxn to be shut down

how do glucagon and cortisol effect glucose vs. insulin

glucagon and cortisol RAISE glucose levels in the blood insulin - lowers blood glucose

which group has highly EN, high electron affinities, highly reactive with metal, good oxidizing agents (they want to be reduced)

halogens

Which of the following fetal adaptations allows direct transfer of blood between the right and left atria? A. Ductus venosus B. Ductus arteriosus C. Umbilical vein D. Umbilical artery E. Foramen ovale CHECKEXHIBIT

he foramen ovale is a hole in which slightly oxygenated blood can travel directly from the right atrium to the left atrium. Choice [E] is correct. The ductus venosus allows oxygenated blood coming from the umbilical vein to flow into the inferior vena cava and mix with deoxygenated blood, while the ductus arteriosus allows the deoxygenated blood to flow out the pulmonary artery and into the descending aorta. Both ductus do not allow transfer of blood between the two atria, and therefore choices [A] and [B] are incorrect. The umbilical vein that carries oxygenated, nutrient-rich blood from the placental to the fetus, while the umbilical artery carry deoxygenated, nutrient-depleted blood from the fetus to the placenta. They do not allow transfer of blood between atria; choices [C] and [D] are incorrect. Topic:Anatomy and Physiology

Find the mean, median, and mode for the following data set: {2, 2, 3, 5, 5, 5, 6, 6, 14, 22} A. mean = 7, median = 5, mode = 2 B. mean = 7, median = 5, mode = 5 C. mean = 7, median = 5.5, mode = 6 D. mean = 8, median = 5, mode = 5 E. mean = 8, median = 6, mode = 5 CHECKEXHIBIT

he mean is calculated by dividing the sum of the terms of the data set by the number of terms in the data set. The median is found by finding the number that lies in the exact center of the data set after you arrange the numbers from least to greatest. As the numbers are already given to us, this is very easy. {2, 2, 3, 5, 5, 5, 6, 6, 14, 22} Since there is an even number of terms in the set, we take the average of the two middle terms to find the median. Since the average of 5 and 5 is 5, this is our median. The mode is the number that is repeated most often in the data set. The 3, 14, and 22 appear once, the 2 and the 6 appear twice, and the 5 appears three times. Since 5 is the value that appears the most, it is our mode. Since our mean is 7, our median is 5, and our mode is 5, the correct answer is [B].

reaction with nitrobenzene and Cl2 and AlCl3 will form which of the following?

he nitro group on our starting molecule is an electron withdrawing group and meta director, meaning Cl should only be added meta to the NO2 (eliminating [A] and [B]). [C] and [D] both have Cl added meta to the NO2, but will this reaction be slower or faster than the chlorination of benzene? NO2 being an electron withdrawing group is said to deactivate the ring, making it less reactive. Thus this reaction will occur slower than if we were chlorinating benzene itself.

how does EPINEPHRINE affect: heart rate, respiratory rate blood glucose, blood flow to skeletal muscle glycogenolysis blood vessels pupils blood pressure and flow to brain

heart rate, respiratory rate - increase blood glucose, blood flow to skeletal muscle - increase glycogenolysis - increase rate blood vessel - CONSTRICTION to DECREASE blood supply to digestive tract and kidneys pupils - dilate (gather more light) blood pressure and flow to brain - increase

2. gas molecules collisions with each other are perfectly elastic (no IM forces)is most accurate at

high temperatures, and low IM forces

Hybrid F2 breakdown

refers to when the second generation of hybrids suffer from decreased fitness.

NaBH4 and LiAlH4 will reduce ketones to ____.

secondary alcohols

mucous cells

secrete mucus - lubes the stomach/ protects from HCL produced

parathyroid gland

secretes parathyroid hormone (PTH - increases blood calcium levels). secretes parathyroid hormone

x not equal to 0 Quantity A: x^(6-3) Quantity B: x^6 - x^3

simplify then plug in positive 1 and negative (-1) because x not equal to zero. Let us begin by simplifying quantity A as much as we can: Quantity A = x(6-3) = x3 We are not able to simplify quantity B any further because the exponents of the terms are not the same. For some values of x, quantity A is larger. For other quantities of x, quantity B is larger. We can illustrate this by plugging 1 and -1 in for x. Quantity A = x3 = (1)3 = 1 Quantity B = x6 - x3 = (1)6 - (1)3 = 0 When x = 1, quantity A is larger than quantity B. Quantity A = x3 = (-1)3 = -1 Quantity B = x6 - x3 = (-1)6 - (-1)3 = 1 - (-1) = 2 When x = -1, quantity B is larger than quantity A. Since quantity A could be either larger or smaller than quantity B depending on the value of x, we are not able to determine the relationship between the quantities. Option [D] is the correct answer.

what is (Na2Cr2O7) ?

strong oxidizing agent

boiling point elevation

the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent