DAT Question of the Day

Glycosylation, sulfation and phosphorylation (of proteins) represent functions of which cell organelle? A. Endoplasmic reticulum. B. Golgi apparatus. C. Nucleus. D. Ribosomes. E. Centriole.

B. Golgi apparatus. 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.

Which one of the following reactions of alkenes does the Anti-Markovnikov's rule apply instead of Markovnikov's rule? A. Hydration B. Oxymercuration-demercuration C. Hydroboration-oxidation D. Addition of HCl E. Addition of Br2

C. Hydroboration-oxidation The electronegativity of the hydrogen atom is stronger than that of boron, which means hydrogen is relatively negatively charged compared to boron. So in this case, the hydrogen will be added to the end containing more substituents and the boron part will be added to the end containing more hydrogen atoms, which will then convert to the hydroxyl group. This is the Anti-Markovnikov product.

The forces responsible for the relatively high melting point and boiling point of water, H2O, are: A. Intermolecular ver der Waals or Dispersion forces B. Intramolecular covalent bonding C. Intermolecular hydrogen bonding D. Intermolecular ionic bonding E. Intramolecular dipole-dipole forces

C. Intermolecular hydrogen bonding. The atoms within water molecules are bonded together by covalent bonding, but it is the intermolecular hydrogen bonding thatprovides the strong forces of attraction between the molecules which gives water its relatively high (for its mass) melting point of 0 oC and boiling point of 100 oC.

n a reaction between Mg and Ar, which of the following is most likely to occur? A. no reaction would occur B. a precipitate would form C. a gas would be produced D. a color change would occur E. an aqueous solution would form

A. no reaction would occur Noble gases are inert and do not react under normal conditions. Therefore, the reaction would not take place. In order for a gas to be produced, a chemical reaction would need to occur. The same is true for the color change and the formation of a precipitate as these signal that a chemical change has happened. However, these would not form/occur in this case because the two reactants would not react chemically.

A human embryo would exhibit which type of cleavage? A. radial B. spiral C. central D. bilateral E. lateral

A. radial Spiral cleavage results in daughter cells after cell division, being located at an angle in relationship to each other. This is common in protostomes. Whereas radial cleavage results in the daughter cells after cell division being stacked on top of each other. This type of cleavage is seen in deuterostomes. Humans are deuterostomes and therefore would exhibit the more complex cleavage type, radial cleavage.

How many cubic centimeters of water will approximately be required to fill a cylinder with a 3 cm radius and 7 cm height? A. 63 B. 66 C. 132 D. 198 E. 496

D. 198 The volume of a cylinder is πr2 × h = π × 32 × 7 = 63π. If π is approximated as 22/7, then 63π = 63 × 22/7 = 198.

The 1H NMR spectrum of an unknown compound shows the following signals: triplet, quintet and triplet (relative integrals 1:2:3, respectively). Which compound is consistent with this data? A. 1,1-dibromopropane B. 1,2-dibromopropane C. 1,3-dibromopropane D. 2-bromopropane E. 1,1-dibromoethane

A. 1,1-dibromopropane An approximated 1H NMR spectrum of 1,1-dibromopropane (CH3CH2CHBr2) is shown below:

A researcher is attempting to predict the number of lions in an African habitat based on previous data. He has formed a regression equation which is: Y = 25 + 0.5X - 2ZX, where X is the number of years since the first population sample, and Z is the death rate of the lions. If it has been 10 years, and the death rate is 1 lion per year, what is the predicted number of lions in the habitat? A. 10 B. 12 C. 16 D. 18 E. 20

A. 10 We are given a regression equation, which is Y = 25 +0.5X - 2ZX, where X is 10 years and Z is 1 lion per year. This means that the equation can be substituted as Y = 25 +0.5(10) - 2(10)(1) = 10 lions remaining after 10 years. Y=25+0.5X-2Z X=10 years, Z=1 lion death per year Y=25+0.5(10)-2(10)(1)= 10 lions remaining

Mark's car began a journey from a point at 7 AM, traveling at 30 mph. At 8 AM Jason's car started traveling from the same point at 40 mph in the same direction as Jason. At what time will Jason pass Mark? A. 11 AM B. 10 AM C. 10:30 AM D. 11:30 AM E. Jason never passes Mark

A. 11 AM Let x be the number of hours it takes Jason to pass Mark. During this time, Jason travels 40x miles. Mark started an hour earlier, so he has driven for x+1 hours, during which he travels 30(x+1) miles. Therefore, 40x = 30(x+1) x=3 3 hours from 8 AM is: 11 AM.

One of the tanks that a pediatric dentist uses to administer nitrous oxide is "empty", meaning that the N2O inside is at the same temperature and pressure as the room. The ML-6 type cylinder has an internal volume of 165 liters. How many moles of nitrous oxide remain in the empty tank (Ideal gas constant = 0.082 L atm/K mol; assume the apparatus is at sea level; the ambient temperature is 22° C)? A. 6.8 moles B. 0.15 moles C. 21.8 moles D. 22.4 moles E. Zero moles; the tank is empty

A. 6.8 moles This question requires the use of the ideal gas law: PV = nRT. We are solving for number of moles (n). The temperature in the equation is in Kelvin, so a 22° C room would actually be 295 K approximately. The pressure (P) at sea level is 1 atmosphere. So, (1 atm X 165 L) / (0.082 L atm/K mol X 295 K) = 6.8 moles

In how many different ways can the first, second and third prize winners be selected from a group of 8 people running a race? [assume that there are no ties]. A. 8! / 5! B. 8! / (5! × 3!) C. 8! D. 38 E. 8! / (5! × 3)

A. 8! / 5! If this was about choosing 3 people out of a group of 8 (where the order of the three people didn't matter), the answer would have been: (8/3) = 8! / (8-3)!x3! = 8! / 5!x3! = 8x7x6 / 3x2 = 8x7 = 56 However, in this case, we need to distinguish between the first, second and third prize winners, and it becomes a permutation problem. The number of ways to select the three winners is: 8^P(sub)3 = 8! / (8-3)! = 8!/5! = 8x7x6 = 336

The hardest substance known is diamond. Which best describes the structure of diamond? A. A 3D network lattice of covalently bonded carbon atoms. B. A 2D network lattice of covalently bonded carbon atoms. C. A 3D network lattice of carbon ions held together by ionic bonds. D. A 3D network lattice of carbon ions in a sea of mobile valence electrons held together by metallic bonds. E. A 3D network lattice of carbon atoms held together by hydrogen bonding and dispersion forces.

A. A 3D network lattice of covalently bonded carbon atoms. Diamond is a 3D network lattice of covalently bonded carbon atoms, far right. Graphite, another allotrope of carbon, is a 2D network lattice of covalently bonded carbon atoms, left. A 3D network lattice of carbon ions held together by ionic bonds. Does not exist, as carbon does not form ions and elements cannot be ionic, only compounds can. A 3D network lattice of carbon ions in a sea of mobile valence electrons held together by metallic bonds. This description is more metallic and similar to the description of graphite, which can conduct electricity, but not diamond. A 3D network lattice of carbon atoms held together by hydrogen bonding and dispersion forces. Hydrogen bonding and dispersion forces are intermolecular forces, although dispersion forces are everywhere, but very weak.

Methods of extraction are important for use in industry and research. One of the typical steps in an extraction is the use of either acid or base to treat an unknown mixture. This step is applied in order to: a. Change the water solubility of an unknown compound b. Change the boiling point of an unknown compound c. Change the molecular weight of an unknown compound d. Change the optical activity of an unknown compound e. Change the melting point of an unknown compound

A. Change the water solubility of an unknown compound Adding acid or base to a mixture of unknown compounds is designed to change the water solubility. The loss or gain of protons will make the compound become ionic in nature, and thus soluble in water. On the other hand, compounds that are already ionic may become neutrally charged, resulting in lower solubility in water.

TNT explosions are very fast reactions involving the production of enormous quantities of heat and gaseous products. Thermodynamically, explosions are best described as: A. High entropy, exothermic reactions with a low activation energy. B. High entropy, endothermic reactions with a low activation energy. C. High entropy, exothermic reactions with a high activation energy. D. Low entropy, exothermic reactions with a low activation energy. E. Low entropy, endothermic reactions with a high activation energy.

A. High entropy, exothermic reactions with a low activation energy. TNT explosions are very fast reactions (the lower the activation energy the less a reaction is impeded) involving the production of enormous quantities of heat (exothermic) and gaseous products (the production of hot gases from a solid explosive dramatically increases the disorder of the system, thus high entropy).

The cyanide ion has which of the following molecular geometries? A. Linear B. Trigonal Planar C. Tetrahedral D. Trigonal Planar-Bent E. Tetrahedral-Bent

A. Linear Cyanide is CN-1 and this compound has 10 valence electrons to use to bind together. The only orientation that works with these elements is with a triple bond between the C and N, with each element having a single pair of non-bonded electrons. This would give rise to a linear molecular geometry.

During what stage of meiosis do homologous chromosomes exchange genetic information? A. Prophase I B. Prophase II C. Anaphase II D. Telophase I E. Cytokinesis I

A. Prophase I The process described is crossing over. Crossing over occurs during the first stage of meiosis called prophase I. In this stage the homologous chromosomes begin to come together and they form tetrads. The homologous chromosomes are able to "cross over" sections of the chromosome between the homologous pair. The point at which the new chromosomal pieces attach is referred to as the chiasmata.

Which of the following would result in allopatric speciation? A. Two squirrel populations separated by a river B. Two birds living in different parts of a tree C. Two lion prides living in the same savannah D. A group of insects with the same mating call E. Two groups of dogs that have different fur colors.

A. Two squirrel populations separated by a river In allopatric speciation, two species result due to the geographical barrier between the two species. Two birds living in different parts of the tree may result in two separate species over time, if the birds have different mating rituals or mating seasons. This would not be due to a geographical barrier and would be an example of sympatric speciation. Lion prides could still reproduce with one another especially since they inhabit the same area and climate. Insects with the same mating call would interbreed and this would not result in two different species over time. Similarly, two groups of dogs with different fur color should still be able to reproduce. However, two squirrel populations separated by a river may evolve into two different species over time, as the squirrels may be inhabiting different environments and are separated by the body of water.

Microtubules are essential components of which of the following structures? A. cilia B. nucleus C. nucleolus D. cell membrane E. peroxisomes

A. cilia. The microtubules are part of the cytoskeleton and are comprised of a specialized protein called tubulin. Microtubules are integral in cell division and cell movement. Cilia are a type of cell movement and are made up of microtubules.

Which of the following is a major distinction between veins and arteries? A. veins have valves B. arteries carry blood to the heart C. veins carry blood away from the heart D. arteries have thinner cell walls. E. veins are under high pressure.

A. veins have valves Veins carry blood to the heart, recollecting it from the body. Conversely, arteries carry blood away from the heart to the body. To prevent backflow and to promote the movement against gravity, veins have valves whereas arteries do not. Arteries also have very thick, muscular walls that enable pumping from the heart to the body. Veins are thinner in comparison and are not considered to have to "pump" blood or be under high pressure.

John, Jack and Jason share an amount in the ratio of 4:3:7, respectively. If Jason received $32 more than Jack, what is the total amount they shared? A. $64 B. $112 C. $148 D. $172 E. $96

B. $112 Since the ratio is 4:3:7, we can assume that the amounts received by John, Jack and Jason are 4x,3x and 7x, rescpectively. Since Jason received $32 more than Jack, 7x - 3x = 32 , x = 8 Therefore, the total amount they shared is 4x + 3x + 7x = 14 x = 14 * 8 = 112

Albert and Samuel are given $10,000 each by their grandparents. Albert puts his money into the stock market immediately, earning 5% interest each year. Samuel holds onto his money for 2 years, before also investing in the stock market at the same interest rate as Albert. After 4 years, how much more money does Albert have? A. $1025 B. $1130 C. $2050 D. $2155 E. $2260

B. $1130 Albert's money after 4 years is equal to 10,000 x (1.05)4, according to the interest equation FV = PV*(1+I)n, where FV is future value, PV is present value, I is interest rate, and n is number of years. Likewise, Samuel's money value is 10,000 x (1.05)2, with the only difference being the number of years. Taking the difference of these two values, we find that Albert will have about $1130 more after 4 years.

Gestrinone is a synthetic steroid hormone that is marketed as a treatment for endometriosis. What is the index of hydrogen deficiency (IHD)-or degree of unsaturation-for gestrinone? A. 9 B. 10 C. 11 D. 12 E. 13

B. 10 Recall that the degrees of unsaturation corresponds to the sum of pi bonds and/or rings present in a molecule. Each ring and each pi bond contributes one degree of unsaturation; triple bonds, possessing one sigma and two pi bonds, contribute two degrees of unsaturation. Gestrinone has four rings (4), three alkenes (3), one carbonyl (1) and one alkyne (2). Thus IHD = 4 + 3 + 1 + 2 = 10

What is the maximum perimeter of a square that can fit inside a circle of radius 5 cm? A. 20 B. 20√2 C. 10/√2 D. 40 E. 20/√2

B. 20√2 As can be seen from the figure below, the diagonal of the square is equal to the diameter of the circle, which is 5×2=10 cm. If the length of one side of the square is x, the diagonal is given by √2 x. Therefore, √2(x) = 10 -> x = 5√2 and the perimeter is 4 × 5√2 = 20√2.

A scientist translates an enzyme from pre-processed cell mRNA in a test tube (in vitro). However, the in vitro enzyme is found to be inactive compared to the extracted in vivo enzyme from a live cell culture. Which statement is the LEAST likely explanation for this phenomenon? A. The extracted mRNA contains introns, which were translated as well. B. A nonsense mutation occurred in the extracted mRNA. C. The in vitro enzyme was not phosphorylated. D. The in vitro enzyme was not cleaved into its active form. E. Molecular chaperones were not present in vitro to properly fold the enzyme.

B. A nonsense mutation occurred in the extracted mRNA. This is a great example of a comprehension DAT biology question. All of the answer choices are plausible, but only one stands out like a sore thumb. A nonsense mutation leads to a premature stop codon in the mRNA, halting translation and the production of the protein, which would lead to a lack of activity. However, this is the least likely situation, as mutations are already very rare. It is much more likely that one of the other scenarios occurred. Leaving the introns (the non-coding regions of the DNA) in the mRNA would destroy the intended enzyme by not allowing it to properly fold, leading to inactivation. Introns are normally removed as mRNA is processed through the nucleus, directly extracting "pre-processed" mRNA would likely leave the introns in place. This is why scientists often use cDNA, or complementary DNA, which is the intended gene sans introns and can be directly translated. Most enzymes also undergo post-translational modifications to become active, such as phosphorylation or get cleaved at a specific environment to control their activity. This is especially useful in the production of pepsin in the stomach; producing an inactive version of pepsin (pepsinogen) allows us to control the activity of the enzyme so it does not end up eating the cell that produced it! Molecular chaperones are often present in cellular translation to help an enzyme fold properly.

In the developing embryo, which of the following would be formed from the mesoderm germ layer? A. Skin B. Blood C. Hair D. Brain E. Lens of the eye

B. Blood The three primary germ layers of the embryo include: the ectoderm, endoderm, and mesoderm. The endoderm differentiates to form the gastrointestinal tract, the lungs, the pharynx and parts of the urinary system. The ectoderm is the outer layer of the three germ layers and results in the formation of the epidermis and related structures like hair, nails, and external sense organs. The ectoderm also forms the spinal cord and the brain. The mesoderm is the middle layer of the three germ layers and eventually develops into connective tissues (including bone), cartilage, muscle, and the blood vessels. Blood is considered a type of connective tissue, thus the correct answer is [B].

Which of the following are responsible for the alignment of the chromosomes along the metaphase plate (equatorial plate) during mitosis? a) Molecular Chaperones b) Centrosomes c) Nucleosomes d) Nuclear pores e) rRNA

B. Centrosomes. The chromosomes are aligned in the center of the cell by the attachment of mitotic spindles from the centrosomes to the kinetochores of each chromosome. These spindles, composed of microtubules, maintain a constant length once the chromosomes are aligned along the metaphase plate.

Mixture A is formed using KCl and H2O and mixture B is formed using MgCl2 and H2O. If the two mixtures have the same molality, which of the following statements would be true about the boiling point of the mixtures? A. Mixture A would have a higher boiling point B. Mixture A would have a lower boiling point C. Mixture B would have a lower boiling point D. The mixtures have the same boiling point E. The mixtures would vaporize at the same rate

B. Mixture A would have a lower boiling point The two mixtures have the same concentration a.k.a. molality. However, they do have differing ionic solutes. Mixture A has an ionic solute that would dissociate to form two ions (K+ and Cl-) whereas Mixture B has an ionic solute that forms three ions (Mg2+ and 2Cl-). In the equation: ∆T(boiling) = m x Kb x i, the "I" or vant Hoff factor would be the only variable. The higher the vant Hoff factor, the greater the effect on the boiling point and/or freezing point. The von hoff factor for Mixture A is 2, but for Mixture B is 3. Therefore, Mixture B would have the greater affect on the boiling point, making it higher than normal. Between the two mixtures, B would have a higher boiling point than mixture A.

What reagent can be used to convert 2,2-dimethylbutan-1-ol into 2,2-dimethylbutanal? A. H2CrO4 B. PCC C. KMnO4 D. O3 E. LiAlH4

B. PCC The conversion of 2,2-dimethylbutan-1-ol to 2,2-dimethylbutanal is an oxidation (alcohol -> aldehyde). Lithium aluminum hydride (E) is a strong reducing agent. Potassium permanganate (C) is used in the oxidation of alkenes to diols, and is generally not strong enough to further oxidize aliphatic alcohols. Ozone (D) is used in the oxidative cleavage of alkenes into the corresponding aldehydes or ketones. Chromic acid (A) is a harsh oxidant, oxidizing primary alcohols up to the corresponding carboxylic acid, and secondary alcohols up to the corresponding ketone. PCC (B, pyridinium chlorochromate) is a milder chromium-based oxidant used in the selective oxidation of primary alcohols to aldehydes.

An entire forest is leveled after a forest fire. The process by which organisms will repopulate an area is called: A. primary succession B. secondary succession C. spontaneous generation D. homeostasis E. biological regeneration

B. Secondary Succession Succession is the process that ecological areas go through to repopulate a community. Following a forest fire, the environment is beginning from the producers level and must first grow small grasses, then small shrubs, before consumers and higher-level consumers will repopulate the area. In the event of a volcano, this would be an example of primary succession, as there is no soil to sustain plants. Instead, bacteria populate the area, and eventually give rise to soil and plants and animals. Homeostasis refers to the internal regulation of an organism as opposed to the process an external environment goes through. Biological regeneration is a distractor answer choice testing your true knowledge of the topic at hand.

In the vertebrate nervous system, the term "Node of Ranvier" refers to: a) The multilayered lipid-based coating that covers neurons b) The gap between the myelin sheath segments c) The gap between the axon terminal and dendrite of the next neuron d) The tip of a dendrite extension from a neuron e) The gap between the neuron nucleus and the first Schwann cell

B. The gap between the myelin sheath segments The correct answer is B. The gap between the axon terminal and dendrite of the next neuron is called the synaptic cleft. The lipid-based coating that covers the neurons is the myelin sheath, and this sheath covers segments along the axon called internodes and the gaps between these internodes are called the Nodes of Ranvier.

Which of the following statements best describes the structural relationship between cis-1,2-dibromocyclopropane and trans-1,2-dibromocyclopropane? A. The two compounds are mirror images of one another B. The two compounds can be separated by ordinary physical chemical separation methods C. The two compounds have the same melting points D. All of the above

B. The two compounds can be separated by ordinary physical chemical separation methods Cis and trans-1,2-dibromocyclopropane (pictured below) share a diastereomeric relationship; that is, the molecules are stereoisomers that are not enantiomers. Diastereomerism occurs when two or more stereoisomers (i.e. same connectivities) of a compound have different configurations at one or more (but not all) of the equivalent stereocenters and are not mirror images of each other. Accordingly, diastereomers are distinct molecules with different chemical properties, and can be separated by ordinary physical means. Recall that enantiomers are mirror images of each other and are identical in all physical aspects except for their direction of rotation of plane polarized light.

Histones are a kind of protein that is known to play a very important role in packaging DNA into chromatin. What of the following characteristics about histones is true? A. They are responsible for the methylation of DNA and switching on and off of genes B. They are responsible for the supercoiling of DNA C. They interact with DNA through covalent interactions D. An octet of histones and a length of DNA forms a helix E. They are responsible for helping topoisomerases bind to the DNA

B. They are responsible for the supercoiling of DNA. Histones are not responsible for methylating DNA(A) or helping topoisomerase enzymes bind. Histones interact with DNA through ELECTROSTATIC interactions, and an octet of histones plus a length of DNA forms a NUCLEOSOME and causes the DNA to form its tertiary structure and become supercoiled.

X is a multiple of A. A is always even, and is always divisible by B. X is also never divisible by C. Which of the following statements must be true? A. A is divisible by C. B. X is divisible by B. C. Division of X by A equals B. D. B is divisible by C. E. A * X is always odd.

B. X is divisible by B. Given that X is a multiple of A, we know that X is always divisible by A. Following, if A is always divisible by B, then A must be a multiple of B. Thus, it logically follows that if A is divisible by B, and X is divisible by A, then X must be divisible by B.

Which of the following is a specialized type of fungi that lives on the roots of many vascular plants and enables nutrient absorption? A. rhizome B. mycorrhizae C. apical meristem D. cork cambium E. vascular cambium

B. mycorrhizae The mycorrhizae inhabit the roots of vascular plants and help to increase the surface area of the roots leading to higher rates of nutrient and water absorption. Rhizomes are underground stems that can sprout to produce new shoots and roots for the plant. Likewise, the apical meristem is the portion on the stem that enables upward growth of the stem. The vascular cambium produces secondary xylem and phloem that help sustain the plant as it grows laterally each year. In addition, the cork cambium forms the "woody" part of the plant helping to provide the plant with structure and support as it grows laterally.

Which of the following is the chemical released by activated cytotoxic T-cells to fight a viral infection? A. actin B. perforin C. tubulin D. histamine E. antibodies

B. perforin Cytotoxic T-cells are able to rid the body of infections that have spread to cells. To do this, cytotoxic T-cells release perforin, which disintegrates the cell membrane, causing the infected cell to lyse and then be engulfed by macrophages. Antibodies are released from B-cells that then aggregate to an antigen, tagging it to be eaten by macrophages. Actin and tubulin are proteins present in the cytoskeleton and histamine is a chemical released during an allergic reaction or to initiate an inflammatory response.

A black-eyed, black coat rabbit, is crossed with a red-eyed, white coat rabbit. If the offspring is black-eyed and white coat, this is due to which of the following? A. restriction enzymes B. recombinant DNA C. genetic drift D. genetic mutations E. gel electrophoresis

B. recombinant DNA The phenotype of the offspring is a mixture of the two parents' phenotype. This would be due to recombinant DNA, specifically crossing over that likely occurred during meiosis I (prophase I). Restriction enzymes cut the DNA at specific sequences and would not be the direct cause of the change in phenotype observed. Genetic drift describes the change in allele frequency over time not in one generation. Genetic mutations can lead to different features in an offspring than what was present in the parents, however the offspring resemble the parents, with one phenotypic characteristic from each parent expressed.

What is the final oxidation number of carbon in the following chemical reaction? 6CO2 + 6H2O -> C6H12O6 + 6O2 A. -4 B. -2 C. 0 D. 2 E. 4

C. 0 In the equation, carbon is used from carbon dioxide to form glucose, C6H12O6. The final form of carbon is in glucose. In this compound, the oxygens each have an oxidation number of -2 and the hydrogen also have a fixed oxidation number of +1 each. Therefore, the sum of hydrogen's oxidation numbers is +12 and the sum of oxygen's oxidation numbers is -12. Since glucose is a neutral compound the sum of all the oxidation numbers of all the elements in the compound must be equal to zero. So, carbon must have an oxidation number of 0 because the sum of the hydrogen and oxygen oxidation numbers is already equal to zero.

A car starts from a static position and accelerates uniformly until it reaches a certain speed. If five cars reach the following speeds in the given amounts of time, which car will have gone the farthest distance after 1 second? A. 0 to 60 mph in 4 seconds B. 0 to 75 mph in 5 seconds C. 0 to 55 mph in 3.5 seconds D. 0 to 45 mph in 3 seconds E. 0 to 65 mph in 4.5 seconds

C. 0 to 55 mph in 3.5 seconds This can be solved using the formulas of kinetics, but may require some time. However, there is an easier way of solving this. A uniform acceleration implies that the speed increases linearly. So, at the end of the first second, the speed for the first car will be simply 60 / 4 = 15 mph, which is the same for the answer choices B and D as well. The speed after 1 sec for choice C is higher than 15 mph, and that for E is lower than 15 mph. So, the car in C has the highest speed after 1 sec. Since its average speed over this 1 sec period is higher than the rest of the cars, it must have traveled more distance than the others during this period as well.

A 1 mol sample of ammonia gas (NH3) at 1 atm and 273 K is compressed to 2 atm. What is the difference in volume before and after compression? A. 22.4 liters B. 18.5 liters C. 11.2 liters D. 5.91 liters E. 1 liter

C. 11.2 L This is solved using the ideal gas law. However, it should be recognized that 1 mol of any gas at 1 atm and 273K (or 0 deg Celsius) is approximately 22.4 L in volume. If this is not recognized, it can still be calculated from the ideal gas law, PV = nRT. We recognize that if pressure doubles while temperature and mols remain the same, the volume should be halved. Thus, the new volume is 11.2 L, which is a difference of 11.2 liters, or answer C.

Bacteria such as V. cholerae are known to follow an exponential growth curve rate, and will double their number every 15 minutes. Fortunately, anti-bacterial hand wash can kill 99.9% of bacteria on a surface. If a colony of 500 V. cholerae cells are left alone for 2 hours, then anti-bacterial handwash is applied thoroughly, how many bacterial cells are left? A. 4 cells B. 64 cells C. 128 cells D. 256 cells E. 512 cells

C. 128 cells If the bacteria double every 15 minutes, then that means over the course of 2 hours, they will double 8 times. 500 x 28 = 128,000 cells on the surface. Then we apply the anti bacterial wash, which kills 99.9% of cells, meaning 0.1%, or 0.001 of the cells remain. 128,000 x 0.001 = 128 cells.

An Olympic gold medalist runs 100 meters in 9.7 seconds. What is his average speed in miles per hour? A. 17 B. 8 C. 23 D. 28 E. 11

C. 23 100 meters = 0.1 km = 0.1 × 0.62 = 0.062 miles, and 9.7 seconds = 9.7/3600 hours. Therefore, speed = 0.062 / (9.7/3600) = 23 miles per hour.

Two trains are approaching each other from opposite directions with the speeds 10 miles per hour and 20 miles per hour, and heading for a collision. If they are a quarter mile apart, how long will it take for them to collide? A. 45 seconds B. 20 seconds C. 30 seconds D. 40 seconds E. 1 minute

C. 30 seconds The speed at which the two trains are closing the gap between them is 10 + 20 = 30 mph. At the is speed, it will take (0.25/30) × 3600 = 30 seconds to close a gap of 0.25 miles.

From a group of 5 men and 7 women, in how many different ways can a team of 2 men and 3 women be formed? A. 95040 B. 792 C. 350 D. 4200 E. 18

C. 350 2 men can be picked from a group of 5 in (5|2) = 10 different ways, and 3 women can be picked from a group of 7 in (7|3) = 35 different ways. Therefore, the total number of ways a team can be formed is 10 × 35 = 350. Extended explanation: If you got D. 4200, you interpreted this problem as a permutation, not as a combination. We do not care what order the men are picked in or what order the women are picked in, all we care is that there is a team of 2 men and a team of 3 women. Permutation equation: P(n,r) = n! / (n-r)! Combination equation: C(n,r) = n! / r!(n-r)! Where n = total number of the group and r = the number of people we want. Hence, n = 5 men r = 2 men We have 10 total possible combinations using the above formula. The same goes for women. n = 7 women r = 3 women We have 35 total possible combinations using the above formula. Multiplied together, we have 350 possible combinations.

There are 5 white, 7 red and 8 black balls in a box. If you are blindly picking up balls from the box, what is the minimum number of balls you need to take out of the box to ensure that you have at least 2 balls of the same color? A. 2 B. 3 C. 4 D. 5 E. 6

C. 4 After the first ball is picked, the second may not be the same color. After two balls picked, the third may still be a different color than the first two (since there are a total of 3 colors). But when the fourth ball is picked, it must match one of the prior colors. Therefore, picking 4 balls will ensure that you have at least one set of 2 balls with the same color. The numbers 5, 7, 8 do not matter here (they could matter if these numbers were lower, or the number of balls picked were higher).

In the normal distribution, what percentage of scores fall within one standard deviation of the mean? a. 33% b. 50% c. 68% d. 75% e. 90%

C. 68% This question doesn't require any calculation, but rather knowledge of the standard deviation sets. Typically, about 68% is included in the first standard deviation, and 95% is included in the 2nd standard deviation. 99.5% of all people fall within three standard deviations of the mean in the normal curve.

In a certain course, the Professor has two different grading policies, from which he picks the best. The first policy is to put 40% and 60% weights, respectively, on the midterm and final exams. Under the second grading policy, these weights are 50% each. A student has scored 85% on the midterm, and needs to score at least x% on the final to make a B (a total of 82%). What is the value of x? A. 82 B. 80 C. 79 D. 81 E. 78

C. 79 For a grade of B, either the condition 85 × 0.4 + x × 0.6 ≥ 82 needs to be met under the first policy, or the condition 85 × 0.5 + x × 0.5 ≥ 82 needs to be met under the second policy. These two conditions yield x ≥ 80 and x ≥ 79, respectively. Since the minimum value of x is to be computed, we pick the lower of these two bounds, which is 79.

Which of the following will not dissolve in water? A. Salt, NaCl B. Ethanol, CH3CH2OH C. Benzene, C6H6 D. Hydrogen chloride, HCl E. Acetic acid, CH3COOH

C. Benzene, C6H6. The law of solubility is that "Like dissolves Like", that is non-polar solvents dissolve non-polar substances and polar solvents dissolve polar and most ionic substances. Water is a polar solvent thus: Salt, NaCl - ionic and very soluble in water, sea water. Ethanol, CH3CH2OH - polar molecular (-OH) will dissolve in water, beer/wine/spirits. Benzene, C6H6 - non-polar molecular will not dissolve in polar water. Hydrogen chloride, HCl - polar molecular will dissolve in water, hydrochloric acid. Acetic acid, CH3COOH - polar molecular (-COOH) will dissolve in water, vinegar.

What is the anticodon to the DNA sequence CTG ACG TTA? A. GAC UGC AAU B. CTG ACG TTA C. CUG ACG UUA D. GAC UGC AAT E. AUG ACG UUA

C. CUG ACG UUA The tRNA has the anticodon to the codon on the mRNA. To solve this problem, you must first transcribe the mRNA from the given DNA strand, which would result in: GAC UGC AAU. Note: For the mRNA, A (Adenine) pairs with U (Uracil) not T (Thymine). Next, you have to find the complementary bases to the mRNA to determine the anticodon. So, the anticodon would be: CUG ACG UUA.

The group of organisms that are amoeboid and exhibit a slug stage are: A. Rhizopods. B. Bryophytes. C. Cellular slime molds. D. Dinoflagellates. E. Zoomastigotes.

C. Cellular slime molds Bryophytes are a type of plant and can be eliminated. While the rest of the choices are unicellular protists, only cellular slime molds exhibit an amoeboid characteristic and "slug stage", when many cells combine in a mass.

A male who is homozygous dominant for hair texture has straight hair. His brother, who is heterozygous for hair texture also has straight hair. This phenotypic similarity is a result of which of the following? A. Incomplete dominance B. Codominance C. Complete Dominance D. Independent Assortment E. Law of Segregation

C. Complete Dominance Both of the brothers are phenotypically identical in regards to their hair texture. Genotypically, the two are different, as one is homozygous dominant and the other is heterozygous for hair texture. Despite the genotype differences the brothers are phenotypically similar with their hair texture because the dominant allele is the one being expressed. In both the case of Hh and HH, the presence of the dominant allele results in straight hair. This is due to complete dominance. In incomplete dominance, the heterozygote phenotypically is a hybrid between the two parents (i.e. a red and white flower make a pink flower). Whereas with codominance the heterozygote is phenotypically like both parents, i.e. red and white flower makes white plant with red spots. Law of independent assortment and law of segregation refer to Mendelian genetics, but are not the explanations for the phenotypic similarity between the two genotypes.

Which of the following hormones is responsible for the thickening of the endometrium? A. Testosterone B. Oxytocin C. Estrogen D. Luteinizing hormone E. Follicle stimulating hormone

C. Estrogen Follicle stimulating hormone causes the follicle in the ovary to begin to divide to complete meiosis II. The growing follicle that will eventually release the egg during ovulation secretes estrogen. The estrogen then spurs the secretion of luteinizing hormone by the anterior pituitary gland, causing the follicle to rupture and release the egg. It is the estrogen and progesterone that is responsible for readying the endometrium for implantation should fertilization occur.

Which of the following statements is correct? A. High molecular dipole moments are characteristic of nonpolar molecules B. Polar solutes tend to be more soluble in nonpolar solvents C. The polarity of a molecule is dependent on its 3-D structure D. All polar molecules are capable of hydrogen bonding E. London dispersion interactions are usually stronger than dipole-dipole interactions

C. The polarity of a molecule is dependent on its 3-D structure A molecule's dipole is an electric dipole with an inherent electric field (not be confused with a magnetic dipole which generates a magnetic field). Molecules can have dipole moments due to non-uniform distributions of positive and negative charges on the various atoms. For diatomic molecules there is only one (single or multiple) bond so the bond dipole moment is the molecular dipole moment, with typical values in the range of 0 to 11 D. For polyatomic molecules there is more than one bond, and the total molecular dipole moment may be approximated as the vector sum of all individual bond dipole moments.

For a mixture of gases in a container, the total pressure is equal to __________ because of what law? A. The pressure of the largest gas, First Law of Thermodynamics B. The pressure of the smallest gas, First Law of thermodynamics C. The sum of the partial pressures of all gases, Dalton's law of partial pressure D. The pressure of the greatest gas, Dalton's law E. The sum of the top two gases in the mixture, Dalton's law of partial pressure

C. The sum of the partial pressures of all gases, Dalton's law of partial pressure In a mixture of gases, the total gaseous pressure is the sum of the partial pressures of all gases, according to Dalton's law of partial pressure.

As urine moves through the descending loop of Henle, which of the following is true? A. Sodium is reabsorbed into the bloodstream. B. Sodium is secreted into the loop of Henle. C. Water is reabsorbed into the bloodstream. D. Water is secreted into the loop of Henle. E. Potassium is reabsorbed into the bloodstream.

C. Water is reabsorbed into the bloodstream. The descending loop of Henle is only permeable to water. As the urine moves through the loop of Henle, it will become more concentrated as the water is reabsorbed back into the bloodstream. The ascending loop of Henle is permeable to sodium and during this portion of the loop, the urine will be come more diluted, as sodium ions are reabsorbed into the bloodstream.

In cattle, black hair color is dominant to red hair color. Which of the following would a farmer use to mate with a black haired cow to determine the black cow's genotype? A. a homozygous black haired cow B. a heterozygous black haired cow C. a homozygous red haired cow D. a heterozygous white cow E. a homozygous albino cow

C. a homozygous red haired cow In genetics, a test cross is used to determine the genotype of an organism that expresses the dominant phenotype. The black cow could be BB or Bb for the black hair color. If you were to mate the cow with a homozygous black cow BB, all of the offspring would be black haired and this would not help the farmer determine the genotype of the original black cow. Likewise using a heterozygous black cow (Bb), could result in all black offspring, since there is only a 25% chance of getting a red haired cow if the original cow was heterozygous (Bb). A white cow nor an albino cow are not mentioned in the original question and would not be relevant in determining the genotype of the black cow. A test cross, uses a homozygous recessive individual, since this genotype is easily physically identified. If the 50% of the offspring are black and 50% are red, then the black cow was heterozygous (Bb). If all black offspring result, then the black cow was homozygous dominant (BB).

Which of the following would result in a non-functional protein? A. a silent mutation B. a missense mutation C. a nonsense mutation D. a transfer mutation E. nucleotide diversity

C. a nonsense mutation A silent mutation often occurs in the wobble site of the codon on the mRNA strand. For most codons, if the third base pair is changed, the correct amino acid can still be made. A missense mutation results in the addition of an incorrect amino acid, but can still lead to a functional protein. Nonsense mutations result in a polypeptide chain that is shorter and is non-functional. For nonsense mutations, an insertion or deletion of a nucleotide base creates a premature stop codon (UGA, UAG, or UAA), terminating translation before the polypeptide can be completed. Transfer mutation is not an accurate term in biology.

The distribution of materials in the cytoplasm of an embryo can influence development. Which of the following regions in the zygote would exhibit higher rates of cell division? A. yolk sac B. placenta C. animal pole D. vegetal pole E. mitotic pole

C. animal pole The animal pole does not have yolk and can divide through mitosis at a quicker rate than the vegetal pole (the region with the yolk). The placenta is not known as having high rates of mitosis and is best known as the structure for which the embryo can release waste, perform gas exchange and nutrient absorption.

A particle that can bind in the active site of an enzyme, preventing the binding of the substrate is referred to as which of the following? A. positive inhibitor B. negative inhibitor C. competitive inhibitor D. non-competitive inhibitor E. regulator proteins

C. competitive inhibitor If the particle can bind to the active site, it is competing for the active site with the substrate. A non-competitive inhibitor would bind to an allosteric site on the enzyme, causing a conformational change to the active site, preventing the substrate from binding. Positive and negative inhibitors are terms that do not exist in biology.

For carbonyls that are part of a conjugated π-network, the C=O stretch: A. has a higher frequency than the analogous C=O in a non-conjugated system B. is always located at 1715 cm-1 C. has a lower frequency than the analogous C=O in a non-conjugated system D. exhibits a much lower magnitude of peak intensity E. is identical to the analogous C=O stretch in a non-conjugated system

C. has a lower frequency than the analogous C=O in a non-conjugated system All carbonyl compounds absorb in the IR region of 1760-1665 cm-1 owing to the stretching vibration of the C=O bond. This carbonyl band is distinct with a characteristic high intensity, and therefore is quite useful for diagnostic purposes because few other functional groups absorb in this region. Conjugation with a double bond or benzene ring lowers the stretching frequency, usually by 30 to 40 cm-1. The stretching frequency of the conjugated double bond is also lowered and may be enhanced in intensity. An example of this phenomenon is provided:

Which of the following is the process by which an unstable nucleus is transformed into a more stable nucleus with lower energy? A. nucleation B. combustion C. nuclear decay D. oxidation E. nuclear fusion

C. nuclear decay Nuclear decay involves the splitting of an unstable nucleus and emitting a radioactive particle. This process also decreases the energy of the original element. Nucleation though a chemistry term is related to the process of making a crystal from a supersaturated solution. A combustion reaction does generally result in the release of energy, but is not a mechanism used to make a nucleus more stable. Nuclear fusion is the process of adding elements together, increasing their energy, not decreasing their energy.

The human respiratory rate is regulated by chemoreceptors that monitor which of the following? A. oxygen B. methane C. pH levels D. hemoglobin E. proton levels

C. pH levels The brain triggers the diaphragm to contract and lower to spur inhalation when the pH levels begin to drop. In the presence of high amounts of CO2, the blood's pH begins to become acidic, which is detected by chemoreceptors. This will initiate inhalation, where CO2 will be expelled and oxygen will be absorbed into the capillaries in the alveoli, thereby restoring blood's neutral pH.

The first step of glycolysis is the phosphorylation of one molecule of glucose to generate glucose 6-phosphate. This reaction: A. is reversible. B. occurs in anaerobic organisms only. C. prevents glucose from leaking through the plasma membrane. D. takes place in the inner membrane of mitochondria. E. takes place in the outer membrane of mitochondria.

C. prevents glucose from leaking through the plasma membrane. Glycolysis takes place in the cytosol. It is a characteristic of eukaryotic and prokaryotic cells. The first reaction of glycolysis is irreversible since it requires an energy investment. Glucose-6-phosphate cannot pass back through the plasma membrane.

Which of the following is the charge of iron in the compound, Fe(SO4)2? A. +1 B. +2 C. -2 D. +4 E. -4

D. +4 This is an example of an ionic compound. For every 1 iron atom, 2 sulfate ions are needed. If sulfate has a charge of -2 and 2 sulfates are present, then this results in a charge of -4. Since the ionic compound in the question is neutral, there should not be a charge left on the compound. Therefore, if sulfate has a -4 (is looking to gain 4 electrons), then the iron must have a +4 charge (be willing to transfer 4 electrons).

The fundamental mechanism of evolution whereby an organism changes on its own as a result of environmental influence is called __________________. a) Differential reproduction b) Mutation c) Migration d) Natural selection e) Genetic drift

D. Natural selection. One of the basic principles of evolutionary theory, natural selection, relies on environmental influence on the genomes of organisms to cause trait variations. Variations that affect survival are the ones that become predominant in the population, as those without the preferred variant eventually die off.

How many degrees of unsaturation are present in the anxiolytic drug Valium (diazepam), molecular formula C16H13ClN2O? A. 8 B. 9 C. 10 D. 11 E. 12

D. 11 Degree of Unsaturation (or index of hydrogen deficiency, IHD), or rings plus pi bonds, lets you determine the number of rings, double bonds and triple bonds present in the compound if the molecular formul is known. It does not give the exact number of rings or double or triple bonds, but rather the sum of the number of rings and double bonds plus twice the number of triple bonds. Degree of Unsaturation = C - (H/2) - (X/2) + (N/2) +1 (C=#carbon, H=#hydrogen, X=#halogen, N=#nitrogen) = 16 - (13/2) - (1/2) + (2/2) + 1 = 11 Extended Explanation First use the saturated formula CnH(2n+2) which will get you to C16H34 Now lets deal with the Cl. How does it play a role in this molecule? It connects with a carbon and TAKES the place of a H. So the saturated molecule should have 1 less Hydrogen from what we predicted. Now we have C16H33 Now the two nitrogens. Lets assume they are amines for the saturated solution. They connect with the carbon and TAKE the place of a hydrogen BUT add on TWO hydrogens (NH2). Net gain of 1 hydrogen per N. So the saturated molecules would have 2 more H of the current formula we predicted. Now we have C16H35. All you have to do now is subtract the H difference divided by two. 35-13 = 22/2 = 11 degrees of unsaturation

If the area and perimeter of a right triangle are 30 cm2 and 30 cm, respectively, what is the length of the hypotenuse (the side opposite the right angle)? A. 9 B. 11 C. 12 D. 13 E. 15

D. 13 If we denote the hypotenuse of the triangle as c and the two other sides as a and b, then the values of the area and perimeter can be written as (1/2)ab = 30 and a + b + c = 30. We have three unknowns but two equations so far. However, a right triangle also follows the relation a2 + b2 = c2. We can now solve these three equations and obtain c = 13. However, the "spirit" of the problem is not checking whether you can solve this system of 3 equations (which is pretty complicated!) - instead, this problem is trying to see if you can come up with a "shortcut" to get to the right answer. Since both the perimeter and area are both nice, whole numbers, we can conclude that the lengths of the sides are also nice, whole numbers, most likely from one of the "special" triangles that we know about (eg. 3-4-5, 5-12-13) or a similar triangle. We can immediately see that the sides of the 5-12-13 triangle add up to 30. The area of the 5-12-13 triangle is 30 as well, and we can thus get to the correct answer without doing any solving at all. The work is shown below for your convenience, however.

It takes 6 minutes and 12 minutes, respectively, to run two computer programs when they are run one at a time. However, their speeds are reduced by 50% and 40%, respectively, if running in parallel. If a PC starts running the two programs together, how long will it take for them to finish? A. 17.4 minutes B. 18 minutes C. 16 minutes D. 16.8 minutes E. 15.5 minutes

D. 16.8 minutes At a 50% reduced speed, the first program will take (6×100)/(100-50)=12 minutes to complete, and at a 40% reduced speed, the second program will take (12×100)/(100-40)=20 minutes to complete. However, if they are started together, the first program will be completed after the first 12 minutes, and the second program will run alone at the regular speed. In 12 minutes, only (12×100)/20=60% of the second program will be complete. For the remaining 40%, it will run at its full speed and take another (12×40)/100=4.8 minutes to complete. The total time required to finish both the programs is 12+4.8=16.8 minutes.

According to the ideal gas law at STP, which of the following is the value of the ratio between moles (assume 1 mole), the gas constant R, temperature and the pressure? A. 1 B. 8.314 C. 20 D. 22.4 E. 44.8

D. 22.4 The ideal gas law, PV = nRT when divided by P results in: (nRT) / P = V, assuming that there is 1 mol at STP, this would equal 22.4L, which is also known as the molar volume of an ideal gas.

In how many different orders can six books be organized in a shelf? A. 1 B. 64 C. 1296 D. 720 E. 36

D. 720 This is clearly a permutation problem since the order of the books matters. The number of arrangements is 6P6 = 6! = 720.

Which of the following elements would contain the valence electron configuration 4s24p5? A. Fluorine B. Sulfur C. Calcium D. Bromine E. Antimony

D. Bromine The valence shell is the outer shell of an element. It is the electrons in the valence shell that interact to form compounds, either ionic or covalent. If the valence shell ends in the 4th energy level, this means the compound must be in the fourth row of the periodic table, therefore eliminating answer options A, B, and E. The valence shell shows a total of 7 valence electrons, 2 from the s and 5 from the p. The only element that has 7 valence electrons and is in the 4th row is Bromine (Br).

If an unknown compound is found to have an empirical formula of CH4, which of the following is the molecular formula if the molar mass was determined to be 128 g/mol? A. CH4 B. CH12 C. C8H12 D. C8H32 E. C12H16

D. C8H32 To determine the molecular formula using an empirical formula, the ratio of the molecular mass to the empirical mass must be calculated. Dividing the molecular mass of 128 grams by the empirical mass of ~16 grams (C = 12g + H = 1g, but there are 4 hydrogens in the compound) gives you approximately 8. This indicates that the empirical subscripts must be multiplied by 8 to result in the molecular formula of the unknown compound, C8H32.

DNA polymerases catalyze the production of polynucleotide chains. Which of the following statements holds true: A. DNA polymerases do not require a primer in order to initiate the reaction B. DNA polymerases require a primer with a free 5'-end C. DNA polymerases require a primer base-paired to the template with a free 5'-end D. DNA polymerases require a RNA primer base-paired to the template and with a free 3'-end. E. DNA polymerases require a DNA primer base-paired to the template and with a free 5'-end.

D. DNA polymerases require a primer base-paired to the template and with a free 3′-end. DNA polymerase can add dNTPs (deoxynucleoside triphosphates) only to a pre-existing oligonucleotide chain that is annealed to the template DNA. The enzyme adds dNTPs on a free 3′-OH- group. Primers in replication are RNA based. These primers are then cut out via endonuclease activity and replaced with DNA nucleotides. Finally, DNA ligase fuses the gap between the fragments of DNA.

Which is the best leaving group in a substitution reaction of an alkyl halide from the following choices? A. F- B. Cl- C. Br- D. I- E. All are equally good leaving groups

D. I- As size increases, basicity decreases, meaning a species will be less likely to act as a base; that is, the species will be less likely to share its electrons. Iodine is the largest in the series.

Which of the following structures is responsible for the release of calcium ions? A. Neuron B. Sarcomere C. Intercalated disks D. Sarcoplasmic reticulum E. Endoplasmic reticulum

D. Sarcoplasmic reticulum Calcium ions are essential for muscle contraction to occur. Without the release of calcium, the myosin head would be unable to bind to the actin at the binding sites. It is the calcium that binds and removes troponin from the myosin binding sites on the actin. This is done when the axon terminal nearest a muscle fiber releases acetylcholine, a neurotransmitter, which then causes the sarcoplasmic reticulum to release calcium into the muscle cell to allow for muscle contraction. The endoplasmic reticulum is responsible for protein modification following translation on a ribosome.

Which of the following functions would you NOT expect to result from the secretion of glucocorticoids (i.e. cortisol) by the adrenal glands? A. Stimulate gluconeogenesis. B. Stimulate lipolysis in adipose tissue. C. Behave as an immunosuppressive. D. Stimulate sodium reabsorption by the kidneys. E. Act as an anti-inflammatory.

D. Stimulate sodium reabsorption by the kidneys. When the adrenal cortex secretes glucocorticoids, many actions are initiated. Cortisol, for example, is released during times of stress. Gluconeogenesis (the process of creating glucose from non-carbohydrates) and lipolysis (the breakdown of fats) are both activated to generate more energy for the both during times of stress. Immunologic response, inflammatory response, glucose uptake by muscle and fat tissues, and protein construction are all restricted as these are energetically expensive and the body needs to place its energy reserves into other areas. Sodium reabsorption by the kidneys is regulated by secretion of mineralocorticoids of the adrenal cortex, such as aldosterone.

A real gas approaches the behavior of an Ideal Gas when: A. The gas is under high pressure and low temperature. B. The gas is under low pressure and low temperature. C. The gas is under high pressure and high temperature. D. The gas is under low pressure and high temperature. E. The gas is at any pressure and temperature, as long as it is a gas it is ideal.

D. The gas is under low pressure and high temperature. An ideal gas is a gas which obeys the Ideal Gas Laws. Real gases behave ideally when their particles are moving at high speed (high temperature)and there is lots of space between the particles (low pressure).The lower the temperature and higher the pressure the less ideal the gas behaves, especially as it approaches its liquidation point.

Which of the following is the specialized structure on the sperm that contains hydrolytic enzymes? A. flagella B. plasmid C. capsid D. acrosome E. sperm tail

D. acrosome The head of the sperm contains the acrosome, which has specialized enzymes that when released, help the sperm to penetrate and fertilize the egg. A plasmid is a small bacterium that can be used in recombinant DNA formation. The capsid is the protein coat that encapsulates a virus' genetic material. The flagella are important for motility of the sperm but do not contain any enzymes.

Which of the following is at the highest energy during an endothermic chemical reaction? A. reactants B. products C. catalyst D. activated complex E. intermediates

D. activated complex During a chemical reaction, enough energy must be absorbed for the reaction to take place. This is termed the activation energy. At the height of the activation energy is the activated complex, which is an intermediate between the reactant and the product. This forms when the reactants have gained enough energy and have collided with the right orientation to start the reaction. It is this activated complex that has the highest energy of the answer options given.

Which of the following is the correct pairing of the extraembryonic membrane and its function? A. yolk sac - fluid sac that protects the growing embryo. B. amnion - provides food for the growing embryo. C. chorion - stores waste for the embryo. D. allantois - participates in gas exchange. E. placenta - provides cushion for the embryo

D. allantois - participates in gas exchange. The yolk sac provides food for the growing embryo, especially true with birds. The amnion forms the fluid filled sac that provides for cushion and protection to the embryo. The chorion is the outermost membrane, encasing the other extraembryonic membranes. Only answer option D is correctly paired.

Trypsin is a proteolytic enzyme secreted by the pancreas in an inactive form (trypsinogen). Trypsinogen can be converted to trypsin by the action of: A. pepsin B. chymotrypsin C. amylase D. enteropeptidase and trypsin E. pepsinogen

D. enteropeptidase and trypsin After releasing trypsinogen from the pancreas, enteropeptidase cleaves the inactive protein at specific sites. As a consequence of this action trypsin is generated. This enzyme has ability to generate trypsinogen on its own and to release an active enzyme.

The resting potential of a neuron arises due to which of the following? A. the concentration of potassium ions in the extracellular space is greater than the concentration of sodium ions inside the axon. B. the concentration of potassium ions in the extracellular space is less than the concentration of sodium ions inside the axon. C. the concentration of potassium ions in the extracellular space is equal to the concentration of sodium ions inside the axon. D. the concentration of sodium ions in the extracellular space is greater than the concentration of potassium ions inside the axon. E. the concentration of sodium ions in the extracellular space is less than the concentration of potassium ions inside the axon.

D. the concentration of sodium ions in the extracellular space is greater than the concentration of potassium ions inside the axon. In a resting neuron, there is more potassium ions inside of the axon than outside in the extracellular space. Likewise there is more sodium in the extracellular space than inside of the axon. The difference in the concentrations of the ions results in a resting potential inside of the axon of -70mV (in humans). When the action potential occurs, sodium/potassium channels open, allowing the free movement of sodium ions into the axon and potassium ions out of the axon. This causes the axon to depolarize and become positive. After the action potential, the resting potential is restored using the sodium/potassium pumps.

Which of the following data sets contains the smallest variance? A. {12,14,16} B. {12, 14, 18} C. {120, 140, 160} D. {60, 61, 59} E. {20, 20, 25}

D. {60, 61, 59} This can be done by computing the variance of each of these expressions. Also, by inspection, it can be seen that the numbers in D vary by the least amount from each other.

If 45.1 grams of a solute is added to 302 grams of water to make a 0.65M solution, what is the molar mass of a solute? A. (45.1 grams)/(0.302 moles) B. (0.65(.302) grams)/(45.1 moles) C. (45.1 grams)/(0.65 moles) D. (0.65 grams)/(0.302 moles) E. (45.1 grams)/(0.65(.302) moles)

E. (45.1 grams)/(0.65(.302)moles) To determine the molar mass, the molarity equation will be needed. Molarity = (moles of solute)/(Liters of solution) Plugging in the values from the problem results in: 0.65 = (moles of solute)/(.302 L) Note: The amount of the solution is given in terms of grams of water, this can be converted to mL by using the density of water (1.0 grams/mL) and then converting the mL into liters. Cross-multiplying gives the following: 0.65(.302) = moles of solute The molar mass of a compound is in grams per mole. Therefore the molar mass of the unknown solute would be 45.1 grams of solute (from the question) divided by the number of moles just calculated 0.65(.302). Putting the pieces together results in a molar mass of the unknown solute of: (45.1 grams)/0.65(.302)moles

Which of the following statements is correct regarding nucleophilic acyl substitution? A. Protonation of the carbonyl is followed immediately by loss of the leaving group. B. SN2 reaction is the primary mechanism for this reaction. C. Ester hydrolysis proceeds in a single, concerted step. D. Loss of the leaving group is followed by carbocation rearrangement. E. Addition of a nucleophile to the carbonyl is followed by loss of the leaving group.

E. Addition of a nucleophile to the carbonyl is followed by loss of the leaving group. Carbonyl compounds react with nucleophiles via an addition mechanism: the nucleophile attacks the carbonyl carbon, forming a tetrahedral intermediate. The tetrahedral intermediate itself can be an alcohol or alkoxide, depending on the pH of the reaction. The tetrahedral intermediate of an acyl compound contains a substituent attached to the central carbon that can act as a leaving group. After the tetrahedral intermediate forms, it collapses, recreating the carbonyl C=O bond and ejecting the leaving group in an elimination reaction. In nucleophilic acyl substitution, the leaving group is ejected in a separate exothermic step. The Hammond Postulate predicts that the transition state for this step resembles the tetrahedral intermediate. Therefore, in the transition state for this step minimal bond breaking has occurred, and the importance of the nature of the leaving group is diminished.

Mitochondria utilize the process of chemiosmosis, whereby protons are transferred across the inner mitochondrial membrane. This generates potential energy in the form of A: ATP. B: a pH gradient. C: an electrical potential. D: All of the above. E: B and C only.

E. B and C only During cell respiration, inner mitochondrial membranes permit the selective movement of ions between the inner matrix and the inner membrane space, down their concentration gradient. Chemiosmosis is the process by which hydrogen ions diffuse into the inner membrane space, which generates potential energy in the form of an electrochemical gradient. This potential energy consists of an electrical potential and a pH gradient or chemical potential. Although ATP is formed by ATP synthase as a result of the potential energy generated from the gradient, ATP itself is NOT a form of potential energy that is generated by the process of chemiosmosis. ATP is a form of chemical potential energy. Thus E) is the only correct answer.

Which of the following is a method for initiating the uptake of a plasmid into a target eukaryotic cell? A. Electroporation. B. Pillus. C. Lambdaphage viral vector. D. Heat shock in the presence of CaCl2. E. Both A and D.

E. Both A and D. The correct answer is E. Bacteria utilize a pillus for conjugation, in order to exchange genetic material. The lambdaphage viral vector can be used injecting a specific sequence of DNA into a target cell, but not for encouraging the cell to uptake plasmid DNA. Electroporation involves using a small charge to cause the cell membrane to become more porous and uptake the plasmid. Heat shock involves heating up the target cells to ~42ºC after keeping them on ice in the presence of CaCl2, the cell membranes will become more porous and uptake the plasmid as with electroporation.

Which of the following structures of the skeletal system is innervated? A. Hair B. Nails C. Cartilage D. Osteoclasts E. Haversian canals

E. Haversian canals Innervated refers to the structure having nerves and blood vessels that run through it. Nails and hair are consider dead/dying cells and would not have blood vessels that run through the exterior nail structure. Cartilage is not innervated which attributes to the long healing time of sprained joints. Osteoclasts are cells that help to break down bone cells and these cells themselves do not have blood vessels or nerves. The Haversian canals are a network of opening in the bone that allow for nerves and blood vessels to weave in and out of the bone.

Which of the following is NOT classified correctly? A. Sponge - Invertebrate - Asymmetrical B. Cnidaria - Invertebrate - Radial C. Mollusk - Invertebrate - Bilateral D. Chordate - Vertebrate - Bilateral E. Nematode - Invertebrate - Radial

E. Nematode - Invertebrate - Radial For the animal kingdom, the simplest invertebrates are the sponges, which have no body symmetry. As animals become more advanced, invertebrates move from having no symmetry to having radial symmetry. The most advanced invertebrates have bilateral symmetry. Nematoda are round worms and are more advanced than the cnidarian like the jellyfish; therefore nematodes should have bilateral symmetry, not radial symmetry. Likewise, the chordate or vertebrate are all characterized as having bilateral symmetry. The only incorrect grouping is [E].

The enthalpy of a system of gas is dependent on which of the following? A. Pressure only B. Volume only C. Internal energy only D. Pressure and volume E. Pressure, volume and internal energy

E. Pressure, volume and internal energy The correct answer is E. The equation that governs enthalpy for a homogenous system (all gas or all liquid) is H = U + PV, where U is internal energy, P is pressure, and V is volume.

Which of these properties is not a colligative property of a salt solution? A. Lowering of vapor pressure with increasing concentration. B. Elevation of the boiling point with increasing concentration. C. Depression of freezing point with increasing concentration. D. Osmotic pressure increases with increasing concentration. E. The lower density of ice than the solution from which it forms.

E. The lower density of ice than the solution from which it forms. The lowering of vapor pressure, elevation of the boiling point, depression of freezing point and increase in osmotic pressure with increasing solute concentration are all colligative properties of the solution, as they all depend on the concentration of solution only and not the type of solute. The lower density of ice than the solution it forms from is due to hydrogen bonding between the water molecules in the solid ice holding the water molecules further apart than they are in the liquid state. This is true for all water solutions and pure water and does not depend on concentration.

Which piece of laboratory glassware is best used to measure 1.000 L of solution accurately? A. Beaker B. Buret C. Volumetric pipette D. Measuring cylinder E. Volumetric flask

E. Volumetric Beaker: holds liquids, should not be used for accurate measurement. Buret: accurately measures unknown volumes up to 50.00 mL. Volumetric Pipette: accurately measures known small volumes like; 5.00 ml, 10.00 mL, 20.00 mL, 25.00 mL and 50.00 mL. Measuring cylinder: good for measuring volumes up to a 2 L, but not as accurately as the... Volumetric flask: specifically prepared to measure larger known volumes with an accuracy of 1 mL in a Liter.

Which of the radioactive decay particles have the lowest penetrating power? A. proton B. positron C. gamma rays D. beta particles E. alpha particles

E. alpha particles In order of increasing penetration power, alpha particles have the lowest, then beta particles, then gamma rays. Protons are not known to have penetrating power and a positron is generally unstable and quickly decomposes, so its penetrating power is considered to be negligible.

The addition of heat and acid to 2-oxocyclopentanecarboxylic acid produces: A. cyclopentene B. cyclopentanol C. cyclopentaldehyde D. cyclopentanecarboxylic acid E. cyclopentanone

E. cyclopentanone Beta-keto carboxylic acids undergo decarboxylation through ring formations. The carbonyl bond of the ketone will react with the alcohol group of the carboxylic acid to form a ring and release the carboxylic acid as CO2. The remaining enol will tautomerize into a carbonyl group again, leaving cyclopentanone. Notice a cyclopentaldehyde can't even be a possible answer, aldehydes cannot exist in cyclo compounds.

Which of the following molecules is amphipathic? A. water B. glucose C. steroids D. triglycerides E. phospholipids

E. phospholipids An amphipathic molecule has both a hydrophilic ("water loving") and a hydrophobic ("water fearing") region. Water is hydrophilic, whereas a triglyceride (or lipid) is hydrophobic. Glucose is also hydrophilic. Steroids are derived from lipids and also would be hydrophobic. A phospholipid is made of a phosphate group (hydrophilic) and two fatty acid chains (hydrophobic) and is amphipathic.

How does the C-N bond in CN-1 differ from the C-H bond in CH4? A. the C-H bond is longer because it is a double bond. B. the C-N bond is longer because it is a single bond. C. the C-H bond is shorter because it is a double bond. D. the C-H bond is shorter because it is a triple bond. E. the C-N bond is shorter because it is a triple bond.

E. the C-N bond is shorter because it is a triple bond. The bond length depends on the type of bond. Single bonds are longer than double bonds, which are longer than triple bonds. Drawing the Lewis dot diagrams for these compounds gives some insight into the type of bonds formed between C and N and C and H. The C-N bond is shorter as it is a triple bond. The C-H bond would be longer since it is a single bond. The magnitude of the difference cannot be calculated based on the limited information in the question, but at least the relative sizes of the bonds can still be determined.

The absorption of what type of electromagnetic radiation results in electronic transitions? A. microwaves B. X-rays C. radio waves D. infrared light E. ultraviolet light

E. ultraviolet light Ultraviolet-visible spectroscopy (UV-Vis or UV/Vis) refers to absorption/reflectance spectroscopy UV-Vis spectral region. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, molecules undergo electronic transitions. Molecules containing π-electrons or non-bonding electrons (n-electrons) can absorb the energy in the form of ultraviolet or visible light to excite these electrons to higher anti-bonding molecular orbitals. The more easily excited the electrons (i.e. lower energy gap between HOMO and the LUMO), the longer the wavelength of light it can absorb.

If the temperature drops by 18o Fahrenheit in a given day, how much did it drop in degrees Celsius? a) -14 b) 10 c) 32.4 d) -7.78 e) 25.2

b) 10 The ratio of "change in degrees Fahrenheit" to "change in degrees Celsius" is simply 9 to 5, and therefore, (18×5) / 9 = 10. If you were converting a temperature of 18o Fahrenheit to degrees Celsius, then it would be ((18-32) × 5) / 9 = -7.78o Celsius.

A father's age is twice the sum of the ages of his four sons. In 30 years, the total of the sons' ages will be twice the age of their father. How old is the father now? a) 24 b) 48 c) 32 d) 40 e) 36

d) 40 If the sum of the four son's ages is x at present, the father's age is 2x. In 30 years, the total of the son's ages will be x+4×30=x+120, whereas the father's age will be 2x+30. Therefore, x+120=2(2x+30), which yields x=20, and hence, the father's age at present is 2x=40.