Biology/Biochemistry

Name the three accessory glands

seminal vesicle (2 of them), prostate gland, bulbourethral gland (2 of them). All three produce fluids that are included in semen.

True or False: Prokaryotic cells reproduce asexually. Prokaryotes are also capable of acquiring genetic material from outside the cell and using that genetic material.

True. Asexual reproduction via binary fission. The outside genetic material is called plasmids.

All amino acids are chiral, except

Glycine, the simplest amino acid, in which R=H.

Viruses: - Are they considered living things? Why? - What is the difference between eukaryotes and viruses?

No, viruses are not considered living things because they are acellular. Unlike eukaryotes, viruses do not have a nucleus or organelles.

What is the role of connective tissue? What are examples of connective tissues?

Supports the body and provides the framework for the epithelial cells to carry out their functions. Most cells in connective tissues produce and secret materials such as collagen and elastin to form the extra-cellular matrix. Bone, cartilage, tendons, ligaments, adipose tissue, and blood are examples of connective tissues.

Lipoteichoic acid vs lipopolysaccharides

- Lipoteichoic acid is found in gram positive cells. The function of this acid to the bacterium is unknown, but the human immune system may be activated by exposure to this chemical. - Lipopolysaccharides are found in gram negative cells. They trigger an immune response in human beings; the inflammatory response to lipopolysaccharides is much stronger than the response to lipoteichoic acid.

Classification of Bacteria based on Oxygen use

- Obligate aerobes: Require oxygen. - Anaerobes: Do not require oxygen. - Obligate anaerobes: The presence of oxygen leads to the production of reactive oxygen-containing radicals in these species, which leads to cell death. - Facultative anaerobes: Can toggle between metabolic process, using oxygen to aerobic metabolism if it is present, and switching to anaerobic metabolism if it isn't. - Aerotolerant anaerobes: Unable to use oxygen for metabolism, but are not harmed by its presence in the environment.

Mitochondria Structure

- Outer Membrane: serves as the barrier between the cytosol and the inner environment of the mitochondrion. - Inner Membrane: which is thrown into numerous infoldings called Cristae and contains the molecules and enzymes necessary for the electron transport chain. The space inside the inner membrane is called the Matrix. - Intermembrane Space: The space between the inner and outer membranes.

What is the structure of viruses?

Viruses contain genetic materials, a protein coat, and sometimes an envelope containing lipids. The genetic information my be circular or linear, single or double stranded, and composed of either DNA or RNA.

What are microfilaments' role in mitosis, specifically cytokinesis (the devision of materials between daughter cells)?

During cytokinesis, the cleavage furrow is formed from microfilaments, which organize as a ring at the site of division between the two new daughter cells. As the actin filaments within the ring contract, the ring becomes smaller, eventually pinching off the connection between the two daughter cells.

Steps of peptide bond formation

1. The nucleophilic amino group of R2 attacks the electrophilic carbonyl group of R1. 2. The carbonyl bond reforms with the elimination of hydroxide ion. 3. The hydroxide ion abstracts a proton - elimination of water - and the positive charge on nitrogen is neutralized. The results in the formation of a new bond - peptide bond between the two amino acids. *This is a simplistic representation of peptide bond formation. Peptide-protein synthesis in biological systems involve catalysts, cofactors, and enzymes.

9+2 structure

9 prs microtubules surrounding 2 central microtubules for stability (structure of cilia&flagella).

Cytoskeletons

A network of long, straight proteins that provide structure for the cell. There are three components of the cytoskeleton: microfilaments, microtubules, and intermediate filaments.

What are the two common means of hydrolysis?

Acid hydrolysis: using strong acids. Acid hydrolysis, when combined with heat, is a nonspecific way of cleaving peptide bonds. Proteolysis: using protease. Proteolysis is a specific cleavage of the peptide bond.

Why are proline and glycine known as alpha helix breakers?

Because they play an important role in alpha helix disruption due to proline forming double covalent bonds and the flexibility of glycine.

What is the process the results in the brain controlling the gonads?

Brain, specifically the hypothalamus, produces the gonadotropin releasing hormone (GNRH), which triggers the interior pituitary (organ right underneath the hypothalamus) to produce leutinzing hormone (LH) and follicle stimulating hormone (FSH), which control the female and male gonads.

Conjugation

Conjugation is the bacterial form of mating (sexual reproduction). It involves two cells forming a conjugation bridge between them that allows for the transfer of genetic material. The transfer is unidirectional from the donor male (+) to the recipient (-). The bridge is made of sex pili that are found on the donor male. To form a pius, bacteria must contain plasmids known as sex factors that contain the necessary genes. The female recipient (-) is able to form a pilus after conjugation is complete which allows the bacterium to become a male donor (+) and transfer the genetic information to another recipient.

Peroxisomes

Contain hydrogen peroxide. One of their primary functions is the breakdown of very long chain fatty acids via B-oxidation. Peroxisomes participate in the synthesis of phospholipids and contain some the enzymes involved the pentose phosphate pathway.

What are the possible functions of epithelial cells? What does it mean that epithelial cells are often polarized?

Epithelial cells cover the body and line its cavities, providing a means for protection against pathogen invasion and desiccation. In certain organs, epithelial cells are involved in absorption, secretion, and sensation. Epithelial cells are often polarized, meaning that one sided faces a lumen (the hollow inside of an organ or tube) or the outside world, while the other side interacts with underlying blood vessels and structural cells. (Ex. In the small intestines, one side of the cell will be involved in absorption of nutrients from the lumen, while the other side will be involved in releasing those nutrients into circulation for use in the rest of the body).

RNA Viruses

Have genetic material stored as RNA, as opposed to DNA. They can have their genome directly used by host cell replication machinery as if it were mRNA and then translated directly into protein. Or they can have their RNA serve as template for another RNA strand, that is then used for protein translation. Some well known examples of RNA viruses are the coronavirus, which was responsible for the SARS epidemic; the influenze virus responsible for the flu; and the paramixovirus which is the virus responsible for measles.

Where is the ribosomal RNA (rRNA) synthesized?

In the nucleolus, which is a subsection of the nucleus. The nucleolus takes up 25% of the entire nucleus and usually can be identified as a darker spot in the nucleus.

What is the isoelectric point (pl) of amino acids?

Isoelectric point is the point along the pH scale where the amino acid has zero net charge. When the net charge is 0, the form of amino acid is called zwitterion. The formula for isoelectric point is shown in the image.

Why is it difficult to make specific antibiotics that target bacteria? What are scientists targeting now?

It can be difficult to develop medicines that target only bacteria because of the similar analogous structure bacteria and eukaryotic cells share. Most antibiotics target the bacterial ribosome (significantly smaller than the eukaryotic ribosome) or the bacterial flagellum.

What are the phases of bacterial growth?

Lag phase: no growth; bacteria adapting to new environment. Exponential/log phase: exponential growth is noted. Death phase: All resources are used and bacteria start to die.

ncRNA

Non-coding RNA: a functional RNA molecule that skips the last step of being translated into a protein and can directly perform functions within the cell as an RNA molecule. Examples of functional RNA: transfer RNA, ribosomal RNA; which are both used for the translation of messenger RNA into proteins.

Micofilaments

PART OF CYTOSKELETON - they are made up of solid polymerized rods of actin. The actin filaments are organized into bundles and networks and are resistant to both compression and fracture, providing protection for the cell. Actin filaments can also use ATP to generate force for movement by interacting with Myosin, such as in muscle contraction.

Micotubules

PART OF THE CYTOSKELETON - hollow polymers of tubulin proteins. Microtubules radiate throughout the cell, providing the primary pathways along which motor proteins like kinesin and dynein carry vesicles. Cilia and flagella are motile structures composed of microtubules.

intermediate filaments

PART OF THE CYTOSKELETON - they are a diverse group of filamentous proteins, including keratin, desmin, vimentin, and lamins. Many intermediate filaments are involved in cell-to-cell adhesion or maintenance of the overall integrity of the cytoskeleton. Intermediate filaments are able to withstand an tremendous amount of tension, making the cell structure more rigid. In addition, intermediate filaments contribute in anchoring other organelles, including the nucleus.

What are plasmids and what benefits do they have for the bacterium? What else can attach to plasmids?

Plasmids are "extra" DNA in prokaryotes that are not required for survival. They are separate from the DNA chromosome. They are not considered part of the genome of the bacterium - but they may confer an advantage such as antibiotic resistance. - Virulence factors are traits that increase how pathogenic a bacterium is, such as toxin production, projections that allow the bacterium to attach to certain types of cells, or the invasion of the host's immune system. - Episomes are subsets of plasmids that are capable of integrating into the genome of the bacterium.

What are the different forces that keep proteins structures together?

Primary - covalent bond (amide/peptide bond). Secondary - hydrogen bonds. Tertiary - Ionic bonds, disulfide bonds, hydrophobic interactions, hydrogen bonding. Quaternary - Ionic bonding, disulfide bonds, hydrophobic interactions, hydrogen bonding.

Gram Stain

Process: Crystal Violet stain is used followed by safranin. Results: If the prokaryotic wall absorbs the crystal violet stain it appears dark purple - Gram positive meaning the cell wall consists of a thick layer of peptidoglycan and also contains lipoteichoic acid. If the prokaryotic cell absorbs the safranin and the wall appears pink-red - Gram negative meaning the cell wall consists of a very thin layer of peptidoglycan and also contains lipopolysaccharides.

Resonance Structures

Resonance structures are different representations of the same molecule; the arrangement of the atoms remains the same, but the electrons are distributed differently amongst the atoms. Resonance structures exist when there is a possibility of movement of electrons between neighboring functional groups, as in the case of polypeptides.

Mnemonic: Pathway of sperm through the male reproductive system SEVE(N) UP

Seminiferous tubules Epididymis Vas deferens (also called the ductus deferens) Ejaculatory duct (Nothing) Urethra Penis

What is SRY?

Sex-determining region Y of the Y chromosome. This region codes for a transcription factor that initiates testis differentiation and, thus, the formation of male gonads.

Epididymis: location and function

Sit on top of the testes on either side. Sperm move from testes to epididymis to gain more mitochondria and flagella prior to ejaculation.

Since prokaryotes lack mitochondria, how do they generate ATP?

The cell membrane in prokaryotes is used for the electron transport chain and generation of ATP.

Transduction

Transduction is the only genetic recombination process that requires a vector (a virus that carries genetic material from one bacterium to another). Viruses are obligate intracellular pathogens, which means they cannot reproduce outside of a host cell. Because of this , bacteriophages (viruses that infect the bacteria) can accidently trap a segment of host DNA during assembly. When the bacteriophage infects another bacterium, it can release the trapped DNA into the new host cell. This transferred DNA can then be integrated into the new host DNA.

Transformation

Transformation results in the integration of foreign genetic material into the host genome (episomes). The foreign material most likely comes from other bacterium that, upon lysing, spilled their contents in the vicinity of the bacterium capable of transformation. Many gram negative rods are able to carry out this process.

Vas deferans

These are tubes arising from the testes which carry sperms from the testes to the urethra.

How do eukaryotic cell replicate?

Through the cell cycle, which consists of four stages: G1 (presynthetic phase), S (Synthesis of DNA), G2 (postsynthetic phase), and M (mitosis). G0 is when the cell is not replicating and simply living and serving a function. Interphase includes G1, S, and G2. Prophase, metaphase, anaphase, and telophase are included in the M (mitosis) stage.

Transposons

Transposons are genetic elements capable of inserting and removing themselves from the genome. This phenomenon is not limited to prokaryotes; it has been seen in eukaryotes as well. If a transposon is inserted within a coding region of a gene, that gene may be disrupted.

How is a peptide bond broken?

Via hydrolysis forming free amino acids after breaking the peptide bond.

A woman is at a restaurant and orders a spicy entreée. After the first bite, she experiences burning in her mouth and becomes concerned that her food is too hot for her. The next few bites are similarly uncomfortable, but after a while the spiciness seems to subside somewhat, and by the end of the meal, she doesn't notice the spice level. The end of the meal experience is best described as: a. adaptation. b. signal detection. c. a difference threshold. d. pain perception.

[A] is the correct answer: Adaptation. The spicy food can be considered an extreme stimulus because it eclipses what the woman believes she can handle in terms of heat. However, after experiencing the stimulus over and over, the experience of spice drops to barely perceptible. This is sensory adaptation: a reduction in response to a stimulus over time.

Which of the following characteristics is NOT attributed to antibodies? a. Antibodies bind to more than one distinct antigen. b. Antibodies label antigens for targeting by other immune cells. c. Antibodies can cause agglutination by interaction with antigen. d. Antibodies have two heavy chains and two light chains.

[A] is the correct answer: Antibodies bind to more than one distinct antigen. Antibodies are specific to a single antigen. Each B-cell produces a single type of antibody with a constant region that is specific to the host and a variable region that is specific to an antigen.

In high doses, aspirin functions as a mitochondrial uncoupler. How would this affect glycogen stores? a. It causes depletion of glycogen stores. b. It has no effect on glycogen stores. c. It promotes additional storage of glucose as glycogen. d. Its effect on glycogen stores varies from cell to cell.

[A] is the correct answer: It causes depletion of glycogen stores. Uncouplers inhibit ATP synthesis without affecting the electron transport chain. Because the body must burn more fuel to maintain the proton-motive force, glycogen stores will be mobilized to feed into glycolysis, then the TCA, and finally oxidative phosphorylation.

Matt and Cati discuss the reasons why they avoid driving above the speed limit. Matt says that he wants to avoid a traffic fine, while Cati says that speeding is dangerous and, if everyone did it, there would be more accidents and people would get hurt. According to Kohlberg, which of the following describes the phases of moral reasoning demonstrated by Matt and Cati, respectively? a. Preconventional; conventional b. Preconventional; postconventional c. Conventional; preconventional d. Postconventional; conventional

[A] is the correct answer: Preconventional; conventional. Matt's reasoning reflects a desire to avoid punishment, which reflects stage one in Kohlberg's preconventional phase (obedience). Cati's reasoning takes into account social order, reflecting stage four in the conventional phase (law and order).

When you first meet Dustin, he is very rude to you. You run into him twice more and he is very friendly, but you still dislike him because of your first meeting. What impression bias does this describe? a. Primacy effect b. Recency effect c. Reliance on central traits d. Proximity

[A] is the correct answer: Primary effect. The impressions we form when meeting others are influenced by a number of perceptual biases. The primacy effect refers to those occasions when first impressions are more important than subsequent impressions.

The swimming times for all members of a swim team are tracked over a six-month period in team-only practices and at public meets. For 14 of the 16 members, top times were clocked at the meets. What social phenomenon does this evidence support? a. Social facilitation b. Peer pressure c. Identification d. Group polarization

[A] is the correct answer: Social facilitation. For 14 out of the 16 members, the record times were obtained during public meets. The fact that the team members performed better when in front of a crowd supports the notion of social facilitation.

A researcher uses a partial-report procedure after presenting participants with an array of nine numbers for a fraction of a second. Which of the following is the most likely result of this procedure? a. The participant will be able to recall any of the rows or columns in great detail but only immediately after presentation. b. The participant will only be able to recall the first few numbers in the array due to the serial position effect. c. The participant will be able to recall approximately seven of the numbers for a few seconds following presentation of the stimulus. d. The participant will not be able to recall any of the numbers verbally, but will be able to draw the full array under hypnosis.

[A] is the correct answer: The participant will be able to recall any of the rows or columns in great detail but only immediately after presentation. Partial-report procedures, in which the individual is asked to recall a specific portion of the stimulus, are incredibly accurate, but only for a very brief time. This is a method of studying sensory (specifically, iconic) memory. Both the serial position effect, choice (B), and the 7 ± 2 rule, choice (C), are characteristics of short-term memory.

Which ion channels are responsible for maintaining the resting membrane potential? a. Ungated channels b. Voltage-gated channels c. Ligand-gated channels d. No ion channels are involved in maintenance of the resting membrane potential.

[A] is the correct answer: Ungated channels. The resting membrane potential is displayed by cells that are not actively involved in signal transduction. Ungated or "leak" channels permit limited free flow of ions, while the sodium-potassium pump is also active and corrects for this leakage. Ligand-gated and voltage-gated channels are involved in cell signaling and in the pacemaker potentials of certain cells, but cause deviation from—not maintenance of—the resting membrane potential.

Over the last few decades, the United States population has become: a. bigger, older, and more diverse. b. bigger, younger, and more diverse. c. smaller, older, and less diverse. d. smaller, older, and more diverse .

[A] is the correct answer: bigger, older, and more diverse. With a decrease in mortality rate and a higher immigration rate than emigration rate, the United States population continues to grow, with an increasing average age and increasing racial and ethnic diversity.

Biochemical reactions that involve the transfer of electrons produce an electromotive force. Given the following standard reduction potentials: Zn (2+) + 2e- -> Zn E0 (red) = -0.763 V Ag (+) + e- -> Ag E0 (red) = +0.337 V What is the standard electromotive force of the following reaction? Zn (2+) + 2 Ag -> 2Ag(+) + Zn ANSWER SELECTION a. -2.2 V b. -1.1 V c. +1.1 V d. +2.2 V

[B] is the correct answer: -1.1 V To determine the standard electromotive force of a cell, simply subtract the standard reduction potentials of the two electrodes. In this case, the cathode is zinc because it is being reduced; the anode is silver because it is being oxidized. Thus, E°cell = E°red,cathode - E°red,anode = -0.763 - 0.337 = -1.10 V. While we must multiply the silver half-reaction by two to balance electrons, the actual value for the reduction potential does not change. Remember that the standard reduction potential is determined by the identity of the electrode, not the amount of it present.

Photons and other energy sources can exite electrons into higher energy levels, though these excitations are typically short-lived. X-ray imaging succeeds because different tissue types are differently able to absorb the energy of a photon in order to excite an electron. Suppose an electron falls from n = 4 to its ground state, n = 1. Which of the following effects is most likely? a. A photon is absorbed. b. A photon is emitted. c. The electron moves into a p-orbital. d. The electron moves into a d-orbital.

[B] is the correct answer: A photon is emitted. Because the electron is moving into the n = 1 shell, the only subshell available is the 1s subshell, which eliminates choices (C) and (D). There will be some energy change, however, as the electron must lose energy to return to the minimum-energy ground state. That will require emitting radiation in the form of a photon.

Which of the following is true about cholesterol? a. Cholesterol always increases membrane fluidity in cells. b. Cholesterol is a steroid precursor. c. Cholesterol is a precursor for vitamin A, which is produced in the skin. d. Cholesterol interacts only with the hydrophobic tails of phospholipids.

[B] is the correct answer: Cholesterol is a steroid precursor. Cholesterol is a steroid precursor that has variable effects on membrane fluidity depending on temperature, eliminating choice (A). It interacts with both the hydrophobic tails and the hydrophilic heads of membrane lipids, nullifying choice (D). It is also a precursor for vitamin D (not vitamin A), which can be produced in the skin in a UV-driven reaction, eliminating choice (C).

How do chylomicrons and VLDLs differ? a. Chylomicrons contain apoproteins, VLDLs do not. b. Chylomicrons are synthesized in the intestine, VLDLs are synthesized in the liver. c. Chylomicrons transport triacylglycerol, VLDLs transport cholesterol. d. VLDLs are another term for chylomicron remnants; they differ in age.

[B] is the correct answer: Chylomicrons are synthesized in the intestine, VLDLs are synthesized in the liver. Chylomicrons and VLDLs are very similar. Both contain apolipoproteins and primarily transport triacylglycerol, eliminating choices (A) and (C). The only major difference between them is the tissue of origin. Chylomicrons transport dietary triacylglycerol and originate in the small intestine, while VLDLs transport newly synthesized triacylglycerol and originate in the liver.

In some cultures, it is considered taboo for one to show too much sadness at a funeral. In other cultures, wailing and crying loudly is expected. These cultures differ in their: a. characteristic institutions. b. display rules. c. authentic selves. d. peer groups.

[B] is the correct answer: Display rules. Display rules are those that dictate cultural expectations of emotion. In some cultures, sadness is considered personal and internal; in others, sadness is shared externally with the community.

A 28-year-old male comes to a clinic concerned that he has pancreatic cancer. Review of his medical records shows that this is the fourth time in the past year that the patient has appeared for medical attention. No identifiable medical problem is found. When confronted with this history, he confesses that he feels relieved after being told that all of the tests are negative, but soon becomes worried again that he has cancer. Based on the information, the most likely diagnosis for this patient would be: a. major depressive disorder. b. illness anxiety disorder. c. conversion disorder. d. narcissistic personality disorder.

[B] is the correct answer: Illness anxiety disorder. In illness anxiety disorder, the person is preoccupied with fears that he has—or will come down with—a serious disease, and these fears continue even after medical exams and tests have returned negative results.

Ingested acetic acid is a common source of biochemical acetyl groups, including those that form acetyl-CoA. Acetic acid dissociates in solution according to the following equation: CH3COOH = CH3COO- + H+ If sodium acetate is added to a solution of acetic acid in excess water, which of the following effects would be observed in the solution? a. Decreased pH b. Increased pH c. Decreased pKeq (pKa) d. Increased pKeq (pKa)

[B] is the correct answer: Increased pH. Adding sodium acetate increases the number of acetate ions present. According to Le Châtelier's principle, this change will push this reaction to the left, resulting in a decrease in the number of free H+ ions. Because pH is determined by the hydrogen ion concentration, a decrease in the number of free protons will increase the pH. An acid's Ka (which is simply the Keq for acid dissociation) will remain constant under a given temperature and pressure, eliminating choices (C) and (D).

An EMT sees himself as a bit of a rebel, but is highly sociable and is able to keep calm in an emergency. This person would likely score in the lower range of which of the following traits? a. Psychoticism b. Neuroticism c. Extraversion d. Conscientiousness

[B] is the correct answer: Neuroticism. As a rebel and a sociable person, this individual would score highly on both psychoticism and extraversion, respectively. Neuroticism is associated with high emotional arousal in stressful situations, so being able to keep calm in an emergency is a sign of low neuroticism. Conscientiousness, a trait associated with being hardworking and organized instead of impulsive, is not described by the question stem.

Elephant seal males mate with multiple females each mating season, while females only have one mate each. What type of mating system is this? a. Polyandry b. Polygyny c. Monogamy d. Promiscuity

[B] is the correct answer: Polgyny. Polygamy involves a male having exclusive relationships with several females (polygyny) or a female having exclusive relationships with several males (polyandry), choice (A). Monogamy, choice (C), consists of exclusive mating relationships. Promiscuity, choice (D), refers to a member of one sex mating with any member of the opposite sex.

A group of men and women are going to be rated on their driving abilities. The role of gender is emphasized in the experiment and the women perform worse than the men. In another experiment the role of gender is not mentioned and the ratings are comparable between the two groups. Which principle do these results support? a. Institutional discrimination b. Stereotype threat c. Prejudice d. The just-world hypothesis

[B] is the correct answer: Stereotype threat. Stereotype threat refers to the concept of people being concerned or anxious about confirming a negative stereotype about their social group. Stereotype threat can hinder performance, creating a self-fulfilling prophecy.

Sodium hypochlorite (NaClO) is used as a disinfectant and has also been shown to treat chronic skin inflammation. What is the oxidation number of chlorine in NaClO? a. -1 b. 0 c. +1 d. +2

[C] is the correct answer: +1 In NaClO (sodium hypochlorite), sodium carries its typical +1 charge, and oxygen carries its typical -2 charge. This means that the chlorine atom must carry a +1 charge in order to balance the overall charge of zero.

For the most part, biological pH is slightly basic. However, the stomach is very acidic, and its contents must be swiftly neutralized by basic bicarbonate ions upon entering the small intestine, which has a basic pH. How many liters of 2 M Ba(OH)2 are needed to titrate a 4 L solution of 6 M H3PO4? a. 1.33 L b. 12 L c. 18 L d. 56 L

[C] is the correct answer: 18 L. Use the equivalence point equation: NaVa = NbVb Ba(OH)2 can dissociate to give two hydroxide ions, so its normality is 2 M × 2 = 4 N. H3PO4 can dissociate to give three hydronium ions, so its normality is 6 M × 3 = 18 N. Plugging into the equation, we get (18 N)(4 L) = (4 N)(Vb). Therefore, Vb is 18 L.

A young adult male claims to have had sexual relationships mostly with other men, although he has been attracted to women at times. What would be his most likely score on the Kinsey scale? a. 0 b. 1 c. 5 d. 6

[C] is the correct answer: 5. This man is describing his sexuality as mostly homosexual, although he has also had some heterosexual attractions. The Kinsey scale scores a 6, choice (D), as exclusively homo-sexual. A score of 3 would equate to bisexuality. Thus, this man would likely score a 4 or 5.

Which of the following would be most likely to be stored in long-term memory? a. A list of nonsense words b. A list of the dates of birth of 15 randomly selected people c. A list of the names of musicians in an individual's favorite bands d. A list of the dates of battles in the Peloponnesian War

[C] is the correct answer: A list of the names of musicians in an individual's favorite bands. The self-reference effect indicates that information that is most meaningful to an individual is the most likely to be memorized. Choice (C) is the most personally relevant to the individual memorizing the list.

Many pets will run toward the kitchen when they hear the sound of a can opener opening a can of pet food. The sound of the can opener is a: a. conditioned response. b. unconditioned response. c. conditioned stimulus. d. unconditioned stimulus.

[C] is the correct answer: Conditioned stimulus. The sound of a can opener would not normally produce a response on its own, making it a stimulus that must have been conditioned by association with the sound with food.

A student is trying to determine the type of membrane transport occurring in a cell. She finds that the molecule to be transported is very large and polar, and when transported across the membrane, no energy is required. Which of the following is the most likely mechanism of transport? a. Active transport b. Simple diffusion c. Facilitated diffusion d. Exocytosis

[C] is the correct answer: Facilitated diffusion. We are asked to identify the type of transport that would allow a large, polar molecule to cross the membrane without any energy expenditure. This scenario describes facilitated diffusion, which uses a transport protein (or channel) to facilitate the movement of large, polar molecules across the nonpolar, hydrophobic membrane. Facilitated diffusion, like simple diffusion, does not require energy, which explains why no ATP was consumed during this transport process.

Your neighbor asks you to check his mail while he is out of town, and you agree. Later that day, he asks you to water his plants as well. What technique for compliance is he using in this scenario? a. Lowball technique b. That's-not-all technique c. Foot-in-the-door technique d. Door-in-the-face technique

[C] is the correct answer: Foot-in-the-door technique. This is a prime example of the foot-in-the-door technique. The neighbor first asks for a small favor and, after receiving commitment, asks for a larger favor.

According to Erikson's stages of psychosocial development, which of the following would be the most important for a recent college graduate to accomplish? a. Figuring out what identities are most important to him or her. b. Feeling like a contributing member of society. c. Forming an intimate relationship with a significant other. d. Finding a feeling of accomplishment in his or her life.

[C] is the correct answer: Forming an intimate relationship with a significant other. As a postadolescent young adult, this person would be be described by Erikson as experiencing the conflict of intimacy vs. isolation, and so forming significant relationships with others would be a primary goal. Choices (B) and (D) represent the next two stages in life (generativity vs. stagnation and integrity vs. despair, respectively), while choice (A) is the conflict that Erikson would say should have been resolved in adolescence (identity vs. role confusion).

Aerobic respiration ends at the electron transport chain, where protein complexes are reduced and oxidized in turn as electrons make their way to join O2 to form H2O. Consider the following equation: 6 Na (s) + 2NH3 (aq) -> 2Na3N (s) + 3 H2 (g) Which species acts as an oxidizing agent? a. Na b. N in NH3 c. H in NH3 d. H2

[C] is the correct answer: H in NH3. The oxidizing agent is the species that is reduced in any given equation. In this problem, six hydrogen atoms with +1 oxidation states in NH3 are reduced to three neutral H2 molecules.

Glen brings cookies to work. Although you have not yet tasted them, you say to another coworker, "Glen is such a great guy; I'm sure these cookies are fantastic!" What type of bias is this? a. Reliance on central traits b. Direct benefits c. Halo effect d. Similarity

[C] is the correct answer: Halo effect. The halo effect is a cognitive bias in which judgments of an individual's character can be affected by the overall impression of the individual.

An α-helix is most likely to be held together by: a. disulfide bonds. b. hydrophobic effects. c. hydrogen bonds. d. ion attractions between side chains.

[C] is the correct answer: Hydrogen bond. The α-helix is held together primarily by hydrogen bonds between the carboxyl groups and amino groups of amino acids. Disulfide bridges, choice (A), and hydrophobic effects, choice (B), are primarily involved in tertiary structures, not secondary. Even if they were charged, the side chains of amino acids are too far apart to participate in strong interactions in secondary structure.

Researchers discover that polymorphisms in the DRD2 gene can be associated with thrill-seeking behavior, and that individuals with certain forms of the gene are more likely to become extreme athletes and have more dangerous hobbies. Which of the following theories is supported by this discovery? I. The social cognitive perspective II. The behavioral perspective III. The biological perspective a. I only b. III only c. I and III only d. II and III only

[C] is the correct answer: I and III only. This research supports a link between genetic expression and behavior, which is a central tenet of the biological perspective. The social cognitive perspective also holds that people's behaviors and traits shape their environments, which in turn have an effect on their identity, so the discovery also supports this perspective. Behaviorism is not supported, as the discovery is not related to rewards and punishments.

Which of the following is least likely to cause denaturation of proteins? a. Heating the protein to 100 °C b. Adding 8 M urea c. Moving it to a more hypotonic environment d. Adding a detergent such as sodium dodecyl sulfate

[C] is the correct answer: Moving it to a more hypotonic environment. High salt concentrations and detergents can denature a protein, as can high temperatures. But moving a protein to a hypotonic environment—that is, a lower solute concentration— should not lead to denaturation.

A nine-year-old girl is brought to the pediatrician. Her parents describe that any time she is startled, she appears to collapse and fall asleep. She also complains of waking up in the morning unable to move. Which sleep disorder should be suspected? a. Insomnia b. Sleep deprivation c. Narcolepsy d. Sleep apnea

[C] is the correct answer: Narcolepsy. The patient and her parents are describing cataplexy (a sudden loss of muscle tone and intrusion of REM sleep during waking hours, usually in response to a startling or emotional trigger) and sleep paralysis (an inability to move despite being awake, usually when waking up in the morning). These symptoms are highly suggestive of narcolepsy; in fact, some consider cataplexy to be pathognomonic for (absolutely indicative of) the disorder.

Which of the following is NOT a difference that would allow one to distinguish a prokaryotic and a eukaryotic cell? a. Ribosomal subunit weight b. Presence of a nucleus c. Presence of a membrane on the outside surface of the cell d. Presence of membrane-bound organelles

[C] is the correct answer: Presence of a membrane on the outside surface of the cell. The main differences between prokaryotes and eukaryotes include: prokaryotes do not have a nucleus, while eukaryotes do, eliminating choice (B); prokaryotes have ribosomal subunits of 30S and 50S, while eukaryotes have ribosomal subunits of 40S and 60S, eliminating choice (A); and prokaryotes do not have membrane-bound organelles, whereas eukaryotes do, eliminating choice (D). The presence of a membrane on the outer surface of the cell could not distinguish a prokaryotic cell from a eukaryotic one because both gram-negative bacteria and animal cells share this feature. Thus, choice (C) is the correct answer.

A rat is trained to press a lever to obtain food under a fixed-interval schedule. Which of the following behaviors would the rat most likely exhibit? a. Pressing the lever continuously whenever it is hungry. b. Pressing the lever exactly once and waiting for the food pellet before pressing it again. c. Pressing the lever slowly at first, but with increasing frequency as the end of the interval approaches. d. None of the above; the association formed by fixed-interval schedules is too weak to increase behavior.

[C] is the correct answer: Pressing the lever slowly at first, but with increasing frequency as the end of the interval approaches. In a fixed-interval schedule, the desired behavior is rewarded the first time it is exhibited after the fixed interval has elapsed. Both fixed-interval and fixed-ratio schedules tend to show this phenomenon: almost no response immediately after the reward is given, but the behavior increases as the rat gets close to receiving the reward.

Glucocorticoids have been implicated in stress-related weight gain because: a. They increase appetite and decrease satiety signals. b. They increase the activity of catabolic hormones. c. They increase glucose levels, which causes insulin secretion. d. They interfere with activity of the leptin receptor.

[C] is the correct answer: They increase glucose levels, which causes insulin secretion. Short-term glucocorticoid exposure causes a release of glucose and the hydrolysis of fats from adipocytes. However, if this glucose is not used for metabolism, it causes an increase in glucose level which promotes fat storage. The net result is the release of glucose from the liver to be converted into lipids in the adipose tissue under insulin stimulation.

Which of the following is NOT a method by which enzymes decrease the activation energy for biological reactions? a. Modifying the local charge environment b. Forming transient covalent bonds c. Acting as electron donors or acceptors d. Breaking bonds in the enzyme to provide energy

[D] is the correct answer: Breaking bonds in the enzyme to provide energy. Enzymes are not altered by the process of catalysis. A molecule that breaks intramolecular bonds to provide activation energy would not be able to be reused.

Charged molecules are often sequested within cellular compartments due to their difficulting passing through the hydrophobic interior of phospholipid bilayers. A positive charge on the molecule shown would have greater stability than a positive charge on a straight-chain alkane version of the same molecule. What property most explains this effect? a. Steric hindrance b. Nitrogen electronegativity c. Induction d. Conjugation

[D] is the correct answer: Conjugation. This molecule is more stable with a positive charge than a straight-chain alkane due to the conjugation of the benzene ring. This permits delocalization of the charge through resonance. Although induction, choice (C), does have an effect on the stabilization of the molecule, this effect is much less significant than the impact of having a conjugated system. The electronegativity of nitrogen, choice (B), which primarily affects induction, is also not a vital component of the stabilization by this molecule of a positive charge because oxygen is more electronegative. Steric hindrance, choice (A), would affect the reactivity of a molecule, but not its ability to stabilize charge.

Which process is expected to begin earliest in a prolonged fast? a. Ketone bodies are used by the brain. b. Glycogen storage is halted. c. Proteins are broken down. d. Enzyme phosphorylation and dephosphorylation.

[D] is the correct answer: Enzyme phosphorylation and dephosphorylation. A prolonged fast is characterized by an increase in glucagon, which accomplishes its cellular activity by phosphorylating and dephosphorylating metabolic enzymes. Glycogen storage, choice (B), is then halted, but this requires enzyme regulation by glucagon to occur. Later in the postabsorptive state, protein breakdown, choice (C), begins. Eventually, in starvation, ketone bodies, choice (A), are used by the brain for its main energy source.

A medical student is feeling a high level of stress due to upcoming exams and pressure from his family to engage in activities at home. He chooses to go the gym for a workout to help himself relax. This workout is which type of stress? a. Hassle b. Frustration c. Distress d. Eustress

[D] is the correct answer: Eustress. A positive stressor creates eustress. Because working out is used to relax, it is considered a eustress. Hassle, choice (A), and frustration, choice (B), are both types of distress, choice (C), or negative stressors.

Humans have evolved to notice patterns and shapes. A corporate logo uses five unconnected angles equally spaced in a circular fashion. When viewed, it appears to be a star. Which of the following is the logo artist using to create a complete pattern to viewers? a. Bottom-up processing b. Top-down processing c. Gate theory d. Gestalt principles

[D] is the correct answer: Gestalt principles. Gestalt principles are the basis for many optical illusions and include the tendency of people to see continuity even when lines are unconnected. Specifically, this logo appears to rely on the law of closure to create one complete star from five nontouching angles.

Which of the following concepts are LEAST likely to coincide? a. Hazardous waste facilities and low-income neighborhoods b. Tuberculosis and poor living conditions c. Environmental pollution and high minority population d. Globalization and global equality

[D] is the correct answer: Globalization and global equality. Globalization does not typically lead to global equality; rather, globalization tends to create further global inequalities. In regard to environmental justice, higher numbers of hazardous waste facilities tend to be found in low-income neighborhoods, choice (A). Poor living conditions tend to be associated with greater health problems, including tuberculosis, choice (B). Finally, environmental pollution is more prevalent in areas with minority populations, especially low-income minority populations, choice (C).

A patient comes in with a tumor of the pituitary gland, which grows upwards into the optic chiasm and causes a visual field defect. The most likely defect from compression of the optic chiasm is: a. complete blindness in one eye. b. loss of the upper visual fields in both eyes. c. loss of the nasal visual fields in both eyes. d. loss of the temporal visual fields in both eyes.

[D] is the correct answer: loss of the temporal visual fields in both eyes. The optic chiasm houses the crossing fibers from each optic nerve. Specifically, the fibers coming from the nasal half of the retina in each eye cross in the chiasm to join the optic tract on the opposite side. Remember that the lens of the eye causes inversion, so images on the nasal half of the retina actually originate in the temporal visual field. This condition is called bitemporal hemianopsia.

After a brief period of intense exercise, the activity of muscle pyruvate dehydrogenase is greatly increased. This increased activity is most likely due to: a. decreased ADP. b. increased acetyl-CoA. c. increased NADH/NAD+ ratio. d. increased pyruvate concentration.

[D] is the correct answer: Increased pyruvate concentration. In most biochemical pathways, only a few enzymatic reactions are under regulatory control. These often occur either at the beginning of pathways or at pathway branch points. The pyruvate dehydrogenase (PDH) complex controls the link between glycolysis and the citric acid cycle, and decarboxylates pyruvate (the end product of glycolysis) with production of NADH and acetyl-CoA (the substrate for the citric acid cycle). After intense exercise, one would expect PDH to be highly active to generate ATP. ADP levels (choice (A)) should be high because ATP was just burned by the muscle. Acetyl-CoA (choice (B)) is an inhibitor of PDH, causing a shift of pyruvate into the gluconeogenesis pathway. A high NADH/NAD+ ratio (choice (C)) would imply that the cell is already energetically satisfied and not in need of energy, which would not be expected in intensely exercising muscle.

What role does peptidyl transferase play in protein synthesis? a. It transports the initiator aminoacyl-tRNA complex. b. It helps the ribosome to advance three nucleotides along the mRNA in the 5′ to 3′ direction. c. It holds the proteins in its tertiary structure. d. It catalyzes the formation of a peptide bond.

[D] is the correct answer: It catalyzes the formation of a peptide bond. Peptidyl transferase is an enzyme that catalyzes the formation of a peptide bond between the incoming amino acid in the A site and the growing polypeptide chain in the P site. Initiation and elongation factors help transport charged tRNA molecules into the ribosome and advance the ribosome down the mRNA transcript, as in choices (A) and (B). Chaperones maintain a protein's three-dimensional shape as it is formed, as in choice (C).

Many double-displacement reactions are enzyme-catalyzed via the "ping pong" mechasism, so called because the reactants appear to bounce off the enzyme like a ping pong ball. These reactions typically have two reactants and two products. In a third-order reaction involving two reactants and two products, doubling the concentration of the first reactant causes the rate to increase by a factor of 2. What will happen to the rate of this reaction if the concentration of the second reactant is cut in half? a. It will increase by a factor of 2. b. It will increase by a factor of 4. c. It will decrease by a factor of 2. d. It will decrease by a factor of 4.

[D] is the correct answer: It will decrease by a factor of 4. Based on the information given in the question, the rate is first-order with respect to the concentration of the first reactant; when the concentration of that reactant doubles, the rate also doubles. Because the reaction is third-order, the sum of the exponents in the rate law must be equal to 3. Therefore, the reaction order with respect to the other reactant must be 3 - 1 = 2. If the concentration of this second reactant is multi- plied by 1/2, the rate will be multiplied by (1/2)2 = 1/4.

Which of the following INCORRECTLY pairs a digestive hormone with its function? a. Trypsin—hydrolyzes specific peptide bonds b. Lactase—hydrolyzes lactose to glucose and galactose c. Pancreatic amylase—hydrolyzes starch to maltose d. Lipase—emulsifies fats

[D] is the correct answer: Lipase - emulsifies fats. Lipase is involved in the digestion of fats, but its function is not to emulsify fats—this is the job of bile. Rather, lipase chemically digests fats in the duodenum, allowing them to be brought into duodenal cells and packaged into chylomicrons. The other associations given here are all correct.

Where does β-oxidation of fatty acids occur within the cell? a. Cytosol b. Mitochondria c. Smooth endoplasmic reticulum d. Plasma membrane

[D] is the correct answer: Plasma membrane. The liver is the major metabolic organ in the body and is responsible for much of the synthesis and interconversion of fuel sources. Most of the triacylglycerols that are synthesized in the liver are transported as VLDL to adipose tissue for storage. Both the adipocytes, choice (A) and dietary intake, choice (B), constitute a minor source of triacylglycerol.

How does prokaryotic DNA differ from eukaryotic DNA? I. Prokaryotic DNA lacks nucleosomes. II. Eukaryotic DNA has telomeres. III. Prokaryotic DNA is replicated by a different DNA polymerase. IV. Eukaryotic DNA is circular when unbound by centromeres. a. I only b. IV only c. II and III only d. I, II, and III only

[D] is the correct answer: Prokaryptic DNA lacks nusleosomes, Eukaryptoc DNA has telpmeres, and Prokaryotic DNA is replicated by a different DNA polymerase. Prokaryotic DNA is circular and lacks histone proteins, and thus does not form nucleosomes. Both prokaryotic and eukaryotic DNA are replicated by DNA polymerases, although these polymerases differ in identity. Eukaryotic DNA is organized into chromatin, which can condense to form linear chromosomes; only prokaryotes have circular chromosomes. Only eukaryotic DNA has telomeres.

When practicing her recital song at home, a teenage girl sounds perfectly in pitch to her family and friends. However, when performing at the recital in front of a large audience of peers, strangers, and coaches, her pitch and tone are off, resulting in a poor performance. This second performance is best explained by: a. drive reduction theory. b. instinct approach theory. c. Maslow's hierarchy of needs. d. the Yerkes-Dodson law.

[D] is the correct answer: The Yerkes-Dodson Law. The Yerkes-Dodson law states that there is an optimal level of arousal necessary to perform. If levels of arousal are too high, poor performance can result. In the case of the girl performing at her recital, her arousal level is very high as a result of nerves and anxiety, resulting in a poor performance.

Consider a biochemical reaction A → B, which is catalyzed by A-B dehydrogenase. Which of the following statements is true? a. The reaction will proceed until the enzyme concentration decreases. b. The reaction will be most favorable at 0 °C. c. A component of the enzyme is transferred from A to B. d. The free energy change (ΔG) of the catalyzed reaction is the same as for the uncatalyzed reaction.

[D] is the correct answer: The free energy change (ΔG) of the catalyzed reaction is the same as for the uncatalyzed reaction. Enzymes catalyze reactions by lowering their activation energy, and are not changed or consumed during the course of the reaction. While the activation energy is lowered, the free energy of the reaction, ΔG, remains unchanged in the presence of an enzyme. A reaction will continue to occur in the presence or absence of an enzyme; it simply runs slower without the enzyme, eliminating choice (A). Most physiological reactions are optimized at body temperature, 37 °C, eliminating choice (B). Finally, dehydrogenases catalyze oxidation-reduction reactions, not transfer reactions, eliminating choice (C).

Adding salt to water causes the boiling point of water to: a. Increase, requiring a greater average kinetic energy of the liquid to produce a vapor pressure equal to the external pressure. b. Increase, requiring a greater average kinetic energy of the liquid to produce a vapor pressure that is greater than the external pressure. c. Decrease, requiring a lower average kinetic energy of the liquid to produce a vapor pressure equal to the external pressure. d. Decrease requiring a lower average kinetic energy of the liquid to produce a vapor pressure that is less than the external pressure.

a. Increase, requiring a greater average kinetic energy of the liquid to produce a vapor pressure equal to the external pressure. Remember: Boiling point is defined as the temperature at which the vapor pressure of the solution is equal to the atmospheric pressure.

Boiling chips and vacuum distillation, respectively, are used in distillations to: a. Provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; lower the boiling points of the substances to be distilled. b. Lower the boiling points of the substances to be distilled; work synergistically with the vacuum system to further lower the boiling points. c. Lower the boiling points of the substances to be distilled; provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating. d. P rovide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; speed up the distillation process by vacuuming the first distillate out of the apparatus.

a. Provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; lower the boiling points of the substances to be distilled. Explanation: When transitioning from liquid to gas during boiling, the liquid needs nucleation sites, or places to start forming bubbles. This is typically achieved either by scratching the inside of the flask or by introducing boiling chips. This eliminates all options except for A and D. Next, remember that boiling occurs when p(vap)=p(atm). Typically, we boil substances by increasing the temp, thereby increasing p(vap). Alternatively, we can lower the boiling point by reducing p(atm) via vacuum.

Water is a rare substance in that the solid is less dense than the liquid at the freezing point, resulting in a solid form that floats on top of the liquid. Which of the following best explains this phenomenon? a. The bent structure of the water molecule results in a molecular dipole that maximizes the close molecular packing structure in the solid state. b. The bent structure of the water molecule and ratio of covalently-bonded hydrogens to lone pairs of electrons on the oxygen atom maximizes the hydrogen bonding that occurs in the solid phase, producing a hexagonal structure with large empty spaces. c. The degree of ionization in the solid state is less than in the liquid state. d. The London dispersion forces of water significantly decrease in the solid phase as compared with the liquid phase.

b. The bent structure of the water molecule and ratio of covalently-bonded hydrogens to lone pairs of electrons on the oxygen atom maximizes the hydrogen bonding that occurs in the solid phase, producing a hexagonal structure with large empty spaces. Explanation: A: While water does have a bent structure and a molecular dipole, "close" packing of the molecules in the solid state would imply that the solid phase of water is more dense than the liquid. The question asks to explain the opposite phenomenon. C: Water does auto-ionize in its liquid, but presumably not in its solid, phase. However, this activity has no clear effect on the density of the solid compared to the liquid. D: Water does experience London dispersion forces, but these are the weakest of the intermolecular forces and are unlikely to have a significant effect in this case.

spermatic cord

extends upward from the epididymis and is attached to each testicle. It contains an artery and vein that serve the testes.

Centrioles

organizing center for microtubules. Have a 9+0 structure. Have a role in cytokinesis during mitosis: centrioles migrate to opposite poles of the dividing cell and organize the mitotic spindle.

testes function

produce sperm and testosterone.

seminal vesicles

secrete fluid essential to sperm movement and for successful ejaculation and fertilization. The fluid is 60% of semen volume and is somewhat alkaline (basic - pH>7) which aids survival in the acidic vaginal environment. It is also rich in fructose for mitochondrial use to transfer into ATP.