BIS 2A - Final Study Guide

A glucose molecule is processed through glycolysis, pyruvate oxidation, and the TCA cycle. The molecule is completely oxidized to CO2, a process that involves a substantial loss of free energy (a negative ΔG). At this point, in what form is some of that energy retained by the cell? (A) As ATP and NADH (B) As carbohydrates (C) As a proton gradient (D) As fats or oils (E) As ATP and NAD+

(A) As ATP and NADH

Which of the carbon atoms below is most reduced? (A) CH4 (B) CH3OH (C) CH2O (D) CO2 (E) There's no way to tell without seeing the structures

(A) CH4

List the following elements in order of their increasing electronegativity (list element with strongest attraction for electrons last). (A) H < N < O (B) O < N < C (C) N < O < H (D) C < O < H (E) O < N < H

(A) H < N < O

Most animal cells are diploid - meaning their G1 nuclei have two copies of every gene. In plants, while the cells of embryos are diploid, many cells in the adult plant are "endoreduplicated." This means their nuclei have many copies of the genome (up to 64 copies per nucleus, instead of 2). Obviously creating a 64x nucleus from a 2x nucleus requires a new kind of cell cycle. This could be achieved by...? (A) Moving from G1 to S and then straight back to G1. Repeat until you reach 64 copies (B) Undergoing interphase and mitosis, but not cytokinesis. Repeat as needed (C) Undergoing cytokinesis, but not mitosis. Repeat without interphase (D) Undergoing mitosis and cytokinesis, but skipping the S phase of the cell cycle (E) Repeatedly failing to separate homologs during mitosis

(A) Moving from G1 to S and then straight back to G1. Repeat until you reach 64 copies

Methanogens used to be one of the dominant life forms on Earth. Today their growth is restricted to very specialized environments. This is because they...? (A) Need H2, and O2 is toxic to them (B) Need Methane (CH4), and O2 is toxic to them (C) Need O2, and H2 is toxic (D) Need methane, and H2 is toxic (E) Are UV-sensitive

(A) Need H2, and O2 is toxic to them

Fermentation allows a cell to...? (A) Recycle NADH (B) Use NADH as a terminal electron acceptor (C) Convert photons to reducing power (D) Use oxidation of NADH to provide power for formation of a proton gradient (E) Synthesize ATP via ATP synthase

(A) Recycle NADH

Two mice are heterozygous for a defective allele of telomerase (genotype T/t). They have entirely normal phenotypes. These two mice are crossed. Among their progeny are two mice that are completely defective in telomerase (genotype t/t). These mice also have completely normal phenotypes. They are bred together to produce lots of t/t progeny. All of these mice have abnormal phenotypes: small size, early aging, and many tumors. Karyotyping of these defective mice reveals that their chromosomes are very unusual - some are very short and broken, and the telomeres are missing. From this, we can conclude that...? (A) Telomeres in mice are long, and son can shrink for several life cycles before they are lost (B) Telomeres in mice require only one cell generation to be lost (C) Mice don't require telomeres to grow normally (D) Telomerase needs to be present at all times in the cell for it to survive (E) Mouse chromosomes are circular

(A) Telomeres in mice are long, and son can shrink for several life cycles before they are lost

A protein that forms an ion channel through a membrane is most likely to be...? (A) A peripheral protein (B) A transmembrane protein (C) A phospholipid (D) An enzyme (E) Entirely outside the phospholipid bilayer

(B) A transmembrane protein

In animals, if the fuel consumed exceeds energy expended, fats are synthesized from carbohydrates in order to store the excess energy. Acetyl-CoA Carboxylase catalyzes the first dedicated step in the fatty acid synthesis. This enzyme responds to a large number of cellular signals. A logical strategy for the regulation of Acetyl-CoA Carboxylase might include...? (A) Activation when concentration of AMP is high vs. the concentration of ATP (B) Activation when concentration of AMP is low vs. the concentration of ATP (C) Inhibition when the concentration of AMP is low vs. the concentration of ATP (D) Inhibition by insulin, reflecting high levels of glucose (E) Both c and d

(B) Activation when concentration of AMP is low vs. the concentration of ATP

The DNA found in mitochondria is of __________ origin and encodes __________. (A) Archean, some of the genes for respiration (B) Bacterial, some of the genes for electron transport (C) Nuclear, some of the genes for glycolysis (D) Bacterial, some of the genes for carbon fixation (E) Cyanobacterial, some of the genes for electron transport

(B) Bacterial, some of the genes for electron transport

Which of the following would diffuse through a lipid bilayer the fastest? (A) Na+ (B) Benzene (C6H6) (C) Water (D) Glucose (E) ATP

(B) Benzene (C6H6)

NAD+ is a product formed by oxidation of NADH during a variety of metabolic processes. Among these are...? (A) Glycolysis (B) Fermentation (C) The TCA Cycle (D) The light reactions of photosynthesis (E) Both A and B are processes in which NAD+ is formed

(B) Fermentation

The dark reactions of photosynthesis provide the cell with....? (A) Highly reducing pigments (B) Fuel (C) Water and photons (D) CO2 and RuBP carboxylase (E) ATP and NADPH

(B) Fuel

Where would CO2 be fixed into sugars in green plants? (A) In the matrix (B) In the chloroplast (C) Between the inner and outer membrane of the mitochondrion (D) In the cristae (E) In the cytoplasm

(B) In the chloroplast

A person decides to get in better shape by eating less and exercising more. They lose weight, some of which is in the form of carbon. Where does the carbon go, and in what form? (A) Down the toilet, as excreted fats (B) Into the air, as CO2 (C) It is lost as energy (heat) (D) Into the intermembrane space, as protons

(B) Into the air, as CO2

Sexual reproduction increases genetic diversity in three ways. Which of the mechanisms described below is not one of these ways? (A) New combinations of alleles on a single chromosome are created by crossing over (B) New combinations of alleles are created via increased mutation rate (C) New combinations of alleles are created via fertilization (D) New combinations of alleles are created via segregation of homologs to the poles

(B) New combinations of alleles are created via increased mutation rate

Pyruvate is the end product of glycolysis. The pyruvate is then...? (A) Excreted from the cell as waste (B) Oxidized, if respiration is occurring (C) Oxidized, if fermentation is occurring (D) Reduced, if respiration is occurring (E) Carboxylated by RuBP carboxylase

(B) Oxidized, if respiration is occurring

DNA differs from RNA in that it lacks an OH group at the 2' position - thus it's called "deoxyribose." Nucleotide 5' triphosphates (NTPs) can also be synthesized in the lab that are "dideoxyribose;" these are missing the OH group at the 3', as well as the 2' position. If DNA polymerase was to attempt to add dideoxyNTP to an otherwise normal primer and template, what would be the consequences for the extension of that primer? (A) The dideoxyNTP couldn't be added to the chain (B) The dideoxyNTP could be added, but no additional bases could be added after (C) There would be no effect on chain growth; this OH group is not important (D) The chain would grow normally, ut it would be unusually unstable, compared with normal DNA (E) The chain would grow, but it would have U instead of T

(B) The dideoxyNTP could be added, but no additional bases could be added after

Newly synthesized DNA is illustrated. The Okazaki fragments have not yet been processed. Which of the Okazaki fragments was synthesized first? (A) The one on the right (B) The one on the left (C) The one in the middle (D) There's no way to tell

(B) The one on the left

Which of the statements below best describes ionic bonds in an aqueous environment? (A) The sharing of a hydrogen atom between two molecules (B) The transfer of an electron from one atom to another, a relatively weak bond (C) The transfer of an electron from one atom to another, a relatively strong bond (D) The sharing of an electron pair between two atoms; a relatively weak bond (E) The sharing of an electron pair between two atoms; a relatively strong bond

(B) The transfer of an electron from one atom to another, a relatively weak bond

Which of the following is true for oxygenic photosynthesis? (A) Only ATP can be formed - not NADPH (B) Water is oxidized (C) Only NADPH can be formed - not ATP (D) It occurs only in green plants (E) Water is reduced

(B) Water is oxidized

Glycolysis is usually immediately followed by either fermentation or respiration. When would your muscle cells "choose" to perform fermentation? (A) When you have too much alcohol in your body (B) When you are exercising anaerobically, and the muscle is short on O2 (C) When there is plenty of oxygen in the muscle cells (D) When you are dieting, as fermentation is wasteful (E) When you are starved for fuel, as fermentation uses fuel efficiently

(B) When you are exercising anaerobically, and the muscle is short on O2

The partial sequence of a DNA is 5' CGATCGAT 3'. The sequence of the complimentary DNA strand, written (as always) 5' to 3' is...? (A) 5' CGATCGAT 3' (B) 5' TAGCTAGC 3' (C) 5' ATCGATCG 3' (D) 5' GCTAGCTA 3' (E) 5' AUCGAUCG 3'

(C) 5' ATCGATCG 3'

Which of the following lifestyles must have evolved most recently? (A) Fermentation (B) Oxygenic photosynthesis (C) Aerobic respiration (D) Anaerobic respiration (E) Nonoxygenic photosynthesis

(C) Aerobic respiration

Which of the following endergonic reactions could made to proceed as written if it were coupled to the hydrolysis of ATP to ADP + Pi? (ΔG = -7.3 kcal/mol)? (A) A + B -> X (ΔG = 12) (B) A + C -> Z (ΔG = 9) (C) C + B -> W (ΔG = 7) (D) D + E -> X (ΔG = 8) (E) All of these reactions would proceed as written, even without coupling to ATP hydrolysis

(C) C + B -> W (ΔG = 7)

Photosystems include many chlorophyll molecules, but most of these molecules...? (A) Cannot absorb photons (B) Cannot transfer energy between pigments (C) Cannot donate an electron to the electron transport chain (D) Are there to attract pollinators (E) Molecules are there to transport protons

(C) Cannot donate an electron to the electron transport chain

Motor proteins transport vesicles within eukaryotic cells. In contrast, many cytoplasmic proteins arrive at their destinations within the cell through simple diffusion. Why can't vesicles get where they need to be through diffusion? (A) Vesicles are too small to diffuse within the cytoplasm (B) Vesicles are made up largely of lipids, and so cannot diffuse (C) Diffusion of a vesicle would take a much longer time than diffusion of a protein - it would be too slow (D) The cytoplasm is very viscous - this slows proteins but not vesicles (E) Both C and D are good reasons to use motor proteins to transport vesicles

(C) Diffusion of a vesicle would take a much longer time than diffusion of a protein - it would be too slow

Using the electron tower provided, which of these compounds would be the strongest electron donor? (A) Succinate (B) H+ (C) H2S (D) Fe2+ (E) N2

(C) H2S

A key difference between respiration and the light reactions of oxygenic photosynthesis is (are)....? (A) The light reactions of photosynthesis generate ATP, but respiration consumes ATP (B) In respiration, ATP is produced indirectly through a proton motive force created by transferring electrons between several electron/H+ carriers, but in photosynthesis, ATP is formed through substrate level phosphorylation (C) Respiration consumes reducing equivalents (NADH) to make ATP, but the light reactions synthesize reducing equivalents (NADPH) while also synthesizing ATP (D) In photosynthesis, fuel is oxidized, while in respiration, fuel is reduced (E) The electron transport chain of respiration ends with the reduction of NAD+, while the electron transport chain of photosynthesis starts with the reduction of NADP+

(C) Respiration consumes reducing equivalents (NADH) to make ATP, but the light reactions synthesize reducing equivalents (NADPH) while also synthesizing ATP

The graph illustrates the results of an experiment in which you measured the initial rate of production (micromoles generated/minute of product P). If we set up this experiment with exactly half as much enzyme in our reaction, we expect to see...? (A) The maximum rate of the catalyzed reaction will drop by half, the initial rate will stay the same (B) The initial rate of the catalyzed reaction will drop by half, the maximum rate will stay the same (C) The rate of the catalyzed reaction will be cut in half at all concentrations of substrate (D) There will be no effect of the rate of the reaction (E) The rate of the catalyzed reaction will double for all concentrations of substrate

(C) The rate of the catalyzed reaction will be cut in half at all concentrations of substrate

Cells that lack cell walls are at a disadvantage vs. cells that possess them, because...? (A) They can't engulf other cells (B) They can swell up and explode in a high-salt environment (C) They can swell up and explode when placed in pure water (D) They cannot transport substances across their membrane (E) They are sensitive to oxygen

(C) They can swell up and explode when placed in pure water

Using the electron tower provided at the end of the exam, which reaction would not proceed spontaneously? (A) H2 + NAD+ -> H+ + NADH (B) NADH + Ubiquinone(ox) -> NAD+ + Ubiquinone(red) (C) Ubiquinone(red) + Cytochrome b(ox) -> Ubiquinone(ox) + Cytochrome b(red) (D) NADH + Pyruvate -> Lactate + NAD+ (E) Glucose + O2 -> CO2 + H2O

(C) Ubiquinone(red) + Cytochrome b(ox) -> Ubiquinone(ox) + Cytochrome b(red)

In horses, D is dominant allele of the Dun gene that results in what is considered to be the "wild-type" coat color: dull brown with black mane, tail, legs, and dorsal stripe (called "dun" or "buckskin"). Homozygosity for d, a recessive allele, results in a rich, vivid coat color (black, bay, chestnut, etc.). You have a dun male horse and want to determine whether he is heterozygous or homozygous for D, so you cross him to a bay female. The resulting offspring is bay. From this you can conclude...? (A) Your dun horse is homozygous (DD) (B) Your dun horse is homozygous (dd) (C) Your dun horse is heterozygous (Dd) (D) There are not enough offspring to be able to conclude anything (E) The male horses' phenotype already tells you his genotype

(C) Your dun horse is heterozygous (Dd)

Elephants and mosses differ in many interesting ways. Strangely, the only difference specifically described in this course is the fact that...? (A) After fertilization but before meiosis, elephant cells undergo mitoses but moss cells don't (B) After fertilization but before meiosis, moss cells undergo many mitoses but elephant cells don't (C) After meiosis but before fertilization, elephant cells undergo many mitoses but moss cells don't (D) After meiosis but before fertilization, moss cells undergo many mitoses but elephant cells don't (E) After meiosis is complete, moss cells can undergo another round of meiosis, but elephants don't do this

(D) After meiosis but before fertilization, moss cells undergo many mitoses but elephant cells don't

Some methanogens are chemoautotrophs. This means that they can....? (A) Fix carbon from CO2 (B) Make their own ATP from ADP + Pi without eating other organisms (C) Synthesize NADH from NAD+ without eating other organisms (D) All of the above (E) None of the above

(D) All of the above

Ecosystems exist deep under the ocean, where no light penetrates. The chemical disequilibrium at deep sea vents provides energy and electrons that are captured by __________, which then act as fuel sources for __________. (A) Photoheterotrophs, organotrophs (B) Photoautotrophs, photoheterotrophs (C) Chemoheterotrophs, organotrophs (D) Chemoautotrophs, organotrophs (E) Organotrophs, chemoautotrophs

(D) Chemoautotrophs, organotrophs

Consider the free energy diagram, which describes the energy state of molecules undergoing the reaction X <-> Y. Decreasing the concentration of Y would decrease the value (length) of which arrow? (A) A (Energy of Reactants) (B) B (Activation Energy) (C) C (Total Energy Change of System) (D) D (Energy of Products) (E) Changes in concentration would not effect an of these values

(D) D (Energy of Products) - if ΔG is not in standard state (E) Changes in concentration would not effect an of these values - if ΔG is in standard state

In the well-lit chloroplast...? (A) The citric acid cycle is carried out in the stroma to concentrate protons in the chloroplast lumen (B) The Calvin cycle is carried out in the lumen of the thylakoids to concentrate sugars in that space (C) Protons are concentrated in the stroma and drive ATP synthesis via the ATPase embedded in the outer choroplast membrane (D) Protons are concentrated in the lumen of the thylakoids and drive ATP synthesis by the ATPase embedded in the thylakoid membrane (E) Electrons gain energy from photons and are then able to oxidize NADP

(D) Protons are concentrated in the lumen of the thylakoids and drive ATP synthesis by the ATPase embedded in the thylakoid membrane

Meiosis resembles mitosis in that __________ but differs from mitosis in that __________. (A) Sister chromatids separate, cohesins are not involved in meiosis (B) Sister chromatids separate, kinetochores are not involved in meiosis (C) Homologous chromosomes separate, sister chromatids also separate in meiosis (D) Sister chromatids separate, homologous chromosomes also separate in meiosis (E) DNA replicates before both mitosis and meiosis, cohesins hold sister chromatids together only in mitosis

(D) Sister chromatids separate, homologous chromosomes also separate in meiosis

The energy for photosynthesis is provided by...? (A) The splitting of water (B) The reduction of NADH (C) The citric acid cycle (D) The absorption of photons by chlorophyll (E) Glycolysis

(D) The absorption of photons by chlorophyll

Avery, MacLoed, and McCarty were able to genetically transform "rough" pnemococcus to "smooth," using an extract from killed pneumococci, they concluded that DNA rather than protein was the genetic material because...? (A) The extract, when treated with RNAse, failed to transform cells (B) The extract, when treated with protease, no longer transformed cells (C) The extract, when treated with DNAse, still transformed cells (D) The extract, when treated with DNAse, no longer transformed cells

(D) The extract, when treated with DNAse, no longer transformed cells

"Pumps" push solutes up/against a gradient. Because this activity increases the potential energy stored in the gradient, the cell "pays" for this through...? (A) Hydrolysis of ATP (B) Counter-flow of another solute down a gradient (C) The formation of ATP from AMP + PPi (D) Two of the above activities might power a biological "pump" (E) Increasing potential energy is energetically favorable - it doesn't have to be "paid for"

(D) Two of the above activities might power a biological "pump"

Kinetochores play an essential role in mitosis by...? (A) Allowing the centromeres to move along microtubules (B) Holding two sister chromatids together (C) Separating the homologs (D) Establishing tension and so allowing the cell to know when the sister chromatids are properly aligned (E) A and E

(E) A and E

A protein's tertiary structure is stabilized by...? (A) Hydrophobic R groups (B) Ionic bonds (C) Phosphodiester bonds (D) Hydrogen bonds (E) A, B, and D

(E) A, B, and D

The generation of glucose 6-phosphate from glucose, catalyzed by hexokinase, is the first step in glycolysis. What changes might make this energetically favorable reaction become unfavorable (in other words, run backwards)? (A) An increase in the concentration of glucose (B) An increase in the concentration of glucose 6-phosphate (C) A decrease in the concentration of glucose (D) A decrease in the concentration of glucose 6-P (E) Both B and C could reduce the favorability of the reaction

(E) Both B and C could reduce the favorability of the reaction

A human cell is UV-radiated in G1 and undergoes cell cycle arrest. Why is it important to arrest the cell cycle when DNA damage is detected? (A) It isn't important - the cell just slowed down, due to damage. The phase of the cell cycle has nothing to do with DNA repair processes (B) Because in G1 phase you have the most copies of DNA of any phase in the cell cycle, so you have more templates for repair (C) Because progression through S phase results in the loss of a template strand for nucleotide excision repair (D) Because replication past a dimer can be mutagenic (E) Both C and D are true

(E) Both C and D are true

Figure shows sibling mice derived from a mother mouse transgenic for the Green Fluorescent Protein, expressed in the skin. Some of the siblings have glowing eyes and ears; others don't. The mother mouse was...? (A) Heterozygous for the transgene, possibly chimeric for transformed cells (B) Heterozygous for the transgene, definitely chimeric for transformed cells (C) Homozygous for the transgene, definitely chimeric for transformed cells (D) Homozygous for the transgene, possibly chimeric for the transformed cells (E) It's impossible to determine from this data whether she was chimeric and/or heterozygous, but both are possible

(E) It's impossible to determine from this data whether she was chimeric and/or heterozygous, but both are possible

Consider the free energy diagram, which describes the energy state of molecules undergoing the reaction X <-> Y. Adding an appropriate catalyst would increase the value (length) of which arrow? (A) A (Energy of Reactants) (B) B (Activation Energy) (C) C (Total Energy Change of System) (D) D (Energy of Products) (E) None of these arrows would increase in value

(E) None of these arrows would increase in value

The active site of an enzyme has to fit its substrate. The 3-dimensional shape of the enzyme's active site is formed by...? (A) The folding of a linear chain of nucleic acids (B) Carving of a protein by a protease (C) The fitting of the protein into a template strand (D) Reverse translation (E) The folding of a linear chain of amino acids

(E) The folding of a linear chain of amino acids

Consider the phylogenetic tree of placental mammals below, based on molecular data. Which of the following statements is correct? (A) The Chiroptera and the Perissodactyla share a common ancestor not shared with the Carnivora (B) Afrotheria are more closely related to the Euarchonta than to Glires (C) The Xenarthra and Glires share a common ancestor not shared with Euarchonta (D) The Perissocactyla and the Xenarthra share a common ancestor not shared with Glires (E) Xenarthra and Euarchonta share a common ancestor

(E) Xenarthra and Euarchonta share a common ancestor