chapter 5, Chapter 8, Chapter 13, Chapter 9, Chapter 3, Chapter 4, Chapter 6, Chapter 10, Chapter 11, Chapter 18, Chapter 19, Chapter 17, Chapter 16, Chapter 20, Chapter 14, Chapter 15

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The functioning of enhancers is an example of

transcriptional control of gene expression.

Which of the following variations on translation would be most disadvantageous for a cell?

translating polypeptides directly from DNA

Which of the following is not true of RNA processing?

Exons are cut out before mRNA leaves the nucleus.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

UUU.

Why does recombination between linked genes continue to occur?

New allele combinations are acted upon by natural selection.

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

The centimorgan (cM) is a unit named in honor of Thomas Hunt Morgan. To what is it equal?

1% frequency of recombination between two genes

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?

1/2

Skin color in a certain species of fish is inherited via a single gene with four different alleles. One fish of this type has alleles 1 and 3 (S1S3) and its mate has alleles 2 and 4 (S2S4). If each allele confers a unit of color darkness such that S1 has one unit, S2 has two units, and so on, then what proportion of their offspring would be expected to have five units of color?

1/2

A certain kind of snail can have a right-handed direction of shell coiling (D) or left-handed coiling (d). If direction of coiling is due to a protein deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and a dd sperm-producing snail will have offspring of which genotype(s) and phenotype(s)?

1/2 Dd:1/2 dd; all right coiling

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

1/4 of the gametes will be n + 1, 1/4 will be n - 1, and 1/2 will be n.

A phenotypically normal prospective couple seeks genetic counseling because the man knows that he has a translocation of a portion of his chromosome 4 that has been exchanged with a portion of his chromosome 12. Although he is normal because his translocation is balanced, he and his wife want to know the probability that his sperm will be abnormal. What is your prognosis regarding his sperm?

1/4 will be normal, 1/4 will have the translocation, and 1/2 will have duplications and deletions

In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?

1/64

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes?

100%

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F₁ males will have cinnabar eyes?

100%

Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present) have a gene structure similar to our own, but many very different plants and animals. One species of a small birdlike animal has an extremely variable tail length, which is a highly polymorphic trait. Geneticists have come to realize that there are eight separate genes for tail length per haploid genome, with each gene having two alleles. One allele for each gene (a, b, and so on) increases the length by 1 cm, whereas the other allele (a2, b2, and so on) increases it by 0.5 cm. One bird was analyzed and found to have the following genotype: a1a1b2b2c1c2d1d2e2e2f1f2g1g1h1h2 What is the length of its tail?

12 cm

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many artificial mRNA 3 nucleotide codons would be possible?

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F₁ individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F₂ offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers?

190

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. How many genes must be responsible for these coat colors in Labrador retrievers?

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA.

2, 1, 4

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons would be possible?

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?

2:1 male to female

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'

Drosophila (fruit flies) usually have long wings (+) but mutations in two different genes can result in bent wings (bt) or vestigial wings (vg). If flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only?

3/16

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F₁ individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F₂ offspring, what is the probability of plants with white axial flowers?

3/16

Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?

3/4

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?

Which of the following is true of aneuploidies in general?

45 X is the only known human live-born monosomy.

Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual?

47, +21

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5' A C G U U A G G 3'

An Okazaki fragment has which of the following arrangements?

5' RNA nucleotides, DNA nucleotides 3'

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol?

5' UTR E₁ E₂ E₃ E₄ UTR 3'

Which of the following can be effective in preventing the onset of viral infection in humans?

getting vaccinated

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. In the F₂ generation of the above cross, which of the following phenotypic ratios would be expected?

6:3:3:2:1:1

Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. If snapdragons are heterozygous for height as well as for flower color, a mating between them will result in what ratio?

6:3:3:2:1:1

In humans, male-pattern baldness is controlled by an autosomal gene that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald?

75%

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

If a protein is coded for by a single gene and this protein has six clearly defined domains, which number of exons below is the gene likely to have?

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F2 would segregate in which of the following ratios?

9 sharp-spined:3 dull-spined:4 spineless

Which bonds are created during the formation of the primary structure of a protein? A) peptide bonds B) hydrogen bonds C) disulfide bonds D) phosphodiester bonds E) peptide bonds, hydrogen bonds, and disulfide bonds

A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance? A) It is a strong acid that ionizes completely in water. B) It is a strong base that ionizes completely in water. C) It is a weak acid. D) It is a weak base. E) It is neither an acid nor a base.

A chemical reaction that has a positive ΔG is correctly described as A) endergonic. B) endothermic. C) enthalpic. D) spontaneous. E) exothermic.

A human cell containing 22 autosomes and a Y chromosome is A) a sperm. B) an egg. C) a zygote. D) a somatic cell of a male. E) a somatic cell of a female.

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? A) The mutant yeast will be unable to grow anaerobically. B) The mutant yeast will grow anaerobically only when given glucose. C) The mutant yeast will be unable to metabolize glucose. D) The mutant yeast will die because they cannot regenerate NAD⁺ from NAD. E) The mutant yeast will metabolize only fatty acids.

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. If the power fails and the lights go dark, what will happen to CO₂ levels? A) CO₂ will rise as a result of both animal and plant respiration. B) CO₂ will rise as a result of animal respiration only. C) CO₂ will remain balanced because plants will continue to fix CO₂ in the dark. D) CO₂ will fall because plants will increase CO₂ fixation. E) CO₂ will fall because plants will cease to respire in the dark.

A strong acid like HCl A) ionizes completely in an aqueous solution. B) increases the pH when added to an aqueous solution. C) reacts with strong bases to create a buffered solution. D) is a strong buffer at low pH. E) both ionizes completely in aqueous solutions and is a strong buffer at low pH.

How does the sexual life cycle increase the genetic variation in a species? A) by allowing crossing over B) by allowing fertilization C) by increasing gene stability D) by conserving chromosomal gene order E) by decreasing mutation frequency

What do we mean when we use the terms monohybrid cross and dihybrid cross?

A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one.

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells cannot move NADH from glycolysis into the mitochondria. C) His cells contain something that inhibits oxygen use in his mitochondria. D) His cells lack the enzyme in glycolysis that forms pyruvate. E) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.

All of the following are polysaccharides except A) lactose. B) glycogen. C) chitin. D) cellulose. E) amylopectin.

Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxyl ion concentration of this lake? A) 1 × 10⁻¹⁰ mol of hydroxyl ion per liter of lake water B) 1 × 10⁻⁴ mol of hydroxyl ion per liter of lake water C) 10.0 M with regard to hydroxyl ion concentration D) 4.0 M with regard to hydroxyl ion concentration E) 1 × 10⁻⁴ mol of hydroxyl ion per liter of lake water and 4.0 M with regard to hydrogen ion concentration

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellar eukaryotic organisms, A) has occurred in accordance with the laws of thermodynamics. B) has caused an increase in the entropy of the planet. C) has been made possible by expending Earth's energy resources. D) has occurred in accordance with the laws of thermodynamics, by expending Earth's energy resources and causing an increase in the entropy of the planet. E) violates the laws of thermodynamics because Earth is a closed system.

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they A) fix CO₂ into organic acids during the night. B) fix CO₂ into sugars in the bundle-sheath cells. C) fix CO₂ into pyruvate in the mesophyll cells. D) use the enzyme phosphofructokinase, which outcompetes rubisco for CO₂. E) use photosystem I and photosystem II at night.

Carbon dioxide (CO₂) is readily soluble in water, according to the equation CO₂ + H₂O ↔ H₂CO₃. Carbonic acid (H₂CO₃) is a weak acid. Respiring cells release CO₂ into the bloodstream. What will be the effect on pH of blood as that blood first comes in contact with respiring cells? A) Blood pH will decrease slightly. B) Blood pH will increase slightly. C) Blood pH will remain unchanged. D) Blood pH will first increase, then decrease as CO₂ combines with hemoglobin. E) Blood pH will first decrease, then increase sharply as CO₂ combines with hemoglobin.

Cells require which of the following to form cilia or flagella? A) centrosomes B) laminin C) actin D) intermediate filaments E) secretory vesicles

Centrioles, cilia, flagella, and basal bodies have remarkably similar structural elements and arrangements. Which of the following hypotheses is most plausible in light of such structural similarities? A) Cilia and flagella arise from the centrioles. B) Loss of basal bodies should lead to loss of all cilia, flagella, and centrioles. C) Motor proteins such as dynein must have evolved before any of these four kinds of structure. D) Cilia and flagella coevolved in the same ancestral eukaryotic organism. E) Natural selection for cell motility repeatedly selected for microtubular arrays in circular patterns in the evolution of each of these structures.

Compared to C₃ plants, C₄ plants A) can continue to fix CO₂ even at relatively low CO2 concentrations and high oxygen concentrations. B) have higher rates of photorespiration. C) do not use rubisco for carbon fixation. D) grow better under cool, moist conditions. E) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger. A) cAMP B) G protein C) GTP D) adenylyl cyclase E) G protein-coupled receptor

Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the A) mitochondria. B) ribosomes. C) peroxisomes. D) lysosomes. E) endoplasmic reticulum.

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated further, however, the ability to synthesize ATP is lost. After the first disruption, when electron transfer and ATP synthesis still occur, what must be present? A) all of the electron transport proteins as well as ATP synthase B) all of the electron transport system and the ability to add CoA to acetyl groups C) the ATP synthase system D) the electron transport system E) plasma membranes like those bacteria use for respiration

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated further, however, the ability to synthesize ATP is lost. These inside-out membrane vesicles A) will become acidic inside the vesicles when NADH is added. B) will become alkaline inside the vesicles when NADH is added. C) will make ATP from ADP and i if transferred to a pH 4 buffered solution after incubation in a pH 7 buffered solution. D) will hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior. E) will reverse electron flow to generate NADH from NAD⁺ in the absence of oxygen.

For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Synaptonemal complexes form or are still present. A) I only B) I and IV only C) I and VIII only D) II and VI only E) I, II, III, and IV only

How is natural selection related to sexual reproduction as opposed to asexual reproduction? A) Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction. B) Sexual reproduction results in the most appropriate and healthiest balance of two sexes in the population. C) Sexual reproduction results in the greatest number of new mutations. D) Sexual reproduction allows the greatest number of offspring to be produced. E) Sexual reproduction utilizes far less energy than asexual reproduction.

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? A) two B) four C) six D) eight E) ten

Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. The description above illustrates which of the following? A) Just because a drug acts on one type of receptor does not mean that it will act on another type. B) Beta blockers can be used effectively on any type of muscle. C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites.

Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) nonpolar substances that have an attraction for water molecules. C) polar substances that repel water molecules. D) polar substances that have an affinity for water. E) charged molecules that hydrogen-bond with water molecules.

If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has half the amount of DNA as the cell that began meiosis. B) It has the same number of chromosomes but each of them has different alleles than another cell from the same meiosis. C) It has half the chromosomes but twice the DNA of the originating cell. D) It has one-fourth the DNA and one-half the chromosomes as the originating cell. E) It is identical in content to another cell from the same meiosis.

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to A) add more of the enzyme. B) heat the solution to 90°C. C) add more substrate. D) add an allosteric inhibitor. E) add a noncompetitive inhibitor.

If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? A) at most, 2 alleles for that gene B) up to 18 chromosomes with that gene C) up to 18 genes for that trait D) a haploid number of 9 chromosomes E) up to, but not more than, 18 different traits

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, this means that A) the concentration of H⁺ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix. B) the concentration of H⁺ ions is tenfold higher in the mitochondrial matrix than in the cytoplasm. C) the concentration of H⁺ ions in the cytoplasm is 7/8 the concentration in the mitochondrial matrix. D) the mitochondrial matrix is more acidic than the cytoplasm. E) the concentration of H⁺ ions in the cytoplasm is 8/7 the concentration in the mitochondrial matrix.

In C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways? A) It prevents the caspase activity of ced-3 and ced-4. B) Ced-9 remains inactive until it is signaled by ced-3 and other caspases. C) Ced-9 cleaves to produce ced-3 and ced-4. D) Ced-9 enters the nucleus and activates apoptotic genes. E) Ced-9 prevents blebbing by its action on the cell membrane.

In a cyanobacterium, the reactions that produce NADPH occur in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.

In a life cycle such as that shown in part III of Figure 13.1, if the zygote's chromosome number is 10, which of the following will be true? A) The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5. B) The sporophyte's chromosome number per cell is 5 and the gametophyte's is 10. C) The sporophyte and gametophyte each have 10 chromosomes per cell. D) The sporophyte and gametophyte each have 5 chromosomes per cell. E) The sporophyte and gametophyte each have 20 chromosomes per cell.

In alcohol fermentation, NAD⁺ is regenerated from NADH by A) reduction of acetaldehyde to ethanol (ethyl alcohol). B) oxidation of pyruvate to acetyl CoA. C) reduction of pyruvate to form lactate. D) oxidation of ethanol to acetyl CoA. E) reduction of ethanol to pyruvate.

In an experiment studying photosynthesis performed during the day, you provide a plant with radioactive carbon (¹⁴C) dioxide as a metabolic tracer. The ¹⁴C is incorporated first into oxaloacetate. The plant is best characterized as a A) C₄ plant. B) C₃ plant. C) CAM plant. D) heterotroph. E) chemoautotroph.

In an experiment to track the movement of growth factor molecules from secretion to the point of receptor binding in a particular species of mammal, a student found a 20-fold reduction in mm traveled when in the presence of an adrenal hormone. This is in part attributable to which of the following? A) The growth factor is a paracrine signal. B) The growth factor depends on osmosis. C) The mammal only carries growth factor through the lymph. D) The growth factor is an exocrine signal. E) The growth factor is an endocrine signal.

In general, a signal transmitted via phosphorylation of a series of proteins A) brings a conformational change to each protein. B) requires binding of a hormone to a cytosol receptor. C) cannot occur in yeasts because they lack protein phosphatases. D) requires phosphorylase activity. E) allows target cells to change their shape and therefore their activity.

Where are the molecules of the electron transport chain found in plant cells? A) thylakoid membranes of chloroplasts B) stroma of chloroplasts C) outer membrane of mitochondria D) matrix of mitochondria E) cytoplasm

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling? A) Growth factor ligands do not bind as efficiently to receptors. B) Their lower hormone concentrations elicit a lesser response. C) cAMP levels change very frequently. D) Enzymatic activity declines. E) ATP production decreases.

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of A) ATP, CO₂, and ethanol (ethyl alcohol). B) ATP, CO₂, and lactate. C) ATP, NADH, and pyruvate. D) ATP, pyruvate, and oxygen. E) ATP, pyruvate, and acetyl CoA.

In the human species, all somatic cells have 46 chromosomes. Which of the following can also be true? A) A plant species (privet shrubs) has 46 chromosomes per cell. B) Some adult humans have 69 chromosomes per cell. C) Some adult humans have 23 chromosomes per cell. D) A certain fungal species has only one chromosome per cell. E) A certain bacterial species has 23 chromosomes.

Independent assortment of chromosomes is a result of A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. B) the random nature of the fertilization of ova by sperm. C) the random distribution of the sister chromatids to the two daughter cells during anaphase II. D) the relatively small degree of homology shared by the X and Y chromosomes. E) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I, the random nature of the fertilization of ova by sperm, the random distribution of the sister chromatids to the two daughter cells during anaphase II, and the relatively small degree of homology shared by the X and Y chromosomes.

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement? A) a steroid B) cellulose C) DNA D) an enzyme E) a contractile protein

Measurements show that the pH of a particular lake is 4.0. What is the hydroxide ion concentration of the lake? A) 10⁻¹⁰ M B) 10⁻⁴ M C) 10⁻⁷ M D) 10⁻¹⁴ M E) 10 M

Meiosis II is similar to mitosis in that A) sister chromatids separate during anaphase. B) DNA replicates before the division. C) the daughter cells are diploid. D) homologous chromosomes synapse. E) the chromosome number is reduced.

Movement of vesicles within the cell depends on what cellular structures? A) microtubules and motor proteins B) actin filaments and microtubules C) actin filaments and ribosomes D) centrioles and motor proteins E) actin filaments and motor proteins

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to A) the active site of an allosteric enzyme that binds to a specific substrate. B) tRNA specifying which amino acids are in a polypeptide. C) a metabolic pathway operating within a specific organelle. D) an enzyme having an optimum pH and temperature for activity. E) an antibody in the immune system.

On food packages, to what does the term insoluble fiber refer? A) cellulose B) polypeptides C) starch D) amylopectin E) chitin

One inhibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vessels and increase of blood in the penis, facilitating erection. Since cGMP is inhibited, the signal is prolonged. The original signal that is now inhibited would have A) hydrolyzed cGMP to GMP. B) hydrolyzed GTP to GDP. C) phosphorylated GDP. D) dephosphorylated cGMP. E) removed GMP from the cell.

One of the buffers that contribute to pH stability in human blood is carbonic acid (H₂CO₃). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO₃⁻ and a hydrogen ion (H⁺). Thus, H₂CO₃ ↔ HCO₃⁻ + H⁺ If the pH of the blood increases, one would expect A) a decrease in the concentration of H₂CO₃ and an increase in the concentration of HCO₃⁻. B) an increase in the concentration of H₂CO₃ and a decrease in the concentration of HCO₃⁻. C) a decrease in the concentration of HCO₃⁻ and an increase in the concentration of H⁺. D) an increase in the concentration of HCO₃⁻ and a decrease in the concentration of OH⁻. E) a decrease in the concentration of HCO₃⁻ and an increase in the concentration of both HH₂CO₃ and H⁺.

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to A) inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle. B) activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. C) inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle. D) activate the enzyme and increase the rates of glycolysis and the citric acid cycle. E) inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.

Professor Jamey Marth at the University of California, Santa Barbara, identified 70 molecules that are used to build cellular macromolecules and structures. These include at least 34 saccharides, 8 nucleosides, and 20 amino acids. In theory, then, which class of biological polymer has the greatest information-coding capacity? A) polysaccharides B) proteins C) DNA D) RNA

Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catalyze removal of phosphate(s) from phosphorylated proteins. Phosphorylation and dephosphorylation can function as an on-off switch for a protein's activity, most likely through A) the change in a protein's charge leading to a conformational change. B) the change in a protein's charge leading to cleavage. C) a change in the optimal pH at which a reaction will occur. D) a change in the optimal temperature at which a reaction will occur. E) the excision of one or more peptides.

Where do the enzymatic reactions of the Calvin cycle take place? A) stroma of the chloroplast B) thylakoid membranes C) matrix of the mitochondria D) cytosol around the chloroplast E) thylakoid space

Where does the Calvin cycle take place? A) stroma of the chloroplast B) thylakoid membrane C) cytoplasm surrounding the chloroplast D) interior of the thylakoid (thylakoid space) E) outer membrane of the chloroplast

Recent evidence shows that signals from the extracellular matrix (ECM) can regulate the expression of genes in the cell nucleus. A likely mechanism is that A) mechanical signals of the ECM can alter the cytoskeleton, which can alter intracellular signaling. B) intracellular signals might cause changes in the fibronectin binding to the cell surface. C) orientation of microtubules to the ECM can change gene activity. D) integrins that receive signals from the ECM migrate to the nucleus. E) proteoglycans in the ECM undergo endocytosis and produce intracellular signaling molecules.

Reduction of NADP⁺ occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.

Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses? A) in or near the active site B) at an allosteric site C) at a cofactor binding site D) in regions of the protein that determine packaging into the virus capsid E) such mutations could occur anywhere with equal probability

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen? A) The isolated chloroplasts will make ATP. B) The Calvin cycle will be activated. C) Cyclic photophosphorylation will occur. D) The isolated chloroplasts will generate oxygen gas. E) The isolated chloroplasts will reduce NADP⁺ to NADPH.

The ATP made during glycolysis is generated by A) substrate-level phosphorylation. B) electron transport. C) photophosphorylation. D) chemiosmosis. E) oxidation of NADH to NAD⁺.

The NADPH required for the Calvin cycle comes from A) reactions initiated in photosystem I. B) reactions initiated in photosystem II. C) the citric acid cycle. D) glycolysis. E) oxidative phosphorylation.

The activation of receptor tyrosine kinases is characterized by A) dimerization and phosphorylation. B) dimerization and IP3 binding. C) a phosphorylation cascade. D) GTP hydrolysis. E) channel protein shape change.

The bonding of two amino acid molecules to form a larger molecule requires A) the release of a water molecule. B) the release of a carbon dioxide molecule. C) the addition of a nitrogen atom. D) the addition of a water molecule. E) the release of a nitrous oxide molecule.

The bonding of two amino acid molecules to form a larger molecule requires which of the following? A) removal of a water molecule B) addition of a water molecule C) formation of a glycosidic bond D) formation of a hydrogen bond E) both removal of a water molecule and formation of a hydrogen bond

The complexity and variety of organic molecules is due to A) the chemical versatility of carbon atoms. B) the variety of rare elements in organic molecules. C) the fact that they can be synthesized only in living organisms. D) their interaction with water. E) their tremendously large sizes.

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the α form. Which of the following could amylase break down? A) glycogen, starch, and amylopectin B) glycogen and cellulose C) cellulose and chitin D) starch and chitin E) starch, amylopectin, and cellulose

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down? A) glycogen B) cellulose C) chitin D) glycogen and chitin only E) glycogen, cellulose, and chitin

The evolution of eukaryotic cells most likely involved A) endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria. B) anaerobic archaea taking up residence inside a larger bacterial host cell to escape toxic oxygen-the anaerobic bacterium evolved into chloroplasts. C) an endosymbiotic fungal cell evolved into the nucleus. D) acquisition of an endomembrane system, and subsequent evolution of mitochondria from a portion of the Golgi.

The fact that the outer membrane of the nuclear envelope has bound ribosomes allows one to most reliably conclude that A) at least some of the proteins that function in the nuclear envelope are made by the ribosomes on the nuclear envelope. B) the nuclear envelope is not part of the endomembrane system. C) the nuclear envelope is physically separated from the endoplasmic reticulum. D) small vesicles from the Golgi fuse with the nuclear envelope. E) nuclear pore complexes contain proteins.

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A) oxygen. B) water. C) NAD⁺. D) pyruvate. E) ADP.

The human genome is minimally contained in which of the following? A) every human cell B) each human chromosome C) the entire DNA of a single human D) the entire human population E) each human gene

The molecular weight of water is 18 daltons. What is the molarity of 1 liter of pure water? (Hint: What is the mass of 1 liter of pure water?) A) 55.6 M B) 18 M C) 37 M D) 0.66 M E) 1.0 M

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find? A) The pH within the thylakoid is less than that of the stroma. B) The pH of the stroma is lower than that of the other two measurements. C) The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol. D) The pH of the thylakoid space is higher than that anywhere else in the cell. E) There is no consistent relationship.

The reactions that produce molecular oxygen (O₂) take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but are not part of photosynthesis.

The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is A) a mitochondrion. B) a microtubule. C) a ribosome. D) a microfilament. E) a nuclear pore.

The structural level of a protein least affected by a disruption in hydrogen bonding is the A) primary level. B) secondary level. C) tertiary level. D) quaternary level. E) All structural levels are equally affected.

The toxin of Vibrio cholerae causes profuse diarrhea because it A) modifies a G protein involved in regulating salt and water secretion. B) decreases the cytosolic concentration of calcium ions, making the cells hypotonic. C) binds with adenylyl cyclase and triggers the formation of cAMP. D) signals IP3 to act as a second messenger for the release of calcium. E) modifies calmodulin and activates a cascade of protein kinases.

The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion? A) active transport B) diffusion C) facilitated diffusion D) through a channel E) through a pore

Using the yeast signal transduction pathways, both types of mating cells release the mating factors. These factors bind to specific receptors on the correct cells, A) which induce changes in the cells that lead to cell fusion. B) which produce more of the a factor in a positive feedback. C) then one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. D) stimulating cell membrane disintegration, releasing the mating factors that lead to new yeast cells. E) which in turn releases a growth factor that stimulates mitosis in both cells.

Water molecules are able to form hydrogen bonds with A) compounds that have polar covalent bonds. B) oils. C) oxygen gas (O₂) molecules. D) chloride ions. E) any compound that is not soluble in water.

What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions? A) glucose B) ethanol C) pyruvate D) lactic acid E) either ethanol or lactic acid

What does the chemiosmotic process in chloroplasts involve? A) establishment of a proton gradient across the thylakoid membrane B) diffusion of electrons through the thylakoid membrane C) reduction of water to produce ATP energy D) movement of water by osmosis into the thylakoid space from the stroma E) formation of glucose, using carbon dioxide, NADPH, and ATP

What explains the increased concentration of Ca⁺⁺ in the ER? A) Calcium ions are actively imported from the cytoplasm into the ER. B) Calcium concentration is kept low in the cytoplasm because of its high usage level. C) Calcium cannot enter the plasma membrane through ion channels. D) Calcium levels in the blood or other body fluids are extremely low. E) The Ca ions are recycled from other molecules in the ER.

What is the pH of a solution with a hydroxyl ion [OH⁻] concentration of 10⁻¹² M? A) pH 2 B) pH 4 C) pH 10 D) pH 12 E) pH 14

What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division? A) light microscopy B) scanning electron microscopy C) transmission electron microscopy D) confocal fluorescence microscopy E) super-resolution fluorescence microscopy

When does the synaptonemal complex disappear? A) late prophase of meiosis I B) during fertilization or fusion of gametes C) early anaphase of meiosis I D) mid-prophase of meiosis II E) late metaphase of meiosis II

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A) The pH of the matrix increases. B) ATP synthase pumps protons by active transport. C) The electrons gain free energy. D) The cytochromes phosphorylate ADP to form ATP. E) NAD⁺ is oxidized.

When electrons move closer to a more electronegative atom, what happens? A) The more electronegative atom is reduced, and energy is released. B) The more electronegative atom is reduced, and energy is consumed. C) The more electronegative atom is oxidized, and energy is consumed. D) The more electronegative atom is oxidized, and energy is released. E) The more electronegative atom is reduced, and entropy decreases.

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A) Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers. B) Dehydration reactions eliminate water from lipid membranes, and hydrolysis makes lipid membranes water permeable. C) Dehydration reactions can occur only after hydrolysis. D) Hydrolysis creates monomers, and dehydration reactions break down polymers. E) Dehydration reactions ionize water molecules and add hydroxyl groups to polymers; hydrolysis reactions release hydroxyl groups from polymers.

Which of the following contains hydrolytic enzymes? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

Which of the following happens at the conclusion of meiosis I? A) Homologous chromosomes are separated. B) The chromosome number per cell is conserved. C) Sister chromatids are separated. D) Four daughter cells are formed. E) The sperm cells elongate to form a head and a tail end.

Which of the following is a likely explanation of why natural selection favored the evolution of signals for sexual reproduction? A) Even in the simplest organisms, sexual reproduction required several coordinated responses by cells. B) Multicellular eukaryotes required signals that were responded to by multiple organ systems. C) Cells of several kinds of mating types needed to sort themselves to allow self-recognition. D) Rooted plants required chemical diffusible signals that could travel throughout the organism. E) Hormones required a mechanism for introducing changes in their target tissues.

Which of the following is a statement of the first law of thermodynamics? A) Energy cannot be created or destroyed. B) The entropy of the universe is decreasing. C) The entropy of the universe is constant. D) Kinetic energy is stored energy that results from the specific arrangement of matter. E) Energy cannot be transferred or transformed.

Which of the following is not a polymer? A) glucose B) starch C) cellulose D) chitin E) DNA

Which of the following is true for the signaling system in an animal cell that lacks the ability to produce GTP? A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. B) It could activate only the epinephrine system. C) It would be able to carry out reception and transduction but would not be able to respond to a signal. D) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. E) It would employ a transduction pathway directly from an external messenger.

Which of the following is true of both starch and cellulose? A) They are both polymers of glucose. B) They are cis-trans isomers of each other. C) They can both be digested by humans. D) They are both used for energy storage in plants. E) They are both structural components of the plant cell wall.

Which of the following might result in a human zygote with 45 chromosomes? A) an error in either egg or sperm meiotic anaphase B) failure of the egg nucleus to be fertilized by the sperm C) fertilization of a 23 chromosome human egg by a 22 chromosome sperm of a closely related species D) an error in the alignment of chromosomes on the metaphase plate E) lack of chiasmata in prophase I

Which of the following most likely would be an immediate result of growth factor binding to its receptor? A) protein kinase activity B) adenylyl cyclase activity C) GTPase activity D) protein phosphatase activity E) phosphorylase activity

Which of the following normally occurs regardless of whether or not oxygen (O₂) is present? A) glycolysis B) fermentation C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation (chemiosmosis)

Which of the following occurs in the cytosol of a eukaryotic cell? A) glycolysis and fermentation B) fermentation and chemiosmosis C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation

Which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH? A) gastric juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) black coffee at pH 5 E) household bleach at pH 12

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle? A) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP⁺ to the light reactions. B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. C) The light reactions supply the Calvin cycle with CO₂ to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split. E) There is no relationship between the light reactions and the Calvin cycle.

Which of the following statements concerning bacteria and archaea cells is correct? A) Archaea cells contain small membrane-enclosed organellesbacteria do not. B) Archaea cells contain a membrane-bound nucleus bacteria do not. C) DNA is present in both archaea cells and bacteria cells. D) DNA is present in the mitochondria of both bacteria and archaea cells.

Which of the following statements correctly describes cis-trans isomers? A) They have variations in arrangement around a double bond. B) They have an asymmetric carbon that makes them mirror images. C) They have the same chemical properties. D) They have different molecular formulas. E) Their atoms and bonds are arranged in different sequences.

Which of the following statements describes NAD⁺? A) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD⁺ has more chemical energy than NADH. C) NAD⁺ is oxidized by the action of hydrogenases. D) NAD⁺ can donate electrons for use in oxidative phosphorylation. E) In the absence of NAD⁺, glycolysis can still function.

Which of the following statements describes the results of this reaction? C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy A) C₆H₁₂O₆ is oxidized and O₂ is reduced. B) O₂ is oxidized and H₂O is reduced. C) CO₂ is reduced and O₂ is oxidized. D) C₆H₁₂O₆ is reduced and CO₂ is oxidized. E) O₂ is reduced and CO₂ is oxidized.

Which of the following statements is true about enzyme-catalyzed reactions? A) The reaction is faster than the same reaction in the absence of the enzyme. B) The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme. C) The reaction always goes in the direction toward chemical equilibrium. D) Enzyme-catalyzed reactions require energy to activate the enzyme. E) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.

Which of the following statements is true for the class of biological molecules known as lipids? A) They are insoluble in water. B) They are made from glycerol, fatty acids, and phosphate. C) They contain less energy than proteins and carbohydrates. D) They are made by dehydration reactions. E) They contain nitrogen.

Which of the following types of reactions would decrease the entropy within a cell? A) anabolic reactions B) hydrolysis C) respiration D) digestion E) catabolic reactions

Which of these molecules is not formed by dehydration reactions? A) fatty acids B) disaccharides C) DNA D) protein E) amylose

Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth? A) Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya. B) Glycolysis neither uses nor needs O₂. C) Glycolysis is found in all eukaryotic cells. D) The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle. E) Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere.

Which structure is the site of the synthesis of proteins that may be exported from the cell? A) rough ER B) lysosomes C) plasmodesmata D) Golgi vesicles E) free cytoplasmic ribosomes

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A) glucose B) proteins C) fatty acids D) glucose, proteins, and fatty acids E) Such yeast cells will not be capable of catabolizing any food molecules, and will therefore die.

You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body? A) It was released as CO₂ and H₂O. B) It was converted to heat and then released. C) It was converted to ATP, which weighs much less than fat. D) It was broken down to amino acids and eliminated from the body. E) It was converted to urine and eliminated from the body.

electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon? A) use mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities against those of wild-type organisms B) use plants that can carry out both linear and cyclic electron flow, or only one or another of these processes, and compare their light absorbance at different wavelengths and different light intensities C) use bacteria that have only cyclic flow and look for their frequency of mutation damage at different light intensities D) use bacteria with only cyclic flow and measure the number and types of photosynthetic pigments they have in their membranes E) use plants with only photosystem I operative and measure how much damage occurs at different wavelengths

staining usually requires preserved cells. B) GFP fusions enable higher resolution than staining with fluorescent probes. C) GFP permits the position of the protein in the cell more precisely than fluorescent probes. D) GFP permits visualization of protein-protein interactions fluorescent probes do not. E) GFP fusions are not subject to artifacts fluorescent probes may introduce background artifacts.

In an analysis of the nucleotide composition of DNA, which of the following will be found?

A + C = G + T

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A + G = C + T

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

A gene from an organism can theoretically be expressed by any other organism.

Why is it so important to be able to amplify DNA fragments when studying genes?

A gene may represent only a millionth of the cell's DNA.

Which of the following is characteristic of the lytic cycle?

A large number of phages are released at a time.

Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression?

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?

A retrovirus is used to introduce four specific regulatory genes.

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line?

A transgene integrated into a heterochromatic region of the genome.

Which two functional groups are always found in amino acids? A) ketone and methyl B) carbonyl and amino C) carboxyl and amino D) amino and sulfhydryl E) hydroxyl and carboxyl

The nitrogenous base adenine is found in all members of which group?

ATP, RNA, and DNA

The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following?

All of the genes controlling the traits behaved as if they were on different chromosomes.

Suppose that a gene on human chromosome 18 can be imprinted in a given pattern in a female parent but not in a male parent. A couple in whom each maternal meiosis is followed by imprinting of this gene have children. What can we expect as a likely outcome?

All the children will bear their mother's imprinting pattern but only daughters will then pass it down.

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

Allolactose binds to the repressor protein.

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

Which of the following series best reflects what we know about how the flu virus moves between species?

An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.

The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur?

Anterior structures would form in both sides of the embryo.

A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?

Any mutation in the sequence is selected against.

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8(2n = 8)? A) 2 B) 4 C) 8 D) 16 E) 32

A gardener is concerned that her greenhouse is getting too hot from too much light, and seeks to shade her plants with colored translucent plastic sheets. What color should she use to reduce overall light energy, but still maximize plant growth? A) green B) blue C) yellow D) orange E) any color will work equally well

How many electron pairs does carbon share in order to complete its valence shell? A) 1 B) 2 C) 3 D) 4 E) 8

A cell divides to produce two daughter cells that are genetically different. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

A cell with a predominance of free ribosomes is most likely A) producing primarily proteins for secretion. B) producing primarily cytoplasmic proteins. C) constructing an extensive cell wall or extracellular matrix. D) digesting large food particles. E) enlarging its vacuole.

A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound? A) It lacks an asymmetric carbon, and it is probably a fat or lipid. B) It should dissolve in water. C) It should dissolve in a nonpolar solvent. D) It won't form hydrogen bonds with water. E) It is hydrophobic.

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of A) 120 adenine and 120 uracil molecules. B) 120 thymine and 120 adenine molecules. C) 120 cytosine and 120 thymine molecules. D) 120 adenine and 120 cytosine molecules. E) 120 guanine and 120 thymine molecules.

A molecule with the formula C₁₈H3₆O₂ is probably a A) carbohydrate. B) fatty acid. C) protein. D) nucleic acid. E) hydrocarbon.

A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism A) is more closely related to humans than to frogs. B) is more closely related to frogs than to humans. C) evolved at about the same time as frogs, which is much earlier than primates and mammals. D) is more closely related to humans than to rats. E) is more closely related to frogs than to humans and also evolved at about the same time as frogs, which is much earlier than primates and mammals.

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment? A) red and yellow B) blue and violet C) green and yellow D) blue, green, and red E) green, blue, and yellow

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. With respect to the enzyme that converts X to Y, substance A functions as A) a coenzyme. B) an allosteric inhibitor. C) the substrate. D) an intermediate. E) a competitive inhibitor.

A tetrad includes which of the following sets of DNA strands? A) two single-stranded chromosomes that have synapsed B) two sets of sister chromatids that have synapsed C) four sets of sister chromatids D) four sets of unique chromosomes E) eight sets of sister chromatids

A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following? A) 63 chromosomes in 31 1/2 pairs B) 63 chromosomes in 21 sets of 3 C) 63 chromosomes, each with three chromatids D) 21 chromosome pairs and 21 unique chromosomes

Affinity chromatography is a method that can be used to purify cell-surface receptors, while they retain their hormone-binding ability. A ligand (hormone) for a receptor of interest is chemically linked to polystyrene beads. A solubilized preparation of membrane proteins is passed over a column containing these beads. Only the receptor binds to the beads. When an excess of the ligand (hormone) is poured through the column after the receptor binding step, what do you expect will occur? A) The ligand will attach to those beads that have the receptor and remain on the column. B) The ligand will cause the receptor to be displaced from the beads and eluted out. C) The ligand will attach to the bead instead of the receptor. D) The ligand will cause the bead to lose its affinity by changing shape. E) The reaction will cause a pH change due to electron transfer.

All of the following contain amino acids except A) hemoglobin. B) cholesterol. C) antibodies. D) enzymes. E) insulin.

An electron loses potential energy when it A) shifts to a less electronegative atom. B) shifts to a more electronegative atom. C) increases its kinetic energy. D) increases its activity as an oxidizing agent. E) moves further away from the nucleus of the atom.

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype? A) prophase B) metaphase C) anaphase D) telophase E) interphase

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity? A) cessation of cellular protein synthesis B) localization of enzymes into specific organelles or membranes C) exporting enzymes out of the cell D) connecting enzymes into large aggregates E) hydrophobic interactions

Carbon dioxide (CO₂) is released during which of the following stages of cellular respiration? A) glycolysis and the oxidation of pyruvate to acetyl CoA B) oxidation of pyruvate to acetyl CoA and the citric acid cycle C) the citric acid cycle and oxidative phosphorylation D) oxidative phosphorylation and fermentation E) fermentation and glycolysis

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants? A) They serve as accessory pigments to increase light absorption. B) They protect against oxidative damage from excessive light energy. C) They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation. D) They reflect orange light and enhance red light absorption by chlorophyll. E) They take up and remove toxins from the groundwater.

Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds, will A) be more flexible in structure. B) be more constrained in structure. C) be more polar. D) have more hydrogen atoms. E) have fewer structurally distinct isomers.

Polysaccharides, triacylglycerides, and proteins are similar in that they A) are synthesized from monomers by the process of hydrolysis. B) are synthesized from subunits by dehydration reactions. C) are synthesized as a result of peptide bond formation between monomers. D) are decomposed into their subunits by dehydration reactions. E) all contain nitrogen in their monomer building blocks.

DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase? A) The two strands of the double helix would separate. B) The phosphodiester bonds between deoxyribose sugars would be broken. C) The purines would be separated from the deoxyribose sugars. D) The pyrimidines would be separated from the deoxyribose sugars. E) All bases would be separated from the deoxyribose sugars.

Differences among organisms are caused by A) large differences in elemental composition from organism to organism. B) differences in the types and relative amounts of organic molecules synthesized by each organism. C) differences in the elements that bond with carbon in each organism. D) differences in the sizes of the organic molecules in each organism. E) differences in inorganic compounds present in each organism.

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction? A) -40 kcal/mol B) -20 kcal/mol C) 0 kcal/mol D) +20 kcal/mol E) +40 kcal/mol

During aerobic respiration, electrons travel downhill in which sequence? A) food → citric acid cycle → ATP → NAD⁺ B) food → NADH → electron transport chain → oxygen C) glucose → pyruvate → ATP → oxygen D) glucose → ATP → electron transport chain → NADH E) food → glycolysis → citric acid cycle → NADH → ATP

During intense exercise, as skeletal muscle cells go into anaerobiosis, the human body will increase its catabolism of A) fats only. B) carbohydrates only. C) proteins only. D) fats, carbohydrates, and proteins. E) fats and proteins only.

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? A) The two strands of the double helix would separate. B) The phosphodiester linkages of the polynucleotide backbone would be broken. C) The purines would be separated from the deoxyribose sugars. D) The pyrimidines would be separated from the deoxyribose sugars. E) All bases would be separated from the deoxyribose sugars

For living organisms, which of the following is an important consequence of the first law of thermodynamics? A) The energy content of an organism is constant. B) The organism ultimately must obtain all of the necessary energy for life from its environment. C) The entropy of an organism decreases with time as the organism grows in complexity. D) Organisms grow by converting energy into organic matter. E) Life does not obey the first law of thermodynamics.

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of A) competitive inhibition. B) allosteric regulation. C) the specificity of enzymes for their substrates. D) an enzyme requiring a cofactor. E) positive feedback regulation.

Homologous chromosomes move toward opposite poles of a dividing cell during A) mitosis. B) meiosis I. C) meiosis II. D) fertilization. E) binary fission.

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? A) by binding at the active site of the enzyme B) by changing the shape of the enzyme's active site C) by changing the free energy change of the reaction D) by acting as a coenzyme for the reaction E) by decreasing the activation energy of the reaction

How many structural isomers are possible for a substance having the molecular formula C₄H₁₀? A) 1 B) 2 C) 4 D) 3 E) 11

Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells? A) chloroplast B) lysosome C) central vacuole D) peroxisome E) glyoxysome

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence A) 5'TAACGT3'. B) 5'TGCAAT3'. C) 5'UAACGU3'. D) 3'UAACGU5'. E) 5'UGCAAU3'.

In C₃ photosynthesis, the reactions that require ATP take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.

In animal metabolism, most of the monomers released by digestion of food macromolecules are metabolized to provide energy. Only a small portion of these monomers are used for synthesis of new macromolecules. The net result is that A) water is generated by animal metabolism. B) water is consumed by animal metabolism. C) the water consumed is exactly balanced by the water generated, to maintain homeostasis. D) water is consumed during homeostasis, but water is generated during periods of growth. E) water is generated during homeostasis, but water is consumed during periods of growth.

In cellular respiration, the energy for most ATP synthesis is supplied by A) high energy phosphate bonds in organic molecules. B) a proton gradient across a membrane. C) converting oxygen to ATP. D) transferring electrons from organic molecules to pyruvate. E) generating carbon dioxide and oxygen in the electron transport chain.

Which of the following is present in a prokaryotic cell? A) mitochondrion B) ribosome C) nuclear envelope D) chloroplast E) ER

In glycolysis, for each molecule of glucose oxidized to pyruvate A) two molecules of ATP are used and two molecules of ATP are produced. B) two molecules of ATP are used and four molecules of ATP are produced. C) four molecules of ATP are used and two molecules of ATP are produced. D) two molecules of ATP are used and six molecules of ATP are produced. E) six molecules of ATP are used and six molecules of ATP are produced.

In mechanism, photophosphorylation is most similar to A) substrate-level phosphorylation in glycolysis. B) oxidative phosphorylation in cellular respiration. C) the Calvin cycle. D) carbon fixation. E) reduction of NADP⁺.

In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur? A) The ATP must first have to attach to the tRNA. B) The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. C) The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. D) The tRNA molecule must have to alter its shape in order to be able to fit into the active site with the other two molecules. E) The 3' end of the tRNA must have to be cleaved before it can have an attached amino acid.

In part III of Figure 13.1, the progression of events corresponds to which of the following series? A) zygote, mitosis, gametophyte, mitosis, fertilization, zygote, mitosis B) sporophyte, meiosis, spore, mitosis, gametophyte, mitosis, gametes, fertilization C) fertilization, mitosis, multicellular haploid, mitosis, spores, sporophyte D) gametophyte, meiosis, zygote, spores, sporophyte, zygote E) meiosis, fertilization, zygote, mitosis, adult, meiosis

In the fractionation of homogenized cells using centrifugation, the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is A) the relative solubility of the component. B) the size and weight of the component. C) the percentage of carbohydrates in the component. D) the presence or absence of nucleic acids in the component. E) the presence or absence of lipids in the component.

In the thylakoid membranes, what is the main role of the antenna pigment molecules? A) split water and release oxygen to the reaction-center chlorophyll B) harvest photons and transfer light energy to the reaction-center chlorophyll C) synthesize ATP from ADP and Pi D) transfer electrons to ferredoxin and then NADPH E) concentrate photons within the stroma

In which of the following ways could signal transduction most probably be explored in research to treat cancer? A) removal of serine/threonine phosphate acceptors from transduction pathways in colon pre-cancerous growths B) alteration of protein kinases in cell cycle regulation in order to slow cancer growth C) increase in calcium ion uptake into the cytoplasm in order to modulate the effects of environmental carcinogens D) expansion of the role of transduction inhibitors in the cells before they give rise to cancer E) increase in the concentration of phosphodiesterases in order to produce more AMP

In which of the following ways do plant hormones differ from hormones in animals? A) Plant hormones interact primarily with intracellular receptors. B) Plant hormones may travel in air or through vascular systems. C) Animal hormones are found in much greater concentration. D) Plant hormones are synthesized from two or more distinct molecules. E) Animal hormones are primarily for mating and embryonic development.

Independent assortment of chromosomes occurs. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes could still be carried on by this isolated inner membrane? A) the citric acid cycle B) oxidative phosphorylation C) glycolysis and fermentation D) reduction of NAD⁺ E) both the citric acid cycle and oxidative phosphorylation

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because A) only target cells retain the appropriate DNA segments. B) intracellular receptors are present only in target cells. C) most cells lack the Y chromosome required. D) only target cells possess the cytosolic enzymes that transduce the testosterone. E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

Most CO₂ from catabolism is released during A) glycolysis. B) the citric acid cycle. C) lactate fermentation. D) electron transport. E) oxidative phosphorylation.

One of the primary functions of RNA molecules is to A) transmit genetic information to offspring. B) function in the synthesis of proteins. C) make a copy of itself, thus ensuring genetic continuity. D) act as a pattern or blueprint to form DNA. E) form the genes of higher organisms.

Organic chemistry is currently defined as A) the study of compounds made only by living cells. B) the study of carbon compounds. C) the study of vital forces. D) the study of natural (as opposed to synthetic) compounds. E) the study of hydrocarbons.

Photorespiration lowers the efficiency of photosynthesis by A) carbon dioxide molecules. B) 3-phosphoglycerate molecules. C) ATP molecules. D) ribulose bisphosphate molecules. E) RuBP carboxylase molecules.

Photorespiration occurs when rubisco reacts RuBP with A) CO₂. B) O₂. C) glyceraldehyde 3-phosphate. D) 3-phosphoglycerate. E) NADPH.

Prokaryotes are classified as belonging to two different domains. What are the domains? A) Bacteria and Eukarya B) Bacteria and Archaea C) Archaea and Protista D) Bacteria and Protista E) Bacteria and Fungi

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization? A) ATP is more abundant near the plasma membrane. B) They can more readily encounter and phosphorylate other membrane proteins. C) Membrane localization lowers the activation energy of the phosphorylation reaction. D) They flip back and forth across the membrane to access target proteins on either side. E) They require phospholipids as a cofactor.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's A) entropy. B) activation energy. C) endothermic level. D) equilibrium point. E) free-energy content.

Reactions that require CO₂ take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.

Reduction of oxygen to form water occurs during A) photosynthesis only. B) respiration only. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration only.

Referring to a plant's sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes? A) sporophyte meiosis B) gametophyte mitosis C) gametophyte meiosis D) sporophyte mitosis E) alternation of generations

Since steroid receptors are located intracellularly, which of the following is true? A) The receptor molecules are themselves lipids or glycolipids. B) The steroid/receptor complex can cross the nuclear membrane. C) The unbound steroid receptors are quickly recycled by lysosomes. D) The concentration of steroid receptors must be relatively high in most cells. E) The receptor molecules are free to move in and out of most organelles.

Some photosynthetic bacteria (e.g., purple sulfur bacteria) have only photosystem I, whereas others (e.g., cyanobacteria) have both photosystem I and photosystem II. Which of the following might this observation imply? A) Photosystem II was selected against in some species. B) Photosynthesis with only photosystem I is more ancestral. C) Photosystem II may have evolved to be more photoprotective. D) Linear electron flow is more primitive than cyclic flow of electrons. E) Cyclic flow is more necessary than linear electron flow.

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be A) to determine if they have thylakoids in the chloroplasts. B) to test for liberation of O₂ in the light. C) to test for CO₂ fixation in the dark. D) to do experiments to generate an action spectrum. E) to test for production of either sucrose or starch.

Stanley Miller's 1953 experiments assumed that early Earth's atmosphere contained A) hydrogen cyanide, formaldehyde, hydrogen gas, and water vapor. B) ammonia, methane, hydrogen gas, and water vapor. C) ammonia, methane, oxygen gas, and water vapor. D) amino acids, methane, hydrogen cyanide, and water vapor. E) methane, formaldehyde, ammonia, and carbon dioxide.

Stanley Miller's 1953 experiments proved that A) life arose on Earth from simple inorganic molecules. B) organic molecules can be synthesized abiotically under conditions that may have existed on early Earth. C) life arose on Earth from simple organic molecules, with energy from lightning and volcanoes. D) the conditions on early Earth were conducive to the origin of life. E) the conditions on early Earth were conducive to the abiotic synthesis of organic molecules.

Starting with one molecule of glucose, the energy-containing products of glycolysis are A) 2 NAD⁺, 2 pyruvate, and 2 ATP. B) 2 NADH, 2 pyruvate, and 2 ATP. C) 2 FADH₂, 2 pyruvate, and 4 ATP. D) 6 CO₂, 2 ATP, and 2 pyruvate. E) 6 CO₂, 30 ATP, and 2 pyruvate.

Testosterone and estradiol are A) soluble in water. B) structural isomers of each other. C) proteins. D) lipids. E) enantiomers of each other.

Testosterone functions inside a cell by A) acting as a signal receptor that activates tyrosine kinases. B) binding with a receptor protein that enters the nucleus and activates specific genes. C) acting as a steroid signal receptor that activates ion channel proteins. D) becoming a second messenger that inhibits adenylyl cyclase. E) coordinating a phosphorylation cascade that increases spermatogenesis.

The ATP made during fermentation is generated by which of the following? A) the electron transport chain B) substrate-level phosphorylation C) chemiosmosis D) oxidative phosphorylation E) aerobic respiration

The R group or side chain of the amino acid serine is -CH₂-OH. The R group or side chain of the amino acid leucine is -CH₂-CH-(CH₃)₂. Where would you expect to find these amino acids in a globular protein in aqueous solution? A) Serine would be in the interior, and leucine would be on the exterior of the globular protein. B) Leucine would be in the interior, and serine would be on the exterior of the globular protein. C) Both serine and leucine would be in the interior of the globular protein. D) Both serine and leucine would be on the exterior of the globular protein. E) Both serine and leucine would be in the interior and on the exterior of the globular protein.

The active site of an enzyme is the region that A) binds allosteric regulators of the enzyme. B) is involved in the catalytic reaction of the enzyme. C) binds noncompetitive inhibitors of the enzyme. D) is inhibited by the presence of a coenzyme or a cofactor.

The bonds that are broken when water vaporizes are A) ionic bonds. B) hydrogen bonds between water molecules. C) covalent bonds between atoms within water molecules. D) polar covalent bonds. E) nonpolar covalent bonds.

The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil? A) The hydrogenated vegetable oil has a lower melting point. B) The hydrogenated vegetable oil stays solid at room temperature. C) The hydrogenated vegetable oil has more "kinks" in the fatty acid chains. D) The hydrogenated vegetable oil has fewer trans fatty acids. E) The hydrogenated vegetable oil is less likely to clog arteries.

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells? A) rough ER B) smooth ER C) Golgi apparatus D) nuclear envelope E) transport vesicles

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as A) metabolic inhibition. B) feedback inhibition. C) allosteric inhibition. D) noncooperative inhibition. E) reversible inhibition.

The molar mass of glucose (C₆H₁₂O₆) is 180 g/mol. Which of the following procedures should you carry out to make a 0.5 M solution of glucose? A) Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L. B) Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. C) Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. D) Dissolve 0.5 g of glucose in 1 L of water. E) Dissolve 180 g of glucose in 0.5 L of water.

The molecular formula for glucose is C₆H₁2O₆. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A) C₁₈H₃₆O₁₈ B) C₁₈H₃₂O₁₆ C) C₆H₁₀O₅ D) C1₈H₁₀O₁₅ E) C₃H₆O₃

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction A) gains electrons and gains potential energy. B) loses electrons and loses potential energy. C) gains electrons and loses potential energy. D) loses electrons and gains potential energy. E) neither gains nor loses electrons, but gains or loses potential energy.

The oxygen consumed during cellular respiration is involved directly in which process or event? A) glycolysis B) accepting electrons at the end of the electron transport chain C) the citric acid cycle D) the oxidation of pyruvate to acetyl CoA E) the phosphorylation of ADP to form ATP

The partial negative charge in a molecule of water occurs because A) the oxygen atom acquires an additional electron. B) the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus. C) the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms. D) the oxygen atom forms hybrid orbitals that distribute electrons unequally around the oxygen nucleus. E) one of the hydrogen atoms donates an electron to the oxygen atom.

The primary role of oxygen in cellular respiration is to A) yield energy in the form of ATP as it is passed down the respiratory chain. B) act as an acceptor for electrons and hydrogen, forming water. C) combine with carbon, forming CO₂. D) combine with lactate, forming pyruvate. E) catalyze the reactions of glycolysis.

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called? A) a covalent bond B) a hydrogen bond C) an ionic bond D) a hydrophilic bond E) a van der Waals interaction

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of A) active transport. B) an endergonic reaction coupled to an exergonic reaction. C) a reaction with a positive ΔG . D) osmosis. E) allosteric regulation.

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. If you ran the same experiment without passing light through a prism, what would you predict? A) There would be no difference in results. B) The bacteria would be relatively evenly distributed along the algal filaments. C) The number of bacteria present would decrease due to an increase in the carbon dioxide concentration. D) The number of bacteria present would increase due to an increase in the carbon dioxide concentration. E) The number of bacteria would decrease due to a decrease in the temperature of the water.

Thylakoids, DNA, and ribosomes are all components found in A) vacuoles. B) chloroplasts. C) mitochondria. D) lysosomes. E) nuclei.

What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration? A) the presence or absence of bonds with oxygen atoms B) the presence or absence of double bonds between the carbon atom and other atoms C) the polarity of the covalent bonds between carbon and other atoms D) the presence or absence of bonds with nitrogen atoms E) the solvent that the organic molecule is dissolved in

What is proton-motive force? A) the force required to remove an electron from hydrogen B) the force exerted on a proton by a transmembrane proton concentration gradient C) the force that moves hydrogen into the intermembrane space D) the force that moves hydrogen into the mitochondrion E) the force that moves hydrogen to NAD⁺

What is the relationship between wavelength of light and the quantity of energy per photon? A) They have a direct, linear relationship. B) They are inversely related. C) They are logarithmically related. D) They are separate phenomena. E) They are only related in certain parts of the spectrum.

What is the structural feature that allows DNA to replicate? A) sugar-phosphate backbone B) complementary pairing of the nitrogenous bases C) disulfide bonding (bridging) of the two helixes D) twisting of the molecule to form an α helix E) three-component structure of the nucleotides

What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A) anabolic pathways B) catabolic pathways C) fermentation pathways D) thermodynamic pathways E) bioenergetic pathways

What is the term used for a protein molecule that assists in the proper folding of other proteins? A) tertiary protein B) chaperonin C) enzyme protein D) renaturing protein E) denaturing protein

What maintains the secondary structure of a protein? A) peptide bonds B) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond C) disulfide bonds D) hydrophobic interactions E) hydrogen bonds between the R groups

When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows: A) +ΔG, +ΔH, +ΔS. B) +ΔG, +ΔH, -ΔS. C) +ΔG, -ΔH, -ΔS. D) -ΔG, +ΔH, +ΔS. E) -ΔG, -ΔH, -ΔS.

When oxygen is released as a result of photosynthesis, it is a direct by-product of A) reducing NADP⁺. B) splitting water molecules. C) chemiosmosis. D) the electron transfer system of photosystem I. E) the electron transfer system of photosystem II.

When skeletal muscle cells are oxygen-deprived, the heart still pumps. What must the heart muscle cells be able to do? A) derive sufficient energy from fermentation B) continue aerobic metabolism when skeletal muscle cannot C) transform lactate to pyruvate again D) remove lactate from the blood E) remove oxygen from lactate

When skeletal muscle cells undergo anaerobic respiration, they become fatigued and painful. This is now known to be caused by A) buildup of pyruvate. B) buildup of lactate. C) increase in sodium ions. D) increase in potassium ions. E) increase in ethanol.

Which class of biological polymer has the greatest functional variety? A) polysaccharides B) proteins C) DNA D) RNA

Which level of protein structure do the α helix and the β pleated sheet represent? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

Which of the following are directly associated with photosystem I? A) harvesting of light energy by ATP B) receiving electrons from the thylakoid membrane electron transport chain C) generation of molecular oxygen D) extraction of hydrogen electrons from the splitting of water E) passing electrons to the thylakoid membrane electron transport chain

Which of the following are nitrogenous bases of the purine type? A) cytosine and guanine B) guanine and adenine C) adenine and thymine D) thymine and uracil E) uracil and cytosine

Which of the following are nitrogenous bases of the pyrimidine type? A) guanine and adenine B) cytosine and uracil C) thymine and guanine D) ribose and deoxyribose E) adenine and thymine

Which of the following best describes a karyotype? A) a pictorial representation of all the genes for a species B) a display of each of the chromosomes of a single cell C) the combination of all the maternal and paternal chromosomes of a species D) the collection of all the chromosomes in an individual organism E) a photograph of all the cells with missing or extra chromosomes

Which of the following best describes enthalpy (H)? A) the total kinetic energy of a system B) the heat content of a chemical system C) the system's entropy D) the cell's energy equilibrium E) the condition of a cell that is not able to react

Which of the following effects is produced by the high surface tension of water? A) Lakes don't freeze solid in winter, despite low temperatures. B) A water strider can walk across the surface of a small pond. C) Organisms resist temperature changes, although they give off heat due to chemical reactions. D) Evaporation of sweat from the skin helps to keep people from overheating. E) Water flows upward from the roots to the leaves in plants.

Which of the following is a true statement about sexual vs. asexual reproduction? A) Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi. B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring. C) In asexual reproduction, offspring are produced by fertilization without meiosis. D) Sexual reproduction requires that parents be diploid. E) Asexual reproduction produces only haploid offspring.

Which of the following is an example of alternation of generations? A) A grandparent and grandchild each have dark hair, but the parent has blond hair. B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte). C) A diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote. D) A haploid mushroom produces gametes by mitosis, and the gametes undergo fertilization, which is immediately followed by meiosis. E) A diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetraploid cell.

Which of the following is true for all exergonic reactions? A) The products have more total energy than the reactants. B) The reaction proceeds with a net release of free energy. C) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. D) A net input of energy from the surroundings is required for the reactions to proceed. E) The reactions are rapid.

Which of the following metabolic processes can occur without a net influx of energy from some other process? A) ADP + Pi → ATP + H₂O B) C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O C) 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂ D) amino acids → protein E) glucose + fructose → sucrose

Which of the following occurs in meiosis but not in mitosis? A) chromosome replication B) synapsis of chromosomes C) production of daughter cells D) alignment of chromosomes at the equator E) condensation of chromatin

Which of the following sequences correctly represents the flow of electrons during photosynthesis? A) NADPH → O₂ → CO₂ B) H₂O → NADPH → Calvin cycle C) NADPH → chlorophyll → Calvin cycle D) H₂O → photosystem I → photosystem II E) NADPH → electron transport chain → O₂

Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct? A) The 5' end has a hydroxyl group attached to the number 5 carbon of ribose. B) The 5' end has a phosphate group attached to the number 5 carbon of ribose. C) The 5' end has phosphate attached to the number 5 carbon of the nitrogenous base. D) The 5' end has a carboxyl group attached to the number 5 carbon of ribose. E) The 5' end is the fifth position on one of the nitrogenous bases.

Which of the following statements best describes the relationship between photosynthesis and respiration? A) Respiration runs the biochemical pathways of photosynthesis in reverse. B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it. C) Photosynthesis occurs only in plants and respiration occurs only in animals. D) ATP molecules are produced in photosynthesis and used up in respiration. E) Respiration is anabolic and photosynthesis is catabolic.

Which of the following statements concerning saturated fats is not true? A) They are more common in animals than in plants. B) They have multiple double bonds in the carbon chains of their fatty acids. C) They generally solidify at room temperature. D) They contain more hydrogen than unsaturated fats having the same number of carbon atoms. E) They are one of several factors that contribute to atherosclerosis.

Which of the following statements concerning unsaturated fats is true? A) They are more common in animals than in plants. B) They have double bonds in the carbon chains of their fatty acids. C) They generally solidify at room temperature. D) They contain more hydrogen than do saturated fats having the same number of carbon atoms. E) They have fewer fatty acid molecules per fat molecule.

Which of the following statements is true concerning catabolic pathways? A) They combine molecules into more energy-rich molecules. B) They supply energy, primarily in the form of ATP, for the cell's work. C) They are endergonic. D) They are spontaneous and do not need enzyme catalysis. E) They build up complex molecules such as protein from simpler compounds.

Which of the following statements regarding enzymes is true? A) Enzymes increase the rate of a reaction by making the reaction more exergonic. B) Enzymes increase the rate of a reaction by lowering the activation energy barrier. C) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. D) Enzymes change the equilibrium point of the reactions they catalyze. E) Enzymes make the rate of a reaction independent of substrate concentrations.

Which of the following takes place as an ice cube cools a drink? A) Molecular collisions in the drink increase. B) Kinetic energy in the drink decreases. C) A calorie of heat energy is transferred from the ice to the water of the drink. D) The specific heat of the water in the drink decreases. E) Evaporation of the water in the drink increases.

Which of the following techniques uses the amino acid sequences of polypeptides to predict a protein's three-dimensional structure? A) X-ray crystallography B) bioinformatics C) analysis of amino acid sequence of small fragments D) NMR spectroscopy E) high-speed centrifugation

Which of the life cycles is typical for most fungi and some protists? A) I only B) II only C) III only D) I and II E) I and III

Which of these classes of biological molecules consist of both small molecules and macromolecular polymers? A) lipids B) carbohydrates C) proteins D) nucleic acids E) lipids, carbohydrates, proteins, and nucleic acids all consist of only macromolecular polymers

Which organelle often takes up much of the volume of a plant cell? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

Which process in eukaryotic cells will proceed normally whether oxygen (O₂) is present or absent? A) electron transport B) glycolysis C) the citric acid cycle D) oxidative phosphorylation E) chemiosmosis

Which structure is not part of the endomembrane system? A) nuclear envelope B) chloroplast C) Golgi apparatus D) plasma membrane E) ER

Why are C₄ plants able to photosynthesize with no apparent photorespiration? A) They do not participate in the Calvin cycle. B) They use PEP carboxylase to initially fix CO₂. C) They are adapted to cold, wet climates. D) They conserve water more efficiently. E) They exclude oxygen from their tissues.

Why are human sex hormones considered to be lipids? A) They are essential components of cell membranes. B) They are not soluble in water. C) They are made of fatty acids. D) They are hydrophilic compounds. E) They contribute to atherosclerosis.

Why are hydrocarbons insoluble in water? A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages. B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. C) They are hydrophilic. D) They exhibit considerable molecular complexity and diversity. E) They are lighter than water.

Why does evaporation of water from a surface cause cooling of the surface? A) The breaking of bonds between water molecules absorbs heat. B) The water molecules with the most heat energy evaporate more readily. C) The solute molecules left behind absorb heat. D) Water molecules absorb heat from the surface in order to acquire enough energy to evaporate. E) The expansion of water vapor extracts heat from the surface.

Why does the oxidation of organic compounds by molecular oxygen to produce CO₂ and water release free energy? A) The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. B) Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O). C) The oxidation of organic compounds can be used to make ATP. D) The electrons have a higher potential energy when associated with water and CO₂ than they do in organic compounds. E) The covalent bond in O₂ is unstable and easily broken by electrons from organic molecules.

Why has C. elegans proven to be a useful model for understanding apoptosis? A) The animal has as many genes as complex organisms, but finding those responsible is easier than in a more complex organism. B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. C) This plant has a long-studied aging mechanism that has made understanding its death just a last stage. D) While the organism ages, its cells die progressively until the whole organism is dead. E) All of its genes are constantly being expressed so all of its proteins are available from each cell.

Why is ATP an important molecule in metabolism? A) Its hydrolysis provides an input of free energy for exergonic reactions. B) It provides energy coupling between exergonic and endergonic reactions. C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. D) Its terminal phosphate bond has higher energy than the other two. E) It is one of the four building blocks for DNA synthesis.

Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell? A) Cell death would usually spread from one cell to the next via paracrine signals. B) Lysosomal enzymes exiting the dying cell would damage surrounding cells. C) Released cellular energy would interfere with the neighbors' energy budget. D) Bits of membrane from the dying cell could merge with neighbors and bring in foreign receptors. E) Neighboring cells would activate immunological responses.

Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A) It produces much less ATP than does oxidative phosphorylation. B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. C) It is found in prokaryotic cells but not in eukaryotic cells. D) It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells. E) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.

Why isn't the mitochondrion classified as part of the endomembrane system? A) It is a static structure. B) Its structure is not derived from the ER or Golgi. C) It has too many vesicles. D) It is not involved in protein synthesis. E) It is not attached to the outer nuclear envelope.

alignment determines independent assortment. A) I B) II C) IV D) VI E) VIII

chromosomes moving to the middle of the cell in pairs Which of the steps takes place in both mitosis and meiosis? A) 2 B) 3 C) 5 D) 2 and 3 only E) 2, 3, and 5

enthalpy

that is, molecules that A) have identical chemical formulas but differ in the branching of their carbon skeletons. B) are mirror images of one another. C) exist in either linear chain or ring forms. D) differ in the location of their double bonds. E) differ in the arrangement of atoms around their double bonds.

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible phenotype for the father?

B positive

The DNA fragments making up a genomic library are generally contained in

BACs.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, which of the following would be likely?

Beta galactosidase will be produced.

How many oxygen molecules (O₂) are required each time a molecule of glucose (C₆H₁₂O₆) is completely oxidized to carbon dioxide and water via aerobic respiration,? A) 1 B) 3 C) 6 D) 12 E) 30

Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition? A) the endoplasmic reticulum B) the Golgi apparatus C) the lysosome D) mitochondria E) membrane-bound ribosomes

How might an amino acid change at a site distant from the active site of the enzyme alter the enzyme's substrate specificity? A) by changing the enzyme's stability B) by changing the enzyme's location in the cell C) by changing the shape of the protein D) by changing the enzyme's pH optimum E) an amino acid change away from the active site cannot alter the enzyme's substrate specificity

Which of the following does not occur during the Calvin cycle? A) carbon fixation B) oxidation of NADPH C) release of oxygen D) regeneration of the CO₂ acceptor E) consumption of ATP

A carbon atom is most likely to form what kind of bond(s) with other atoms? A) ionic B) hydrogen C) covalent D) covalent bonds and hydrogen bonds E) ionic bonds, covalent bonds, and hydrogen bonds

A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from A) a bacterium. B) an animal, but not a plant. C) nearly any eukaryotic organism. D) any multicellular organism, like a plant or an animal. E) any kind of organism.

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following? A) lower cytoplasmic levels of cAMP B) an increase in receptor tyrosine kinase activity C) a decrease in transcriptional activity of certain genes D) an increase in cytosolic calcium concentration E) a decrease in G protein activity

A given solution contains 0.0001(10⁻⁴) moles of hydrogen ions [H⁺] per liter. Which of the following best describes this solution? A) acidic: will accept H⁺ from both strong and weak acids B) basic: will accept H⁺ from both strong and weak acids C) acidic: will give H⁺ to weak acids, but accept H+ from strong acids D) basic: will give H⁺ to weak acids, but accept H⁺ from weak acids E) acidic: will give H⁺ to both strong and weak acids

A karyotype results from which of the following? A) a natural cellular arrangement of chromosomes in the nucleus B) an inherited ability of chromosomes to arrange themselves C) the ordering of human chromosome images D) the cutting and pasting of parts of chromosomes to form the standard array E) the separation of homologous chromosomes at metaphase I of meiosis

A newspaper ad for a local toy store indicates that a very inexpensive microscope available for a small child is able to magnify specimens nearly as much as the much more costly microscope available in your college lab. What is the primary reason for the price difference? A) The ad agency is misrepresenting the ability of the toy microscope to magnify. B) The toy microscope does not have the same fine control for focus of the specimen. C) The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images. D) The college microscope produces greater contrast in the specimens. E) The toy microscope usually uses a different wavelength of light source.

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10⁻⁷ while the concentration in the SR is 10⁻², then how is the ATPase acting? A) ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR. B) ATPase activity must be transferring Pi to the SR to enable this to occur. C) ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient. D) ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient. E) ATPase activity must be routing calcium ions from the SR to the cytosol, and then to the cell's environment.

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X? A) a coenzyme B) an allosteric inhibitor C) a substrate D) an intermediate E) the product

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because A) the starch solution has less free energy than the sugar solution. B) the hydrolysis of starch to sugar is endergonic. C) the activation energy barrier for this reaction cannot be surmounted. D) starch cannot be hydrolyzed in the presence of so much water. E) starch hydrolysis is nonspontaneous.

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure? A) full-spectrum white light B) green light C) a mixture of blue and red light D) yellow light E) UV light

Adenylyl cyclase has the opposite effect of which of the following? A) protein kinase B) protein phosphatase C) phosphodiesterase D) phosphorylase E) GTPase

All of the following serve an important role in determining or maintaining the structure of plant cells. Which of the following are distinct from the others in their composition? A) microtubules B) microfilaments C) plant cell walls D) intermediate filaments E) nuclear lamina

Amino acids are acids because they always possess which functional group? A) amino B) carbonyl C) carboxyl D) phosphate E) hydroxyl

An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit? A) resistance to degradation B) independence from cofactor interaction C) water solubility D) lipid solubility E) membrane-spanning domains

Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides. Among these biological polymers, which has the least structural variety? A) polysaccharides B) proteins C) DNA D) RNA

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from? A) photosystem II B) photosystem I C) cyclic electron flow D) linear electron flow E) chlorophyll

At which level of protein structure are interactions between the side chains (R groups) most important? A) primary B) secondary C) tertiary D) quaternary E) all of the above

Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin? A) ATP synthesis and heat generation will both increase. B) ATP synthesis will increase, and heat generation will decrease. C) ATP synthesis will decrease, and heat generation will increase. D) ATP synthesis and heat generation will both decrease. E) ATP synthesis and heat generation will stay the same.

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of A) phosphorylated proteins. B) GTP. C) cAMP. D) adenylyl cyclase. E) activated G proteins.

During aerobic respiration, H₂O is formed. Where does the oxygen atom for the formation of the water come from? A) carbon dioxide (CO₂) B) glucose (C₆H₁₂O₆) C) molecular oxygen (O₂) D) pyruvate (C₃H₃O₃-) E) lactate (C₃H₅O₃-)

During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is A) transferred to ADP, forming ATP. B) transferred directly to ATP. C) retained in the two pyruvates. D) stored in the NADH produced. E) used to phosphorylate fructose to form fructose 6-phosphate.

Equal volumes (5 mL) of vinegar from a freshly opened bottle are added to each of the following solutions. After complete mixing, which of the mixtures will have the highest pH? A) 100 mL of pure water B) 100 mL of freshly brewed coffee C) 100 mL of household cleanser containing 0.5 M ammonia D) 100 mL of freshly squeezed orange juice E) 100 mL of tomato juice

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores A) I, IV, and V B) I, II, and IV C) II, III, and IV D) II, IV, and V E) I, II, III, IV, and V

Experiments with cohesins have found that A) cohesins are protected from destruction throughout meiosis I and II. B) cohesins are cleaved from chromosomes at the centromere before anaphase I. C) cohesins are protected from cleavage at the centromere during meiosis I. D) a protein cleaves cohesins before metaphase I. E) a protein that cleaves cohesins would cause cellular death.

For the hydrolysis of ATP to ADP + Pi, the free energy change is -7.3 kcal/mol under standard conditions (1 M concentration of both reactants and products). In the cellular environment, however, the free energy change is about -13 kcal/mol. What can we conclude about the free energy change for the formation of ATP from ADP and Pi under cellular conditions? A) It is +7.3 kcal/mol. B) It is less than +7.3 kcal/mol. C) It is about +13 kcal/mol. D) It is greater than +13 kcal/mol. E) The information given is insufficient to deduce the free energy change.

GTPase activity is involved in the regulation of signal transduction because it A) increases the available concentration of phosphate. B) decreases the amount of G protein in the membrane. C) hydrolyzes GTP binding to G protein. D) converts cGMP to GTP. E) phosphorylates protein kinases.

Generation of proton gradients across membranes occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.

How is photosynthesis similar in C₄ plants and CAM plants? A) In both cases, only photosystem I is used. B) Both types of plants make sugar without the Calvin cycle. C) In both cases, rubisco is not used to fix carbon initially. D) Both types of plants make most of their sugar in the dark. E) In both cases, thylakoids are not involved in photosynthesis.

How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long? A) 12 B) 11 C) 10 D) 9 E) 8

Humans can digest starch but not cellulose because A) the monomer of starch is glucose, while the monomer of cellulose is galactose. B) humans have enzymes that can hydrolyze the β glycosidic linkages of starch but not the α glycosidic linkages of cellulose. C) humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose. D) humans harbor starch-digesting bacteria in the digestive tract. E) the monomer of starch is glucose, while the monomer of cellulose is glucose with a nitrogen-containing group.

Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. The use of beta 2 antagonist drugs may be useful in asthma because they may A) increase constriction of the skeletal muscle of the chest wall. B) increase heart rate and therefore allow the patient to get more oxygen circulated. C) dilate the bronchioles by relaxing their smooth muscle. D) override the beta blockers that the patient is already taking. E) obstruct all G protein-mediated receptors.

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine? A) 10 B) 20 C) 40 D) 80 E) impossible to tell from the information given

If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized by carbon dioxide and water, how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 0 B) 1 C) 12 D) 14 E) 15

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants? A) Backtrack through her previous experiments to obtain another plant with the same traits. B) Breed this plant with another plant with much weaker traits. C) Clone the plant asexually to produce an identical one. D) Force the plant to self-pollinate to obtain an identical one. E) Add nitrogen to the soil of the offspring of this plant so the desired traits continue.

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound A) that activates epinephrine receptors. B) that increases cAMP production in liver cells. C) to block G protein activity in liver cells. D) that increases phosphorylase activity. E) that keeps sugar molecules from crossing the plasma membrane of liver cells.

If a solution has a pH of 7, this means that A) there are no H⁺ ions in the water. B) this is a solution of pure water. C) the concentration of H⁺ ions in the water equals the concentration of OH⁻ ions in the water. D) this is a solution of pure water, and the concentration of H⁺ ions in the water is 10⁻⁷ M. E) this is a solution of pure water, and the concentration of H⁺ ions equals the concentration of OH⁻ ions in the water.

If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result? A) neurodegeneration B) activation of a developmental pathway found in the worm but not in humans C) a form of cancer in which there is insufficient apoptosis D) webbing of fingers or toes E) excess skin exfoliation

If cells are grown in a medium containing radioactive ³⁵S, which of these molecules will be labeled? A) phospholipids B) nucleic acids C) proteins D) amylose E) both proteins and nucleic acids

If the DNA content of a diploid cell in the G₁ phase of the cell cycle is x, then the DNA content of a single cell at metaphase of meiosis II would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x.

If the pH of a solution is increased from pH 5 to pH 7, it means that the A) concentration of H⁺ is twice (2X) what it was at pH 5. B) concentration of H⁺ is one-half (1/2) what it was at pH 5. C) concentration of OH⁻ is 100 times greater than what it was at pH 5. D) concentration of OH⁻ is one-hundredth (0.01X) what it was at pH 5. E) concentration of H⁺ is 100 times greater and the concentration of OH⁻ is one-hundredth what they were at pH 5.

If ¹⁴C-labeled uridine triphosphate is added to the growth medium of cells, what macromolecules will be labeled? A) phospholipids B) DNA C) RNA D) both DNA and RNA E) proteins

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common? A) Length and position of the centromere only. B) Length, centromere position, and staining pattern only. C) Length, centromere position, staining pattern, and traits coded for by their genes. D) Length, centromere position, staining pattern, and DNA sequences. E) They have nothing in common except they are X-shaped.

In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then A) ATP synthase will increase the rate of ATP synthesis. B) ATP synthase will stop working. C) ATP synthase will hydrolyze ATP and pump protons into the intermembrane space. D) ATP synthase will hydrolyze ATP and pump protons into the matrix.

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by A) hydrogen bonds. B) nonpolar covalent bonds. C) polar covalent bonds. D) ionic bonds. E) van der Waals interactions.

In addition to ATP, what are the end products of glycolysis? A) CO₂ and H₂O B) CO₂ and pyruvate C) NADH and pyruvate D) CO₂ and NADH E) H₂O, FADH₂, and citrate

In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of carbon dioxide to carbohydrate)? A) in chloroplast membranes B) in chloroplast stroma C) in the cytosol D) in the nucleoid E) in the infolded plasma membrane

Which of the life cycles is typical for plants and some algae? A) I only B) II only C) III only D) I and II E) I and III

In experimental tests of enzyme evolution, where a gene encoding an enzyme is subjected to multiple cycles of random mutagenesis and selection for altered substrate specificity, the resulting enzyme had multiple amino acid changes associated with altered substrate specificity. Where in the enzyme were these amino acid changes located? A) only in the active site B) only in the active site or near the active site C) in or near the active site and at surface sites away from the active site D) only at surface sites away from the active site E) only in the hydrophobic interior of the folded protein

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation. E) It allows the liver cell to have fewer mitochondria.

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from A) the stroma to the photosystem II. B) the matrix to the stroma. C) the stroma to the thylakoid space. D) the intermembrane space to the matrix. E) the thylakoid space to the stroma.

In mitochondria, exergonic redox reactions A) are the source of energy driving prokaryotic ATP synthesis. B) are directly coupled to substrate-level phosphorylation. C) provide the energy that establishes the proton gradient. D) reduce carbon atoms to carbon dioxide. E) are coupled via phosphorylated intermediates to endergonic processes.

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during A) photosynthesis only. B) respiration only. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration only.

In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function? A) formation of mating complexes B) secretion of apoptotic signals C) aggregation of bacteria that can cause cavities D) secretion of substances that inhibit foreign bacteria E) digestion of unwanted parasite populations

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO₂, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Why is coenzyme A, a sulfur-containing molecule derived from a B vitamin, added? A) because sulfur is needed for the molecule to enter the mitochondrion B) in order to utilize this portion of a B vitamin which would otherwise be a waste product from another pathway C) to provide a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle D) because it drives the reaction that regenerates NAD⁺ E) in order to remove one molecule of CO₂

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A) denaturization of the enzyme B) allosteric inhibition C) competitive inhibition D) saturation of the enzyme activity E) insufficient cofactors

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules? A) lipids B) glycogen C) proteins D) cellulose E) nucleic acids

Liquid water's high specific heat is mainly a consequence of the A) small size of the water molecules. B) high specific heat of oxygen and hydrogen atoms. C) absorption and release of heat when hydrogen bonds break and form. D) fact that water is a poor heat conductor. E) higher density of liquid water than solid water (ice).

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake? A) 4.0 M B) 10⁻¹⁰ M C) 10⁻⁴ M D) 10⁴ M E) 4%

One function of both alcohol fermentation and lactic acid fermentation is to A) reduce NAD⁺ to NADH. B) reduce FAD⁺ to FADH₂. C) oxidize NADH to NAD⁺. D) reduce FADH₂ to FAD⁺. E) do none of the above.

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because A) they are species specific. B) they always lead to the same cellular response. C) they amplify the original signal manyfold. D) they counter the harmful effects of phosphatases. E) the number of molecules used is small and fixed.

Plants photosynthesize only in the light. Plants respire A) in the dark only. B) in the light only. C) both in light and dark. D) never-they get their ATP from photophosphorylation. E) only when excessive light energy induces photorespiration.

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells? A) peroxisomes B) desmosomes C) gap junctions D) extracellular matrix E) tight junctions

Protein phosphorylation is commonly involved with all of the following except A) regulation of transcription by extracellular signaling molecules. B) enzyme activation. C) activation of G protein-coupled receptors. D) activation of receptor tyrosine kinases. E) activation of protein kinase molecules.

Receptor tyrosine kinases (RTKs) are found at high levels on various cancer cells. A protein, Herceptin, has been found to bind to an RTK known as HER2. This information can now be utilized in breast cancer treatment if which of the following is true? A) If Herceptin is found in the breast lymph nodes of the patient. B) If HER2, administered by injection, is in sufficient concentration. C) If the patient's cancer cells have detectable HER2. D) If the patient's genome codes for the HER2 receptor. E) If the patient's genome codes for the manufacture of Herceptin.

Signals between the ECM and the cytoskeleton may be transmitted by A) fibronectin. B) proteoglycans. C) integrins. D) collagen. E) middle lamella.

Some bacteria are metabolically active in hot springs because A) they are able to maintain a lower internal temperature. B) high temperatures make catalysis unnecessary. C) their enzymes have high optimal temperatures. D) their enzymes are completely insensitive to temperature. E) they use molecules other than proteins or RNAs as their main catalysts.

Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon? A) the change in density when it condenses to form a liquid or solid B) reactions with other atmospheric compounds C) the release of heat by the formation of hydrogen bonds D) the release of heat by the breaking of hydrogen bonds E) the high surface tension of water

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other? A) Testosterone and estradiol are structural isomers but have the same molecular formula. B) Testosterone and estradiol are cis-trans isomers but have the same molecular formula. C) Testosterone and estradiol have different functional groups attached to the same carbon skeleton. D) Testosterone and estradiol have distinctly different chemical structures, with one including four fused rings of carbon atoms, while the other has three rings. E) Testosterone and estradiol are enantiomers of the same organic molecule.

The accumulation of free oxygen in Earth's atmosphere began A) with the origin of life and respiratory metabolism. B) with the origin of photosynthetic bacteria that had photosystem I. C) with the origin of cyanobacteria that had both photosystem I and photosystem II. D) with the origin of chloroplasts in photosynthetic eukaryotic algae. E) with the origin of land plants.

The advantage of light microscopy over electron microscopy is that A) light microscopy provides for higher magnification than electron microscopy. B) light microscopy provides for higher resolving power than electron microscopy. C) light microscopy allows one to view dynamic processes in living cells. D) light microscopy provides higher contrast than electron microscopy. E) specimen preparation for light microcopy does not produce artifacts.

The alternative pathways of photosynthesis using the C₄ or CAM systems are said to be compromises. Why? A) Each one minimizes both water loss and rate of photosynthesis. B) C₄ compromises on water loss and CAM compromises on photorespiration. C) Both minimize photorespiration but expend more ATP during carbon fixation. D) CAM plants allow more water loss, while C₄ plants allow less CO₂ into the plant. E) C₄ plants allow less water loss but CAM plants allow more water loss.

The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by A) the physical separation of most membranes from each other. B) the transportation of membrane lipids among the endomembrane system by small membrane vesicles. C) the function of the Golgi apparatus in sorting and directing membrane components. D) the modification of the membrane components once they reach their final destination. E) the synthesis of different lipids and proteins in each of the organelles of the endomembrane system.

The element present in all organic molecules is A) hydrogen. B) oxygen. C) carbon. D) nitrogen. E) phosphorus.

The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mol and the free energy for the reduction of NAD⁺ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO₂ or water produced as products of glycolysis. E) Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule.

The human population's life expectancy has increased significantly but seems to have an upper limit. Which of the following might be described as an ecological consequence of passing that upper limit by regulating cell death? A) an increase in the relative frequency of deaths from cancer B) an increased need for gerontologists and other professionals to care for the elderly C) an increase in the total population of humans on the planet D) a decrease in the ratio of younger to older members of the population E) a decrease in the birth rate

The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct? A) ΔS is the change in enthalpy, a measure of randomness. B) ΔH is the change in entropy, the energy available to do work. C) ΔG is the change in free energy. D) T is the temperature in degrees Celsius.

The molecular formula for glucose is C₆H₁₂O₆. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions? A) C₆₀H₁₂₀O₆₀ B) C₆H₁₂O₆ C) C₆₀H₁₀₂O₅₁ D) C₆₀H₁₀₀O₅₀ E) C₆₀H₁₁₁O₅₁

The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you expect to be the most likely consequence? A) the loss of all nuclear function B) the inability of the nucleus to divide during cell division C) a change in the shape of the nucleus D) failure of chromosomes to carry genetic information E) inability of the nucleus to keep out destructive chemicals

The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true? A) Privet cells cannot reproduce sexually. B) Privet sex cells have chromosomes that can synapse with human chromosomes in the laboratory. C) Genes of privet chromosomes are significantly different than those in humans. D) Privet shrubs must be metabolically more like animals than like other shrubs. E) Genes on a particular privet chromosome, such as the X, must be on a different human chromosome, such as number 18.

The tertiary structure of a protein is the A) bonding together of several polypeptide chains by weak bonds. B) order in which amino acids are joined in a polypeptide chain. C) unique three-dimensional shape of the fully folded polypeptide. D) organization of a polypeptide chain into an α helix or β pleated sheet. E) overall protein structure resulting from the aggregation of two or more polypeptide subunits.

Which organelle is the primary site of ATP synthesis in eukaryotic cells? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that A) plant cells are capable of having a much higher surface-to-volume ratio than animal cells. B) plant cells have a much more highly convoluted (folded) plasma membrane than animal cells. C) plant cells contain a large vacuole that reduces the volume of the cytoplasm. D) animal cells are more spherical, whereas plant cells are elongated. E) plant cells can have lower surface-to-volume ratios than animal cells because plant cells synthesize their own nutrients.

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. What did Engelmann conclude about the congregation of bacteria in the red and blue areas? A) Bacteria released excess carbon dioxide in these areas. B) Bacteria congregated in these areas due to an increase in the temperature of the red and blue light. C) Bacteria congregated in these areas because these areas had the most oxygen being released. D) Bacteria are attracted to red and blue light and thus these wavelengths are more reactive than other wavelengths. E) Bacteria congregated in these areas due to an increase in the temperature caused by an increase in photosynthesis.

There are 20 different amino acids. What makes one amino acid different from another? A) different side chains (R groups) attached to a carboxyl carbon B) different side chains (R groups) attached to the amino groups C) different side chains (R groups) attached to an α carbon D) different structural and optical isomers E) different asymmetric carbons

There is a group of invertebrate animals called rotifers, among which a particular group of species reproduces, as far as is known, only asexually. These rotifers, however, have survived a long evolutionary history without evidence of having been overcome by excessive mutations. In these asexual rotifers, how does variation occur without meiosis and fertilization? A) The rotifers have evolved a different mechanism to exchange DNA. B) Rotifers must produce haploid spores. C) Variation is caused by mutation and maintained by selection. D) Some rotifers must selectively lose chromosomes. E) Rotifers must live only in specialized environments.

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein? A) 101 B) 100 C) 99 D) 98 E) 97

Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to A) form cleavage furrows during cell division. B) migrate by amoeboid movement. C) separate chromosomes during cell division. D) extend pseudopods. E) maintain the shape of the nucleus.

What are scaffolding proteins? A) ladderlike proteins that allow receptor-ligand complexes to climb through cells from one position to another B) microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores C) large molecules to which several relay proteins attach to facilitate cascade effects D) relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing E) proteins that can reach into the nucleus of a cell to affect transcription

What are the products of linear photophosphorylation? A) heat and fluorescence B) ATP and P700 C) ATP and NADPH D) ADP and NADP E) P700 and P680

What is the chemical reaction mechanism by which cells make polymers from monomers? A) phosphodiester linkages B) hydrolysis C) dehydration reactions D) ionic bonding of monomers E) the formation of disulfide bridges between monomers

What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to tens of nanometers achievable for the best super-resolution light microscope? A) The focal length of the electron microscope is significantly longer. B) Contrast is enhanced by staining with atoms of heavy metal. C) Electron beams have much shorter wavelengths than visible light. D) The electron microscope has a much greater ratio of image size to real size. E) The electron microscope cannot image whole cells at one time.

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes A) hydrolyzed. B) hydrogenated. C) oxidized. D) reduced. E) an oxidizing agent.

When a molecule of NAD⁺ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes A) dehydrogenated. B) oxidized. C) reduced. D) redoxed. E) hydrolyzed.

When a potassium ion (K+) moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures. Which of the following correctly describes the order in which these structures will be encountered by the ion? A) plasma membrane → primary cell wall → cytoplasm → vacuole B) secondary cell wall → plasma membrane → primary cell wall → cytoplasm → vacuole C) primary cell wall → plasma membrane → cytoplasm → vacuole D) primary cell wall → plasma membrane → lysosome → cytoplasm → vacuole E) primary cell wall → plasma membrane → cytoplasm → secondary cell wall → vacuole

When an individual is exercising heavily and when the muscle becomes oxygen-deprived, muscle cells convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells? A) It is converted to NAD⁺. B) It produces CO₂ and water. C) It is taken to the liver and converted back to pyruvate. D) It reduces FADH₂ to FAD⁺. E) It is converted to alcohol.

When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na⁺) and chloride ions (Cl⁻). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)? A) 1 L of 0.5 M NaCl B) 1 L of 0.5 M glucose C) 1 L of 1.0 M NaCl D) 1 L of 1.0 M glucose E) 1 L of 1.0 M NaCl and 1 L of 1.0 M glucose will contain equal numbers of solute particles.

When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using A) a phase-contrast light microscope. B) a scanning electron microscope. C) a transmission electronic microscope. D) a confocal fluorescence microscope. E) a super-resolution fluorescence microscope.

When homologous chromosomes crossover, what occurs? A) Two chromatids get tangled, resulting in one re-sequencing its DNA. B) Two sister chromatids exchange identical pieces of DNA. C) Specific proteins break the two strands and re-join them with their homologs. D) Each of the four DNA strands of a tetrad is broken and the pieces are mixed. E) Maternal alleles are "corrected" to be like paternal alleles and vice versa.

When you have a severe fever, what grave consequence may occur if the fever is not controlled? A) destruction of your enzymes' primary structure B) removal of amine groups from your proteins C) change in the tertiary structure of your enzymes D) removal of the amino acids in active sites of your enzymes E) binding of your enzymes to inappropriate substrates

Where are the proteins of the electron transport chain located? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix

Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle? A) pyruvate B) malate or fumarate C) acetyl CoA D) α-ketoglutarate E) succinyl CoA

Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties? A) They must persist throughout the cell cycle. B) They must be removed before meiosis can begin. C) They must be removed before anaphase can occur. D) They must reattach to chromosomes during G₁. E) They must be intact for nuclear envelope reformation.

Which cell would be best for studying lyosomes? A) muscle cell B) nerve cell C) phagocytic white blood cell D) leaf cell of a plant E) bacterial cell

Which functional groups can act as acids? A) amino and sulfhydryl B) carbonyl and carboxyl C) carboxyl and phosphate D) hydroxyl and aldehyde E) ketone and amino

Which kind of metabolic poison would most directly interfere with glycolysis? A) an agent that reacts with oxygen and depletes its concentration in the cell B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that reacts with NADH and oxidizes it to NAD⁺ E) an agent that blocks the passage of electrons along the electron transport chain

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A) the citric acid cycle B) the electron transport chain C) glycolysis D) synthesis of acetyl CoA from pyruvate E) reduction of pyruvate to lactate

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells? A) Enzymatic activity was proportional to the amount of calcium added to a cell-free extract. B) Receptor studies indicated that epinephrine was a ligand. C) Glycogen breakdown was observed only when epinephrine was administered to intact cells. D) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. E) Epinephrine was known to have different effects on different types of cells.

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction? A) tyrosines B) glycine and histidine C) serine and threonine D) glycine and glutamic acid E) Any of the 20 amino acids are equally phosphorylated.

Which of the following best describes the frequency of crossing over in mammals? A) ~50 per chromosome pair B) ~2 per meiotic cell C) at least 1-2 per chromosome pair D) ~1 per pair of sister chromatids E) a very rare event among hundreds of cells

Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules? A) both motile cilia and primary (nonmotile) cilia B) centrioles only C) both flagella and motile cilia D) both basal bodies and primary (nonmotile) cilia E) both centrioles and basal bodies

Which of the following descriptions best fits the class of molecules known as nucleotides? A) a nitrogenous base and a phosphate group B) a nitrogenous base and a pentose sugar C) a nitrogenous base, a phosphate group, and a pentose sugar D) a phosphate group and an adenine or uracil E) a pentose sugar and a purine or pyrimidine

Which plant cell organelle contains its own DNA and ribosomes? A) glyoxysome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

Which of the following is (are) true for anabolic pathways? A) They do not depend on enzymes. B) They are usually highly spontaneous chemical reactions. C) They consume energy to build up polymers from monomers. D) They release energy as they degrade polymers to monomers. E) They consume energy to decrease the entropy of the organism and its environment.

Which of the following is a correct association? A) kinase activity and the addition of a tyrosine B) phosphodiesterase activity and the removal of phosphate groups C) GTPase activity and hydrolysis of GTP to GDP D) phosphorylase activity and the catabolism of glucose E) adenylyl cyclase activity and the conversion of cAMP to AMP

Which of the following is a hydrophobic material? A) paper B) table salt C) wax D) sugar E) pasta

Which of the following is an example of cooperativity? A) the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway B) one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway C) a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three D) the effect of increasing temperature on the rate of an enzymatic reaction E) binding of an ATP molecule along with one of the substrate molecules in an active site

Which of the following is characterized by a cell releasing a signal molecule into the environment, followed by a number of cells in the immediate vicinity responding? A) hormonal signaling B) autocrine signaling C) paracrine signaling D) endocrine signaling E) synaptic signaling

Which of the following is most similar in structure to ATP? A) a pentose sugar B) a DNA nucleotide C) an RNA nucleotide D) an amino acid with three phosphate groups attached E) a phospholipid

Which of the following is not a monomer/polymer pairing? A) monosaccharide/polysaccharide B) amino acid/protein C) triglyceride/phospholipid bilayer D) deoxyribonucleotide/DNA E) ribonucleotide/RNA

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps? A) Most of the steps were already in place because they are steps in other pathways. B) Multiple steps in a pathway require the least amount of ATP. C) Multiple steps provide for greater possible amplification of a signal. D) Each individual step can remove excess phosphate groups from the cytoplasm. E) Each step can be activated by several G proteins simultaneously.

Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca2⁺ concentration in its cytosol compared with the extracellular fluid? A) blockage of the synaptic signal B) loss of transcription factors C) insufficient ATP levels in the cytoplasm D) low oxygen concentration around the cell E) low levels of protein kinase in the cell

Which of the following is true of a species that has a chromosome number of 2n = 16? A) The species is diploid with 32 chromosomes per cell. B) The species has 16 sets of chromosomes per cell. C) Each cell has eight homologous pairs. D) During the S phase of the cell cycle there will be 32 separate chromosomes. E) A gamete from this species has four chromosomes.

Which of the following is true regarding saturated fatty acids? A) They are the predominant fatty acid in corn oil. B) They have double bonds between carbon atoms of the fatty acids. C) They are the principal molecules in lard and butter. D) They are usually liquid at room temperature. E) They are usually produced by plants.

Which of the following people was the first to synthesize an organic compound, urea, from inorganic starting materials? A) Stanley Miller B) Jakob Berzelius C) Friedrich Wohler D) Hermann Kolbe E) August Kekulé

Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein? A) +ΔH, +ΔS, +ΔG B) +ΔH, -ΔS, -ΔG C) +ΔH, -ΔS, +ΔG D) -ΔH, -ΔS, +ΔG E) -ΔH, +ΔS, +ΔG

Which of the following statements about the cytoskeleton is true? A) The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large variety of proteins into complex aggregates. B) Microfilaments are structurally rigid and resist compression, whereas microtubules resist tension (stretching). C) Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other. D) Chemicals that block the assembly of the cytoskeleton would cause little effect on the cell's response to external signals and stimuli. E) Transport vesicles among the membranes of the endomembrane system produce the cytoskeleton.

Which of the following statements best summarizes the differences between DNA and RNA? A) DNA encodes hereditary information, whereas RNA does not. B) The bases in DNA form base-paired duplexes, whereas the bases in RNA do not. C) DNA nucleotides contain a different sugar than RNA nucleotides. D) DNA contains the base uracil, whereas RNA contains the base thymine. E) DNA encodes hereditary information, whereas RNA does not; the bases in DNA form base-paired duplexes, whereas the bases in RNA do not; and DNA nucleotides contain a different sugar than RNA nucleotides.

Which of the following statements correctly describes some aspect of protein secretion from prokaryotic cells? A) Prokaryotes are unlikely to be able to secrete proteins because they lack an endomembrane system. B) The mechanism of protein secretion in prokaryotes is probably the same as that in eukaryotes. C) Proteins that are secreted by prokaryotes are synthesized on ribosomes that are bound to the cytoplasmic surface of the plasma membrane. D) In prokaryotes, the ribosomes that are used for the synthesis of secreted proteins are located outside of the cell. E) Prokaryotes contain large pores in their plasma membrane that permit the movement of proteins out of the cell.

Which of the following statements describes enzyme cooperativity? A) A multienzyme complex contains all the enzymes of a metabolic pathway. B) A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. C) A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits. D) Several substrate molecules can be catalyzed by the same enzyme. E) A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.

Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids? A) ribosome B) lysosome C) smooth endoplasmic reticulum D) mitochondrion E) contractile vacuole

You have two beakers. One contains a solution of HCl at pH = 1.0. The other contains a solution of NaOH at pH = 13. Into a third beaker, you slowly and cautiously pour 20 mL of the HCl and 20 mL of the NaOH. After complete stirring, the pH of the mixture will be A) 2.0. B) 12.0. C) 7.0. D) 5.0. E) 9.0.

but as more crystals are added, the crystals will begin to dissolve faster and faster.

they are relatively cool. C) temperature is usually uniform throughout a cell. D) heat can never be used to do work. E) heat must remain constant during work.

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Based on this information, which of the following is correct? A) Succinate dehydrogenase is the enzyme, and fumarate is the substrate. B) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate. C) Succinate is the substrate, and fumarate is the product. D) Fumarate is the product, and malonic acid is a noncompetitive inhibitor. E) Malonic acid is the product, and fumarate is a competitive inhibitor.

C Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. What is malonic acid's role with respect to succinate dehydrogenase? A) It is a competitive inhibitor. B) It blocks the binding of fumarate. C) It is a noncompetitive inhibitor. D) It is able to bind to succinate. E) It is an allosteric regulator. Answer: A

Which of the following calculations require that you utilize the addition rule?

Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. Which of the following is most likely to occur?

Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture.

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained?

Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible

In 1956 Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

Chromosomes were piled up on top of one another in the nucleus, chromosomes were not distinguishable during interphase, and a method had not yet been devised to halt mitosis at metaphase.

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?

Cloning to produce embryonic stem cells may lead to great medical benefits for many.

A lack of which molecule would result in the cell's inability to "turn off" genes?

Corepressor

How could you best predict the maximum number of alleles for a single gene whose polypeptide product is known?

Count the number of DNA nucleotides that are in the code for the polypeptides.

Recombination between linked genes comes about for what reason?

Crossovers between these genes result in chromosomal exchange.

How many grams of acetic acid (C₂H₄O₂) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.) A) 10 g B) 0.1 g C) 6.0 g D) 60 g E) 0.6 g

A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light, whereas organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively, A) mitochondria and chloroplasts. B) chloroplasts and peroxisomes. C) peroxisomes and chloroplasts. D) chloroplasts and mitochondria. E) mitochondria and peroxisomes.

A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water it A) would function only as an acid because of the carboxyl group. B) would function only as a base because of the amino group. C) would function as neither an acid nor a base. D) would function as both an acid and a base. E) is impossible to determine how it would function.

A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so? A) carboxyl B) sulfhydryl C) hydroxyl D) amino E) phosphate

A dietary Calorie equals 1 kilocalorie. Which of the following statements correctly defines 1 kilocalorie? A) 1,000 calories, or the amount of heat required to raise the temperature of 1 g of water by 1,000°C B) 100 calories, or the amount of heat required to raise the temperature of 100 g of water by 1°C C) 10,000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°F D) 1,000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C E) 1,000 calories, or the amount of heat required to raise the temperature of 100 g of water by 100°C

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. A) The dissolved oxygen in the flask with algae will always be higher. B) The dissolved oxygen in the flask with algae will always be lower. C) The dissolved oxygen in the flask with algae will be higher in the light, but the same in the dark. D) The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark. E) The dissolved oxygen in the flask with algae will not be different from the control flask at any time.

A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. If you wish to design an experiment to block the G protein-coupled receptor interaction, the block would preferentially affect which of the following? A) the exterior (cytoplasmic) end of the receptor B) the cytosolic end of the receptor C) the phospholipid's transmembrane domain D) the amino acid sequence in the binding site for the G protein E) the amino acids in the binding site for the transduction molecules

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its A) nuclear lamina and nuclear matrix. B) nuclear matrix and extracellular matrix. C) mitochondria and Golgi apparatus. D) Golgi apparatus and extracellular matrix. E) nuclear pores and secretory vesicles.

A primary objective of cell fractionation is to A) view the structure of cell membranes. B) sort cells based on their size and weight. C) determine the size of various organelles. D) separate the major organelles so that their particular functions can be determined. E) separate lipid-soluble from water-soluble molecules.

According to the induced fit hypothesis of enzyme catalysis, which of the following is correct? A) The binding of the substrate depends on the shape of the active site. B) Some enzymes change their structure when activators bind to the enzyme. C) A competitive inhibitor can outcompete the substrate for the active site. D) The binding of the substrate changes the shape of the enzyme's active site. E) The active site creates a microenvironment ideal for the reaction.

After telophase I of meiosis, the chromosomal makeup of each daughter cell is A) diploid, and the chromosomes are each composed of a single chromatid. B) diploid, and the chromosomes are each composed of two chromatids. C) haploid, and the chromosomes are each composed of a single chromatid. D) haploid, and the chromosomes are each composed of two chromatids. E) tetraploid, and the chromosomes are each composed of two chromatids.

Allosteric enzyme regulation is usually associated with A) lack of cooperativity. B) feedback inhibition. C) activating activity. D) an enzyme with more than one subunit. E) the need for cofactors.

An inhibitor of phosphodiesterase activity would have which of the following effects? A) block the response of epinephrine B) decrease the amount of cAMP in the cytoplasm C) block the activation of G proteins in response to epinephrine binding to its receptor D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm E) block the activation of protein kinase A

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? A) tyrosine kinases B) serine/threonine kinases C) phosphodiesterase D) phospholipase C E) adenylyl cyclase

Apoptosis involves all but which of the following? A) fragmentation of the DNA B) cell-signaling pathways C) activation of cellular enzymes D) lysis of the cell E) digestion of cellular contents by scavenger cells

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes? A) the splitting of water B) the absorption of light energy by chlorophyll C) the flow of electrons from photosystem II to photosystem I D) the synthesis of ATP E) the reduction of NADP⁺

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? A) Estrogen is produced in very large concentration and therefore diffuses widely. B) Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding. C) Estrogen is kept away from the surface of any cells not able to bind it at the surface. D) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding. E) The subcomponents of estrogen, when metabolized, can influence cell response.

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane? A) receptor tyrosine kinase B) G protein-coupled receptor C) phosphorylated receptor tyrosine kinase dimer D) ligand-gated ion channel E) intracellular receptor

Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell? A) a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium B) a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings C) an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment D) a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway E) no possibility of having chemical equilibrium in any living cell

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in A) all cells, but only in the presence of oxygen. B) only eukaryotic cells, in the presence of oxygen. C) only in mitochondria, using either oxygen or other electron acceptors. D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors. E) all cells, in the absence of respiration.

Energy released by the electron transport chain is used to pump H⁺ into which location in eukaryotic cells? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix

Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur? A) in photosynthetic cells in the light, while photosynthesis occurs concurrently B) in nonphotosynthesizing cells only C) in cells that are storing glucose only D) in all cells all the time E) in photosynthesizing cells in the light and in other tissues in the dark

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated further, however, the ability to synthesize ATP is lost. After the further agitation of the membrane vesicles, what must be lost from the membrane? A) the ability of NADH to transfer electrons to the first acceptor in the electron transport chain B) the prosthetic groups like heme from the transport system C) cytochromes D) ATP synthase, in whole or in part E) the contact required between inner and outer membrane surfaces

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis? A) They have twice the amount of cytoplasm and half the amount of DNA. B) They have half the number of chromosomes and half the amount of DNA. C) They have the same number of chromosomes and half the amount of DNA. D) They have half the number of chromosomes and one-fourth the amount of DNA. E) They have half the amount of cytoplasm and twice the amount of DNA.

How does the cell multiply its peroxisomes? A) They bud off from the Golgi. B) They are brought into the cell from the environment. C) They are built de novo from cytosol materials. D) They split in two after they become sufficiently large. E) The cell synthesizes hydrogen peroxide and encloses it in a membrane.

How would acidification of seawater affect marine organisms? A) Acidification would increase dissolved carbonate concentrations and promote faster growth of corals and shell-building animals. B) Acidification would decrease dissolved carbonate concentrations and promote faster growth of corals and shell-building animals. C) Acidification would increase dissolved carbonate concentrations and hinder growth of corals and shell-building animals. D) Acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals. E) Acidification would increase dissolved bicarbonate concentrations, and cause increased calcification of corals and shellfish.

Humans and mice differ because A) their cells have different small organic molecules. B) their cells make different types of large biological molecules. C) their cells make different types of lipids. D) their cells have some differences in the sequence of nucleotides in their nucleic acids. E) their cells make different types of proteins.

Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. Beta 2 antagonist drugs might also be used most effectively for which of the following? A) cardiac arrhythmias B) increased gastric acid production C) neuropathy of the extremities D) increasing low blood pressure E) decreasing peristalsis

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound A) that mimics epinephrine and can bind to the epinephrine receptor. B) that stimulates cAMP production in liver cells. C) to stimulate G protein activity in liver cells. D) that increases phosphodiesterase activity. E) that does any of the above.

If an individual has abnormal microtubules, due to a hereditary condition, in which organs or tissues would you expect dysfunction? A) limbs, hearts, areas with a good deal of contraction B) microvilli, alveoli, and glomeruli: cellular projections that increase surface area C) all ducts, such as those from salivary or sebaceous glands, that transport fluids D) sperm, larynx, and trachea: cells and tissues that contain flagella or cilia E) phagocytic cells and white blood cells that exhibit amoeboid movement

If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur? A) Photosynthetic efficiency would be reduced at low light intensities. B) Cells would carry on the Calvin cycle at a much slower rate. C) Less ATP would be generated. D) There would be more light-induced damage to the cells. E) Less oxygen would be produced.

If radioactive deoxythymidine triphosphate (dTTP) is added to a culture of rapidly growing bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity? A) nucleus B) cytoplasm C) endoplasmic reticulum D) nucleoid E) ribosomes

If the DNA content of a diploid cell in the G₁ phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x.

In a liver cell detoxifying alcohol and some other poisons, the enzymes of the peroxisome remove hydrogen from these molecules and A) combine the hydrogen with water molecules to generate hydrogen peroxide. B) use the hydrogen to break down hydrogen peroxide. C) transfer the hydrogen to the mitochondria. D) transfer the hydrogen to oxygen molecules to generate hydrogen peroxide.

In a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine? A) in the interior of the folded protein, away from water B) on the exterior surface of the protein, interacting with water C) in the transmembrane portion interacting with lipid fatty acid chains D) in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty acid chains E) anywhere in the protein, with equal probability

In a plant cell, DNA may be found A) only in the nucleus. B) only in the nucleus and mitochondria. C) only in the nucleus and chloroplasts. D) in the nucleus, mitochondria, and chloroplasts. E) in the nucleus, mitochondria, chloroplasts, and peroxisomes.

In a plant cell, where are the ATP synthase complexes located? A) thylakoid membrane only B) plasma membrane only C) inner mitochondrial membrane only D) thylakoid membrane and inner mitochondrial membrane E) thylakoid membrane and plasma membrane

In a plant leaf, the reactions that produce NADH occur in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.

In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary? A) autotrophs and heterotrophs B) producers and primary consumers C) photosynthesizers D) autotrophs E) green plants

In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP? A) energy released as electrons flow through the electron transport system B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, against the electrochemical gradient D) energy released from movement of protons through ATP synthase, down the electrochemical gradient E) No external source of energy is required because the reaction is exergonic.

In the process of carbon fixation, RuBP attaches a CO₂ to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle? A) addition of a pair of electrons from NADPH B) inactivation of RuBP carboxylase enzyme C) regeneration of ATP from ADP D) regeneration of RuBP E) regeneration of NADP⁺

In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic "knobs" of ATP synthase would be located A) on the side facing the thylakoid space. B) on the ATP molecules themselves. C) on the pigment molecules of photosystem I and photosystem II. D) on the stromal side of the membrane. E) built into the center of the thylakoid stack (granum).

In yeast signal transduction, the yeast cells A) must physically and directly interact. B) produce signal molecules that change themselves so they can interact with one another. C) produce response molecules that diffuse to other yeast cells. D) secrete molecules that result in response by other yeast cells. E) mate, after which the new cells secrete hybrid signals.

Increased atmospheric CO₂ concentrations might have what effect on seawater? A) Seawater will become more acidic, and bicarbonate concentrations will decrease. B) Seawater will become more alkaline, and carbonate concentrations will decrease. C) There will be no change in the pH of seawater, because carbonate will turn to bicarbonate. D) Seawater will become more acidic, and carbonate concentrations will decrease. E) Seawater will become more acidic, and carbonate concentrations will increase.

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified? A) as a pentose B) as a hexose C) as a monosaccharide D) as a disaccharide E) as a polysaccharide

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? A) Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time. B) Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe. C) Living organisms do not follow the laws of thermodynamics. D) As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth. E) Living organisms are able to transform energy into entropy.

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? A) water's change in density when it condenses B) water's ability to dissolve molecules in the air C) the release of heat by the formation of hydrogen bonds D) the absorption of heat by the breaking of hydrogen bonds E) water's high surface tension

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides? A) Alzheimer's only B) Parkinson's only C) diabetes mellitus only D) Alzheimer's and Parkinson's only E) Alzheimer's, Parkinson's, and diabetes mellitus

Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures? A) sites of energy production in cellular respiration B) membrane proteins C) ribosomes D) cytoskeletal structures E) cellulose fibers in the cell wall

Mutations that result in single amino acid substitutions in an enzyme A) can have no effect on the activity or properties of the enzyme. B) will almost always destroy the activity of the enzyme. C) will often cause a change in the substrate specificity of the enzyme. D) may affect the physicochemical properties of the enzyme such as its optimal temperature and pH. E) may, in rare cases, cause the enzyme to run reactions in reverse.

One liter of a solution of pH 2 has how many more hydrogen ions (H⁺) than 1 L of a solution of pH 6? A) 4 times more B) 16 times more C) 40,000 times more D) 10,000 times more E) 100,000 times more

One of the buffers that contribute to pH stability in human blood is carbonic acid (H₂CO₃). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO₃⁻) and a hydrogen ion (H⁺). Thus, H₂CO₃ ↔ HCO₃⁻ + H⁺ If the pH of the blood drops, one would expect A) a decrease in the concentration of H₂CO₃ and an increase in the concentration of HCO₃⁻. B) the concentration of hydroxide ion (OH⁻) to increase. C) the concentration of bicarbonate ion (HCO₃⁻) to increase. D) the HCO₃⁻ to act as a base and remove excess H⁺ with the formation of H₂CO₃. E) the HCO₃⁻ to act as an acid and remove excess H⁺ with the formation of H₂CO₃.

One of the key innovations in the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. What eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system? A) plasma membrane B) chloroplasts C) mitochondria D) nuclear envelope E) none of these

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? A) G protein-coupled receptors B) ligand-gated ion channels C) steroid receptors D) receptor tyrosine kinases

P680⁺ is said to be the strongest biological oxidizing agent. Why? A) It is the receptor for the most excited electron in either photosystem. B) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system. C) It transfers its electrons to reduce NADP⁺ to NADPH. D) This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water. E) It has a positive charge.

Research indicates that acid precipitation can damage living organisms by A) buffering aquatic systems such as lakes and streams. B) decreasing the H⁺ concentration of lakes and streams. C) increasing the OH⁻ concentration of lakes and streams. D) washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth. E) both decreasing the H⁺ concentration of lakes and streams and increasing the OH⁻ concentration of lakes and streams.

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures? A) They must block water and small molecules in order to regulate the exchange of matter and energy with their environment. B) They must permit information transfer between the cell's cytoplasm and the nucleus. C) They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. D) They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell. E) They are composed of a mixture of lipids and carbohydrates.

What types of proteins are not synthesized in the rough ER? A) endoplasmic reticulum proteins B) extracellular matrix proteins C) secreted proteins D) mitochondrial proteins E) plasma membrane proteins

The chemical reactions involved in respiration are virtually identical between prokaryotic and eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. In light of the endosymbiont theory for the evolutionary origin of mitochondria, where is most ATP synthesis likely to occur in prokaryotic cells? A) in the cytoplasm B) on the inner mitochondrial membrane C) on the endoplasmic reticulum D) on the plasma membrane E) on the inner nuclear envelope

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is A) oxidation of glucose to CO₂ and water. B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers. C) the final transfer of electrons to oxygen. D) the proton-motive force across the inner mitochondrial membrane. E) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.

The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following? A) gap junctions B) the nucleus C) DNA and RNA D) integrins E) plasmodesmata

The human X and Y chromosomes A) are both present in every somatic cell of males and females alike. B) are of approximately equal size and number of genes. C) are almost entirely homologous, despite their different names. D) include genes that determine an individual's sex. E) include only genes that govern sex determination.

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the A) oxidation of glucose and other organic compounds. B) flow of electrons down the electron transport chain. C) affinity of oxygen for electrons. D) H⁺ concentration across the membrane holding ATP synthase. E) transfer of phosphate to ADP.

The light reactions of photosynthesis supply the Calvin cycle with A) light energy. B) CO₂ and ATP. C) H₂O and NADPH. D) ATP and NADPH. E) sugar and O₂.

The nutritional information on a cereal box shows that one serving of a dry cereal has 200 kilocalories. If one were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature of 20 kg of water how many degrees Celsius? A) 0.2°C B) 1.0°C C) 2.0°C D) 10.0°C E) 20.0°C

The phylogenetic distribution of the enzyme rubisco is limited to A) C₃ plants only. B) C₃ and C₄ plants. C) all photosynthetic eukaryotes. D) all known photoautotrophs, both bacterial and eukaryotic. E) all living cells.

The receptors for a group of signaling molecules known as growth factors are often A) ligand-gated ion channels. B) G protein-coupled receptors. C) cyclic AMP. D) receptor tyrosine kinases. E) neurotransmitters.

The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.

The termination phase of cell signaling requires which of the following? A) removal of the receptor B) activation of a different set of relay molecules C) converting ATP to camp D) incompatibility of the binding of the signal molecule to the receptor E) apoptosis

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. An outcome of this experiment was to help determine A) the relationship between heterotrophic and autotrophic organisms. B) the relationship between wavelengths of light and the rate of aerobic respiration. C) the relationship between wavelengths of light and the amount of heat released. D) the relationship between wavelengths of light and the rate of photosynthesis. E) the relationship between the concentration of carbon dioxide and the rate of photosynthesis.

Three "turns" of the Calvin cycle generate a "surplus" molecule of glyceraldehyde 3-phosphate (G3P). Which of the following is a consequence of this? A) Formation of a molecule of glucose would require nine "turns." B) G3P more readily forms sucrose and other disaccharides than it does monosaccharides. C) Some plants would not taste sweet to us. D) The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements. E) Plants accumulate and store G3P.

To view and analyze human chromosomes in a dividing cell, which of the following is/are required? A) electron microscope B) radioactive staining C) fluorescent staining D) DNA stain and a light microscope E) a stain particular to human cells

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source? A) 1/6 B) 1/3 C) 1/2 D) 2/3 E) 100/100

What is most likely to happen to an animal's target cells that lack receptors for local regulators? A) They might compensate by receiving nutrients via a factor. B) They could develop normally in response to neurotransmitters instead. C) They could divide but never reach full size. D) They might not be able to multiply in response to growth factors from nearby cells. E) Hormones would not be able to interact with target cells.

What is the hydrogen ion [H⁺] concentration of a solution of pH 8? A) 8 M B) 8 x 10⁻⁶ M C) 0.01 M D) 10⁻⁸ M E) 10⁻⁶ M

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell? A) ER → Golgi → nucleus B) Golgi →ER →lysosome C) nucleus →ER →Golgi D) ER →Golgi →vesicles that fuse with plasma membrane E) ER →lysosomes →vesicles that fuse with plasma membrane

What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide's specific three-dimensional shape? A) ionic bond B) hydrophobic interaction C) van der Waals interaction D) disulfide bond E) hydrogen bond

When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell? A) The phosphate is released as an excretory waste. B) The phosphate can only be used to regenerate more ATP. C) The phosphate can be added to water and excreted as a liquid. D) The phosphate may be incorporated into any molecule that contains phosphate. E) It enters the nucleus to affect gene expression.

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway? A) receptor B) relay molecule C) transducer D) signal molecule E) endocrine molecule

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated? A) It is used to power yet more cellular work. B) It is used to store energy as more ATP. C) It is used to generate ADP from nucleotide precursors. D) It is lost to the environment. E) It is transported to specific organs such as the brain.

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the A) formation of ATP. B) reduction of NAD⁺. C) restoration of the Na⁺/K⁺ balance across the membrane. D) creation of a proton-motive force. E) lowering of pH in the mitochondrial matrix.

When we see chiasmata under a microscope, that lets us know which of the following has occurred? A) asexual reproduction B) meiosis II C) anaphase II D) prophase I E) separation of homologs

Whenever energy is transformed, there is always an increase in the A) free energy of the system. B) free energy of the universe. C) entropy of the system. D) entropy of the universe. E) enthalpy of the universe.

Where is ATP synthase located in the mitochondrion? A) cytosol B) electron transport chain C) outer membrane D) inner membrane E) mitochondrial matrix

Which chemical group is most likely to be responsible for an organic molecule behaving as a base? A) hydroxyl B) carbonyl C) carboxyl D) amino E) phosphate

Which life cycle stage is found in plants but not animals? A) gamete B) zygote C) multicellular diploid D) multicellular haploid E) unicellular diploid

Which metabolic pathway is common to both cellular respiration and fermentation? A) the oxidation of pyruvate to acetyl CoA B) the citric acid cycle C) oxidative phosphorylation D) glycolysis E) chemiosmosis

Which modifications of fatty acids will best keep triglycerides solid at warmer temperatures? A) creating cis double bonds to the fatty acids B) adding hydrogens to the fatty acids C) creating trans double bonds to the fatty acids D) adding hydrogens and trans double bonds to the fatty acids E) adding cis double bonds and trans double bonds to the fatty acids

Which of the following can utilize both mitosis and meiosis in the correct circumstances? A) a haploid animal cell B) a diploid cell from a plant stem C) any diploid animal cell D) a plantlike protist E) an archaebacterium

Which of the following categories includes all others in the list? A) monosaccharide B) disaccharide C) starch D) carbohydrate E) polysaccharide

Which of the following describes the events of apoptosis? A) The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. B) Its DNA and organelles become fragmented, it dies, and it is phagocytized. C) The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. D) Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests. E) Its nucleus and organelles are lysed, then the cell enlarges and bursts.

Which of the following hydrocarbons has a double bond in its carbon skeleton? A) C₃H₈ B) C₂H₆ C) CH₄ D) C₂H₄ E) C₂H₂

Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO₂) from one molecule of pyruvate? A) lactate B) glyceraldehydes-3-phosphate C) oxaloacetate D) acetyl CoA E) citrate

Which of the following is a false statement concerning amino groups? A) They are basic in pH. B) They are found in amino acids. C) They contain nitrogen. D) They are nonpolar. E) They are components of urea.

Which of the following is a major cause of the size limits for certain types of cells? A) limitation on the strength and integrity of the plasma membrane as cell size increases B) the difference in plasma membranes between prokaryotes and eukaryotes C) evolutionary progression in cell size more primitive cells have smaller sizes D) the need for a surface area of sufficient area to support the cell's metabolic needs E) rigid cell walls that limit cell size expansion

Which of the following is an example of hydrolysis? A) the reaction of two monosaccharides, forming a disaccharide with the release of water B) the synthesis of two amino acids, forming a peptide with the release of water C) the reaction of a fat, forming glycerol and fatty acids with the release of water D) the reaction of a fat, forming glycerol and fatty acids with the consumption of water E) the synthesis of a nucleotide from a phosphate, a pentose sugar, and a nitrogenous base with the production of a molecule of water

Which of the following is an example of potential rather than kinetic energy? A) the muscle contractions of a person mowing grass B) water rushing over Niagara Falls C) light flashes emitted by a firefly D) a molecule of glucose E) the flight of an insect foraging for food

Which of the following is true of cellulose? A) It is a polymer composed of enantiomers of glucose. B) It is a storage polysaccharide for energy in plant cells. C) It is digestible by bacteria in the human gut. D) It is a major structural component of plant cell walls. E) It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major structural component of plant cell walls.

Which of the following is true of enzymes? A) Nonprotein cofactors alter the substrate specificity of enzymes. B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered. C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers. E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

Which of the following is true of metabolism in its entirety in all organisms? A) Metabolism depends on a constant supply of energy from food. B) Metabolism depends on an organism's adequate hydration. C) Metabolism uses all of an organism's resources. D) Metabolism consists of all the energy transformation reactions in an organism. E) Metabolism manages the increase of entropy in an organism.

Which of the following is true of transcription factors? A) They regulate the synthesis of DNA in response to a signal. B) They transcribe ATP into cAMP. C) They initiate the epinephrine response in animal cells. D) They control gene expression. E) They regulate the synthesis of lipids in the cytoplasm.

Which of the following makes it necessary for animal cells, although they have no cell walls, to have intercellular junctions? A) Cell membranes do not distinguish the types of ions and molecules passing through them. B) Large molecules, such as proteins and RNA molecules, do not readily get through one, much less two, adjacent cell membranes. C) Cell-to-cell communication requires physical attachment of one cell to another. D) Maintenance of tissue integrity and barriers to fluid leakage requires cells to adhere tightly to one another. E) The relative shapelessness of animal cells requires a mechanism for keeping the cells aligned.

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA? A) 5'-purine-pyrimidine-purine-pyrimidine-3' with 3'-purine-pyrimidine-purine-pyrimidine-5' B) 5'-AGCT-3' with 5'-TCGA-3' C) 5'-GCGC-3' with 5'-TATA-3' D) 5'-ATGC-3' with 5'-GCAT-3' E) All of these pairs are correct.

Which of the following polymers contain nitrogen? A) starch B) glycogen C) cellulose D) chitin E) amylopectin

Which of the following produces and modifies polysaccharides that will be secreted? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

Which of the following statements best describes the carbon atoms present in a seed-eating bird? A) Inorganic carbon atoms in the seeds were incorporated into organic molecules by the bird. B) The carbon atoms ultimately came from the soil. C) The carbon atoms are ultimately derived from coal. D) The carbon atoms ultimately came from carbon dioxide incorporated into sugars through photosynthesis. E) The carbon atoms ultimately came from simple organic compounds that formed abiotically from inorganic carbon, hydrogen, oxygen, and nitrogen atoms.

Which of the following statements is a correct distinction between autotrophs and heterotrophs? A) Only heterotrophs require chemical compounds from the environment. B) Cellular respiration is unique to heterotrophs. C) Only heterotrophs have mitochondria. D) Autotrophs, but not heterotrophs, can nourish themselves beginning with CO₂ and other nutrients that are inorganic. E) Only heterotrophs require oxygen.

Which of the following statements is a logical consequence of the second law of thermodynamics? A) If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe. B) If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. C) Every energy transfer requires activation energy from the environment. D) Every chemical reaction must increase the total entropy of the universe. E) Energy can be transferred or transformed, but it cannot be created or destroyed.

Which of the following statements is representative of the second law of thermodynamics? A) Conversion of energy from one form to another is always accompanied by some gain of free energy. B) Heat represents a form of energy that can be used by most organisms to do work. C) Without an input of energy, organisms would tend toward decreasing entropy. D) Cells require a constant input of energy to maintain their high level of organization. E) Every energy transformation by a cell decreases the entropy of the universe.

Which of the following statements is true about buffer solutions? A) They maintain a constant pH when bases are added to them but not when acids are added to them. B) They maintain a constant pH when acids are added to them but not when bases are added to them. C) They maintain a relatively constant pH of approximately 7 when either acids or bases are added to them. D) They maintain a relatively constant pH when either acids or bases are added to them. E) They are found only in living systems and biological fluids.

Which of these statements is false? A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome. B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY). C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote. D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis. E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization.

Which organelle or structure is absent in plant cells? A) mitochondria B) Golgi vesicles C) microtubules D) centrosomes E) peroxisomes

Which process is most directly driven by light energy? A) creation of a pH gradient by pumping protons across the thylakoid membrane B) carbon fixation in the stroma C) reduction of NADP⁺ molecules D) removal of electrons from chlorophyll molecules E) ATP synthesis

Which statement describes the functioning of photosystem II? A) Light energy excites electrons in the thylakoid membrane electron transport chain. B) Photons are passed along to a reaction-center chlorophyll. C) The P680 chlorophyll donates a pair of protons to NADP⁺, which is thus converted to NADPH. D) The electron vacancies in P680⁺ are filled by electrons derived from water. E) The splitting of water yields molecular carbon dioxide as a by-product.

Which structure is common to plant and animal cells? A) chloroplast B) wall made of cellulose C) central vacuole D) mitochondrion E) centriole

Which type of bond must be broken for water to vaporize? A) ionic bonds B) both hydrogen bonds and ionic bonds C) polar covalent bonds D) hydrogen bonds E) both polar covalent bonds and hydrogen bonds

Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins? A) hydrophobic interactions B) disulfide bonds C) ionic bonds D) hydrogen bonds E) peptide bonds

Which type of organelle is found in plant cells but not in animal cells? A) ribosomes B) mitochondria C) nuclei D) plastids E) none of these

Why are carbohydrates and fats considered high energy foods? A) They have a lot of oxygen atoms. B) They have no nitrogen in their makeup. C) They can have very long carbon skeletons. D) They have a lot of electrons associated with hydrogen. E) They are easily reduced.

Why does ice float in liquid water? A) The high surface tension of liquid water keeps the ice on top. B) The ionic bonds between the molecules in ice prevent the ice from sinking. C) Ice always has air bubbles that keep it afloat. D) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water. E) The crystalline lattice of ice causes it to be denser than liquid water.

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n) A) competitive inhibitor of the enzyme. B) noncompetitive inhibitor of the enzyme. C) allosteric activator of the enzyme. D) cofactor necessary for enzyme activity. E) coenzyme derived from a vitamin.

it is primed to do cellular work. E) has less energy than before its phosphorylation and therefore less energy for cellular work.

Which animal cell organelle contains enzymes that transfer hydrogen from various substrates to oxygen? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

Which component is not directly involved in translation?

DNA

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?

DNA contains phosphorus, whereas protein does not.

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive.

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?

DNA ligase

Which of the following tools of recombinant DNA technology is incorrectly paired with its use?

DNA ligasecutting DNA, creating sticky ends of restriction fragments

Two potential devices that eukaryotic cells use to regulate transcription are

DNA methylation and histone modification.

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

DNA polymerase III

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

DNA polymerase can join new nucleotides only to the 3' end of a growing strand.

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end.

Which of the following provides some evidence that RNA probably evolved before DNA?

DNA polymerase uses primer, usually made of RNA.

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?

Darwin's explanation of natural selection

After mixing a heat-killed, phosphorescent strain of bacteria with a living nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?

Descendants of the living cells are also phosphorescent.

A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Of the following, which is the best use of this discovery?

Design a test for identifying heterozygous carriers of the allele.

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. Within the first quarter hour, the researcher sees that the intact RNA is found in the cells. After 3 hours, she is not surprised to find that

Dicer enzyme has reduced it to smaller double-stranded pieces.

Gene expression in the domain Archaea in part resembles that of bacteria and in part that of the domain Eukarya. In which way is it most like the domain Eukarya?

Domain Archaea have numerous transcription factors.

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

Drosophila genes cluster into four distinct groups of linked genes.

A beaker contains 100 mL of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the results of this mixing? A) The concentration of Na⁺ ion rises. B) The concentration of Cl⁻ ion will be 0.1 M. C) The concentration of undissociated H₂O molecules remains unchanged. D) The pH of the beaker's contents will be neutral. E) The pH of the beaker's contents falls.

A biologist wants specifically to examine the surfaces of different types of cells in kidney tubules of small mammals. The cells in question can be distinguished by external shape, size, and 3-D characteristics. Which of the following would be the optimum method for her study? A) transmission electron microscopy B) cell fractionation C) light microscopy using stains specific to kidney function D) light microscopy of living unstained material E) scanning electron microscopy

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? A) It must be human. B) It must be a primate. C) It must be an animal. D) It must be sexually reproducing. E) Its gametes must have 23 chromosomes.

A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. The coupled G protein most likely interacts with this receptor A) at the NH₃ end. B) at the COO- end. C) along the exterior margin. D) along the interior margin. E) at the loop between H5 and H6.

A molecule with the chemical formula C₆H₁₂O₆ is probably a A) carbohydrate. B) lipid. C) monosaccharide D) carbohydrate and lipid only. E) carbohydrate and monosaccharide only.

A mycoplasma is an organism with a diameter between 0.1 and 1.0 µm. What does the organism's size tell you about how it might be classified? A) It must be a single-celled protist. B) It must be a single-celled fungus. C) It could be almost any typical bacterium. D) It could be a typical virus. E) It could be a very small bacterium.

A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (Note: A liter of cold water weighs about 1 kg.) A) 50°C B) 5°C C) 1°C D) 100°C E) 10°C

A solution contains 0.0000001(10⁻⁷) moles of hydroxyl ions [OH⁻] per liter. Which of the following best describes this solution? A) acidic: H⁺ acceptor B) basic: H⁺ acceptor C) acidic: H⁺ donor D) basic: H⁺ donor E) neutral

A system at chemical equilibrium A) consumes energy at a steady rate. B) releases energy at a steady rate. C) consumes or releases energy, depending on whether it is exergonic or endergonic. D) has zero kinetic energy. E) can do no work.

All of the following are part of a prokaryotic cell except A) DNA. B) a cell wall. C) a plasma membrane. D) ribosomes. E) an endoplasmic reticulum.

An organism is discovered that thrives both in the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism A) must use a molecule other than oxygen to accept electrons from the electron transport chain. B) is a normal eukaryotic organism. C) is photosynthetic. D) is an anaerobic organism. E) is a facultative anaerobe.

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C₆H₁₂O₆) in aerobic cellular respiration? A) 2 B) 4 C) 15 D) 30-32 E) 60-64

Because most receptors are membrane proteins, which of the following is usually true? A) They lead to changes in intracellular ion concentration. B) They open and close in response to protein signals. C) They are only attached to one membrane surface: exterior or interior. D) They preferentially bind with lipid or glycolipid signal molecules. E) They change their conformation after binding with signal polypeptides.

Buffers are substances that help resist shifts in pH by A) releasing H⁺ to a solution when acids are added. B) donating H⁺ to a solution when bases are added. C) releasing OH⁻ to a solution when bases are added. D) accepting H⁺ from a solution when acids are added. E) both donating H⁺ to a solution when bases are added, and accepting H⁺ when acids are added.

Changing a single amino acid in a protein consisting of 325 amino acids would A) alter the primary structure of the protein, but not its tertiary structure or function. B) cause the tertiary structure of the protein to unfold. C) always alter the biological activity or function of the protein. D) always alter the primary structure of the protein and disrupt its biological activity. E) always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and affect its biological activity.

Chromatids are separated from each other. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.

Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to A) perform amoeboid movement. B) form cleavage furrows. C) contract muscle fibers. D) extend pseudopodia. E) move vesicles around the cell.

Dehydration reactions are used in forming which of the following compounds? A) triacylglycerides B) polysaccharides C) proteins D) triacylglycerides and proteins only E) triacylglycerides, polysaccharides, and proteins

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? A) NAD+ B) NADH C) ATP D) ADP + Pi E) FADH2

During cellular respiration, acetyl CoA accumulates in which location? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix

ECM proteins are made by ribosomes in which part of a eukaryotic cell? A) mitochondria B) cytoplasm C) nuclear envelope D) Golgi apparatus E) rough ER

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 23 B) 46 C) 460 D) 920 E) about 8 million

For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Centromeres of sister chromatids disjoin and chromatids separate. A) II B) III C) IV D) V E) VII

Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb? A) red and yellow B) blue, green, and red C) green and yellow D) red and green E) blue and red

Hermann Kolbe's synthesis of an organic compound, acetic acid, from inorganic substances that had been prepared directly from pure elements was a significant milestone for what reason? A) It solved an industrial shortage of acetic acid. B) It proved that organic compounds could be synthesized from inorganic compounds. C) It disproved the concept of vitalism. D) It showed that life originated from simple inorganic chemicals. E) It proved that organic compounds could be synthesized from inorganic compounds and disproved the concept of vitalism.

How many different kinds of polypeptides, each composed of 12 amino acids, could be synthesized using the 20 common amino acids? A) 4¹² B) 12²⁰ C) 240 D) 20 E) 20¹²

How many molecules of glucose (C₆H₁₂O₆ molecular mass = 180 daltons) would be present in 90 grams of glucose? A) 90 × 10²³ B) (6.02/180) × 10²³ C) (6.02/90) × 10²³ D) (90 x 6.02) × 10²³ E) (90/180) × 6.02 × 10²³

How will brief heating (to 95°C) affect macromolecular structures in aqueous solution? A) DNA duplexes will unwind and separate. B) Proteins will unfold (denature). C) Starch will hydrolyze into monomeric sugars. D) Proteins will hydrolyze into amino acids. E) DNA duplexes will unwind and separate, and proteins will unfold (denature).

If cells are grown in a medium containing radioactive ³²P-labeled phosphate, which of these molecules will be labeled? A) phospholipids B) nucleic acids C) proteins D) amylose E) both phospholipids and nucleic acids

If cells are grown in a medium containing radioactive ¹⁵N, which of these molecules will be labeled? A) fatty acids only B) nucleic acids only C) proteins only D) amylase only E) both proteins and nucleic acids

If photosynthesizing green algae are provided with CO₂ synthesized with heavy oxygen (¹⁸O), later analysis will show that all but one of the following compounds produced by the algae contain the ¹⁸O label. That one is A) 3-phosphoglycerate. B) glyceraldehyde 3-phosphate (G3P). C) glucose. D) ribulose bisphosphate (RuBP). E) O₂.

If the pH of a solution is decreased from 9 to 8, it means that the A) concentration of H⁺ has decreased to one-tenth (1/10) what it was at pH 9. B) concentration of H⁺ has increased tenfold (10X) compared to what it was at pH 9. C) concentration of OH⁻ has increased tenfold (10X) compared to what it was at pH 9. D) concentration of OH⁻ has decreased to one-tenth (1/10) what it was at pH 9. E) concentration of H⁺ has increased tenfold (10X) and the concentration of OH⁻ has decreased to one-tenth (1/10) what they were at pH 9.

In metabolic processes of cell respiration and photosynthesis, prosthetic groups such as heme and iron-sulfur complexes are encountered in components of the electron transport chain. What do they do? A) donate electrons B) act as reducing agents C) act as oxidizing agents D) transport protons within the mitochondria and chloroplasts E) both oxidize and reduce during electron transport

In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue? A) to increase the rate of oxidative phosphorylation from its few mitochondria B) to allow the animals to regulate their metabolic rate when it is especially hot C) to increase the production of ATP D) to allow other membranes of the cell to perform mitochondrial functions E) to regulate temperature by converting most of the energy from NADH oxidation to heat

Inside an active mitochondrion, most electrons follow which pathway? A) glycolysis → NADH → oxidative phosphorylation → ATP → oxygen B) citric acid cycle → FADH₂ → electron transport chain → ATP C) electron transport chain → citric acid cycle → ATP → oxygen D) pyruvate → citric acid cycle → ATP → NADH → oxygen E) citric acid cycle → NADH → electron transport chain → oxygen

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through A) plasmodesmata. B) intermediate filaments. C) tight junctions. D) desmosomes. E) gap junctions.

Molecules with which functional groups may form polymers via dehydration reactions? A) hydroxyl groups B) carbonyl groups C) carboxyl groups D) either carbonyl or carboxyl groups E) either hydroxyl or carboxyl groups

Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits A) altered primary structure. B) altered secondary structure. C) altered tertiary structure. D) altered quaternary structure. E) altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.

One idea to mitigate the effects of burning fossil fuels on atmospheric CO₂ concentrations is to pipe liquid CO₂ into the ocean at depths of 2,500 feet or greater. At the high pressures at such depths, CO₂ is heavier than water. What potential effects might result from implementing such a scheme? A) increased photosynthetic carbon fixation because of the increased dissolved carbon dioxide in the deep water B) increased carbonate concentrations in the deep waters C) reduced growth of corals from a change in the carbonate—bicarbonate equilibrium D) no effect because carbon dioxide is not soluble in water E) both increased acidity of the deep waters and changes in the growth of bottom-dwelling organisms with calcium carbonate shells

One liter of a solution of pH 9 has how many more hydroxyl ions (OH⁻) than 1 L of a solution of pH 4? A) 5 times more B) 32 times more C) 50,000 times more D) 10,000 times more E) 100,000 times more

One mole (mol) of glucose (molecular mass = 180 daltons) is A) 180 × 10²³ molecules of glucose. B) 1 kg of glucose dissolved in 1 L of solution. C) the largest amount of glucose that can be dissolved in 1 L of solution. D) 180 kilograms of glucose. E) both 180 grams of glucose and 6.02 × 10²³ molecules of glucose.

Organic molecules with only hydrogens and five carbon atoms can have different structures in all of the following ways except A) by branching of the carbon skeleton. B) by varying the number of double bonds between carbon atoms. C) by varying the position of double bonds between carbon atoms. D) by forming a ring. E) by forming enantiomers.

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity? A) It is inhibited by AMP. B) It is activated by ATP. C) It is activated by citrate, an intermediate of the citric acid cycle. D) It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis. E) It is an allosteric enzyme.

Photosynthesis is not responsible for A) oxygen in the atmosphere. B) the ozone layer. C) most of the organic carbon on Earth's surface. D) atmospheric CO₂. E) fossil fuels.

Recent evidence shows that when chromosomes decondense during interphase, their DNA molecules do not intermingle. Instead, they occupy distinct territories within the nucleus. Considering the structure and location of the following structures, which is most likely to be involved in chromosome location? A) nuclear pores B) the nucleolus C) microfilaments D) the nuclear lamina E) the nuclear matrix

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A) 0% B) 2% C) 10% D) 38% E) 100%

Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H₂S A) will ionize more readily. B) will have greater cohesion to other molecules of H₂S. C) will have a greater tendency to form hydrogen bonds with each other. D) will have a higher capacity to absorb heat for the same change in temperature. E) will not form hydrogen bonds with each other.

Sutherland discovered that epinephrine signals A) a decrease in levels of cAMP as a result of bypassing the plasma membrane. B) lower blood glucose by binding to liver cells. C) interactions with insulin inside muscle cells. D) interactions directly with glycogen phosphorylase. E) elevation of cytosolic concentrations of cyclic AMP.

The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity? A) Transport vesicles fuse with one side of the Golgi and leave from the opposite side. B) Proteins in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. C) Lipids in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. D) Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. E) All of the above correctly describe polar characteristics of the Golgi function.

The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by A) covalent bonds. B) peptide bonds. C) ionic bonds. D) polar bonds. E) hydrogen bonds.

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA A) is a six-carbon sugar and the sugar in RNA is a five-carbon sugar. B) can form a double-stranded molecule. C) is an aldehyde sugar and the sugar in RNA is a keto sugar. D) is in the α configuration and the sugar in RNA is in the β configuration. E) contains one less oxygen atom.

The experimental approach taken in current biological investigations presumes that A) simple organic compounds can be synthesized in the laboratory from inorganic precursors, but complex organic compounds like carbohydrates and proteins can only be synthesized by living organisms. B) a life force ultimately controls the activities of living organisms and this life force cannot be studied by physical or chemical methods. C) although a life force, or vitalism, exists in living organisms, this life force cannot be studied by physical or chemical methods. D) living organisms are composed of the same elements present in nonliving things, plus a few special trace elements found only in living organisms or their products. E) living organisms can be understood in terms of the same physical and chemical laws that can be used to explain all natural phenomena.

The function of phosphatases in signal transduction is best described as to A) move the phosphate group of the transduction pathway to the next molecule of a series. B) prevent a protein kinase from being reused when there is another extracellular signal. C) amplify the transduction signal so it affects multiple transducers. D) amplify the second messengers such as cAMP. E) inactivate protein kinases and turn off the signal transduction.

The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following? A) mitosis in her ovary B) metaphase I of one meiotic event C) telophase II of one meiotic event D) telophase I of one meiotic event E) either anaphase I or II

The molar mass of glucose is 180 g/mol. Which of the following procedures should you carry out to make a 1 M solution of glucose? A) Dissolve 1 g of glucose in 1 L of water. B) Dissolve 180 g of glucose in 1 L of water. C) Dissolve 180 g of glucose in 180 g of water. D) Dissolve 180 milligrams (mg) of glucose in 1 L of water. E) Dissolve 180 g of glucose in 0.8 L of water, and then add more water until the total volume of the solution is 1 L.

There is a group of invertebrate animals called rotifers, among which a particular group of species reproduces, as far as is known, only asexually. These rotifers, however, have survived a long evolutionary history without evidence of having been overcome by excessive mutations. Assuming that the eggs are diploid, tetraploid, or partially tetraploid, what mechanism may still occur without fertilization? A) meiosis in each generation B) meiosis in every second generation C) independent assortment of maternal and paternal chromosomes D) meiosis in times of adverse environmental conditions E) crossing over of homologs

There is a group of invertebrate animals called rotifers, among which a particular group of species reproduces, as far as is known, only asexually. These rotifers, however, have survived a long evolutionary history without evidence of having been overcome by excessive mutations. Since the rotifers develop from eggs, but asexually, what can you predict? A) The eggs and the zygotes are all haploid. B) The animals are all hermaphrodites. C) While asexual, both males and females are found in nature. D) All males can produce eggs. E) No males can be found.

To visualize and identify meiotic cells at metaphase with a microscope, what would you look for? A) sister chromatids grouped at the poles B) individual chromosomes all at the cell's center C) an uninterrupted spindle array D) the synaptonemal complex E) tetrads all aligned at the cell's center

We can be sure that a mole of table sugar and a mole of vitamin C are equal in their A) mass in daltons. B) mass in grams. C) volume. D) number of atoms. E) number of molecules.

What aspects of protein structure are stabilized or assisted by hydrogen bonds? A) primary structure B) secondary structure C) tertiary structure D) quaternary structure E) secondary, tertiary, and quaternary structures, but not primary structure

What do the cell walls of plants and the extracellular matrix of animal cells have in common? A) They are largely composed of phospholipids and glycoproteins. B) Their proteins are made by free cytoplasmic ribosomes. C) They form rigid structures that provide structural support for cells but limit their expansion. D) They limit the passage of small molecules. E) They have functional connections with the cytoskeleton inside the cell.

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA? A) The sugar molecule is different. B) The nitrogen-containing base is different. C) The number of phosphates is three instead of one. D) The number of phosphates is three instead of two. E) There is no difference.

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H⁺ → Lactate + NAD⁺ A) oxygen B) NADH C) NAD⁺ D) lactate E) pyruvate

What is the pH of a 1 millimolar NaOH solution? A) pH 3 B) pH 8 C) pH 9 D) pH 10 E) pH 11

What is the primary function of the Calvin cycle? A) use ATP to release carbon dioxide B) use NADPH to release carbon dioxide C) split water and release oxygen D) transport RuBP out of the chloroplast E) synthesize simple sugars from carbon dioxide

What is the purpose of beta oxidation in respiration? A) oxidation of glucose B) oxidation of pyruvate C) feedback regulation D) control of ATP accumulation E) breakdown of fatty acids

What methods may be used to elucidate the structures of purified proteins? A) X-ray crystallography B) bioinformatics C) analysis of amino acid sequence of small fragments D) NMR spectroscopy E) both X-ray crystallography and NMR spectroscopy

When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation? A) Cells are open systems, but a test tube is a closed system. B) Cells are less efficient at heat production than nonliving systems. C) The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube. D) The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes. E) Reactant and product concentrations in the test tube are different from those in the cell.

When Stanley Miller applied heat and electrical sparks to a mixture of simple inorganic compounds such as methane, hydrogen gas, ammonia, and water vapor, what compounds were produced? A) mostly amino acids B) only simple organic compounds such as formaldehyde and cyanide C) mostly hydrocarbons D) only simple inorganic compounds E) both simple organic compounds and more complex organic compounds such as amino acids and hydrocarbons

Where do apoptotic signals come from? A) the nucleus only B) the ER only C) ligand binding only D) mitochondrial protein leakage only E) all of the above

Where does glycolysis take place in eukaryotic cells? A) mitochondrial matrix B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) cytosol

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available? A) glycolysis and fermentation only B) glycolysis and the citric acid cycle only C) glycolysis, pyruvate oxidation, and the citric acid cycle D) oxidative phosphorylation only E) glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen

Which of the events listed below occurs in the light reactions of photosynthesis? A) NADP is produced. B) NADPH is reduced to NADP⁺. C) Carbon dioxide is incorporated into PGA. D) ATP is phosphorylated to yield ADP. E) Light is absorbed and funneled to reaction-center chlorophyll a.

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? A) CO₂ and glucose B) H₂O and O₂ C) ADP, Pi, and NADP⁺ D) electrons and H⁺ E) ATP and NADPH

Which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge? A) ribosomes, nucleus, mitochondria B) chloroplasts, ribosomes, vacuoles C) nucleus, ribosomes, chloroplasts D) vacuoles, ribosomes, nucleus E) nucleus, mitochondria, ribosomes

Which of the following defines a genome? A) representation of a complete set of a cell's polypeptides B) the complete set of an organism's polypeptides C) the complete set of a species' polypeptides D) a karyotype E) the complete set of an organism's genes

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)? A) NaCl B) HCl C) NH₃ D) H₂CO₃ E) NaOH

Which of the following is the smallest closed system? A) a cell B) an organism C) an ecosystem D) Earth E) the universe

Which of the following produces the most ATP when glucose (C₆H₁₂O₆) is completely oxidized to carbon dioxide (CO₂) and water? A) glycolysis B) fermentation C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation (chemiosmosis)

Which of the following statements best describes the carbon atoms present in a seed-eating bird? A) They were incorporated into organic molecules by plants. B) They were processed into sugars through photosynthesis. C) They are ultimately derived from carbon dioxide. D) They were incorporated into organic molecules by plants, and they are ultimately derived from carbon dioxide. E) They were incorporated into organic molecules by plants, they were processed into sugars through photosynthesis, and they are ultimately derived from carbon dioxide.

Which of the following statements is true of signal molecules? A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. B) In response to some G protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP₃ and calcium. C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. E) Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins? A) G protein-coupled receptor signaling B) ligand-gated ion channel signaling C) adenylyl cyclase activity D) phosphatase activity E) receptor tyrosine kinase activity

Which structure-function pair is mismatched? A) nucleolus production of ribosomal subunits B) lysosome intracellular digestion C) ribosome protein synthesis D) Golgi protein trafficking E) microtubule muscle contraction

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? A) catalysis B) metabolism C) anabolism D) dehydration E) catabolism

Why is glycolysis described as having an investment phase and a payoff phase? A) It both splits molecules and assembles molecules. B) It attaches and detaches phosphate groups. C) It uses glucose and generates pyruvate. D) It shifts molecules from cytosol to mitochondrion. E) It uses stored ATP and then forms a net increase in ATP.

You have a freshly prepared 0.1 M solution of glucose in water. Each liter of this solution contains how many glucose molecules? A) 6.02 × 10²³ B) 3.01 × 10²³ C) 6.02 × 10²⁴ D) 12.04 × 10²³ E) 6.02 × 10²²

You have a freshly prepared 1 M solution of glucose in water. You carefully pour out a 100 mL sample of that solution. How many glucose molecules are included in that 100 mL sample? A) 6.02 × 10²³ B) 3.01 × 10²³ C) 6.02 × 10²⁴ D) 12.04 × 10²³ E) 6.02 × 10²²

molecular mass = 92) would be present in 1 L of a 1 M glycerol solution? A) 1 × 10⁶ B) 14 × 6.02 × 10²³ C) 92 × 6.02 × 10²³ D) 6.02 × 10²⁶ E) 6.02 × 10²³

solution Y has a pH of 7. From this information, we can reasonably conclude that A) solution Y has no free hydrogen ions (H⁺). B) the concentration of hydrogen ions in solution X is 30 times as great as the concentration of hydrogen ions in solution Y. C) the concentration of hydrogen ions in solution Y is 1,000 times as great as the concentration of hydrogen ions in solution X. D) the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y. E) the concentration of hydrogen ions in solution X is 1,000 times as great as the concentration of hydrogen ions in solution Y.

the reaction will stay at equilibrium.

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?

E site

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. If both children are of blood type M, which of the following is possible?

Each parent is either M or MN.

Epistasis is involved.

Which of the following investigators was/were responsible for the following discovery?

Erwin Chargaff

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

Eukaryotic exons may be spliced in alternative patterns

CML (chronic myelogenous leukemia) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than usual, and it is known as a Philadelphia (Ph') chromosome. The junction at the site of the translocation causes overexpression of a thymine kinase receptor. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early. Which of the following would be a reasonably efficient technique for confirming the diagnosis of CML?

FISH study to determine the chromosomal location of all chromosome 22 fragments

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?

GGCC CCGG

What is the function of GTP in translation?

GTP energizes the formation of the initiation complex, using initiation factors.

Which of the following mechanisms is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells?

Genes are organized into clusters, with local chromatin structures influencing the expression of all the genes at once.

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

Which of the following statements describes chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Mendel was able to draw his ideas of segregation and independent assortment because of the influence of which of the following?

His reading of the scientific literature current in the field.

Which of the following statements is true of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

In prophase I of meiosis in female Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. Which of the following is the most likely hypothesis?

Histone tail phosphorylation prohibits chromosome condensation.

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

Use the following list of choices for the following question I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase Which of the enzymes separates the DNA strands during replication?

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious. Which treatment could definitively determine whether or not the component is a viroid?

Thomas Hunt Morgan's choice of Drosophila melanogaster has been proven to be useful even today. Which of the following has/have continued to make it a most useful species? I. its four pairs of chromosomes II. a very large number of visible as well as biochemically mutant phenotypes III. easy and inexpensive maintenance IV. short generation time and large number of offspring

I, II, III, IV, and V

At what point in cell division is a chromosome lost so that, after fertilization with a normal gamete, the result is an embryo with 45, X? I. an error in anaphase I II. an error in anaphase II III. an error of the first postfertilization mitosis IV. an error in pairing

I, II, III, or IV

IAi

IBi

Use the following list of choices for the following question I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase Which of the enzymes covalently connects segments of DNA?

III

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

III

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.

III, II, IV, V, I

Use the following list of choices for the following question I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious Which treatment would you use to determine if the agent is a prion?

IV only

The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true?

If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only).

Down syndrome has a frequency in the U.S. population of ~1/700 live births. In which of the following groups would you expect this frequency to be significantly higher?

No groups have such higher frequency.

Which of the following provides an example of epistasis?

In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

Inducer

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator

Inducer

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' Which of the following is a useful feature of introns for this model?

Introns allow exon shuffling.

Silencing of selected genes is often done using RNA interference (RNAi). Which of the following questions would not be answered with this process?

Is gene HA292 responsible for this disorder in humans?

What is the function of the release factor (RF)?

It binds to the stop codon in the A site in place of a tRNA.

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?

It cannot bind to the inducer.

Which of the following is a function of a poly-A signal sequence?

It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~1035 nucleotides away.

Which of the following statements describes the eukaryotic chromosome?

It consists of a single linear molecule of double-stranded DNA plus proteins.

Which of the following would not be true of cDNA produced using human brain tissue as the starting material?

It could be used to create a complete genomic library.

Which of the following is not true of a codon?

It extends from one end of a tRNA molecule.

What is the effect of a nonsense mutation in a gene?

It introduces a premature stop codon into the mRNA.

Which of the following is characteristic of the product of the p53 gene?

It is an activator for other genes.

Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present) have a gene structure similar to our own, but many very different plants and animals. Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

It is pleiotropic.

Which of the following is true of transcription in domain Archaea?

It is roughly simultaneous with translation.

Which of the following statements about the DNA in one of your brain cells is true?

It is the same as the DNA in one of your heart cells.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism of such sigma switching?

It might allow the polymerase to recognize different promoters under certain environmental conditions.

Why might a point mutation in DNA make a difference in the level of protein's activity?

It might substitute an amino acid in the active site.

Which of the following describes the function of an enzyme known as Dicer?

It trims small double-stranded RNAs into molecules that can block translation.

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

Garrod's information about the enzyme alteration resulting in alkaptonuria led to further elucidation of the same pathway in humans. Phenylketonuria (PKU) occurs when another enzyme in the pathway is altered or missing, resulting in a failure of phenylalanine (phe) to be metabolized to another amino acid: tyrosine. Tyrosine is an earlier substrate in the pathway altered in alkaptonuria. How might PKU affect the presence or absence of alkaptonuria?

It would have no effect, because tyrosine is also available from the diet

When the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?

Its signal sequence must target it to the ER, from which it goes to the Golgi.

Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In areas of the world in which malaria is endemic, notably in sub-Saharan Africa, EBV can cause Burkitt's lymphoma in children, which is usually associated with large tumors of the jaw. Which of the following is consistent with these findings?

Malarial response of the immune system prevents an individual from making EBV antibodies.

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?

Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.

Genomic imprinting is generally due to the addition of methyl (-CH3) groups to C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

Methylation must be reversible in ovarian and testicular cells.

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?

Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.

In his transformation experiments, what did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

No replication fork will be formed.

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

One member of the couple underwent nondisjunction in gamete production.

Suppose that a mutation alters the formation of a tRNA such that it still attaches to the same amino acid (phe) but its anticodon loop has the sequence AAU that binds to the mRNA codon UUA (that usually specifies leucine leu).

One mutated tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.

One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation?

One of the parents has very mild expression of the gene.

Why did the F₁ offspring of Mendel's classic pea cross always look like one of the two parental varieties?

One phenotype was completely dominant over another.

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is found as well in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following?

Pax-6 is highly conserved and shows shared evolutionary ancestry.

Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present) have a gene structure similar to our own, but many very different plants and animals. If the environmental parameters, such as temperature, humidity, atmosphere, sunlight, and so on, are mostly Earthlike, which of the following do you expect of its types of leaves, stems, and flowers?

Phenotypes would be selected for or against by these environmental factors.

Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

Proto-oncogenes normally help regulate cell division

During splicing, which molecular component of the spliceosome catalyzes the excision reaction?

RNA

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called

RNA interference.

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

RNA polymerase II

For a repressible operon to be transcribed, which of the following must occur?

RNA polymerase must bind to the promoter, and the repressor must be inactive.

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Which of the following uses reverse transcriptase to make cDNA followed by amplification?

RT-PCR

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize a particular amino acid. The amino acid is not otherwise produced by humans. Therefore, the most efficient and effective treatment is which of the following?

Regulate the diet of the affected persons to severely limit the uptake of the amino acid.

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' Suppose that an induced mutation removes most of the 5' end of the 5' UTR. What might result?

Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade.

Why do RNA viruses appear to have higher rates of mutation?

Replication of their genomes does not involve proofreading.

An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur?

Some abnormal gametes may be formed.

Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present) have a gene structure similar to our own, but many very different plants and animals. One species of green plant, with frondlike leaves, a spine-coated stem, and purple cup-shaped flowers, is found to be self-pollinating. Which of the following is true of this species?

Some of the seeds would have true-breeding traits.

A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher continues to study the reactions of the embryo to these new proteins and you hypothesize that he is most likely to see which of the following (while embryonic genes are still not being expressed)?

Spatial axes (anterior → posterior, etc.) begin to be determined.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

T4 protein and T4 DNA.

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Why are BACs preferred today rather than bacteriophages for making genomic libraries?

The BAC carries more DNA, the BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.

Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment?

The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.

An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?

The amino acid methionine will not bind.

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The cell's DNA couldn't be packed into its nucleus.

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?

The cells from the two sources exhibit different patterns of DNA methylation.

Which of the following statements is true of linkage?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility and death, usually from coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the following represents the most likely assumption?

The disorder may be due to mutation in a single protein-coding gene.

One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy?

The engineered cells, when reintroduced into the patient, find their way back to the bone marrow.

In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication?

The entire template molecule is represented in the product.

Three genes at three loci are being mapped in a particular species. Each has two phenotypes, one of which is markedly different from the wild type. The unusual allele of the first gene is inherited with either of the others about 50% of the time. However, the unusual alleles of the other two genes are inherited together 14.4% of the time. Which of the following describes what is happening?

The first gene is assorting independently from the other two that are linked.

In order to identify a specific restriction fragment using a probe, what must be done?

The fragments must be separated by electrophoresis, the fragments must be treated with heat or chemicals to separate the strands of the double helix, and the probe must be hybridized with the fragment.

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons?

The frequency of crossing over varies along the length of the chromosome.

When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

The gene involved is on the X chromosome.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to a position upstream from the promoter, what would occur?

The lac operon will be expressed continuously.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, which will you expect to occur?

The lac operon will function normally.

Which of the following differentiates between independent assortment and segregation?

The law of independent assortment requires describing two or more genes relative to one another.

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?

The molecule is digested by exonucleases since it is no longer protected at the 5' end.

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?

The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

Which of the following statements describes the lysogenic cycle of lambda (λ) phage?

The phage genome replicates along with the host genome.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. In addition, she finds what other evidence of this single-stranded RNA piece's activity?

The rate of accumulation of the polypeptide to be translated from the target mRNA is reduced.

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to the far end of the operon (past the transacetylase gene), which of the following would likely occur when the cell is exposed to lactose?

The structural genes will be transcribed continuously.

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. One of the human leukemias, called CML (chronic myelogenous leukemia), is associated with a chromosomal translocation between chromosomes 9 and 22 in somatic cells of bone marrow. Which of the following allows CML to provide further evidence of this multistep nature of cancer?

The translocation requires breaks in both chromosomes 9 and 22, followed by fusion between the reciprocal pieces.

How would one explain a testcross involving F₁ dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?

The two genes are closely linked on the same chromosome.

What does a frequency of recombination of 50% indicate?

The two genes are likely to be located on different chromosomes.

A group of six students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in a particular gene of interest. Analysis of the data obtained shows that two students each have two fragments, two students each have three fragments, and two students each have one only. What does this demonstrate?

The two students who have two fragments have one restriction site in this region.

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

The two types of tetramers associate to form an octamer.

The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations?

The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the genome is all that enters the nucleus.

What do gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common?

Their products act as transcription factors.

In animals, what is the difference between reproductive cloning and therapeutic cloning?

Therapeutic cloning supplies cells for repair of diseased or injured organs.

When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?

There are also genes for RNAs other than mRNA.

Most genes have many more than two alleles. However, which of the following is also true?

There may still be only two phenotypes for the trait.

Why are yeast cells frequently used as hosts for cloning?

They are eukaryotic cells.

What is the reason that linked genes are inherited together?

They are located close together on the same chromosome.

Which of the following describes plant virus infections?

They are spread via the plasmodesmata.

Which of the following statements describes proto-oncogenes?

They can code for proteins associated with cell growth.

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way?

They cannot repair thymine dimers.

Which of the following is true of embryonic stem cells but not of adult stem cells?

They make up the majority of cells of the tissue from which they are derived.

They must all be males with affected female relatives.

Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. A very rare human allele of a gene called XLP, or X-linked lymphoproliferative syndrome, causes a small number of people from many different parts of the world to get cancer following even childhood exposure to EBV. Given the previous information, what might be going on?

They must be unable to mount an immune response to EBV.

Pharmacogenetics is an increasingly important discipline that uses genetic information to tailor the prescription of drug treatments to individuals. In the case of chemotherapy for breast cancer, for example, different patients need and/or respond to different treatments. Breast tumor biopsy specimens can be typed for a number of gene expression patterns. Together, these can provide risk analysis for the likely aggressive growth and metastasis of the tumor. How can this most help the physician and patient?

This can help them to decide whether and what kind of chemotherapy is warranted.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

Traits are inherited in discrete units, and are not the results of "blending."

Which of the following is one of the technical reasons why gene therapy is problematic?

Transferred genes may not have appropriately controlled activity.

Which of the following statements is true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress.

Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?

TtRr—tall and pink

Use the following list of choices for the following question I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase Which of the enzymes synthesizes short segments of RNA?

Duchenne muscular dystrophy (DMD) is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

Very rarely would a woman have this condition; the condition would be due to a chromosome error.

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Viral genomes are usually similar to the genome of the host cell.

Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In a different part of the world, namely in parts of southeast Asia, the same virus is associated with a different kind of cancer of the throat. Which of the following is most probable?

Viral infection is correlated with a different immunological reaction.

Which of the following represents a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

In the 1920s Muller discovered that X-rays caused mutation in Drosophila. In a related series of experiments in the 1940s, Charlotte Auerbach discovered that chemicals-she used nitrogen mustards-have a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why do we test for its ability to induce mutation?

We want to prevent any increase in mutation frequency.

Which of the following describes the transfer of polypeptide sequences to a membrane to analyze gene expression?

Western blotting

A student wishes to clone a sequence of DNA of ~200 kb. Which vector would be appropriate?

a BAC

Of the following, which is the most current description of a gene?

a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors?

a YAC with appropriate cellular enzymes

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why?

X inactivation in the embryo is random and produces different patterns.

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?

XCXc and XCY

The major advantage of using artificial chromosomes such as YACs and BACs for cloning genes is that

YACs and BACs can carry much larger DNA fragments than ordinary plasmids can.

You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the following might best give you an answer?

You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same

In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?

a bacterial promoter sequence

Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein?

a base deletion near the start of a gene

Which of the following DNA mutations is the most likely to be damaging to the protein it specifies?

a base-pair deletion

Which of the following is most likely to have a small protein called ubiquitin attached to it?

a cyclin that usually acts in G₁, now that the cell is in G₂

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

a deletion of two nucleotides

SRY is best described in which of the following ways?

a gene region present on the Y chromosome that triggers male development

A gene is considered to be non-Mendelian in its inheritance pattern if it seems to "violate" Mendel's laws. Which of the following would be considered Mendelian?

a gene transmitted to males from the maternal line and from fathers to daughters

What is a syndrome?

a group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation

Which of the following is known as a Philadelphia chromosome?

a human chromosome 22 that has had a specific translocation

Calico cats are female because

a male inherits only one of the two X-linked genes controlling hair color.

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for

a pattern shared among some or all of the samples that indicates gene expression differing from control samples.

In recombinant DNA methods, the term vector can refer to

a plasmid used to transfer DNA into a living cell.

Which of the following is the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

Which of the following problems with animal cloning might result in premature death of the clones?

abnormal regulation due to variant methylation

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in

a polypeptide missing an amino acid.

Which of the following would you expect of a eukaryote lacking telomerase?

a reduction in chromosome length in gametes

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because

a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

Which of the following best describes siRNA?

a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by

a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane.

Which of the following mutations is most likely to cause a phenotypic change?

a single nucleotide deletion in an exon coding for an active site

Which of the following mutations would be most likely to have a harmful effect on an organism?

a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Plants are more readily manipulated by genetic engineering than are animals because

a somatic plant cell can often give rise to a complete plant.

Which of the following produces a Mendelian pattern of inheritance?

a trait acted upon by many genes

Which of the following nucleotide triplets best represents a codon?

a triplet in the same reading frame as an upstream AUG

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. Which of the following results would she most likely see?

abnormalities of mouse embryos

In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first event of this differentiation?

activation of SRY in male embryos and masculinization of the gonads

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

alignment of tetrads at the equator

Drosophila (fruit flies) usually have long wings (+) but mutations in two different genes can result in bent wings (bt) or vestigial wings (vg). If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect?

all +bt +vg heterozygotes

If a Drosophila female has a homozygous mutation for a maternal effect gene,

all of her offspring will show the mutant phenotype, regardless of their genotype

Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problems? I. the possibility that, once introduced into the patient, the iPS cells produce nonpancreatic cells II. the failure of the iPS cells to take up residence in the pancreas III. the inability of the iPS cells to respond to appropriate regulatory signals

all of them

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce

all sharp-spined progeny.

DNA microarrays have made a huge impact on genomic studies because they

allow the expression of many or even all of the genes in the genome to be compared at once.

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

allowing the organism to adjust to changes in environmental conditions

In response to chemical signals, prokaryotes can do which of the following

alter the level of production of various enzymes

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?

altering the nucleotide sequence of the DNA fragment

An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?

amniocentesis

What is a ribozyme?

an RNA with enzymatic activity

A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?

an accumulation of A and no production of B and C

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate?

an assembled ribosome with a polypeptide attached to the tRNA in the P site

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. Which of the following would you expect?

an earlier age of onset in child one

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

anaphase I of meiosis

Viral envelopes can best be analyzed with which of the following techniques?

antibodies against specific proteins not found in the host membranes

The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. In order to be able to remain latent in an infected live cell, HSV must be able to shut down what process?

apoptosis of a virally infected cell

In animals, embryonic stem cells differ from adult stem cells in that

embryonic stem cells are totipotent, and adult stem cells are pluripotent.

How do we describe transformation in bacteria?

assimilation of external DNA into a cell

Which of the following two genes are closest on a genetic map of Drosophila?

b and rb

A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that

bacteria cannot remove eukaryotic introns.

To cause a human pandemic, the H5N1 avian flu virus would have to

become capable of human-to-human transmission.

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. Some time later, she finds that the introduced strand separates into single-stranded RNAs, one of which is degraded. What does this enable the remaining strand to do?

bind to complementary regions of target mRNAs

In eukaryotes, general transcription factors

bind to other proteins or to a sequence element within the promoter called the TATA box

The role of a metabolite that controls a repressible operon is to

bind to the repressor protein and activate it

Steroid hormones produce their effects in cells by

binding to intracellular receptors and promoting transcription of specific genes.

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.

How does a bacterial cell protect its own DNA from restriction enzymes?

by adding methyl groups to adenines and cytosines

Alternative RNA splicing

can allow the production of proteins of different sizes from a single mRNA.

Tumor-suppressor genes

can encode proteins that promote DNA repair or cell-cell adhesion.

During DNA replication,

methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication.

Yeast artificial chromosomes contain which of the following elements?

centromeres, telomeres, and an origin of replication

Correns described that the inheritance of variegated color on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe?

chloroplast inheritance

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

colorectal only

The anticodon of a particular tRNA molecule is

complementary to the corresponding mRNA codon.

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

continuous transcription of the operon's genes

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

continuous transcription of the structural gene controlled by that regulator

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?

control of more than one gene in an operon

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life?

copies of the herpesvirus genome permanently maintained in host nuclei

Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses

creation of products that will remove poisons from the human body

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to

cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?

endonuclease, DNA polymerase I, DNA ligase

In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP?

decrease in glucose and increase in cAMP

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see?

decreased chromatin condensation

A nonreciprocal crossover causes which of the following products?

deletion and duplication

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase.

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?

different possible alignments of chromosomes

The fact that plants can be cloned from somatic cells demonstrates that

differentiated cells retain all the genes of the zygote.

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

double-stranded DNA, four kinds of dNTPs, primers, origins

A frameshift mutation could result from

either an insertion or a deletion of a base.

electrophoresis of the fragments, followed by the use of a probe.

To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would find more probable success with which of the following methods?

electroporation followed by recombination

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

environmental factors such as soil pH

Genomic imprinting, DNA methylation, and histone acetylation are all examples of

epigenetic phenomena.

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of

epistasis.

Muscle cells differ from nerve cells mainly because they

express different genes.

Abnormal chromosomes are frequently found in malignant tumors. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse?

expression of inappropriate gene products

In 1997, Dolly the sheep was cloned. Which of the following processes was used?

fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

gaps left at the 5' end of the lagging strand

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell, supporting Knudsen's hypothesis. Which of the following kinds of genes would you expect to be mutated?

genes involved in control of the cell cycle

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

genetic material composed of nucleic acid

Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. A blue budgie is crossed with a white budgie. Which of the following results is not possible?

green and yellow offspring

Forms of the Ras protein found in tumors usually cause which of the following?

growth factor signaling to be hyperactive

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their sons would be color-blind and of normal height?

half

If you were to observe the activity of methylated DNA, you would expect it to

have turned off or slowed down the process of transcription.

In a nucleosome, the DNA is wrapped around

histones

Mutations in which of the following genes lead to transformations in the identity of entire body parts?

homeotic genes

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome.

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria that contain the plasmid, but not the eukaryotic gene, would grow

in all four types of broth.

The product of the bicoid gene in Drosophila provides essential information about

the anterior-posterior axis.

Which of the following techniques used to analyze gene function depends on the specificity of DNA base complementarity?

in vitro mutagenesis

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see?

inactivation of the selected genes

Genetically engineered plants

include a transgenic rice plant that can help prevent vitamin A deficiency.

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I₁). What might occur?

inclusion of I₁ in the mRNA

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. The flower color trait in radishes is an example of which of the following?

incomplete dominance

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see?

increased chromatin condensation

If glucose is available in the environment of E. coli, the cell responds with a very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect to be a measurable effect?

increased concentrations of sugars such as arabinose in the cell

One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Which of the following best describes this phenomenon?

inherited inability to repair UV-induced mutation

The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection?

interference with new viral replication in preexisting cases

Antiviral drugs that have become useful are usually associated with which of the following properties?

interference with viral replication

DNA technology has many medical applications. Which of the following is not done routinely at present?

introduction of genetically engineered genes into human gametes

The reason for using Taq polymerase for PCR is that

it is heat stable and can withstand the temperature changes of the cycler.

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

methylation and phosphorylation of histone tails

At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype?

late prophase or metaphase

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent

leading strands and Okazaki fragments.

Males are more often affected by sex-linked traits than females because

males are hemizygous for the X chromosome.

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that

many noncoding stretches of nucleotides are present in mRNA.

Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because

metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.

If A, B, and C are all required for growth, a strain mutant for the gene-encoding enzyme B would be capable of growing on which of the following media?

minimal medium supplemented with C only

If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on which of the following media?

minimal medium supplemented with nutrient B only

What are prions?

misfolded versions of normal brain protein

Women (and all female mammals) have one active X chromosome per cell instead of two. What causes this?

modification of the XIST gene so that it is active only on one X chromosome, which then becomes inactive

Emerging viruses arise by

mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species.

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Which component of the complex described enters the exit tunnel through the large subunit of the ribosome?

newly formed polypeptide

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Of the lines that express the transgene, one is transcribed but not translated. Which of the following is a likely explanation?

no AUG in any frame

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for most of the rest?

non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

What is the source of the extra chromosome 21 in an individual with Down syndrome?

nondisjunction or translocation in either parent

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their daughters might be expected to be color-blind dwarfs?

none

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to

nonidentical genes that produce different versions of globins during development.

A woman is found to have 47 chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

normal female

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene

normally leads to formation of head structures.

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

nuclease, DNA polymerase, DNA ligase

Which of the following represents the order of increasingly higher levels of organization of chromatin?

nucleosome, 30-nm chromatin fiber, looped domain

E. coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

one low-density and one intermediate-density band

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Knudsen and colleagues also noted that persons with hereditary retinoblastoma that had been treated successfully lived on but then had a higher frequency of developing osteosarcomas (bone cancers) later in life. This provided further evidence of their theory because

one of the mutations involved in retinoblastoma is also one of the changes involved in osteosarcoma.

Which of the following is most closely identical to the formation of twins?

organismal cloning

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains that are also specific for binding. In general, which of the following would you expect many of them to be able to bind?

other transcription factors

Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development?

pattern formation

Embryonic lethal mutations result in

phenotypes that are never born/hatched.

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as

piRNA.

Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?

pleiotropy

Which of the following describes the ability of a single gene to have multiple phenotypic effects?

pleiotropy

A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). To compare a specific region of the DNA from the sample with DNA from living birds, which of the following would be most useful for increasing the amount of dodo DNA available for testing?

polymerase chain reaction (PCR)

The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following?

polypeptide factors plus GTP

Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of

post-transcriptional processing.

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that

proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F₁ will be expected to be which of the following?

purple and long

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

rabies

A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted this into a cell. In order to have the mutated sequence disable the function of the gene, what must then occur?

recombination resulting in replacement of the wild type with the mutated gene

The cancer-causing forms of the Ras protein are involved in which of the following processes?

relaying a signal from a growth factor receptor

What is the function of topoisomerase?

relieving strain in the DNA ahead of the replication fork

Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell?

removal of the 5' cap

Polytene chromosomes of Drosophila salivary glands each consist of multiple identical DNA strands that are aligned in parallel arrays. How could these arise?

replication without separation

Which of the following is a protein produced by a regulatory gene

repressor

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?

retroviruses

Which of the following is used to make complementary DNA (cDNA) from RNA?

reverse transcriptase

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using

reverse transcriptase to reconstruct the gene from its mRNA.

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. In a cell-free system, what other components would you have to provide for this virus to express its genes?

ribosomes, tRNAs, amino acids, and GTP

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

roan × roan

Gap genes and pair-rule genes fall into which of the following categories?

segmentation genes

Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo?

segmentation genes

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?

sequence of bases

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

several transcription factors (TFs)

In eukaryotic cells, transcription cannot begin until

several transcription factors have bound to the promoter.

In large scale, genome-wide association studies in humans, correlation is sought between

single nucleotide polymorphisms found only in persons with a particular disorder.

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand binding proteins

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome?

size and shape of the capsid

Which of the following is an example of polygenic inheritance?

skin pigmentation in humans

In his work with pneumonia-causing bacteria and mice, Griffith found that

some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.

Transcription of the structural genes in an inducible operon

starts when the pathway's substrate is present

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?

that the critical function of telomeres must be maintained

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest?

that the parents were both heterozygous for a single trait

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

the 30-nm chromatin fiber

Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What part of the poliovirus would first interact with host cell ribosomes to mediate translation?

the VPg protein

One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Given the damage caused by UV, the kind of gene affected in those with XP is one whose product is involved with

the ability to excise single-strand damage and replace it.

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

the amino acid acts as a corepressor

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in

the ampicillin broth and the nutrient broth.

The lactose operon is likely to be transcribed when

the cyclic AMP and lactose levels are both high within the cell.

Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?

the diameter of the helix

Pharmacogenetics is an increasingly important discipline that uses genetic information to tailor the prescription of drug treatments to individuals. In the case of chemotherapy for breast cancer, for example, different patients need and/or respond to different treatments. Patients whose tumors are HER-2 positive respond to herceptin whereas other patients do not. Patients whose tumors have estrogen receptors will be best served if

the estrogen receptors are blocked by other molecules that can use the same receptors.

The leading and the lagging strands differ in that

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue?

the need to legislate for the protection of the privacy of genetic information

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore, in which body systems would you expect most mitochondrial gene mutations to be exhibited?

the nervous and muscular systems

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that

the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

The TATA sequence is found only several nucleotides away from the start site of transcription. This most probably relates to which of the following?

the number of hydrogen bonds between A and T in DNA

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria that do not take up any plasmids would grow on which media?

the nutrient broth only

What is considered to be the first evidence of differentiation in the cells of an embryo?

the occurrence of mRNAs for the production of tissue-specific proteins

Which of the following is the best statement of the use of the addition rule of probability?

the probability that either one of two independent events will occur

An ideal procedure for fetal testing in humans would have which of the following features?

the procedure that can be performed at the earliest time in the pregnancy

Cell differentiation always involves

the production of tissue-specific proteins, such as muscle actin.

The host range of a virus is determined by

the proteins on its surface and that of the host.

Within a cell, the amount of protein made using a given mRNA molecule depends partly on

the rate at which the mRNA is degraded.

Which of the following is an example of post-transcriptional control of gene expression?

the removal of introns and alternative splicing of exons

A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher in question measures the amount of new polypeptide production in embryos from 2—8 hours following fertilization and the results show a steady and significant rise in polypeptide concentration over that time. The researcher concludes that

the resulting new polypeptides are due to translation of maternal mRNAs.

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that

the rules for base pairing between the third base of a codon and tRNA are flexible.

Which of the following is the first event to take place in translation in eukaryotes?

the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?

the various domains of the polypeptide product

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

their normal products participate in repair of DNA damage.

What is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper?

to attach the DNA fragments to a permanent substrate

RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of mRNA. For which of the following might it more possibly be useful?

to decrease the production from a harmful gain-of-function mutated gene

to find which of the students has which alleles

Why did Mendel continue some of his experiments to the F₂ or F₃ generation?

to observe whether or not a recessive trait would reappear

Why might a laboratory be using dideoxy nucleotides?

to sequence a DNA fragment

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' When the spliceosome binds to elements of this structure, where can it attach?

to the end of an intron

Which of the following is a function of a signal peptide?

to translocate polypeptides across the ER membrane

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

tortoiseshell females; black males

Mendel accounted for the observation that traits which had disappeared in the F₁ generation reappeared in the F₂ generation by proposing that

traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F₁.

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure?

translation rate

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?

translocation

Sex determination in mammals is due to the SRY region of the Y chromosome. An abnormality of this region could allow which of the following to have a male phenotype?

translocation of SRY to an autosome of a 46, XX individual

The tryptophan operon is a repressible operon that is

turned off whenever tryptophan is added to the growth medium

The difference between vertical and horizontal transmission of plant viruses is that

vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. In one type cross of black × black, the results were as follows: 9/16 black 4/16 yellow 3/16 brown The genotype aabb must result in which of the following?

yellow

Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. Two blue budgies were crossed. Over the years, they produced 22 offspring, 5 of which were white. What are the most likely genotypes for the two blue budgies?

yyBb and yyBb

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. If this virus has capsomeres with 20 facets, how many proteins form each one?

Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. How many nucleotides of the genome would you expect to find in one capsid?

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