Unit 5 Ap bio Heredity

If 2n = 48 for a particular cell, then the chromosome number in each cell after meiosis would be

24

Four trials measuring recombination frequency between gene R and gene L were conducted, and the results are shown in Table 1. The mean map distance between gene R and gene L is closest to which of the following?

28 map units

How many degrees of freedom should be used when looking up the critical value for a chi-square analysis of the ratios of phenotypes observed among the F2 offspring versus the expected phenotypic ratio assuming independent assortment?

3

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'

Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the warblers?

4 chromosomes close together in the spindle

Which of the following helps to stabilize mRNA by inhibiting its degradation?

5' cap and poly (A) tail

researchers performed a dihybrid cross with coffee beans plants to investigate whether the inheritance of two traits (height and stem circumference) follows Mendel's law of independent assortment. The data for the F2 generation are presented in the table which of the following is closest to the calculated chi square value for the data presented in table 1?

72.01

In most vertebrates, the sperm cell normally contributes which of the following to the new organism?

A haploid complement of chromosomes

Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction?

A mutation affecting checkpoint 33 proteins that prevents attachment of spindle fibers

The diagram above illustrates which of the following processes? A) Crossing-Over B) Base pair substitution C) Duplication D) Deletion E) Posttranscriptional processing

A) Crossing-Over

Which of the following best describes the role of mitosis in the cell cycle? A) Distributing replicated chromosomes to daughter nuclei B) Dividing the cytoplasm to form four gametes C) Producing organelles and replicating chromosomes D) Exchanging genetic material between homologous chromosomes

A) Distributing replicated chromosomes to daughter nuclei

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell? A) Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell. B) Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell. C) The nuclear envelope will break down, and the spindle will begin to form. D) The chromatin will decondense, and the daughter cell will enter interphase.

A) Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell.

A researcher is conducting an experiment in which cells in different phases of the cell cycle are fused together. The researcher then records what happens to the nuclei of the resulting cell (Table 1). Which of the following research questions is best addressed by the experiment? A) How do chemical messengers affect a cell's transition between the phases of the cell cycle? B) How does the number of chromosomes affect when a cell transitions to the next phase of the cell cycle? C) How does the amount of genetic information change throughout the cell cycle? D) How does the checkpoint at G2 serve to prevent the transmission of mutations?

A) How do chemical messengers affect a cell's transition between the phases of the cell cycle?

Figure 1. Model of crossing over between homologous chromosomes, indicating crossing over rate of selected loci. During prophase II replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1 ? A) Is the distance between two gene loci related to crossover rate? B) Does crossing over occur more often in some chromosomes than in others? C) Is crossing over inhibited by methylation? D) Is crossing over promoted by methylation?

A) Is the distance between two gene loci related to crossover rate?

Scientists have found that DNA methylation suppresses crossing-over in the fungus Ascobolus immersus. Which of the following questions is most appropriately raised by this specific observation? A) Is the level of genetic variation in the gametes related to the amount of DNA methylation observed? B) Without crossing-over, will gametes be viable and be able to produce zygotes? C) Does DNA methylation result in shorter chromosomes? D) Is this species of fungus a diploid organism?

A) Is the level of genetic variation in the gametes related to the amount of DNA methylation observed?

The diploid number of chromosomes in the cell of a domesticated dog is 7878. Which of the following options includes the correct number of chromosomes in a cell after each cellular process (G2 checkpoint, meiosis, and fertilization, respectively)?

After G2 Checkpoint: 78 After Meiosis: 39 After Fertilization:78

Which of the following is most likely the immediate cause of the first appearance of Huntington's disease in a person?

An allele with more than 39 CAG repeats was inherited by the affected person.

Which of the following is most likely the cause of the pattern of frequency of trisomy 21 births in the selected maternal age-groups?

At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction.

During mitosis, which of the following normally occurs? A) Homologous chromosomes pair. B) Replicated chromosomes line up on the equatorial plate. C) Tetrads form. D) Unreplicated chromosomes become oriented in the center of the cell. E) Maternal and paternal chromatids pair.

B) Replicated chromosomes line up on the equatorial plate.

Which of the following occurs during mitosis but not during meiosis I ? A) The chromosomes are pulled to opposite poles of the spindle apparatus. B) The chromatids of each chromosome are separated. C) The nuclear envelope breaks down. D) Both synapsis and crossing-over take place. E) The diploid number of chromosomes is reduced to the haploid number.

B) The chromatids of each chromosome are separated.

Humans have a diploid number (2n) of 46. Which of the following statements best predicts the consequence if meiosis did not occur during gametogenesis? A) The gametes would get larger from one generation to the next. B) The chromosome number would double with each generation. C) The chromosome number would be halved with each generation. D) The chromosome number would triple with each generation.

B) The chromosome number would double with each generation.

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell? A Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell. B Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell. C The nuclear envelope will break down, and the spindle will begin to form. D The chromatin will decondense, and the daughter cell will enter interphase.

B.) Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell.

If 2n = 48 for a particular cell, then the chromosome number in each cell after meiosis would be A) 96 B) 48 C) 24 D) 12 E) 6

C) 24

In most vertebrates, the sperm cell normally contributes which of the following to the new organism? A) Many mitochondria B) Significant amounts of RNA C) A haploid complement of chromosomes D) Most of the cytoplasm of the zygote E) Two sex chromosomes

C) A haploid complement of chromosomes

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ? A) DNA replication occurs between metaphase and anaphase, doubling the number of chromosomes. Between telophase and cytokinesis, the cell divides in two, with each cell receiving half of the replicated chromosomes. B) New chromosomes formed during prophase are doubled during anaphase and are recombined before cytokinesis. C) Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells. D) At anaphase a cell contains two identical copies of each chromosome, but following telophase, one of the copies is broken down into nucleotides.

C) Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

Table 1 shows the stage and number of cells and chromosomes per cell at the end of the stage in a 2n=24 organism. Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I? A) Each daughter cell contains 12 chromatids. Each chromatid is one of two from a single chromosome with the other one of the pair found in the other daughter cell. B) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Since the chromosomes were randomly divided, one daughter cell may contain both of a pair of homologous chromosomes, while the other cell contains both of another pair of homologous chromosomes. C) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter cell. D) Each daughter cell contains 24 separate chromatids. Since every two chromatids were originally joined, forming one homologous chromosome, the number of chromatids is divided by two to determine the number of chromosomes.

C) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter cell.

A model showing two possible arrangements of chromosomes during meiosis is shown in Figure 1. Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ? A) Does crossing-over generate more genetic diversity than the fusion of gametes does? B) Does DNA methylation prevent independent assortment during metaphase II? C) How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity? D) Do daughter cells that are not genetically identical to parent cells produce viable zygotes?

C) How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?

The events listed below generally take place during meiosis. I. Synapsis occurs. II. Crossing-over is completed. III. Condensation of chromosomes begins. IV. Separation of homologous chromosomes begins. Which of the following is the correct sequence of these events? A) I, II, III, IV B) II, I, III, IV C) III, I, II, IV D) III, IV, II, I E) IV, II, III, I

C) III, I, II, IV

Melanocytes are skin cells that can become cancerous and develop into a cancer known as melanoma. Some cancerous melanocytes have developed resistance to the drugs currently used to treat melanoma. As a result, researchers are investigating the effects of a new compound (drug X) on four different melanoma cell lines. Researchers analyzed cell survival in two cell lines (Figure 1) and oxygen consumption in the presence of drug X in all four cell lines (Figure 2). Figure 3 shows the proposed mechanism by which drug X affects cells. Figure 1. Percent survival of normal melanocytes and cancerous melanocyte (melanoma) lines 1 and 2 after treatment with different concentrations of drug X Figure 2. Oxygen consumption per cell in four melanoma lines after treatment with either solvent alone or solvent containing drug XX. Error bars represent ±2SEx¯ Figure 3. Pathway leading to cell survival, growth, and proliferation and the likely effect of drug X Based on Figure 2, which of the following best supports the claim that drug XX inhibits oxygen consumption? A) In the absence of drug X, melanoma lines 1 and 4 consume similar amounts of oxygen B) In the presence of drug X, melanoma line 2 consumes statistically more oxygen per cell than does melanoma line 3. C) Melanoma line 3 consumes statistically less oxygen per cell in the presence of drug X than it does in the presence of the solvent alone. D) Melanoma line 2 in the presence of drug X consumes statistically less oxygen than does melanoma line 4 in the absence of drug X.

C) Melanoma line 3 consumes statistically less oxygen per cell in the presence of drug X than it does in the presence of the solvent alone.

Which of the following best describes the cellular process illustrated in Figure 1 ? A) Sister chromatids separating during anaphase of mitosis B) Chromosomes lining up along the midline of the cell during mitosis C) Reducing the chromosome number during anaphase II of meiosis D) Chromatids failing to separate during meiosis

C) Reducing the chromosome number during anaphase II of meiosis

Which of the following occurs in both meiosis and mitosis? A) Separation of homologous chromosomes B) Reduction of chromosome number C) Separation of sister chromatids D) Crossing-over between homologous chromosomes E) Production of four daughter cells

C) Separation of sister chromatids

Which of the following best explains why triploid bananas do not produce seeds? A) The cells of the banana plant are unable to replicate DNA, thus preventing cell division and limiting growth. B) The banana plants lack enough genetic diversity to properly hybridize. C) The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis. D) The production of seeds is not required because triploid plants produce gametes without fertilization.

C) The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis.

Which of the following best describes the cells that result from the process of meiosis in mammals? A) They are diploid. B) They can be used to repair injuries. C) They are genetically different from the parent cell. D) They are genetically identical to all the other cells in the body. E) They are identical to each other.

C) They are genetically different from the parent cell.

In most vertebrates, the sperm cell normally contributes which of the following to the new organism? A Many mitochondria B Significant amounts of RNA C A haploid complement of chromosomes D Most of the cytoplasm of the zygote E Two sex chromosomes

C.) A haploid complement of chromosomes

The diagram above illustrates which of the following processes?

Crossing-over

Figure 1. Diagram of the cell cycle with key checkpoints Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction? A) A mutation affecting checkpoint 1 proteins that forces cells to enter G0 B) A mutation affecting checkpoint 2 proteins that allows cells to divide with DNA damage C) A mutation affecting checkpoint 3 proteins that prevents attachment of spindle fibers D) A mutation affecting checkpoint 2 proteins that prevents duplication of the chromosomes

D) A mutation affecting checkpoint 2 proteins that prevents duplication of the chromosomes

The process depicted in the image above is best summarized by which of the following descriptions? A) During the synthesis phase of the cell cycle, DNA molecules replicate to generate identical daughter cells. B) Centromeres align specific gene sequences of homologous chromosomes during mitotic divisions. C) The spindle apparatus attaches at chiasma during metaphase of mitosis. D) During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

D) During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how mitosis and meiosis result in daughter cells with different numbers of chromosomes? A) In mitosis, the chromosomes consist of a single chromatid, which is passed to two haploid daughter cells. In meiosis, the chromosomes consist of two chromatids during the first round of division and one chromatid during the second round of division, resulting in two haploid daughter cells. B) In mitosis, synapsis of homologous chromosomes results in four haploid daughter cells after one division. In meiosis, synapsis of homologous chromosomes occurs during the second division and results in four diploid daughter cells. C) Mitosis produces one identical daughter cell after one round of division. Meiosis has two rounds of division and doubles the number of chromosomes in the second round of division, producing four diploid cells. D) Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

D) Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

The relative amount of DNA in a cell at various stages of the cell cycle is shown in Figure 1 . A) The amount of DNA doubles as the DNA is replicated. B)The amount of DNA slightly increases as a result of new organelle synthesis. C) The amount of DNA does not change while the cell grows. D) The amount of DNA is halved as the cell divides into two daughter cells.

D) The amount of DNA is halved as the cell divides into two daughter cells.

Saccharomyces cerevisiae is a diploid yeast species that can reproduce either sexually or asexually. An experiment was performed to induce mitotically dividing S. cerevisiae cells in G2 to undergo meiosis. Which of the following best describes the steps these cells will follow to form gametes? A) The first division will result in crossing over between homologous chromosomes, and the second division will reduce the original number of chromosomes by half in the daughter cells. B) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will result in each daughter cell having one-fourth of the original number of chromosomes. C) The first division will move single chromatids to each daughter cell, and the second division will double the number of chromosomes in each daughter cell. D) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.

D) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.

The process depicted in the image above is best summarized by which of the following descriptions? A During the synthesis phase of the cell cycle, DNA molecules replicate to generate identical daughter cells. B Centromeres align specific gene sequences of homologous chromosomes during mitotic divisions. C The spindle apparatus attaches at chiasma during metaphase of mitosis. D During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

D.) During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

Which of the following correctly explains where DNADNA replication will begin on the strand oriented 5'→3'5′→3′, reading from left to right?

DNA replication will be initiated immediately to the left of the RNA, since DNA polymerase requires an RNA primer.

Which of the following best describes the role of mitosis in the cell cycle?

Distributing replicated chromosomes to daughter nuclei

a model of crossing over during gamete formation is shown in figure one based on the figure which of the following questions could be addressed?

Does synapses of homologous chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells?

The process depicted in the image above is best summarized by which of the following descriptions?

During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

All of the following are true statements about meiosis in mammals EXCEPT: A) It serves as a factor in bringing about variation among offspring. B) It follows DNA replication. C) It occurs only in reproductive structures. D) It produces cells with the haploid number of chromosomes. E) It produces four genetically identical gametes.

E) It produces four genetically identical gametes.

A human cell in prophase of mitosis can be distinguished from a human cell in prophase I of meiosis by the presence of... A) kinetochores in the mitotic cell B) a spindle in the mitotic cell C) twice as many chromosomes in the meiotic cell D) half as many chromosomes in the meiotic cell E) paired homologous chromosomes in the meiotic cell

E) paired homologous chromosomes in the meiotic cell

A human cell in prophase of mitosis can be distinguished from a human cell in prophase I of meiosis by the presence of A kinetochores in the mitotic cell B a spindle in the mitotic cell C twice as many chromosomes in the meiotic cell D half as many chromosomes in the meiotic cell E paired homologous chromosomes in the meiotic cell

E.) paired homologous chromosomes in the meiotic cell

Which of the following best predicts the effect of the chromosomal segregation error shown in Figure 1?

Half of the resulting gametes will have the correct number of chromosomes, and the other half will have an incorrect number of chromosomes.

Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1?

How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?

The events listed below generally take place during meiosis. I. Synapsis occurs. II. Crossing-over is completed. III. Condensation of chromosomes begins. IV. Separation of homologous chromosomes begins. Which of the following is the correct sequence of these events?

III, I, II, IV

In sweet pea plants, two heterozygous plants for color and pollen shape were crossed and the results were not 9:3:3:1 ratio. Which of the following statements provides the most reasonable prediction to account for the deviation from the expected results?

In sweet pea plants, the gene for flower color and the gene for pollen grain shape are genetically linked.

During prophase I replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1?

Is the distance between two gene loci related to crossover rate?

During prophase II replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1 ?

Is the distance between two gene loci related to crossover rate?

The tadpoles of Mexican spadefoot toads are known to exhibit phenotypic plasticity depending on food availability. Tadpole mouthparts can vary significantly, prompting researchers to categorize them as either omnivore-morph or carnivore-morph. Carnivore-morph tadpoles are larger and have mouthparts that are better suited for predation. Remarkably, carnivore-morph tadpoles can change into omnivore-morph tadpoles when the food supply changes. Which of the following best describes an advantage of the phenotypic plasticity displayed by the tadpoles?

It gives the tadpoles increased versatility with respect to diet.

Which of the following is true of mitosis?

It maintains the same chromosome number in the daughter cells as in the parent cell.

All of the following are true statements about meiosis in mammals EXCEPT:

It produces four genetically identical gametes.

When a mustard plant seedling is transferred to an environment with higher levels of carbon dioxide, the new leaves have a lower stomata-to-surface-area ratio than do the seedling's original leaves. Which of the following best explains how the leaves from the same plant can have different stomatal densities when exposed to an elevated carbon dioxide level?

Leaf growth is promoted through increased photosynthesis, but the genetically regulated rate of stomatal production is not altered, leading to a decrease in stomatal density.

Sweet pea plants have a diploid (2n) chromosome number of 14. Which of the following best explains how the sweet pea plants in the parental generation produce F1 offspring with 14 chromosomes?

Meiosis I and II lead to the formation of cells with 7 chromosomes. During meiosis I, homologous chromosomes separate. During meiosis II, sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.

Melanocytes are skin cells that can become cancerous and develop into a cancer known as melanoma. Some cancerous melanocytes have developed resistance to the drugs currently used to treat melanoma. As a result, researchers are investigating the effects of a new compound (drug XX) on four different melanoma cell lines. Researchers analyzed cell survival in two cell lines (Figure 1) and oxygen consumption in the presence of drug XX in all four cell lines (Figure 2). Figure 3 shows the proposed mechanism by which drug XX affects cells. Based on Figure 2, which of the following best supports the claim that drug XX inhibits oxygen consumption?

Melanoma line 33 consumes statistically less oxygen per cell in the presence of drug X than it does in the presence of the solvent alone.

Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how mitosis and meiosis results in daughter cells with different numbers of chromosomes?

Mitosis produces two identical daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

Which of the following best explains the distribution of lactase persistence in the areas shown in Figure 1?

Mutations conferring lactase persistence likely arose independently in different geographic areas and offered a selective advantage.

A model of a process involving nucleic acids is shown in Figure 1. Which of the following best explains what process is represented in Figure 1 ?

New DNADNA strands are being synthesized in the 5'5′ to 3'3′ direction from their DNADNA templates.

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1#1 and nucleic acid #2#2 ?

Nucleic acid #1#1 contains adenine-thymine base pairs, whereas nucleic acid #2#2 does not.

Glycolysis is a metabolic pathway that converts glucose into pyruvate and is observed in each of the three domains. The hexokinase family of enzymes is required during glycolysis to phosphorylate six-carbon sugars. Researchers designed a general hexokinase inhibitor that is effective in the neurons of rats. Which of the following best predicts the effect of adding this inhibitor to a culture of plant cells?

Plant cells will be unable to perform glycolysis due to the inhibitor and will die.

In pea plants, purple flower color is dominant to red flower color and long pollen grains are dominant to round pollen grains. Researchers crossed two pure-breeding lines of the pea plants to investigate whether the genes controlling flower color and pollen shape segregate independently. The procedure for the genetics experiment is summarized in Figure 1. Which of the following tables best shows the expected values in the F2 generation for a chi-square goodness-of-fit test for a model of independent assortment?

Purple, long 1199 Purple, round 400 Red, long 400 Red,round 133

During mitosis, which of the following normally occurs?

Replicated chromosomes line up on the equatorial plate.

Which of the following best explains how continuity of genetic information in cells is ensured across generations?

Replication uses a parental strand of DNA as a template to create a new strand of DNA.

The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ?

Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.

Which of the following occurs in both meiosis and mitosis?

Separation of sister chromatids

Table 1. Nucleotide composition of sample DNA from selected organisms. Which of the following statements best explains the data set?

Since the %A and %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.

Streptomycin interferes with the proper binding of tRNA to mRNA in prokaryotic ribosomes. Which of the following best predicts the most direct effect of exposing prokaryotic cells to streptomycin?

Synthesis of polypeptides will be inhibited.

A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments. Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?

The bacteria have high genetic variability and high reproductive rates

In corn plants, purple kernel color is dominant to yellow kernel color, and smooth kernels are dominant to wrinkled kernels. Researchers carried out a genetics experiment to investigate whether the genes controlling kernel color and kernel texture segregate independently. In their experiment, the researchers crossed two corn plants that were each heterozygous for both kernel color and kernel texture. The results of the experiment are presented in Table 1. Using a significance level of p=0.05, which of the following statements best completes a chi-square goodness-of-fit test for a model of independent assortment?

The calculated chi-square value is 3.91, and the critical value is 7.82. The null hypothesis cannot be rejected.

Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of the mitotic cyclin?

The cell would be prevented from entering mitosis, and the cell would stop dividing.

Figure 1. Replicated DNADNA produced after a chemical is introduced Which of the following claims is best supported by the data?

The chemical inhibits DNA ligase.

Which of the following occurs during mitosis but not during meiosis I ?

The chromatids of each chromosome are separated.

Humans have a diploid number (2n) of 46. Which of the following statements best predicts the consequence if meiosis did not occur during gametogenesis?

The chromosome number would double with each generation.

Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop dividing. Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

Himalayan rabbits are a breed of rabbits with highly variable fur color. If genetically similar rabbits are raised in environments that have different temperature conditions, the rabbits can have different color patterns. Which of the following statements best explains how the fur color can be different in Himalayan rabbits raised under different temperature conditions?

The environment determines how the genotype is expressed.

FIgure 1 represents part of a process that occurs in eukaryotic cells. These are untranslated regions (UTR) in this sequence. Which of the following best explain the process represented by Figure 1?

The enzyme-regulated processing of pre-RNA into mature mRNA.

Females: 40 red eyes, 13 sepia eyes. Males: 39 red eyes, 11 sepia eyes. Which of the following best describes the likely mode of inheritance for the eye-color gene?

The eye-color gene is likely autosomal because males and females have similar phenotype ratios.

Saccharomyces cerevisiae is a diploid yeast species that can reproduce either sexually or asexually. An experiment was performed to induce mitotically dividing S. cerevisiae cells in G2G2 to undergo meiosis. Which of the following best describes the steps these cells will follow to form gametes?

The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.

In the cross diagrammed above, the expected and observed results are shown. Which of the following best explains the observed results of the cross?

The genes for body color and wing shape are located close to each other on the same chromosome.

Which of the following best explains why ligase is required for DNA replication?

The lagging strand cannot be replicated continuously, and ligase is needed to join the fragments.

Which of the following best explains why triploid bananas do not produce seeds?

The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis.

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.

Table 1. Effect of Exposing Identical Caterpillars to Specific Colors of Light. Which of the following best explains the cause of the phenotypic variation observed in the butterflies?

There was a differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to.

Which of the following best describes the cells that result from the process of meiosis in mammals?

They are genetically different from the parent cell.

Researchers have identified a molecule produced by Ecteinascidia turbinata, a marine invertebrate, from which the drug trabectedin is produced. Soft-tissue tumors treated with trabectedin rapidly decrease in size. In a preliminary study, healthy cells and tumor cells sampled from skin cancer patients treated with trabectedin were collected, and several characteristics of the cells were observed. The observed results of the study are shown in the table. Which of the following best explains the most likely method by which this antitumor drug works?

Trabectedin interferes with the duplication of DNA during interphase and thus prevents cancer cells from passing the G2 checkpoint.

Which of the following questions will best help the genetic counselor to evaluate the risk of a young man developing Huntington's disease and transmitting it to his children?

Were your parents or grandparents ever diagnosed with Huntington's disease?

Which of the following questions would be most useful to researchers trying to determine the role of meiosis in the F2 phenotypic frequencies?

What is the recombination frequency between the genes for petal shape and pollen shape?

which of the following best explains a distinction between metaphase I and metaphase II?

homologous pairs of chromosomes are aligned during metaphase I but individual chromosomes are aligned during metaphase II

in anaphase I of meiosis, cohesion between the centromeres of sister chromatids is maintained while homologous chromosomes migrate to opposite poles of the cell along the meiotic spindle as represented in figure 1

is there a pattern to the movement of homologous chromosomes in the presence of this compound?

Birds feed off of gardens and bird feeders. Which of the following best explains the directional shift in beak length in these birds?

longer beaks allow the birds to better access seeds in bird feeders.

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3'

met-ser-ser-leu-ser-leu

human cell in prophase of mitosis can be distinguished from a human cell in prophase I of meiosis by the presence of

paired homologous chromosomes in the meiotic cell

The blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinated and grew into flowering plants. Of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink flowered offspring?

pink flower color is a trait recessive to blue flower color.

for sexually reproducing diploid parents cells, which of the following statements best explains the production of haploid cells that occurs in meiosis but not in mitosis

separation of chromatids occur once, and there are tow rounds of cell division in meiosis

CTC to CAC, Which of the following best describes the type of mutation shown in Figure 1 that leads to sickle-cell anemia?

substitution