AP Biology Practice Multiple Choice

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. Figure 1. Summary of a genetics experiment using pea plants 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?

1199 - 400 - 400 - 133

A model of crossing over during gamete formation is shown in Figure 1. Figure 1. Model of crossing over during meiosis Based on Figure 1, which of the following questions could best be addressed? A Does synapsis of homologous chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells? B Do sister chromatids separate and form diploid daughter cells? C Do chromatids from nonhomologous chromosomes rearrange to produce identical daughter cells? D Does synapsis of homologous chromosomes produce daughter cells that are identical to the parent cell?

A

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is A 1/2 x 1/2 B 1/2 + 1/2 C (1/2) / (1/2) D 1/2−−−√MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaOaaaeaacaaIXaGaai4laiaaikdaaSqabaaaaa@383B@ E |1/2 — 1/2|

A

Directions: Each group of questions below concerns an experimental or a laboratory situation. In each case, first study the description of the situation. Then choose the one best answer to each question following it. In dogs, one pair of alleles determines coat color (dark and albino). Another pair of alleles determines hair length (short and long). Thus, each gamete will contain one of the coat-color alleles, C or c and one of the hair-length alleles, B or b. In repeated crosses of a specific dark, short-haired dog with an albino, long-haired dog, all the offspring were dark with short hair, as shown in cross I. However, in subsequent crosses of another dark, short-haired dog with a dark, long-haired dog, the ratios shown in cross II below were obtained. Which of the following correctly describes the relationship of the dark-coat-color allele to the albino condition? A It is dominant. B It is recessive. C It is codominant. D It is a polygenic inheritance pattern. E The alleles are linked.

A

Eye color in a particular strain of fly is influenced by one gene with two alleles: a dominant allele that results in red eyes and a recessive allele that results in sepia eyes. A red-eyed female from a true-breeding population is mated with a sepia-eyed male. The F1 offspring are all red-eyed. The F1 flies are allowed to interbreed, producing the following in the F2 generation. 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? A The eye-color gene is likely autosomal because males and females have similar phenotype ratios. B The eye-color gene is likely autosomal because more females have sepia eyes than males do. C The eye-color gene is likely sex-linked because the males and females have similar phenotype ratios. D The eye-color gene is likely sex-linked because the males and females display both phenotypes.

A

Researchers hypothesized that red eye color in Japanese koi, a type of fish, is due to a mutation. To study the inheritance of red eye color in koi, the researchers conducted breeding experiments over several generations. The results are summarized in Figure 1. Figure 1. Inheritance of eye color in Japanese koi Based on the data in Figure 1, which of the following is the best prediction of the mode of inheritance of red eyes in Japanese koi? A The allele for red eyes is inherited in an autosomal dominant pattern. B The allele for red eyes is inherited in an autosomal recessive pattern. C The allele for red eyes is inherited in an XX-linked recessive pattern. D The allele for red eyes is inherited in an XX-linked dominant pattern.

A

Several members of a family are found to involuntarily sneeze when exposed to bright lights, such as sunlight. Following analysis of the condition in the family, a doctor predicts that the symptoms have an underlying genetic basis. A pedigree of the family is shown in Figure 1. Figure 1. Pedigree showing family members with and without symptoms For this condition, which of the following modes of inheritance is most consistent with the observations? A Autosomal dominant B Autosomal recessive C X-linked dominant D X-linked recessive

A

Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white). Based on the data in Table I, which of the following best explains why there are no individuals with constricted pods in the F1generation? A Inflated pod shape is dominant to constricted pod shape. B The inflated-pod offspring in the F1 generation are homozygous. C Constricted pod shape typically arises from a new mutation in the F1 generation. D The constricted-pod offspring are carriers for the inflated pod shape allele.

A

A genetic counselor is consulted by a young man who is worried about developing Huntington's disease, an inherited disorder caused by a dominant allele of a single gene. The young man explains that his cousin was recently diagnosed with Huntington's disease, and the news has caused him to consider his own risk of developing the disorder. Which of the following questions will best help the genetic counselor to evaluate the risk of the young man developing Huntington's disease and transmitting it to his children? A Were you and your cousin born in the same geographical area? B Were your parents or grandparents ever diagnosed with Huntington's disease? C Were you in physical contact with a person diagnosed with Huntington's disease? D Were you ever exposed to substances that are suspected of being mutagens?

B

A true-breeding variety of wheat that produces deep-red-colored grain was crossed with a true-breeding variety that produces a white-colored grain. The resulting F1 offspring all had medium-red-colored grain. Five crosses of the F1 plants were all grown under the same conditions and resulted in plants with a variety of grain color, as indicated in Table 1. Table 1. F2 phenotypes resulting from five crosses Grain ColorCross 1Cross 2Cross 3Cross 4Cross 5Deep red12120Dark red67756Red1513161714Medium red2022212021Light red1516141615Very light red64336White10212 Which of the follow indicates the mean number per cross of F2 plants producing medium-red grain and correctly explains the distribution of the phenotypes? A The mean number of medium-red phenotypes per cross is 20.8. The distribution of phenotypes suggests that grain color is under environmental control. B The mean number of medium-red phenotypes per cross is 20.8. The distribution of phenotypes suggests that multiple genes are involved in grain color determination. C The mean number of medium-red phenotypes per cross is 104. The distribution of phenotypes suggests that grain color is under environmental control. D The mean number of medium-red phenotypes per cross is 104. The distribution of phenotypes suggests that multiple genes are involved in grain color determination.

B

Directions: This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. This group of questions refers to the probabilities below. Assume that the alleles referred to all assort independently. (A) 0 (B) 1/16 (C) 1/4 (D) 1/2 (E) 3/4 Probability that the genotype ccdd will be produced by the parents CcDd x CcDd A 0 B 1/16 C 1/4 D 1/2 E 3/4

B

For following group of questions first study the description of the situation and diagram and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. The pedigree of a family with a history of a particular genetic disease is shown below. Squares represent males and circles represent females. Shaded symbols represent those who have the disease. If Individual 2 were to marry a woman with no family history of the disease, which of the following would most likely be true of their children?(number 16 on the Hereditary Test) A All of the children would have the disease. B None of the children would have the disease. C Only the sons would have the disease. D All of the sons would be carriers of the disease. E None of the daughters would be carriers of the disease.

B

Four trials measuring recombination frequency between gene R and gene L were conducted, and the results are shown in Table 1. Table 1. Recombination frequency Trial 1Trial 2Trial 3Trial 4Frequency of recombination24%33%26%29% The mean map distance between gene R and gene L is closest to which of the following? A 0.28 map units B 28 map units C 0.14 map units D 14 map units

B

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? A Plant cells will be unaffected by the inhibitor as they do not perform glycolysis. B Plant cells will be unable to perform glycolysis due to the inhibitor and will die. C Plant cells will be unable to perform photosynthesis due to the inhibitor and will die. D Plant cells will still be able to perform glycolysis since plant hexokinase is not structurally similar to animal hexokinase.

B

In sheep, eye color is controlled by a single gene with two alleles. When a homozygous brown-eyed sheep is crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. If the blue-eyed sheep are mated with each other, what percent of their offspring will most likely have brown eyes? A 0% B 25% C 50% D 75% E 100%

B

R. C. Punnett conducted experiments on the inheritance of traits in the sweet pea, Lathyrus odoratus. In one experiment, he crossed two different true-breeding sweet pea plant strains, one with erect petals and long pollen, and the other with hooded petals and round pollen. All the offspring (F1 generation) had erect petals and long pollen (Figure 1). Figure 1. Sweet pea plant cross Next, Punnett allowed the F1 generation to self-fertilize and recorded the phenotypes of their offspring. The data are shown in Table 1. Table 1. F2 results of F1 self-fertilization cross Phenotype of F2Number of OffspringErect petals, long pollen765Erect petals, round pollen62Hooded petals, long pollen71Hooded petals, round pollen220Total1,118 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? A 2 B 3 C 4 D 5

B

Researchers performed a dihybrid cross with coffee bean 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 Table 1. Table 1. Data for the F2 generation PhenotypeObservedExpectedDwarf with small stem circumference191172Dwarf with large stem circumference2657Tall with small stem circumference3957Tall with large stem circumference4919TOTAL305305 Which of the following is closest to the calculated chi-square (χ2) value for the data presented in Table 1? A 8.35 B 72.01 C 98.00 D 2,546.00

B

Sex chromosomes determine the phenotype of sex in humans. Embryos containing XX chromosomes develop into females, and embryos containing XY chromosomes develop into males. The sex chromosomes separate during meiosis, going to different gamete cells. A woman is heterozygous for the X-linked recessive trait of hemophilia A. Her sex chromosomes can be designated as XHXh. During meiosis the chromosomes separate as shown in Figure 1. Figure 1. Transmission pattern for sex chromosomes of a woman heterozygous for hemophilia A into gametes If the woman and a man with normal clotting function have children, what is the probability of their children exhibiting hemophiliaA? A 50 percent for daughters, 0 percent for sons B 50 percent for sons, 0 percent for daughters C 50 percent for all children D 0 percent for all children

B

Students carry out a genetics experiment to investigate the inheritance pattern of the white-eye trait in fruit flies. In the experiment, the students cross a red-eyed female with a white-eyed male to produce an F1 generation. The students observe that all the flies in the F1 generation have red eyes. The students then allow the F1 flies to mate and produce an F2 generation. The students will use the F2 data to perform a chi-square goodness-of-fit test based on a null hypothesis of autosomal recessive inheritance. The observed and expected values for the chi-square goodness-of-fit test are shown in Table 1. Table 1. The observed and expected values for a chi-square goodness-of-fit test PhenotypeObservedExpectedRed-eyed female497375Red-eyed male254375White-eyed female0125White-eyed male249125 The students plan to use a significance level of p=0.01. Which of the following is the most appropriate critical value for the students to use in their chi-square goodness-of-fit test? A 7.82 B 11.34 C 13.28 D 326.7

B

Two fruit fly mutations are ebony body (e) and sepia eyes (s). Four different students performed dihybrid crosses with flies that were heterozygous with a mutant allele and a wild-type allele for both genes (EeSs×EeSs). The results are shown in Table 1. Table 1. Offspring of four separate dihybrid crosses Number of OffspringPhenotypeStudent 1Student 2Student 3Student 4Wild-type eyes, wild-type body89928395Wild-type eyes, ebony body22171520Sepia eyes, wild-type body21243016Sepia eyes, ebony body28273229 The mean number of fruit flies per student that are homozygous recessive for both genes is closest to which of the following? A 89.75 B 29.0 C 22.75 D 18.5

B

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? A Increased photosynthesis leads to larger leaves that need more stomata for photosynthesis, leading to an increase in stomatal density. B 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. C Leaf growth is inhibited by decreased photosynthesis, and the genetically regulated rate of stomatal production remains the same, leading to an increase in stomatal density. D Leaf growth is inhibited by decreased photosynthesis, and the genetically regulated rate of stomatal production remains the same, leading to a decrease in stomatal density.

B

1/1 MC point R. C. Punnett conducted experiments on the inheritance of traits in the sweet pea, Lathyrus odoratus. In one experiment, he crossed two different true-breeding sweet pea plant strains, one with erect petals and long pollen, and the other with hooded petals and round pollen. All the offspring (F1 generation) had erect petals and long pollen (Figure 1). Figure 1. Sweet pea plant cross Next, Punnett allowed the F1 generation to self-fertilize and recorded the phenotypes of their offspring. The data are shown in Table 1. Table 1. F2 results of F1 self-fertilization cross Phenotype of F2Number of OffspringErect petals, long pollen765Erect petals, round pollen62Hooded petals, long pollen71Hooded petals, round pollen220Total1,118 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? A Meiosis II and IIII lead to the formation of cells with 14 chromosomes. When two cells combine during fertilization, extra chromosomes are randomly broken down, leading to offspring with 14 chromosomes. B Meiosis II and IIII lead to the formation of cells with 14 chromosomes. When two cells combine during fertilization, extra chromosomes with recessive traits are broken down, leading to offspring with 14 chromosomes. C Meiosis II and IIII lead to the formation of cells with 7 chromosomes. During meiosis II, homologous chromosomes separate. During meiosis IIII, sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes. D Meiosis II and IIII lead to the formation of cells with 7 chromosomes. During meiosis II, sister chromatids separate. During meiosis IIII, homologous chromosomes separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.

C

An African violet grower observes that genetically identical African violet plants growing near the walls of the greenhouse have white flowers, that plants growing farther away from the walls have pale blue flowers, and that plants growing nearest the center of the greenhouse have dark blue flowers. Which of the following best explains the differences in flower color of the African violets in the greenhouse? A Warmer temperatures result in genotypic alterations, which result in flower color differences. B The plants along the walls of the greenhouse are homozygous recessive and therefore have white flowers. C An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center. D More light is available along the walls of the greenhouse, so the flowers need less pigment to absorb sunlight for photosynthesis.

C

Directions: Each group of questions below concerns an experimental or a laboratory situation. In each case, first study the description of the situation. Then choose the one best answer to each question following it. In dogs, one pair of alleles determines coat color (dark and albino). Another pair of alleles determines hair length (short and long). Thus, each gamete will contain one of the coat-color alleles, C or c and one of the hair-length alleles, B or b. In repeated crosses of a specific dark, short-haired dog with an albino, long-haired dog, all the offspring were dark with short hair, as shown in cross I. However, in subsequent crosses of another dark, short-haired dog with a dark, long-haired dog, the ratios shown in cross II below were obtained. Which of the following is probably the genotype of the dark, short-haired parent in cross I? A CcBb B ccbb C CCBB D CCbb E ccBB

C

Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it. Achondroplastic dwarfism is a dominant genetic trait that causes severe malformation of the skeleton. Homozygotes for this condition are spontaneously aborted (hence, the homozygous condition is lethal) but heterozygotes will develop to be dwarfed. Matthew has a family history of the condition, although he does not express the trait. Jane is an achondroplastic dwarf. Matthew and Jane are planning a family of several children and want to know the chances of producing a child with achondroplastic dwarfism. The probability that Matthew and Jane's first child will be an achondroplastic dwarf is A 0% B 25% C 50% D 75% E 100%

C

For following group of questions first study the description of the situation and diagram and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. The pedigree of a family with a history of a particular genetic disease is shown below. Squares represent males and circles represent females. Shaded symbols represent those who have the disease. If Individual 6 marries a woman with the disease, what is the probability that their first child will have the disease?(number 17 on the Hereditary Test) A 0 B 25% C 50% D 75% E 100%

C

For sexually reproducing diploid parent cells, which of the following statements best explains the production of haploid cells that occurs in meiosis but not in mitosis? A Separation of chromatids occurs once, and there is one round of cell division in meiosis. B Separation of chromatids occurs twice, and there are two rounds of cell division in mitosis. C Separation of chromatids occurs once, and there are two rounds of cell division in meiosis. D Separation of chromatids occurs twice, and there is one round of cell division in mitosis.

C

Gregor Mendel's pioneering genetic experiments with pea plants occurred before the discovery of the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery that genes may be linked on a chromosome? A Pea color and pea shape display independent inheritance patterns. B Offspring of a given cross show all possible combinations of traits in equal proportions. C Most offspring of a given cross have a combination of traits that is identical to that of either one parent or the other. D Recessive phenotypes can skip a generation, showing up only in the parental and F2 generations.

C

Huntington's disease has been traced to the number of CAG repeats in the HTT gene, which is located on chromosome 4. The phenotypic influence of individual alleles with different numbers of repeats is shown in Table 1. Table 1: Effect of CAG repeat number on Huntington's disease expression CAG RepeatsExpression<27No symptoms27-35No symptoms but increased risk for offspring36-39May develop symptoms in old age>40Will express symptoms from an early age Which of the following is most likely the immediate cause of the first appearance of Huntington's disease in a person? A A point mutation occurs in the HTTHTT gene. B The first appearance of the CAGCAG repeat occurs in the HTTHTT gene. C An allele with more than 39 CAGCAG repeats was inherited by the affected person. D The person inherited two alleles that each contained 20 CAGCAG repeats.

C

The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true? A The diagram illustrates a genetic condition found in females. B The diagram indicates a mechanism for increasing genetic diversity in subsequent generations. C The diagram illustrates the results of nondisjunction during gamete formation. D The diagram indicates Down syndrome, a genetic condition.

C

The relative location of four genes on a chromosome can be mapped from the following data on crossover frequencies Which of the following represents the relative positions of these four genes on the chromosome? A ABCD B ADCB C CABD D CBAD E DBCA

C

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? A It allows the tadpoles to change their genome in response to environmental pressures. B It enables the tadpoles to develop into a distinct species of toads. C It gives the tadpoles increased versatility with respect to diet. D It allows the tadpoles to delay metamorphosis until there is maximal food available for the adults.

C

1/1 MC point Rubber rabbitbrush plants display heritable variation in plant height and insect-induced gall formation. In a field study, researchers investigated the relationship between plant height and gall number for the rubber rabbitbrush plants in a natural population. The researchers used the data they collected to perform a chi-square test of independence. The null hypothesis for the chi-square test was that plant height and gall number are independent. The data for the chi-square test are presented in Table 1. Table 1. Data for the chi-square test of independence Height Category(cm)Number of Plants with Ten or Fewer GallsNumber of Plants with More than Ten Galls0-3034631-60221661-90142191-1201027 The researchers calculated a chi-square value of 29.25. If there are three degrees of freedom and the significance level is p=0.05, which of the following statements best completes the chi-square test? A The critical value is 0.05, and the null hypothesis cannot be rejected because the calculated chi-square value is greater than the critical value. B The critical value is 0.05, and the null hypothesis can be rejected because the calculated chi-square value is greater than the critical value. C The critical value is 7.82, and the null hypothesis cannot be rejected because the calculated chi-square value is greater than the critical value. D The critical value is 7.82, and the null hypothesis can be rejected because the calculated chi-square value is greater than the critical value.

D

A gene that influences coat color in domestic cats is located on the X chromosome. A female cat that is heterozygous for the gene (XBXO) has a calico-colored coat. In a genetics experiment, researchers mate a calico-colored female cat (XBXO) with an orange-colored male cat (XOY) to produce an F1 generation. The researchers record observations for the cats in the F1 generation and plan to use the data to perform a chi-square goodness-of-fit test for a model of X-linked inheritance. The data for the chi-square goodness-of-fit test are presented in Table 1. Table 1. Data for the chi-square goodness-of-fit test PhenotypeGenotypeObservedExpectedCalico-colored femaleXBXO1510Orange-colored femaleXOXO610Black-colored maleXBY1110Orange-colored maleXOY810 The researchers calculate a chi-square value of 4.6 and choose a significance level of p=0.05. Which of the following statements best completes the chi-square goodness-of-fit test? A The null hypothesis can be rejected because the chi-square value is greater than the critical value. B The null hypothesis can be rejected because the chi-square value is less than the critical value. C The null hypothesis cannot be rejected because the chi-square value is greater than the critical value. D The null hypothesis cannot be rejected because the chi-square value is less than the critical value.

D

A model showing the cells in anaphaseIand anaphaseIIof meiosis during a nondisjunction event is shown in Figure 1. Figure 1. Model of a nondisjunction event Which of the following best predicts the effect of the chromosomal segregation error shown in Figure 1? A All of the resulting gametes will have an extra chromosome. B All of the resulting gametes will be missing a chromosome. C Half of the resulting gametes will have an extra chromosome and the other half will be missing a chromosome. D Half of the resulting gametes will have the correct number of chromosomes, and the other half will have an incorrect number of chromosomes.

D

A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) andcinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a female with wild-type wings and eyes is mated with a male with vestigial wings and cinnabar eyes. All the F1individuals have wild-type wings and eyes. In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. The phenotypes of 500 F2 individuals are shown in the table A The two genes are located on two different chromosomes. B The two genes are sex-linked. C The two genes are located on mitochondrial DNA. D The two genes are linked on an autosome.

D

A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring. Which of the following is supported by the data A The alleles for gray body and long wings are dominant. B The alleles for gray body and long wings are recessive. C Genes for the two traits are located on two different chromosomes, and independent assortment occurred. D Genes for the two traits are located close together on the same chromosome, and crossing over occurred between the two gene loci.

D

Directions: This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. This group of questions refers to the probabilities below. Assume that the alleles referred to all assort independently. (A) 0 (B) 1/16 (C) 1/4 (D) 1/2 (E) 3/4 Probability that the genotype Aa will be produced by the parents Aa x Aa A 0 B 1/16 C 1/4 D 1/2 E 3/4

D

Eye pigment in a particular strain of fly is determined by two genes. An autosomal gene that controls the color of the pigments in the eye has two alleles: a dominant allele ( R ) that results in red eyes and a recessive allele ( r ) that results in sepia eyes. A sex-linked gene that controls the expression of the colored pigments also has two alleles: a dominant allele ( T ) that allows for expression of the colored pigments and a recessive allele ( t ) that does not allow for expression of the colored pigments. Individuals without a T allele have white eyes regardless of the alleles of other eye-color genes. Which of the following represents a cross between a white-eyed female and a red-eyed male? A TtXRXR×ttXrY B TtXrXr×ttXRY C RRXTXT×RrXTY D RrXtXt×RrXTY

D

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? A The genotype does not contribute to coat color in Himalayan rabbits. B The phenotype determines the genotype of coat color in Himalayan rabbits. C Different environments cause specific mutations in the genes controlling pigment production. D The environment determines how the genotype is expressed.

D

If in the F1 and F2 generations the same charac... 1/1 MC point Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it. A male fruit fly (Drosophila melanogaster) with red eyes and long wings was mated with a female with purple eyes and vestigial wings. All of the offspring in the F1 generation had red eyes and long wings. These F1 flies were test crossed with purple-eyed, vestigial-winged flies. Their offspring, the F2 generation, appeared as indicated below. If in the F1 and F2 generations the same characteristics appeared in both males and females, it would be safe to assume that these traits for eye color and wing length A are sex-linked B vary in dominance according to sex C are sex-influenced characteristics D are autosomal characteristics E follow the Mendelian rule of independent assortment

D

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. Figure 1. Migration of homologous chromosomes during anaphase I of meiosis A compound that prevents the separation of the homologous chromosomes in anaphase I is being studied. Which of the following questions can be best answered during this study? A Will the cells produced at the end of meiosis still be genetically identical to each other in the presence of this compound? B Will the long-term development of the individual be affected by this meiotic error? C When do the centrosomes start to move apart during meiosis II as compared to meiosis IIII? D Is there a pattern to the movement of homologous chromosomes in the presence of this compound?

D

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. Table 1. Results of a genetic cross between two heterozygous corn plants Offspring PhenotypeObservedExpectedPurple, smooth kernels918900Purple, wrinkled kernels281300Yellow, smooth kernels314300Yellow, wrinkled kernels87100 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? A The calculated chi-square value is 0.66, and the critical value is 0.05. The null hypothesis can be rejected. B The calculated chi-square value is 0.66, and the critical value is 3.84. The null hypothesis cannot be rejected. C The calculated chi-square value is 3.91, and the critical value is 5.99. The null hypothesis can be rejected. D The calculated chi-square value is 3.91, and the critical value is 7.82. The null hypothesis cannot be rejected.

D

In the pedigree above, circles represent females, squares represent males, and shaded figures represent individuals expressing a specific trait. The expression of this trait is most likely due to which of the following?(number 3 on Hereditary Test) A Sex-linked dominant inheritance B Sex-linked recessive inheritance C Autosomal dominant inheritance D Autosomal recessive inheritance

D

In the pedigree above, squares represent males and circles represent females. Individuals who express a particular trait are represented by shaded figures. Which of the following patterns of inheritance best explains the transmission of the trait?(number 5 on the hereditary test) A Sex-linked dominant B Sex-linked recessive C Autosomal recessive D Autosomal dominant E Incompletely dominant

D

R. C. Punnett conducted experiments on the inheritance of traits in the sweet pea, Lathyrus odoratus. In one experiment, he crossed two different true-breeding sweet pea plant strains, one with erect petals and long pollen, and the other with hooded petals and round pollen. All the offspring (F1 generation) had erect petals and long pollen (Figure 1). Figure 1. Sweet pea plant cross Next, Punnett allowed the F1 generation to self-fertilize and recorded the phenotypes of their offspring. The data are shown in Table 1. Table 1. F2 results of F1 self-fertilization cross Phenotype of F2Number of OffspringErect petals, long pollen765Erect petals, round pollen62Hooded petals, long pollen71Hooded petals, round pollen220Total1,118 Which of the following questions would be most useful to researchers trying to determine the role of meiosis in the F2 phenotypic frequencies? A What is the molecular mechanism underlying the dominance of erect petals and long pollen? B Which phenotypes give pea plants the highest level of fitness: erect or hooded petals and long or round pollen? C How do the phases of meiosis differ between sweet pea plants and other organisms? D What is the recombination frequency between the genes for petal shape and pollen shape?

D

Which of the following best explains a distinction between metaphase I and metaphase II? A The nuclear membrane breaks down during metaphase II but not during metaphase IIII. B Chromosomes align at the equator of the cell during metaphase IIII but not during metaphase II. C The meiotic spindle is needed during metaphase II but not during metaphase IIII. D Homologous pairs of chromosomes are aligned during metaphase II, but individual chromosomes are aligned during metaphase IIII.

D

A couple has 5 children, all sons. If the woman gives birth to a sixth child, what is the probability that the sixth child will be a son? A 5/6 B 1/2 C 1/5 D 1/6 E 1/64

E

A blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow 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? A Blue flowers are incompletely dominant to pink flowers. B Pink flower color is a trait recessive to blue flower color. C Pink flower color is the result of somatic mutations in the flower color gene. D A previous generation of the blue-flowered parent must have included 50 percent pinkflowered plants.

b

Hereditary test number 20 about mathew and jane

d