chapter 11 test bank - rsffa.org · web viewfigure 11–7. 6. infer what do the letters r and i...

Chapter 11 Test Bank

Multiple ChoiceIdentify the choice that best completes the statement or answers the question.

____ 1. Each pea-plant gamete has how many alleles for the height gene?a. 1b. 2c. 3d. 4

____ 2. The different forms of a gene are calleda. traits.b. pollinations.c. alleles.d. hybrids.

____ 3. Gregor Mendel removed the male parts from the flowers of some plants in order toa. prevent hybrids from forming.b. prevent cross-pollination.c. stimulate self-pollination.d. control crosses between plants.

____ 4. If a pea plant has a recessive allele for green peas, it will producea. green peas if it also has a dominant allele for yellow peas.b. both green peas and yellow peas if it also has a dominant allele for yellow peas.c. green peas if it does not also have a dominant allele for yellow peas.d. yellow peas if it does not also have a dominant allele for green peas.

____ 5. When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inheriteda. one allele from each parent.b. two alleles from each parent.c. three alleles from each parent.d. four alleles from each parent.

____ 6. If a pea plant’s alleles for height are tt, what is true of its parents?a. Both parents were tall.b. Both parents were short.c. Both parents contributed a recessive allele.d. Both parents contributed a dominant allele.

____ 7. When Gregor Mendel crossed true-breeding tall plants with true-breeding short plants, why was it impossible to observe segregation?a. Alleles for height do not segregate in the F2.b. Alleles segregate only in the F2 generation.c. Alleles segregate best when two tall plants are crossed.d. Alleles in the F1 must be Tt to have height variety in the F2.

____ 8. A tall plant (TT) is crossed with a short plant (tt). If the tall F1 pea plants are allowed to self-pollinate,a. the offspring will be of medium height.b. all of the offspring will be tall.c. all of the offspring will be short.

d. the offspring can be tall or short.

____ 9. In the P generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 generation becausea. the allele for shortness becomes more common in the F2 generation.b. the allele for shortness becomes dominant in the F2 generation.c. the alleles for both heights segregated when the F1 plants made gametes.d. the alleles for tallness begin to disappear in the F2 generation.

____ 10. When you flip a coin, what is the probability that it will come up tails?a. 1b. 1/2c. 1/4d. 1/8

____ 11. The principles of probability can be used toa. predict the traits of the offspring of genetic crosses.b. determine the actual outcomes of genetic crosses.c. determine which species should be used in genetic crosses.d. decide which organisms are best to use in genetic crosses.

____ 12. A heterozygous tall pea plant is crossed with a short plant. The probability that an F1 plant will be tall isa. 25%.b. 50%.c. 75%.d. 100%.

____ 13. Organisms that have two identical alleles for a particular trait are said to bea. hybrid.b. homozygous.c. heterozygous.d. dominant.

Tt

T t

TTT TT Tt

T TT Tt

T = Tall

t = Short

Figure 11–1

____ 14. In the Punnett square shown in Figure 11–1, which of the following is true about the offspring resulting from the cross?a. About half are expected to be short.b. All are expected to be short.c. About three fourths are expected to be tall.d. All are expected to be tall.

____ 15. What principle states that during gamete formation genes for different traits separate without influencing each other’s inheritance?a. principle of dominanceb. principle of independent assortmentc. principle of probabilitiesd. principle of segregation

RrYy

RY Ry rY ry

RY RRYY RRYy RrYY RrYySeed ShapeR = Round r = Wrinkled

RrYyRy RRYy RRyy RrYy Rryy

Seed ColorY = Yellow y = GreenrY RrYY RrYy rrYY rrYy

ry RrYy Rryy rrYy rryy

Figure 11–2

____ 16. The Punnett square in Figure 11–2 shows that the gene for pea shape and the gene for pea colora. assort independently.b. are linked.c. have the same alleles.d. are always homozygous.

____ 17. How many different allele combinations would be found in the gametes produced by a pea plant whose genotype was RrYY?a. 2b. 4c. 8d. 16

RrYy

RRYyRY Ry RY Ry

RY RRYY RRYy RRYY RRYyRy RRYy RRyy RrYy RRyyrY RrYY RrYy RrYY RrYyry RrYy Rryy RrYy Rryy

Figure 11–3

____ 18. Use Figure 11–3 to answer the following question. If a pea plant that is heterozygous for round, yellow peas (RrYy) is crossed with a pea plant that is homozygous for round peas but heterozygous for yellow peas (RRYy), how many different phenotypes are their offspring expected to show?a. 2b. 4c. 8d. 16

____ 19. Gregor Mendel’s principles of genetics apply toa. plants only.b. animals only.c. pea plants only.d. all organisms.

____ 20. Why did Thomas Hunt Morgan use fruit flies in his studies?a. Fruit flies produce a large number of offspring.b. Fruit flies take a long time to produce offspring.c. Fruit flies share certain characteristics with pea plants.d. Fruit flies have a long life span.

____ 21. A male and female bison that are both heterozygous for normal skin pigmentation (Aa) produce an albino offspring (aa). Which of Mendel’s principles explain(s) why the offspring is albino?a. dominance onlyb. independent assortment onlyc. dominance and segregationd. segregation only

____ 22. Roan cattle show codominance for the color of their hair. There are alleles for red hair and white hair. What would you expect a heterozygous roan bull to look like if the trait showed incomplete dominance instead? a. It would be red.b. It would be white.c. It would be spotted.d. It would be pink.

____ 23. A breed of chicken shows codominance for feather color. One allele codes for black feathers, another codes for white feathers. The feathers of heterozygous chickens of this breed will bea. black.b. white.c. gray.d. speckled.

____ 24. Situations in which one allele for a gene is not completely dominant over another allele for that gene are calleda. multiple alleles.b. incomplete dominance.c. polygenic inheritance.d. multiple genes.

____ 25. In rabbits, there are four different versions of the gene for coat color. What pattern of inheritance is this?a. incomplete dominance.b. polygenic inheritance.c. codominance.d. multiple alleles.

____ 26. Variation in human skin color is an example ofa. incomplete dominance.b. codominance.c. polygenic traits.d. multiple alleles.

____ 27. What determines the color of western white butterflies?a. genes alone.b. the environment alonec. temperature and genesd. exposure to sunlight and genes

____ 28. Which of the following supports the claim that the environment can affect genetic traits?a. Oak trees get taller as they grow.b. Hydrangea flower color varies with soil pH.c. Dandelion plants are self pollinating. d. Pinion trees bear cones every other year.

____ 29. The arctic fox is blue-gray in the summer and white in the winter. What most likely influence(s) this change?a. genes and the environmentb. dominant allelesc. the environment aloned. codominant alleles

____ 30. The number of chromosomes in a gamete is represented by the symbola. Z.b. X.c. N.d. Y.

____ 31. If an organism’s diploid number is 12, its haploid number isa. 12.b. 6.c. 24.d. 3.

____ 32. Gametes havea. homologous chromosomes.b. twice the number of chromosomes found in body cells.c. two sets of chromosomes.

d. one allele for each gene.

____ 33. Gametes are produced by the process ofa. mitosis.b. meiosis.c. crossing-over.d. replication.

Figure 11–4

____ 34. What is shown in Figure 11–4?a. independent assortmentb. anaphase I of meiosisc. crossing-overd. replication

____ 35. Chromosomes form tetrads duringa. prophase I of meiosis.b. metaphase I of meiosis.c. interphase.d. anaphase II of meiosis.

____ 36. A tetrad consists ofa. a homologous pair of chromosomes, each made of two chromatids.b. the four copies of a chromosome that are normally present in cells.c. two sister chromatids that have each been replicated during interphase.d. a parental chromosome that was replicated to form a pair, then replicated again.

____ 37. Unlike mitosis, meiosis results in the formation ofa. diploid cells.b. haploid cells.c. 2N daughter cells.d. body cells.

____ 38. What is formed at the end of meiosis?a. two genetically identical cellsb. four genetically different cellsc. four genetically identical cellsd. two genetically different cells

____ 39. One way that meiosis I is different from mitosis is that

a. replication occurs during interphase before mitosis, but not before meiosis I. b. meiosis I produces 2 haploid daughter cells, but mitosis produces 2 diploid daughter cells.c. homologous chromosomes are segregated during mitosis, but remain together during

meiosis I.d. sister chromatids are pulled apart during meiosis I, but not during mitosis.

____ 40. Which of the following assort independently?a. chromosomesb. linked genesc. multiple allelesd. codominant alleles

____ 41. Linked genesa. are never separated.b. assort independently.c. are on the same chromosome.d. are always recessive.

Gene Map of Chromosome 2 of the Fruit Fly

Figure 11–5

____ 42. Which trait is most likely linked to having a curved wing in the fruit fly in Figure 11–5?a. dumpy wingb. vestigial wingc. arc (bent wings)d. speck wing

____ 43. Gene maps are based ona. the frequencies of crossing-over.b. independent assortment.c. genetic diversity.d. the number of genes in a cell.

____ 44. If two genes are on the same chromosome and rarely assort independently,

a. crossing-over never occurs between the genes.b. crossing-over always occurs between the genes.c. the genes are probably located far apart from each other.d. the genes are probably located close to each other.

____ 45. The farther apart two genes are located on a chromosome, thea. less likely they are to be inherited together.b. more likely they are to be linked.c. less likely they are to assort independently.d. less likely they are to be separated by crossing over.

Modified True/FalseIndicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.

____ 1. A trait is a specific characteristic that can vary from one individual to another. _____________________________ 2. True-breeding plants that produced axial flowers were crossed with true-breeding plants that produced

terminal flowers. The resulting offspring all produced terminal flowers because the allele for terminal flowers is recessive. _________________________

____ 3. During the formation of gametes in a hybrid tall plant, the tall allele and the short allele stay together. _________________________

____ 4. If the alleles for a trait did not segregate during gamete formation, offspring would always show the trait of at least one of the parents. _________________________

____ 5. The principles of probability can explain the numerical results of Mendel’s experiments. _________________________

____ 6. The probability that a gamete produced by a pea plant heterozygous for stem height (Tt) will contain the recessive allele is 100%. _________________________

____ 7. If Mendel had found that an F2 cross of plants that were heterozygous for two traits had made offspring with two phenotypes, this finding would have supported the theory of independent assortment. _________________________

____ 8. A trait in an unidentified plant is controlled by one gene that has two alleles. One allele is dominant over the other. According to Mendel’s principles, one fourth of the offspring made from a cross between two heterozygous plants will show the recessive trait. _________________________

____ 9. If two speckled chickens are mated, according to the principle of codominance, 25% of the offspring are expected to be speckled. _________________________

____ 10. For the trait of blood type in humans, there is an allele for Type A, an allele for Type B, and an allele for Type O. Each person inherits one of these alleles from each of their parents, and their blood type is determined by what combination of these alleles they receive. Blood type is inherited as a polygenic trait.

____ 11. If an organism has 16 chromosomes in each of its egg cells, the organism’s diploid number is 32. _________________________

____ 12. If an organism is heterozygous for a particular gene, the two different alleles will be separated during anaphase II of meiosis, assuming that no crossing-over has occurred. _________________________

____ 13. Mitosis results in two cells, whereas meiosis results in one cell. _____________________________ 14. If an organism has four linkage groups, it has eight chromosomes. _____________________________ 15. Genes in the same linkage group are usually inherited separately. _________________________

CompletionComplete each statement.

1. The plants that Gregor Mendel crossed to produce the F1 generation made up the ____________________ generation.

2. Due to the process of segregation, alleles separate during the production of ____________________ .3. An organism has 38 chromosomes in a body cell. After mitosis each cell has 38 chromosomes. After meiosis

each gamete has ____________________ chromosomes.4. What is the probability of flipping a coin and getting heads 5 times in a row?

Tt

T t

TTT TT Tt

T TT Tt

T = Tall

t = Short

Figure 11–1

5. In the Punnett square shown in Figure 11–1, the genotypes of the offspring are ____________________.6. The principle of independent assortment states that ____________________ for different traits can segregate

independently during the formation of gametes.7. If pea plants that are homozygous for round, yellow seeds (RRYY) were crossed with pea plants that are

heterozygous for round, yellow seeds (RrYy), the expected phenotype(s) of the offspring would be _________________________.

8. ____________________’s principles can be used to study heredity in dogs, cats and sheep.9. The reddish-brown pigment that gives color to a fruit-fly’s eye is controlled by three genes, so a fruit fly’s eye

color is a __________________.10. Western white butterflies that hatch in springtime have more pigment in their wings than those that hatch in

summer. The darker wings help the butterflies stay warmer by absorbing more ____________________ than the lighter-colored wings.

11. The characteristics of an organism are determined by two factors: ____________________.12. In four o’clock plants, flower color is controlled by two alleles that show _________________________.13. An organism’s gametes have ____________________ the number of chromosomes found in the organism’s

body cells.14. Crossing-over occurs during the stage of meiosis called ____________________.15. The relative locations of each known gene can be shown on a ____________________ map.

Short Answer

1. What attributes of the garden pea plant made it an excellent organism for Gregor Mendel’s genetic studies?2. Explain how allowing the F1 generation plants to self-pollinate in producing the F2 generation allowed Mendel

to reach his conclusions about inheritance.3. Explain how a trait might seem to “disappear” for a generation, and then “reappear” in the following

generation.RrYy

RY Ry rY ry

RY RRYY RRYy RrYY RrYySeed ShapeR = Round r = Wrinkled

RrYyRy RRYy RRyy RrYy Rryy

Seed ColorY = Yellow y = GreenrY RrYY RrYy rrYY rrYy

ry RrYy Rryy rrYy rryy

Figure 11–2

4. What is the phenotype ratio of the offspring of the plants in the Punnett square in Figure 11–2?5. A tall pea plant with yellow seeds is heterozygous for height and seed color (TtYy). This plant is crossed with

a pea plant heterozygous for height but homozygous recessive for seed color (Ttyy). If 80 offspring are produced, how many are expected to be tall and have yellow seeds?

6. Mendel chose to use pea plants in his studies and Morgan chose to use fruit flies in his work. What characteristics of these species make them good organisms to use for the study of genetics?

7. What is the probability that a cross between parents who are both homozygous recessive for trait will have offspring that are homozygous recessive for that trait?

8. Arctic foxes have blue-gray fur in summer and change to white fur in winter. What would be one way to test whether this change is influenced by cooling seasonal temperatures?

9. How many sets of chromosomes are in a diploid cell?10. Define homologous chromosomes.11. What happens to the number of chromosomes per cell during meiosis?12. Contrast the cells produced by mitosis with those produced by meiosis.13. What are the only kinds of cells that undergo meiosis?14. Why did Gregor Mendel not observe gene linkage during his experiments with pea plants?

Gene Map of Chromosome 2 of the Fruit Fly

Figure 11–5

15. Figure 11–5, the gene map of a fruit fly’s chromosome 2, shows the relative locations of the star eye, dumpy wing, and black body genes to be 1.3, 13.0, and 48.5, respectively. Between which two genes does crossing-over occur most frequently?

Science Skills

Heterozygous male guinea pigs with black, rough hair (BbRr) are crossed with heterozygous female guinea pigs with black, rough hair (BbRr). The incomplete Punnett square in Figure 11–6 shows the expected results from the cross.

BbRr

BR Br bR br

BR BBRR BBRr BbRR BbRrHair ColorB = Blackb = White

BbRrBr BBRr BBrr BbRr Bbrr

Hair TextureR = Roughr = SmoothbR BbRR BbRr ? bbRr

br BbRr Bbrr bbRr bbrr

Figure 11–6

1. Interpret Tables Identify the genotype of the offspring that would be represented by the question mark in Figure 11–6.

2. Interpret Tables Identify the phenotype of the offspring represented by the question mark in Figure 11–6.3. Analyze Data In Figure 11–6, what are the different phenotypes of the offspring?4. Analyze Data In Figure 11–6, what are the genotypes of the offspring that have black, rough hair?5. Calculate What fraction of the offspring in Figure 11–6 would be expected to have white, smooth hair?

Figure 11–7

6. Infer What do the letters R and I represent in Figure 11–7?7. Interpret Visuals In Figure 11–7, what is the genotype of the pink-flowered snapdragons?8. Infer Explain whether the alleles in Figure 11–7 show dominance, incomplete dominance, or codominance.9. Infer According to Figure 11–7, if red-flowered snapdragons and ivory-flowered snapdragons are crossed,

what percentage of their offspring would be expected to be pink-flowered?10. Infer Could the red snapdragons shown in the P generation of Figure 11–7 ever have white offspring?

Explain your answer.

Figure 11–8

11. Interpret Visuals In Figure 11–8, what is the structure labeled X in stage A?12. Interpret Visuals In Figure 11–8, during which stage might new allele combinations form? Identify the

stage.13. Infer If the stages shown in Figure 11–8 were taking place in a female animal, how many eggs would

generally result from stage G? Explain your answer.14. Interpret Visuals List the stages in Figure 11–8 in which the cells are 2N and those in which the cells are N.15. Infer In Figure 11–8, in which stage does each cell have a single copy of each gene? Identify the stage.

Essay

1. You wish to determine whether a tall pea plant is homozygous or heterozygous for tallness. What cross should you perform to arrive at your answer? Explain your choice of cross.

2. A pea plant with yellow seeds was crossed with a plant with green seeds. The F1 generation produced plants with yellow seeds. Explain why green seeds reappeared in the F2 generation.

3. Why are the results of genetic crosses shown in Punnett squares interpreted as probabilities, not certainties? Give some specific reasons.

4. A cross between two organisms heterozygous for two different genes (AaBb) likely results in a 9 : 3 : 3 : 1 phenotype ratio among the offspring. Is the offspring’s genotype ratio the same? Explain your answer.

5. A plant nursery owner wants to guarantee that the seeds she sells produce only pink-flowered four o’clock plants. How should she obtain the seeds?

6. Suppose you have western white butterflies from a population that hatched in spring, and those butterflies then had offspring that hatched in the summer. What would you expect the offspring born in the summer to look like? Explain your answer.

7. Which has more genetic information, a body cell or a gamete? Explain your answer.8. The stages of meiosis are classified into two phases: meiosis I and meiosis II. Compare and contrast these two

phases.9. Explain why the daughter cells produced by meiosis are genetically different from each other, whereas the

daughter cells produced by mitosis are not.10. Define linkage, and explain how linkage is used to make gene maps.

Chapter 11 Test BankAnswer Section

MULTIPLE CHOICE

1. ANS: A PTS: 1 BLM: knowledge2. ANS: C PTS: 1 BLM: knowledge3. ANS: D PTS: 1 BLM: evaluation4. ANS: C PTS: 1 BLM: synthesis5. ANS: A PTS: 1 BLM: comprehension6. ANS: C PTS: 1 BLM: application7. ANS: D PTS: 1 BLM: analysis8. ANS: D PTS: 1 BLM: application9. ANS: C PTS: 1 BLM: analysis

10. ANS: B PTS: 1 BLM: knowledge11. ANS: A PTS: 1 BLM: analysis12. ANS: B PTS: 1 BLM: synthesis13. ANS: B PTS: 1 BLM: knowledge14. ANS: D PTS: 1 BLM: application15. ANS: B PTS: 1 BLM: knowledge16. ANS: A PTS: 1 BLM: comprehension17. ANS: A PTS: 1 BLM: analysis18. ANS: A PTS: 1 BLM: synthesis19. ANS: D PTS: 1 BLM: knowledge20. ANS: A PTS: 1 BLM: comprehension21. ANS: C PTS: 1 BLM: evaluation22. ANS: D PTS: 1 BLM: evaluation23. ANS: D PTS: 1 BLM: comprehension24. ANS: B PTS: 1 BLM: comprehension25. ANS: D PTS: 1 BLM: comprehension26. ANS: C PTS: 1 BLM: knowledge27. ANS: C PTS: 1 BLM: comprehension28. ANS: B PTS: 1 BLM: evaluation29. ANS: A PTS: 1 BLM: analysis30. ANS: C PTS: 1 BLM: knowledge31. ANS: B PTS: 1 BLM: application32. ANS: D PTS: 1 BLM: synthesis33. ANS: B PTS: 1 BLM: knowledge34. ANS: C PTS: 1 BLM: application35. ANS: A PTS: 1 BLM: application36. ANS: A PTS: 1 BLM: analysis37. ANS: B PTS: 1 BLM: knowledge38. ANS: B PTS: 1 BLM: application39. ANS: B PTS: 1 BLM: synthesis40. ANS: A PTS: 1 BLM: comprehension

41. ANS: C PTS: 1 BLM: comprehension42. ANS: B PTS: 1 BLM: evaluation43. ANS: A PTS: 1 BLM: comprehension44. ANS: D PTS: 1 BLM: analysis45. ANS: A PTS: 1 BLM: evaluation

MODIFIED TRUE/FALSE

1. ANS: T PTS: 1 BLM: comprehension2. ANS: F, dominant

PTS: 1 BLM: application3. ANS: F, separate

PTS: 1 BLM: knowledge4. ANS: T PTS: 1 BLM: evaluation5. ANS: T PTS: 1 BLM: comprehension6. ANS: F

50%

PTS: 1 BLM: application7. ANS: F, contradicted

PTS: 1 BLM: evaluation8. ANS: T PTS: 1 BLM: analysis9. ANS: F, 50%

PTS: 1 BLM: analysis10. ANS: F, trait controlled by multiple alleles

PTS: 1 BLM: application11. ANS: T PTS: 1 BLM: analysis12. ANS: F, anaphase I

PTS: 1 BLM: analysis13. ANS: F, four cells

PTS: 1 BLM: knowledge14. ANS: F, four

PTS: 1 BLM: analysis15. ANS: F, together

PTS: 1 BLM: application

COMPLETION

1. ANS: P

PTS: 1 BLM: application2. ANS: gametes, sex cells

PTS: 1 BLM: comprehension3. ANS: 19

PTS: 1 BLM: analysis4. ANS: 1/2 x 1/2 x 1/2 x 1/2 x 1/2 = 1/32

PTS: 1 BLM: analysis5. ANS: TT and Tt

PTS: 1 BLM: application6. ANS: genes, chromosomes

PTS: 1 BLM: knowledge7. ANS: round yellow seeds only

PTS: 1 BLM: analysis8. ANS: Mendel

PTS: 1 BLM: application9. ANS: polygenic trait

PTS: 1 BLM: comprehension10. ANS: light energy

PTS: 1 BLM: evaluation11. ANS: genes and environmental conditions

PTS: 1 BLM: knowledge12. ANS: incomplete dominance

PTS: 1 BLM: analysis13. ANS: half

PTS: 1 BLM: comprehension14. ANS: prophase I

PTS: 1 BLM: analysis15. ANS: gene

PTS: 1 BLM: knowledge

SHORT ANSWER

1. ANS:

Garden pea plants produce many offspring, they have traits that come in only two forms, and crosses between the plants can be controlled easily.

PTS: 1 BLM: synthesis2. ANS:

Allowing the F1 pea plants to self-pollinate caused the recessive phenotype to reappear in the F2 generation. Self-pollination of the F1 plants also allowed the 3:1 phenotype ratios to occur, supporting Mendel’s theory. Self-pollination showed that traits controlled by recessive alleles could reappear in the F2 generation.


If all of the individuals in a generation receive one dominant allele and one recessive allele, then they would all show the dominant trait. If they are bred, then they will pass on the dominant allele to some of their offspring and the recessive allele to others. Offspring receiving two recessive alleles will show the recessive trait, so it will reappear.

PTS: 1 BLM: analysis4. ANS:

The phenotype ratio is 9 round, yellow seeds : 3 round, green seeds : 3 wrinkled, yellow seeds : 1 wrinkled, green seed.

PTS: 1 BLM: application5. ANS:

Thirty of the offspring are expected to be tall and have yellow seeds.


Both pea plants and fruit flies are small organisms and can be easily manipulated. Both can produce large numbers of offspring in a relatively short period of time.


100%


Keep an arctic fox warm when its native environment would be cool.

PTS: 1 BLM: evaluation9. ANS:

A diploid cell has two sets of chromosomes.

PTS: 1 BLM: knowledge10. ANS:

Homologous chromosomes are the two sets of chromosomes found in a body cell—one set inherited from the male parent and the other inherited from the female parent.

PTS: 1 BLM: comprehension11. ANS:

The number of chromosomes is cut in half.


Mitosis produces diploid body cells, whereas meiosis produces haploid gametes.


sex cells, gametes


The genes that Mendel studied were located on different chromosomes or were located far apart on the same chromosome.


Crossing-over occurs most frequently between the star eye gene and the black body gene.

PTS: 1 BLM: synthesis

SCIENCE SKILLS

1. ANS:The genotype of the offspring is bbRR.


The phenotype of the offspring is white, rough hair.


The phenotypes of the offspring are black, rough hair; black, smooth hair; white, rough hair; and white, smooth hair.


Offspring with black, rough hair have the genotypes BBRR, BBRr, BbRR, and BbRr.


One sixteenth of the offspring would be expected to have white, smooth hair.


R represents the allele for red flowers. I represents the allele for ivory flowers.


The genotype of the pink-flowered snapdragons is RI.


The alleles show incomplete dominance, because a cross between red-flowered snapdragons and ivory-flowered snapdragons produces snapdragons with an in-between trait—pink flowers.


One hundred percent of the offspring would be expected to be pink-flowered.


It is not possible for the red snapdragon to have white offspring. They are homozygous (RR) and therefore do not carry any white alleles. The red snapdragons in Figure 11–7 will always pass the R allele on to offspring and therefore the offspring can only be red or pink.


The structure is a tetrad.


New allele combinations might form during stage A, which is prophase I.


Generally, one egg would result. One of the four haploid cells would form an egg.

PTS: 1 BLM: comprehension14. ANS:

The cells in stages A, B, and C are 2N. The cells in stages D, E, F, and G are N.


Each cell in stage G, telophase II, has a single copy of each gene.

PTS: 1 BLM: analysis

ESSAY

1. ANS:The tall pea plant should be crossed with a short pea plant. If the tall pea plant is homozygous, all of the offspring will be tall. If the tall pea plant is heterozygous, it is likely that about half of the offspring will be tall and half will be short.


When the heterozygous yellow-seed F1 plants produced gametes, their dominant allele for yellow seeds segregated from their recessive allele for green seeds. As a result, some of their gametes had the dominant allele, and others had the recessive allele. When the F1 plants self-pollinated, some male gametes with the recessive allele fused with female gametes with the recessive allele during fertilization. Some of the offspring that resulted had two alleles for green seeds and therefore had green seeds.


The kinds of offspring produced by genetic crosses are the results of chance. For example, the number of gametes produced that contain particular alleles is not certain. Likewise, the fusion of two gametes with particular alleles is not certain. Thus, the results of genetic crosses shown in Punnett squares are just probable results.


The genotype ratio of the offspring is not the same as their phenotype ratio. The same phenotype can be produced by several different genotypes. For example, offspring that are heterozygous for both traits (AaBb) will have the same phenotype as offspring that are homozygous for both traits (AABB).


The alleles that determine flower color in four o’clock plants show incomplete dominance. She should use pollen from white-flowered four o’clock plants to pollinate red-flowered four o’clock plants, or vice versa. She should then collect seeds from the offspring. All of these hybrid seeds will produce only pink-flowered four o’clock plants.


I would expect the offspring to be lighter-colored than their parents. The phenotype for color in these butterflies is determined by two components: genes and environmental conditions. The offspring would have their parents’ genetic material, but they would have a different environmental influence. The butterflies born in the summer would have lower levels of pigment and so would be lighter.


A body cell has more genetic information than a gamete. A gamete is haploid, so it has just one allele for each gene. A body cell is diploid. It has two alleles for each gene. So, a body cell has twice as much genetic information as a sex cell.


Both meiosis I and meiosis II contain a prophase, a metaphase, and an anaphase. However, chromosomes replicate prior to meiosis I but not prior to meiosis II. Also, during meiosis I, tetrads form and align along the center of the cell. Then, the homologous chromosomes are separated and two haploid daughter cells form. During meiosis II, sister chromatids align along the center of the cell and are then separated. Four haploid daughter cells form.


During meiosis, the pairs of homologous chromosomes in the parent cell form tetrads and then separate. As a result, each daughter cell receives only one chromosome from each homologous pair, and the particular chromosomes that it receives are random. Thus, each daughter cell has a different combination of chromosomes. Also, crossing-over may occur during meiosis and may result in new combinations of alleles on the chromosomes in the daughter cells. In contrast, during mitosis, homologous chromosomes usually do not form tetrads and separate, and therefore crossing-over usually does not occur.


Linkage is the condition in which two genes are located on the same chromosome. As a result, the genes’ alleles are usually inherited together. However, if crossing-over occurs between the alleles of the linked genes, those alleles no longer are inherited together. The frequency of crossing-over between linked genes (or the frequency in which linked genes are inherited separately) is used to determine the relative locations of genes on the same chromosome, resulting in a gene map. The greater the frequency of separate inheritance, the farther apart the genes on the chromosome.

PTS: 1 BLM: analysis

chapter 11 test bank - rsffa.org · web viewfigure 11–7. 6. infer what do the letters r and i...

Documents