Final Exam - Homework Questions

A couple are planning to have children and want to calculate the odds that the mother's shoulder dimples will be passed to the children. Shoulder dimples are a dominant trait, the mother's genotype is (Dd) and the father's genotype is (dd). Use the binomial expansion to calculate the odds of having 4 children with shoulder dimples and 1 child without them. (p +q )5 = p^5 + 5p^4q + 10p^3q^2 + 10p^2q^3 + 5pq^4 + q^5 p is the probability of a child having shoulder dimples q is the probability of a child without shoulder dimples

0.16

The following two genotypes are crossed: AaBbCcddEe × AabbCcDdEe. What will be the proportion of the genotype AaBbCcDdEe among the progeny of this cross?

1/32

A cross of Aa x Aa would result in a genotypic ratio of _______.

1:2:1

In cucumbers, dull fruit (D) is dominant over glossy fruit (d), orange fruit (R) is dominant over cream fruit (r), and bitter cotyledons (B) are dominant over nonbitter cotyledons (b). The three characters are encoded by genes located on different pairs of chromosomes. A plant homozygous for dull, orange fruit and bitter cotyledons is crossed with a plant that has glossy, cream fruit and nonbitter cotyledons. The F1 are intercrossed to produce the F2. Give the expected proportion of offspring with a dull, orange, and bitter phenotype or a glossy, orange, and bitter phenotype in the F2.

9/16

In cats, curled ears result from an allele (C) that is dominant over an allele (c) for normal ears. Black color results from an independently assorting allele (G) that is dominant over an allele for gray (g). A gray cat homozygous for curled ears is mated with a homozygous black cat with normal ears. All the F1 cats are black and have curled ears. If two of the F1 cats mate, what phenotypes and proportions are expected in the F2?

9/16 black cats, curled ears; 3/16 black cats, normal ears; 3/16 gray cats, curled ears; and 1/16 gray cats, normal ears

In chickens, congenital baldness is due to a Z-linked recessive gene. A bald rooster is mated with a normal hen. When looking only at the possible females, what percentage of them will be bald? A. 100% bald B. 75% bald C. 25% bald D. 0% bald

A.

Red-green color blindness in humans is due to an X- linked recessive gene. Both John and Cathy have normal color vision. After 10 years of marriage to John, Cathy has given birth to a color-blind daughter and a color-blind son. John filed for divorce, claiming that he is not the father of at least one of the children. Is John justified in his claim of nonpaternity? (Assume that the daughter is homozygous recessive for the colorblindness allele and both children result from gametes produced from normal meiotic events in both parents.) A. Yes. He cannot be the father of Cathy's daughter. B. Yes. He cannot be the father of Cathy's son. C. Yes. He cannot be the father of either child. D. No. He could be the father of both children

A.

Why do sister chromatids remain together in anaphase I of meiosis but separate in anaphase of mitosis and anaphase II of meiosis? A. Shugoshin protects cohesin at the centromeres in anaphase I, protecting it from the action of separase. B. Separase is active only in anaphase II of meiosis and in anaphase of mitosis. C. Cohesin protects shugoshin at the centromeres in anaphase I, protecting it from the action of separase. D. The enzyme separase becomes active at the end of metaphase in both mitosis and meiosis II cleaves the securin protein complex holding the sister chromatids together.

A.

What would be the consequences to the outcome of meiosis if shugoshin is absent during meiosis? A. sister chromatids would fail to separate during anaphase II B. homologous pairs could separate prior to anaphase I C. sister chromatids could separate along with homologous pairs during anaphase I D. homologous pairs could fail to separate during anaphase I E. The absence of shugoshin during meiosis is likely to have no impact on meiosis

C.

Which of the following codes for a phenotypic human male? A. XY with the SRY gene deleted B. XXY with the SRY gene deleted C. XX with the copy of the SRY gene on an autosomal chromosome D. Both A and B E. Both A and C

C.

If you were to roll a ten-sided die twice in a row, what is the probability of obtaining a 7 and then a 9? A. 1/8 B. 1/10 C. 1/32 D. 1/100 E. 1/64

D.

In cucumbers, orange fruit color (R) is dominant over cream fruit color (r). A cucumber plant homozygous for orange fruit is crossed with a plant homozygous for cream fruit. Give the genotypes and phenotypes of the offspring of a backcross between the F1 and the orange parent. A. Orange (RR) B. Orange (Rr) C. Cream (rr) D. Both A and B E. Both B and C

D.

In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Cc X chc. A. 1 full color:1 chinchilla B. 1 full color:1 Himalayan C. 1 chinchilla:1 Himalayan D. 3 full color:1 chinchilla E. 2 full color:1 Himalayan:1 albino

E.

What characteristic is exhibited by an X-linked trait? A. Only females have the trait. B. Males inherit X-linked traits from their paternal parent only. C. Females inherit X-linked traits from their maternal parent only. D. Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers. E. Females can inherit a gene for an X-linked trait from either parent.

E.

In the California poppy, an allele for yellow flowers (C) is dominant over an allele for white flowers (c). At an independently assorting locus, an allele for entire petals (F) is dominant over an allele for fringed petals (f). A plant that is homozygous for yellow and entire petals is crossed with a plant that is white and fringed. A resulting F1 plant is then crossed with a plant that is white and fringed, and the following progeny are produced: 54 yellow and entire, 58 yellow and fringed, 53 white and entire, and 10 white and fringed. Using a chi-square test to compare the observed numbers with those expected for the cross, what can you conclude in regard to whether the ratios observed occurred due to random variations?

With three degrees of freedom, the chi-square value is greater than 12.838 for a probability value of less than 0.005, so the deviation between observed and expected was not likely to occur by chance.

Coat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X+) encodes black fur; another allele (Xo) encodes orange fur. Females can be black (X+X+), orange (XoXo), or a mixture of orange and black called tortoiseshell (X+Xo). Males are either black (X+Y) or orange (XoY). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill's house, spends the night out, and mates with a stray male. Patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. What was the genotype of the stray cat with which Patches mated?

XoY