Mendelian Genetics

Review Questions

Homologous chromosomes move toward opposite poles of a dividing cell during

a. mitosisb. meiosis Ic. meiosis IId. fertilization

Question 1

Homologous chromosomes move toward opposite poles of a dividing cell during

b. meiosis I

Answer 1

Meiosis II is similar to mitosis in thata. Sister chromatids separate during

anaphase.b. DNA replicates before the divisionc. The daughter cells are diploidd. Homologous chromosomes

synapse

Question 2

Meiosis II is similar to mitosis in thata. Sister chromatids separate during

anaphase.b. DNA replicates before the divisionc. The daughter cells are diploidd. Homologous chromosomes

synapse

Answer 2

Monohybrid crossa. Variant for a characterb. Genetic makeup of an individualc. An alternative version of a gened. A cross between individuals

heterozygous for a single character

Question 3

Monohybrid crossa. Variant for a characterb. Genetic makeup of an individualc. An alternative version of a gened. A cross between individuals

heterozygous for a single character

Answer 3

Allelea. Alternative version of a geneb. Has no effect on phenotype in a

heterozygotec. An organism's appearance d. Genetic makeup of an individual

Question 4

Allelea. Alternative version of a geneb. Has no effect on phenotype in a

heterozygotec. An organism's appearance d. Genetic makeup of an individual

Answer 4

A man with type A blood marries a woman with type B blood. Their child has type O blood. What are the genotypes of these individuals? What other genotypes, and in what frequencies, would you expect in offspring from this marriage?

Question 5

Man IAi, Woman IBi, child iiOther genotypes for children are ¼ IAIB, ¼ IAi, ¼, IBi

Answer 5

In tigers, a recessive allele causes an absence of fur pigmentation (white tiger) and a cross-eyed condition. If 2 phenotypically normal tigers that are heterozygous at this locus are mated, what % of their offspring will be cross-eyed? What % of cross-eyed tigers will be white?

Question 6

25% will be cross-eyed; all of the cross-eyed offspring will also be white.

Answer 6

A man with hemophilia (recessive, sex-linked) has a daughter of normal phenotype. She marries a man who is normal for the trait. What is the probability that a daughter of this mating will be a hemophiliac? That a son will be a hemophiliac? If the couple has four sons, what is the probability that all 4 will be born with hemophilia?

Question 7

0; ½; 1/16

Answer 7

Red-green color blindness is caused by a sex-linked recessive allele. A color-blind man marries a woman with normal vision whose father was color-blind. What is the probability that they will have a color-blind daughter? What is the probability that their 1st son will be color-blind? (Note the different wording of the 2 questions)

Question 8

¼ for each daughter ( ½ chance that a child will be female x ½ chance of a homozygous recessive genotype); ½ for 1st son.

Answer 8

A wild-type fruit fly (heterozygous for gray body color & normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild type, 778; black-vestigial, 758; black normal, 158; gray-vestigial, 162. What is the recombination frequency between these genes for body color & wing size?

Question 9

17%

Answer 9

What pattern of inheritance would lead a geneticist to suspect that an inherited disorder of cell metabolism is due to a defective mitochondrial gene?

Question 10

The disorder would always be inherited from the mother.

Answer 10

Pseudohypertrophic muscular dystrophy is an inherited disorder that causes gradual deterioration of the muscles. It is seen almost exclusively in boys born to apparently normal parents & usually results in death in the early teens. Is this disorder caused by a dominant or a recessive allele? Is its inheritance sex-linked or autosomal? Why?

Question 11

Recessive, if it were dominant it would affect at least 1 parent of a child with the disorder. The disorder’s inheritance is sex-linked because it is seen only in boys. For a girl to have the disorder, she would have to inherit recessive alleles form both parents. This would be very rare, since males with the recessive allele on their X chromosome die in their early teens.

Answer 11

How many chromatids are in a duplicated chromosome?

Question 12

2

Answer 12

A chicken has 78 chromosomes in its somatic cells. How many chromosomes did the chicken inherit from each parent? How many chromosomes are in each of the chicken’s gametes? How many chromosomes will be in each somatic cell of the chicken’s offspring?

Question 13

39; 39; 78

Answer 13

What phase are most of your body cells in?

Question 14

Non-dividing state called G₀.

Answer 14

Each sperm of a pea plant contains 7 chromosomes. What are the haploid & diploid numbers for peas?

Question 15

Haploid = (n) 7 Diploid = (2n) 14

Answer 15

What is the original source of all the different alleles of a gene?

Question 16

Mutations in a gene lead to the

different version (alleles) of that gene.

Answer 16

A pea plant heterozygous for inflated pods (Ii) is crossed with a plant homozygous for constricted pods (ii). Draw a Punnett square for this cross. Assume pollen come from the ii plant.

Question 17

i i

I Ii Ii Genotype 2:2

Phenotype 2:2

i ii ii

Answer 17

An organism with the genotype BbDD is mated to one with the genotype BBDd. Assuming independent assortment of these 2 genes, write the genotypes of all possible offspring from this cross & use the rules of probability to calculate the chance of each genotype occurring.

Question 18

¼ BBDD, ¼ BbDD, ¼ BBDd, ¼

BbDd

Answer 18

Incomplete dominance & epistasis are both terms that define genetic relationships. What is the most basic distinction between these terms?

Question 19

Incomplete dominance describes

the relationship between 2 alleles of a single gene, whereas epistasis relates to the genetic relationship between 2 genes and the respective alleles of each.

Answer 19

Andalusian chickens with the genotype CBCB are black, those with the genotype CWCW are white, and those with the genotype CBCW are gray. What is the relationship between the CB and CW alleles?

Question 20

The relationship between the

alleles is one of incomplete dominance.

Answer 20