online quiz 10

Homologous chromosomes in meiosis

d. can adopt two different alignments.

A woman of blood group A has a child with a man of blood group B. The child's blood is type O. What must be the genotype of the parents?
c. Mother: IAio; father: IBio

The 9:3:3:1 ratio is obtained
b. in a dihybrid cross in which the genes are on different chromosomes.

In a test cross, peas of an unknown genotype are crossed with peas of a known genotype. In this example, smooth peas are the unknown and wrinkled peas are the known (rr). If half of the offspring from that cross are smooth and half are wrinkled, what is the genotype of the unknown plant?

d. Heterozygous: Rr

The fact that a trait like height in humans varies over a wide range of values is due to

c. multiple alleles, and the environmental influences on the expression of these genes.

Coat color in mice involves the effects of multiple gene interactions. If a mouse has two recessive alleles (aa) for coat color, it is always albino no matter what the genotype is for the other genes involved in coat color. This is an example of
d. epistasis.

Different genes always assort independently whether the genes reside on the same chromosome or on different chromosomes.

b. False

In pea plants, the gene for yellow seeds, Y, is dominant to the allele for green seeds, y. A plant with green seeds must have the genotype
c. yy.

In humans, brown spotting of teeth is caused by a dominant sex-linked (X-linked) gene. If a man with brown teeth marries a woman with normal teeth ___ have brown teeth.
c. all of their daughters

Incomplete dominance
a. results in a phenotypic ratio of 1:2:1 in a monohybrid cross.

In many animals, including humans, sex is determined by a single ___, or by a pair of them. Both males and females have two copies of each of the rest of the chromosomes, which are called

c. sex chromosome; autosomes.

What is the map distance between two genes with a recombination frequency of 0.08?
a. 8 cM

___ is the term meaning an allele that has more than one distinguishable phenotypic effect.
a. Pleiotropy

Wild type fruit flies have red eyes. In a genetics experiment, you cross a white-eyed female fly with a red-eyed male fly. You then examine the phenotypes of the F1 generation and find that all of the females are red-eyed and all of the males are white-eyed. What type of inheritance pattern is this?

e. Sex-linked on X chromosome

You are examining three different genes, a, b, and c. They all reside on the same chromosome and you want to know the order of the genes along the chromosome. You determine that genes a and b are 10 cM apart, b and care 2 cM apart and that a and c are 8 cM apart. What is the order of these genes?

b. a, c, b

Genes that are found in organelles such as mitochondria, are usually inherited in what fashion.

b. From the mother


b. involves the expression of both alleles at a locus producing two different phenotypes.

A dramatic departure from expected phenotypic ratios may be the result of

e. All of the above

What fraction of offspring of the cross AaBb × AaBb is homozygous for all the dominant alleles, assuming that they are on different chromosomes?

c. 1/16

Unattached earlobes are a dominant trait. Finn and Maggie both have unattached earlobes but their daughter Celia does not. If Finn and Maggie have a second child, what is the probability that it will have attached earlobes?
a. One-fourth

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