Question

Please help last quiz to finish this class for good QUESTION 1

Answer 1

QUESTION 1

The phenotype produced from a pair of alleles Rr is determined by the dominant allele.

QUESTION 2

Huntington's disease is a genetic disorder that causes the breakdown of brain tissue starting during middle age. Huntington's is inherited by anyone carrying a dominant allele. Which of the following genotypes is LEAST likely to have Huntington's disease? 

Answer: hh

QUESTION 3

The two copies of a gene inherited from each parent in animal cells are called alleles.

QUESTION 4

In pea plants the allele for tall is dominant to the allele for short. What would be the phenotype of the parents of this cross?

Answer: tall

QUESTION 5

The ability to roll the tongue in humans is coded by the dominant allele R. The inability to roll the tongue is coded by the recessive allele r. A man with an RR allele combination for the trait produces a zygote with a woman with an rr allele combination for the trait. Which allele combination could occur in the zygote?

Answer: Rr

QUESTION 6

Tay–Sachs disease is caused by a recessive lethal allele, meaning that individuals that are homozygous recessive (tt) will have the disease and die before they are able to have offspring. Two parents that are heterozygous (Tt) carriers for Tay–Sachs want to have children. What are the chances that their children will get Tay-Sachs disease?

The possible phenotypes for the children are TT, Tt, Tt, and tt. Therefore, there is a 1/4 chance that their children will get the disease.

Answer: 25%

QUESTION 7

Cystic Fibrosis is a genetic disease that affects mucus cells in the lungs. The disease affects only those individuals that have a homozygous recessive genotype (ff). Two individuals that are heterozygous carriers for the disease decide to have children. What are the chances that one of their children will have Cystic Fibrosis?

Answer: 25%

QUESTION 8

Hemophilia is a recessive, X-linked genetic disorder. If a male child is born with hemophilia and neither the mother nor the father has hemophilia, which of the following statements is most likely true?

Females have two X chromosomes while males have one, so it is more likely that the mother carried the recessive gene. 

Answer: The mother is the carrier.

QUESTION 9

Hemophilia is an X–linked recessive disorder. If you cross a normal male with a hemophiliac female, what will be the probability of having hemophiliac children?

The parents have phenotypes with hh (mother) and HH (father), and have the potential of having offspring with the following phenotype: Hh. Therefore, the dominant allele in the father will prevent the offspring from having hemophiliac children. 

Answer: 0%

QUESTION 10

Can a male be a carrier for a sex-linked disease?

Answer: No, males have only a single copy of sex-linked genes.

Hope this helps!