Understanding basics of genetics. | Homework Help

1) Tay-Sachs is a recessive genetic disease in humans. If one parent is homozygous normal and the other is a carrier (heterozygous), what are the chances that their child will have this disease?

a) 0%

b) 25%

c) 50%

d) 75%

e) 100%

2) If an organism shows a recessive phenotype, such as short pea plants, it can be

a) either TT or Tt.

b) either TT or tt

c) only Tt.

d) TT, Tt, or tt

e) only tt.

3) In humans, assume red hair is recessive to dark hair. What are the chances of a dark haired couple having a red-haired child if each had one  red-haired parent?

a) 0

b) 25%

c) 50%

d) 75%

e) 100%

4) If the genotype of an organism is YySsTt, then yST would represent

a) the genotype of the offspring.

b) a gamete of that parent organism .

c) a possible phenotype of the offspring.

d) a possible zygote.

e) the P generation.

5) In guinea pigs, B = black, b = brown, S = short hair, s = long hair. A dihybrid reproduces with a dihybrid. The expected results are

a) 9 black long hair, 3 black short hair, 3 brown long hair, one brown short hair.

b) 9 black short hair, 6 black long hair, 3 brown long hair, one black short hair.

c) 9 black short hair, 3 black long hair, 3 brown short hair, one brown long hair.

d) 9 brown short hair, 3 black long hair, 3 brown long hair, one black short hair.

6.Karyotyping can be used to diagnose which of the following genetic disorders?

a) cystic fibrosis

b) Down syndrome

c) neurofibromatosis

d) phenylketonuria

e) hemophilia

7.If a chromosomal segment is turned around 180, the chromosomal mutation is termed a(n)

a) translocation.

b) duplication.

c) deletion.

d) inversion.

e) invertiploid.

8) Which statement is true regarding the Barr body?

a) It is found in the nuclei of males.

b) It is found in the nuclei of females.

c) It is found in the cytoplasm of males.

d) It is found in the cytoplasm of females.

e) It is a condensed inactive Y chromosome.

9) If a person inherits two X chromosomes, this individual will be

a) female.

b) male.

c) colorblind.

d) sterile.

e) a poly-X female.

10) A colorblind (recessive trait) woman will pass the allele to

a) her sons only.

b) her husband.

c) her daughters only.

d) none of her children.

e) all her children.