Genetics Practice Quiz

A couple has six children - all daughters. If they have a seventh child, what is the probability that the seventh child will be a daughter?

• 6/7

• 1/7

• 1/36

• 1/2

Answer explanation

Every child has a 1/2 chance of being a biological daughter or a biological son. Each child recieves their chromosomes independently.

In llamas, coat color is controlled by a gene that exists in two allelic forms. If a homozygous yellow llama is crossed with a homozygous brown llama, the offspring have grey coats. If two of the gray-coated offspring were crossed, what percentage of their offspring would have brown coats?

• 0%

• 25%

• 50%

• 75%

In humans, red-green colorblindness is an X-linked recessive trait. If a man and a woman have a son with red-green colorblindness which of the following is definitely true?

• The mother is a carrier for red-green colorblindness

• The father is a carrier for red-green colorblindness

• Both parents are a carrier for red-green colorblindness

• The boy's paternal grandfather has red-green colorblindness

If a mother has type A blood and her child has type O blood, what are the possible blood types of the father? (Select all that apply)

• O

• A

• B

• AB

Chromosome number is reduced to haploid in meiosis. What event must occur to restore diploid chromosome number?

• synapsis during prophase

• fertilization

• mitosis

• DNA replication

Match the following types of inheritance to their examples:

• Multiple alleles

• Two traits are visible at the same time

• Co-dominance

• One gene controls the expression of a second gene

• Sex-linked

• The trait is controlled by more than 1 allele pair, AaBb

• Epistasis

• The gene is on the X chromosome

• Polygenic

• More than two alleles exsist for the trait, but individuals each have only 2

In cats, one of the genes for fur color is controlled by multiple alleles. B: black fur is dominant to all other genes. b₁: chocolate fur, is next most domiants. b: cinnamon fur, is the most recessive. Which combination of parent cats could potentially have cinnamon colored kittens?

• Black Bb₁ x cinnamon bb

• Chocolate b₁b₁ x cinnamon bb

• Chocolate b₁b₁ x chocolate b₁b

• Black Bb x chocolate b₁b

Which of the following are not true of dominant traits? (Select all that apply)

• A single dominant allele will overpower the recessive allele

• Dominant alleles can skip generations

• Dominant alleles are always more common than recessive alleles

• Huntington's disease is caused by a dominant allele

In a dihybrid cross, assuming the genes are on separate chromosomes and follow Mendelian patterns of inheritance, the phenotype outcome ratio is always ​ (a)   : ​ (b)   : ​ (c)   : ​ (d)  

• 9
• 3
• 1
• 2

In cats, the gene for black fur (D) is dominant to the gene for grey fur (d). If two heterozygous cats have kittens, ​ (a)   are expected to be black and ​ (b)   are expected to be grey.

• 75%
• 25%
• 50%
• 0%
• 100%