1) Which of the following statements does NOT describe an environmental influence on the expression of a gene?
a. Colder incubation temperatures of gecko eggs yield more females and warmer temperatures yield more males.
b. Siamese cats have darkened paws, nose, and tip of tail due to a gene that allows their skin and fur to darken in the parts of their bodies that need to retain more heat, their extremities.
c. More than a single gene is involved in the expression of human height, weight, and skin colour.
d. Exposure to sunlight increases melanin production in human skin.
2) Melanin is a skin pigmentation that absorbs and dissipates broadband UV rays. Since UV radiation causes DNA damage, melanin pigments protect the skin and reduce the risk of cancer. When skin is exposed to sunlight, melanin production is increased, causing the skin to tan. This demonstrates that
a. the environment causes mutations that increase the chance of survival
b. the environment causes mutations that have no effect on the chance of survival
c. the expression of some genes is influenced by the environment
d. the environment causes mutations that have a large effect on the chance of survival
3) In corn plants, a dominant allele (K) allows kernel colour and a recessive allele (k) inhibits kernel colour when homozygous. On a different chromosome, the dominant gene P causes purple kernel colour and the homozygous recessive genotype causes red kernel colour.
A true breeding white corn plant was crossed with a purple corn plant, yielding 50% red corn plants and 50% purple corn plants.
What are the genotypes of the parental corn plants?
a. KKPP X kkPp
b. KkPP X kkPP
c. KKPp X kkpp
d. kkPp X KkPp
4) There are two genes that determine the coat colour expression in dogs: eumelanin and merle. These genes are located on two separate chromosomes.
For the eumelanin gene, black coat colour (E) is dominant over red coat colour (e).
The merle gene controls the degree to which these coat colours are expressed through incomplete dominance.
The following table describes the merle gene expression.
Genotype Phenotype
MM White
Mm Half colour (Grey or light red)
mm Full colour (Black or Red)
A grey dog that is heterozygous for the eumelanin gene mates with a light red dog.
What is the probability they would have a grey puppy?
a. 0.38
b. 0.25
c. 0.13
d. 0.50
5) What is the probability they would have a grey or light red puppy?
a. 0.13
b. 0.50
c. 0.25
d. 0.38
6) Two dogs heterozygous for both traits were crossed. What phenotypic ratio is expected in their offspring?
Phenotype: ANSWER:
White ANSWER
Grey ANSWER
Black ANSWER
Light Red ANSWER
Red ANSWER
7) Feather colour in parakeets is controlled by two genes. Blue colour (B) is dominant over absence of colour (b). Yellow colour (Y) is dominant over absence of colour (y). When a B allele and a Y allele are present, a green parakeet is produced.
The probability of obtaining a female or male parakeet is the same as for humans.
What is the probability of obtaining a male green parakeet when a green parakeet heterozygous for both genes is crossed with a white parakeet?
a. 0.50
b. 0.25
c. 0.13
d. 0.75
8) SEE IMAGE ATTACHED
9) The coat colour of dogs is an example of an epistatic interaction. The common alleles are black (B) and brown (b). There is a separate gene on a separate chromosome that influences coat colour; it prevents colour formation and causes a white coat.
L = prevents color formation and causes a white coat
l = allows colour formation to occur.
If the P1 generation is a white dog (LlBb) crossed with a black dog (llBb), then which of the following represents the correct phenotypes of the F1 offspring?
a. Phenotypes
White Black Brown
1 /2 3 / 8 1 / 8
b. Phenotypes
White Black Brown
1 /2 1 / 8 3 / 8
c. Phenotypes
White Black Brown
3 / 8 1 /2 1 / 8
d. Phenotypes
White Black Brown
1 / 8 1 /2 3 / 8
10) SEE IMAGE ATTACHED
11) If the P1 generation is a rose comb (RRpp) crossed with a pea comb (rrPP), which of the following represents the correct genotype and phenotype of the F1 offspring?
a. Genotype Phenotype
RrPp pea comb
b. Genotype Phenotype
RrPp walnut comb
c. Genotype Phenotype
RRPP walnut comb
d. Genotype Phenotype
RRPP Single comb
12) Which of the following represents the correct phenotypes of the F2 offspring?
a. Phenotype
Single Walnut Pea Rose
1 / 16 9 / 16 3 / 16 3 / 16
b. Phenotype
Single Walnut Pea Rose
3 / 16 1 / 16 9 / 16 3 / 16
c. Phenotype
Single Walnut Pea Rose
3 / 16 9 / 16 1 / 16 3 / 16
d. Phenotype
Single Walnut Pea Rose
9 / 16 3 / 16 3 /16 1 / 16
13) The Labrador Retriever’s coat colours are black, yellow, and chocolate.
Yellow is produced by the presence of a recessive epistatic gene, which has the effect of masking the black and chocolate colour genes. Black (B) is dominant to chocolate (b).
Therefore, the possible genotypes and corresponding phenotypes are:
Phenotype Possible Genotypes
Black G__B__
Brown G__bb
Yellow gg__
Predict the percentage of offspring that would be black in colour for each of the following crosses. Record your answer as a whole number.
Cross: GgBb X GgBB GGBb X GGBb
Percentage
of
Offspring: Answer % Answer %
14) Below is a simplified chart for polygenic trait of eye colour. The amount of melanin in the iris is what determines the colour of the eye. People with brown eyes have more melanin in their iris than people with blue eyes. The amount of melanin is controlled by how many dominant alleles a person has for eye colour as follows:
Number of Genotypes Phenotypes
Dominant
Alleles
4 AABB Very dark brown eyes
3 AaBB or AABb Brown eyes
2 AaBb, aaBB etc. Light brown or hazel
eyes
1 Aabb or aaBb Dark blue eyes
0 aabb Light blue eyes
Which of the following parental crosses explains how two brown-eyed parents can produce a blue-eyed child?
a. AaBB X AaBb
b. AaBB X AABb
c. Aabb X AABB
d. AABB X AaBb
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