Question 1 Marbles is a calico cat with a Manx tail. She wants to have kittens w

Question

Question 1

Marbles is a calico cat with a Manx tail. She wants to have kittens with a male calico, but can't seem to find one. Alas, male calicos are rare; the only ones have the sex chromosome constitution XXY. Male calicos are therefore rare because ___________.

a)

all male cats have a dominant gene on the y that masks the calico gene on the x

b)

most male cats only have one y chromosome, so it cannot be shut off

c)

most male cats have only one x chromosome, so it cannot be shut off   

d)

they die just after birth

Question 2

In cattle, mahogany spots are dominant in males and recessive in females. This trait is _______.

a)

sex-linked

b)

sex-limited

c)

sex-influenced

d)

sexually determined

Question 3

Plumage in chickens is of two varieties, a "hen" pattern and a "cock" pattern. They differ because the trait is sex-limited; that is, males have different feather arrangements than females. The autosomal gene H controls the trait in this manner: Henrietta is one of a flock of hens who has chicks with Boris, the lone rooster. He has tantalizingly beautiful plumage in the cock pattern. If Henrietta is genotype Hh, the probability that a male chick will have his father's gorgeous plumage is ________.

a)

one-eighth

b)

one-fourth

c)

half

d)

one-third

Question 4

Microphthalmia is a condition that causes chickens to have very small eyes, but it only appears in hens. The condition is autosomal recessive. Microphthalmia is sex-influenced and not sex-limited because _______________.

a)

only females express the trait

b)

only males express the trait

c)

it is not transmitted on a sex chromosome

d)

both sexes have eyeballs

Question 5

In males, genes on the X chromosome are ___________.

a)

expressed

b)

silenced

c)

disease-causing

d)

mutant autosomal

a)

all male cats have a dominant gene on the y that masks the calico gene on the x

b)

most male cats only have one y chromosome, so it cannot be shut off

c)

most male cats have only one x chromosome, so it cannot be shut off   

d)

they die just after birth

Explanation / Answer

1. Male calicos cats are rare because they do not have two x chromosomes like female do exhibit both orange and brown fur. Male need to have two x and one y chromosome in order to be calicos.

So the answer is (c)

2. Mahogany spots are colored spotted pattern present on cow. They can vary from red to black. They have zagged edges and can be scattered all over the cow’s body.

It is dominant in male and recessive in female. It is sex influenced

The answer is (c)

3. The rooster have chromosome hh

Henrietta have chromosome Hh

The crossing between Hh and hh will give either hh combination or Hh combination ( same like in humans)

So the chances for cock plumage like father are half.

Answer is (c)

4. Sex influencing traits are influenced by the sexes like sex hormones. Sex limiting traits are present in both the sexes but exhibited by one and shut off in the other.

Here eyeballs are present in both the sexes therefore it is sex influenced.

The answer is (d)

5. Chromosomes is a microscopic thread like structure present in cell. It contains the genetic information.

It expresses the gene.

So the answer is ( a)

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