Genetic Variation Multiple Choice Quiz 1

Which of the following explains why sexual reproduction is advantageous to a species?

Red-green colour blindness is inherited as a sex-linked recessive condition. If a colour-blind woman marries a man with normal vision, what would be the expected phenotypes of their children?

If a red flowered snap dragon is crossed with a white flowered one, the progeny will all be pink flowered.
Which of the following is the most correct prediction of the ratios of offspring when a red snapdragon is crossed with a pink snapdragon?

The pedigree shows the inheritance for a particular condition in a population of sexually reproducing organisms.

What type of inheritance is exhibited by the condition?

Coat colour inheritance in certain cats is sex-linked and codominant. Male cats can have yellow or black coat colours. Female cats may be yellow, black or tortoiseshell in colour.

What would be the probability of having yellow female offspring if a tortoiseshell female is crossed with a yellow male?

Why is the Y chromosome of humans passed on unchanged from one generation to another?

In his book ‘Darwin’s Island’, Steve Jones points out that 20% of the men of North West Ireland have identical Y chromosomes. This is evidence that they are all descended from the same male ancestor, and Jones names a fifth century warlord, ‘Niall the Hostage Taker’ as that ancestor.

Of all the human chromosomes, only the Y chromosome can be passed on unchanged from generation to generation.

Why?

A new species of snake has been found in Borneo which has 3 varietal colours; yellow, brown and patchy yellow and brown. If a yellow snake and a brown snake are mated then all the offspring are patchy yellow and brown. If two of the patchy yellow and brown snakes are mated the ratio of colours in the offspring are 1 yellow: 2 patchy yellow and brown: 1 brown.

This ratio can be best explained by:

A student completed a genetics exercise by preparing a Punnett square. T represents a dominant allele and t represents a recessive allele.

What were the likely genotypes of these parents?

In which of the following do both processes result in genetic variation of offspring?

Colour blindness is a sex-linked recessive trait.
Susan is not colourblind but her father is. Susan is married to James who is also not colourblind. Susan and James are expecting twins, a boy and a girl.
Which row in the table shows the probability of colourblindness in the boy and the girl?

Haemophilia A is a blood clotting disorder that arises from a defect in the gene which is carried on the X chromosome.
A couple is considering starting a family. However, the father suffers from Haemophilia A. The mother is healthy with no family history of the disease.
What is the probability that a potential grandson will have Haemophilia A if they have a daughter who partners with an unaffected man?

It is suspected that a child has a recessive, sex-linked condition. An initial pedigree was developed.
Which of the following is most likely to depict this initial pedigree?