Variation In Humans (24)

Question 1

What is variation?

Answer 1

The differences between members of a species is called variation

Question 2

What is meant by the term ‘crossing over’

Answer 2

When the homologous chromosomes pair during the first division of meiosis, the chromatids may get tangled with one another, a situation know as crossing over.

Question 3

What is meant by a chiasma?

Answer 3

The point where two chromatids cross is called a chiasma

Question 4

What is non-disjunction?

Answer 4

When the homologous chromosomes fail to seperate. In the second meiotic division, one or more of the chromatids may fail to seperate. This is called non-disjunction.

Question 5

What happens in humans if non-disconjunction occurs in one of the chromosome pairs during meiosis?

Answer 5

The resultant gametes will either have 24 or 22 chromosomes (not 23), therefore the zygote produced will either have 47 or 45 chromosomes respectively.