Chapter 24 - Variation

Question 1

What is Variation?

Answer 1

Variation is the diffences between members of the same species

Question 2

What can variation be caused by?

Answer 2

Environmental factors or it can be inherited

Question 3

What four ways can variation by inherited

Answer 3

Independent (or random) assortment
Crossing over
Non-disjunction
Random fertilisation
Mutation

Question 4

What is ‘Random Assortment’

Answer 4

When homologous chromosomes line up and then separate, they do so at random and independent of each other

Question 5

What is ‘Crossing Over’

Answer 5

When homologous chromosomes pair during Meiosis I, the chromatids get tangled which creates two chromosomes where the combination of alleles is different to both parents.

Question 6

What is chiasma in Crossing over

Answer 6

When chromatids cross

Question 7

What is recombination in Crossing over

Answer 7

When two chromatids break and reattach to form a different chromosome.

Question 8

What is ‘Non-Disjunction’

Answer 8

Situations during meiosis that results in one daughter cell receiveing and extra chromosome(s), and; the other daughter cell lacking that chromosome(s). Inheriting extra or fewer chromosomes causes serious defects in the child