Variation Due To Meiosis

Question 1

How does crossing over in prophase 1 result in variation?

Answer 1

-Small regions if the homologues pairs switch over genes.
-Forms recombinant chromosomes.
-The two chromosomes join in a bivalent.
-Chiasma is formed at the point of crossing over before genes are switched.
-So maternal and paternal alleles are mixed.

Question 2

How does random fertilisation cause variation?

Answer 2

-When two gametes meet it is random so increases variation in the zygote.

Question 3

How does independent assortment in metaphase 1 cause variation?

Answer 3

-The bivalent is made of 2 chromosomes and can line up in any order along the equator resulting in lots of combinations.

Question 4

How does a non-disjunction result in variation?

Answer 4

When chromosomes aren’t separated by spindles so end up with too many pairs or not enough on either side.

Question 5

What are the advantages to variation?

Answer 5

-Species can adapt to their environment through evolution.