Variation + SR (meiosis)

Question 1

Prior to meiosis I

Answer 1

The chromosomes which have replicated prior to meiosis I, each consist of 2 genetically identical chromatids attached at the centromere

Question 2

Meiosis I step 1

Answer 2

The chromosomes condense and the homologous chromosomes pair up

Question 3

Meiosis I step 2

Answer 3

Chiasmata form at points of contact between the non-sister chromatids of a homologous pair and sections of DNA are exchanged

Question 4

Meiosis I step 3

Answer 4

This crossing over of DNA is random and produces genetically different recombinant chromosomes

Question 5

Meiosis I step 4

Answer 5

Spindle fibres attach to the homologous pairs and line them up at the equator

Question 6

Meiosis I step 5

Answer 6

The orientation of the pairs of homologous chromosomes at the equator is random

Question 7

Meiosis I step 6

Answer 7

The chromosomes of each homologous pair are separated and move towards opposite poles

Question 8

Meiosis I step 7

Answer 8

Cytokinesis occurs and two daughter cells form

Question 9

Meiosis II

Answer 9

Each of the two cells produced in meiosis I undergoes a further division during which the sister chromatids of each chromosome are separated