Question 20N.2.SL.TZ0.6b
| Date | November 2020 | Marks available | [Maximum mark: 5] | Reference code | 20N.2.SL.TZ0.6b |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Outline | Question number | b | Adapted from | N/A |
Outline what occurs in cells in the first division of meiosis.
[5]
a. halves the chromosome number/produces haploid cells;
b. at start of meiosis each chromosome consists of two sister chromatids attached by a centromere;
c. prophase (I): pairing of homologous chromosomes;
d. crossing over occurs;
e. chromosomes condense by supercoiling;
f. metaphase (I): pairs of homologous chromosomes/bivalents move to equator of spindle
OR
metaphase (I): orientation of pairs of homologous chromosomes (prior to separation) is random;
g. anaphase (I): centromeres do not divide
OR
anaphase (I): spindle fibre pulls chromosome/whole centromere with two sister chromatids to opposite poles;
h. telophase (I): arrival of centromere with sister chromatids at opposite poles;
Some of these can be awarded for correctly annotated diagrams.
No credit for events in meiosis II.
In part (b), those who had been well prepared easily gained the 5 marks, but there was a significant proportion who did not know the difference between mitosis and meiosis.
