Question 21N.2.HL.TZ0.2c
| Date | November 2021 | Marks available | [Maximum mark: 2] | Reference code | 21N.2.HL.TZ0.2c |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Explain | Question number | c | Adapted from | N/A |
Explain gene linkage and its effects on inheritance.
[2]
a. located on the same chromosome;
b. genes/gene loci close together (on the same chromosome);
c. do not follow (the law of) independent assortment;
d. more chance of recombination if genes are further apart;
e. inherited together unless crossing over/recombination occurs;
f. ratios of offspring in dihybrid crosses are different from expected/non-Mendelian
OR
more offspring with parental phenotype combinations than expected;
The was some confusion between autosomal and sex linkage. Candidates tended either to have a secure understanding of the mechanisms at work in autosomal gene linkage, or none. This question and (d) correlated closely with candidates’ overall score on the paper, so distinguished particularly effectively between stronger and weaker candidates.
