| Date | May 2016 | Marks available | 1 | Reference code | 16M.1.HL.TZ0.20 |
| Level | Higher level | Paper | Paper 1 | Time zone | TZ0 |
| Command term | Deduce | Question number | 20 | Adapted from | N/A |
Question
What is the effect of dominant alleles?
I. They mask the effect of recessive alleles.
II. They become more frequent than recessive alleles in a population.
III. They have a joint effect with recessive alleles when characteristics are co-dominant.
A. I only
B. I and II only
C. I and III only
D. I, II and III
Markscheme
A
Examiners report
Although some teachers criticized this question, it is perfectly fair. Many candidates believed that dominant alleles have a joint effect with recessive alleles in co-dominance.
