Question 18M.2.HL.TZ2.3
| Date | May 2018 | Marks available | [Maximum mark: 7] | Reference code | 18M.2.HL.TZ2.3 |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Determine, Identify, Outline | Question number | 3 | Adapted from | N/A |
The micrograph shows a plant cell of Lilium grandiflorum during meiosis.
Identify, giving reasons, the stage of meiosis shown by this cell.
[2]
a. anaphase II
b. as four daughter cells are being formed
OR
the centromeres split / sister chromatids separate
OR
sister chromatids/ chromosomes are pulled «by the spindle microtubules» to opposite poles
Outline the law of independent assortment.
[2]
a. two «or more» traits/genes are inherited independently of one another. Accept vice versa.
b. observed for traits/genes that are not linked/far apart on the chromosome
Can be shown in annotated diagram.
c. «due to homologous» chromosomes aligning independently/randomly on equator during metaphase I/meiosis I
d. during anaphase I homologues pulled to separate poles
Can be shown in annotated diagram.
The genes for cystic fibrosis and blood group are not linked. Two parents are heterozygous for cystic fibrosis. One parent has blood group O and the other has blood group AB. Using a Punnett square, determine the probability that their child will have both cystic fibrosis and blood group A.
[3]
a. correct parental genotypes shown / Ff ii, FfIA IB
b. Punnett square with correct gametes shown
c. correct probability:
OR
12.5%
Must use blood type symbols IB IA and i. No specific letters required to represent cystic fibrosis allele though dominant and recessive must be apparent.
