Problems and variation
Answers are for parents and teachers.
1
Compare complete and incomplete linkage (ratio and cause).
Complete: no crossing over, two classes 1:1; incomplete: crossing over, 4 classes, parent-like ones are more numerous.
2
AB/ab × ab/ab, crossing over 6%, 2000 offspring. How many are parent-like?
1880
3
What fraction of the offspring of red-eyed female (XᵂXʷ) × white-eyed male (XʷY) are red-eyed?
1/2 (half of the daughters and half of the sons).
4
List the kinds of variation and sort them into “hereditary” and “non-hereditary”.
Hereditary: combinative, mutational; non-hereditary: modification; ontogenetic — change with age.
5
Why does the same cotton variety give different yields in different places?
Modification variation: soil, moisture and temperature change the phenotype while the genotype is the same, within the norm of reaction.