2022HSCShort answer

Q22

3 marks

Question

Eggplant fruit comes in three colours: dark purple, white and violet. A genetic cross between the dark purple and white eggplants will always result in the violet phenotype. What phenotypic ratio would you expect to see when two violet offspring are crossed? Show your working.

Try the question before revealing the answer.

Solution

Criteria	Marks
Provides the correct phenotypic ratio of the offspring; provides correct parental genotypes and suitable working	3
Provides the correct phenotypic ratio of the offspring; provides some suitable working OR identifies correct parental genotypes; provides suitable working OR provides appropriate parental genotypes; provides suitable working and relevant phenotypic ratio	2
Provides some relevant information	1

Sample answer:

Both colours are dominant due to blending/both being expressed.

Dark purple = PP
White = WW
Violet = PW

	P	W
P	PP	PW
W	PW	WW

Phenotypic ratio

Dark purple : Violet : White
1 : 2 : 1

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 5 · Heredity

Genetic VariationInterpret inheritance patterns, pedigrees and Punnett squares to model genotype combinations.

Spot a problem? Send feedback