The trait of medium- sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.A cross is made between two plants each with medium- sized leaves.If they produce 80 seedlings,what would be the expected phenotypes,and in what numbers would they be expected?
A)20 large leaves ,20 medium leaves ,40 small leaves
B)40 large leaves ,0 medium leaves ,40 small leaves
C)20 large leaves ,40 medium leaves ,20 small leaves
D)40 large leaves ,40 medium leaves ,0 small leaves
E)10 large leaves ,60 medium leaves ,10 small leaves

Question

The trait of medium- sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.A cross is made between two plants each with medium- sized leaves.If they produce 80 seedlings,what would be the expected phenotypes,and in what numbers would they be expected?
A)20 large leaves ,20 medium leaves ,40 small leaves 
B)40 large leaves ,0 medium leaves ,40 small leaves 
C)20 large leaves ,40 medium leaves ,20 small leaves 
D)40 large leaves ,40 medium leaves ,0 small leaves 
E)10 large leaves ,60 medium leaves ,10 small leaves

Quizplus · Accepted Answer

When two plants with medium-sized leaves are crossed, their genotypes must be P'P'.

The Punnett square for this cross would be:

|   | P'  | P'  |
|---|----|----|
| P' | P'P' | P'P' |
| P' | P'P' | P'P' |

All offspring will have medium-sized leaves since they are all P'P'. Therefore, there will be 40 plants with medium-sized leaves.

However, since this is a monohybrid cross, we can also calculate their expected genotypes using a 1:2:1 ratio for homozygous dominant: heterozygous: homozygous recessive.

Expected genotype ratios: 
- 25% PP (large leaves)
- 50% P'P' (medium leaves)
- 25% P'P' (small leaves)

Therefore, there will be 20 plants with large leaves and 20 plants with small leaves.

Overall:
- 20 large leaves 
- 40 medium leaves 
- 20 small leaves

The Trait of Medium- Sized Leaves in Iris Is Determined