A student is growing a plant derived from the same line as t

A student is growing a plant derived from the same line as those from the table in the lab. The students plant is tall with long pollen. The student is convinced that his plant is homozygous for gene A and heterozygous for gene B, but you are not so sure. Given this information, answer the following questions:

A. Design an experiment to determine whether the students proposed genotype is correct.

B. Predict what results you would expect if the student is correct.

C. Predict what results you would expect if the student is incorrect.

Solution

Answer:

By using test cross we can determine the genotype of the plant.

The unkown genotype is crossed with double recessive parent (aabb)

i). If the unknown plant is double heterozote, during test cross all types of progeny are produced as follows

AaBb x aabb

1:1:1:1

ii). if the unknown plant is homozygous for pollen size and heterozous for plant size (AABb), during test cross allplants have long pollen grains and 50 % of plants are tall and 50% of plants are short

AABb x aabb

1:1

iii) if plant is both the genes are homozygous AABB or aabb, during test cross all progeny are either long pollen & tall plant or short pollen & short plants

AABB X aabb

AaBb (long pollen & tall plant)

aabb x aabb

aabb (short pollen & short plants)