Question

You discover a new plant species and you decide to conduct two mating experiments investigating mutant genes. The results from your experiment are outlined below. Which alleles are dominant? Parents F1 #1 Round x wrinkled All wrinkled seeds 1850 round: 5474 seeds wrinkled #2 Yellow x green All yellow seeds 6022 yellow; 2001 seeds green Select one: a. round and green b. round and wrinkled c. round and yellow d. wrinkled and yellow e. wrinkled and green

Answer 1

Answer: d. Wrinkled and yellow.

Explanation:

Both the crosses are an example of mendelian monohybrid crosses as only one trait of the parents which are crossed is involved.

For cross 1: seed shape is the trait

Note: As a standard in mendelian monohybrid cross, only the dominant trait is expressed in F1 generation and in

F2 generation, dominant:recessive traits are expressed in the phenotypic ratio 3:1

In cross 1 it can be seen that in F1 generation, wrinked seed shape trait is expressed and in F2 generation the wrinkled : round seeds are in the ratio of 5474 : 1850 which is approx 3:1 only.

So for cross 1, dominant trait is wrinkled seeds.

Similarly, cross 2 is also an example of monohybrid cross with the trait seed colour.

There, in F1 generation yellow seed colour trait has been expressed and in F2 generation the ratio of Yellow :Green seeds obtained is 6022:2001 which is approximately 3:1 only.

So the dominant trait in this cross is yellow seed colour.