Question

Some plants fail to produce chlorophyll, due to a recessive trait, and are colored white. If we locate a pea plant that is heterozygous for this trait, self-pollinate it, and harvest the seeds, what are the likely phenotypes of the resulting offspring?

Answer 1

The correct answer will be 3 green (75%) and 1 white(25%).

Explanation:

Failing to produce the chlorophyll is a recessive trait so it will act as like any recessive trait in normal genetic inheritance pattern like monohybrid cross. Let assume the white color is denoted by g and green color is denoted by G in a pea plant so the heterozygous pea plant would be Gg.

Self-pollination of this pea plant will produce the same inheritance pattern as any other monohybrid heterozygous self-pollination do which is a 3:1 ratio of phenotypic ratio. In this 3 or 75% are dominant green color and 1 or 25% is white-colored.

Thus, the correct answer is - 3 green (75%) and 1 white(25%).

Answer 2

Answer: 3 out of 4 organisms (75%) of the resulting offspring will have a chlorophyll producing phenotype, and 1 out of 4 organisms (25%) will have a non chlorophyll producing phenotype.

Step-by-step explanation:

An heterozygous plant for this trait would have a dominant allele for chlorophyll production (we will call it C), combined with a recessive allele (we will call it c).

If the plant self-pollinates, it means that its chromosomes will combine with eachother.

Due to meiosis, each gamete will have either the dominant or the recessive allele. As a result of this, the combination of the gametes will be like this:

C c

C CC Cc

c Cc cc

This means:

A gamete with the C allele will combine with another one with the C allele

A gamete with the C allele will combine with a gamete with the c allele

A gamete with the c allele will combine with a gamete with the C allele

A gamete with the c allele will combine with another one with the c allele

By definition, only the resulting organisms whose genotypes are homozygous for the recessive trait will present the white colouring phenotype. The other resulting organisms, that have at least one dominant allele, will present the normal, green colouring phenotype.

Then, 3 out of 4 organisms (75%) of the resulting offspring will have a chlorophyll producing phenotype, and 1 out of 4 organisms (25%) will have a non chlorophyll producing phenotype.