The diagram represents a dihybrid cross between two pea plants heterozygous for both seed color and seed shape.

what is the phenotypic ratio of the offspring?

a) 1: 1: 1: 1: 2: 2: 2: 2: 4
b) 1: 3: 3: 9
c) 1: 4
d) 4: 12

The correct answer would be B) 1:3:3:9.

Dihybrid cross refers to a cross between two organisms that are differ in only two observable characters or traits.

For example, Mendel crossed pure breed pea plants for two contrasting traits- one with round and yellow seeds (RRYY) and other with wrinkled and green seeds (rryy).

Offsprings of first generation were all genetically heterozygous (RrYy) with same phenotype that is, round and yellow seed. Hence, yellow (Y) is dominant over green (y) and round shape of seed (R) is dominant over wrinkled shape (r).

On selfing, second generation resulted in the formation of four types of phenotypes in 1:3:3:9, where:

The figure attached in the question also shows the same results as were observed by Mendel. Hence, the phenotypic ratio of this cross will also be equal to 1:3:3:9 (wrinkled and green : round and green : wrinkled and yellow : round and yellow).

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.