Q15.5-2CC - Campbell Biology

Question

Reciprocal cross between two primrose varieties, A and B, produced the following results: $Afemale\times Bmale\to offspring$ with all green (non-variegated) leaves; $Bfemale\times Amale\to offspring$ with patterned (variegated) leaves. Explain these results

Step-by-Step Solution

Answer

Plastids are the structures responsible for colors in the leaf. The features of a mother or the maternal characters get transferred to the offspring. The B variety female produces variegated offspring. 

From this, it can be concluded that B-type females possess a wild type and the mutant allele is the reason for producing variegated leaves.

Step 1: Description of reciprocal offspring

A crossing between a pair of parents such as A and B is reciprocated as B and A. In this condition, the first parent is kept as male and the second as female. 

Step 2: Description of variegated and non-variegated leaves

The leaf having more color is known as variegated leaves. The colors may appear in the border of the leaf; bicolored strips are also found.

The leaf filled with chlorophyll pigment and appears only in green color is known as non-variegated leaves. 

Step 3: Reciprocal cross between two primrose and its results

The characteristic of the mother gets inherited by the offspring as per the pattern of inheritance. The plastids determine the color present in the leaf. Chloroplasts are organelles that come under the category of plastids. 

The plastid gene present in the female plant gets inherited by the offspring. In this reciprocal crossing, the B is the mutant variety and wild type to produce variegated leaves. In this condition, the pigment gene is mutated. 

Hence, the reciprocated cross between the B female and A male results in the formation of variegated leaves.