A particular species of plants can have yellow or green seeds. This trait is determined by one gene. The yellow-seeded plants may be homozygous or heterozygous. We could find out which genotype they are by crossing these plants with... (A) homozygous yellow-seeded plants (B) homozygous green-seeded plants (C) heterozygous green-seeded plants (D) heterozygous yellow-seeded plants
Answer (1)
To determine if a yellow-seeded plant is homozygous or heterozygous for the seed color gene, you would perform a test cross. The seed color trait described involves a classic Mendelian inheritance pattern, where yellow seed color is dominant over green.
In this scenario, a yellow-seeded plant could either have a genotype of YY (homozygous dominant) or Yy (heterozygous). Here are the steps to find out:
Test Cross: This involves crossing the unknown genotype with a plant of a known genotype. Specifically, you should choose a plant that is homozygous recessive for the trait, which means it has green seeds.
Reasoning: If you cross the yellow-seeded plant with a homozygous green-seeded plant (yy), the offspring outcomes will help determine the genotype of the yellow-seeded plant.
If the yellow-seeded plant is homozygous (YY), all offspring will be yellow-seeded (Yy), because the dominant allele Y will always mask the recessive y.
If the yellow-seeded plant is heterozygous (Yy), you will get a mixture of offspring: approximately 50% yellow-seeded (Yy) and 50% green-seeded (yy).
Based on these outcomes, the best choice from the options provided would be:
(B) homozygous green-seeded plants
This choice allows you to clearly observe the possible combinations of seed color in the offspring, helping you to identify if the original yellow-seeded plant is homozygous or heterozygous.
