Ask a New Question
Menu

Look at the Punnett square, which shows the predicted offspring of the F2 generation from a cross between a plant with yellow-round seeds (YYRR) and a plant with green-wrinkled seeds (yyrr). Select the correct statement about wrinkled yellow seeds in the F2 generation.

A. Wrinkled and yellow traits are linked in peas.
B. The chance that an individual taken at random from the F2 generation produces wrinkled seeds is 25% and the chance that the same individual produces yellow seeds is 75%.

1 answer

To analyze the statement provided regarding the F2 generation offspring from a cross between YYRR (yellow-round) and yyrr (green-wrinkled) plants, let's first outline the situation.

  1. Genotypes of the Parents:

    • YYRR: Homozygous dominant for both traits (yellow and round seeds).
    • yyrr: Homozygous recessive for both traits (green and wrinkled seeds).

  2. F1 Generation:

    • The offspring of this cross (F1 generation) will all be heterozygous (YyRr) for both traits since they inherit one allele from each parent.

  3. F2 Generation:

    • The F1 plants (YyRr) are then crossed amongst themselves (YyRr x YyRr) to produce the F2 generation.
    • The potential allele combinations for the traits in the F2 generation can be represented in a Punnett square.

Considering the traits:

  • Yellow (Y) is dominant to green (y).
  • Round (R) is dominant to wrinkle (r).

The phenotypic outcomes in the F2 generation would be:

  • Yellow Round (YYRR, YYRr, YyRR, YyRr)
  • Yellow Wrinkled (YYrr, Yyrr)
  • Green Round (yyRR, yyRr)
  • Green Wrinkled (yyrr)

From a typical dihybrid cross, you would expect:

  • 9 Yellow Round: 3 Yellow Wrinkled: 3 Green Round: 1 Green Wrinkled.

Probability Breakdown:

  • 9 out of 16 outcomes will be yellow (this includes both yellow round and yellow wrinkled).
  • 7 out of 16 outcomes will be round (this includes both round yellow and round green).

Now, evaluating the statements:

A. "Wrinkled and yellow traits are linked in peas." - This statement is misleading in this context because the traits are independently assorted according to Mendel's law of independent assortment. So we cannot confirm that wrinkled (r) and yellow (Y) are linked.

B. "The chance that an individual taken at random from the F2 generation produces wrinkled seeds is 25% and the chance that the same individual produces yellow seeds is 75%." - This statement could be interpreted as follows: The total phenotypic ratio suggests a quarter chance of getting wrinkled seeds and a three-quarters chance of getting yellow seeds.

Thus:

Correct Answer: B. The chance that an individual taken at random from the F2 generation produces wrinkled seeds is 25% and the chance that the same individual produces yellow seeds is 75%.