Do you forget things? Absent-mindedness is an inherited recessive trait. The Punnett square shows the genetic cross for absent-mindedness in the Smith family. If the Smith's have six children, how many could be absent-minded?

Responses
A 00
B 11
C 22
D 3

1 answer

To answer your question, we first need to analyze the genetic cross for absent-mindedness, which is described as a recessive trait. If we denote the dominant allele as "A" (non-absent-minded) and the recessive allele as "a" (absent-minded), the possible genetic combinations for the parents are needed.

If we assume that both parents are carriers of the recessive trait (genotype Aa), we can set up a Punnett square. The possible genotypes for their children would be:

  • AA (non-absent-minded)
  • Aa (non-absent-minded, but carriers of the trait)
  • Aa (non-absent-minded, but carriers of the trait)
  • aa (absent-minded)

The Punnett square would yield the following ratios:

  • 1 AA (25%)
  • 2 Aa (50%)
  • 1 aa (25%)

From this, we can conclude that there is a 25% chance for each child to be absent-minded (aa).

If the Smiths have six children, we can calculate the expected number of absent-minded children using the probability:

  • 25% of 6 children = 0.25 * 6 = 1.5

This suggests that, on average, the Smith family could expect about 1 to 2 absent-minded children.

Given the options you provided: A. 0 B. 1 C. 2 D. 3

The most reasonable answer based on the calculations is that 1 or 2 children could be absent-minded. Since the closest explicit answers are B (1) or C (2), either of those would be acceptable depending on how you want to interpret the expected outcome.

If you must choose one, you might choose B (1) as the best approximation for a conservative estimate. However, keep in mind that the exact number could vary.