3 of 203 of 20 Items

Question

01:14
Question
In humans, curly hair is dominant over straight hair. Which cross below has the correct probabilities listed?
Responses
A a woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly haira woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly hair
B a woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly haira woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly hair
C a woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly haira woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly hair
D a woman homozygous dominant for hair curl, a man homozygous recessive for hair curl will produce: 50% straight hair & 50% curly hair

Answer 1

To analyze the probabilities of hair curl (C) being dominant over straight hair (c), let's go through each option systematically based on the genotype of the individuals in each scenario.

1. A: A woman heterozygous for hair curl (Cc) crosses with a man heterozygous for hair curl (Cc):

   • Possible offspring genotypes:
     • CC: 1 (curly)
     • Cc: 2 (curly)
     • cc: 1 (straight)
   • Probability: 75% curly (CC or Cc) and 25% straight (cc).
   • Correct statement.

2. B: A woman homozygous recessive for hair curl (cc) crosses with a man homozygous recessive for hair curl (cc):

   • Possible offspring genotypes:
     • cc (100%)
   • Probability: 100% straight hair.
   • Incorrect statement. (All will be straight hair, not curly.)

3. C: A woman heterozygous for hair curl (Cc) crosses with a man homozygous recessive for hair curl (cc):

   • Possible offspring genotypes:
     • Cc: 1 (curly)
     • cc: 1 (straight)
   • Probability: 50% curly (Cc) and 50% straight (cc).
   • Incorrect statement. (Would be 50% for each, not 75% straight and 25% curly.)

4. D: A woman homozygous dominant for hair curl (CC) crosses with a man homozygous recessive for hair curl (cc):

   • Possible offspring genotypes:
     • CC: 1 (curly)
     • Cc: 1 (curly)
   • Probability: 100% curly (CC or Cc).
   • Incorrect statement. (All offspring would be curly, not 50% straight and 50% curly.)

Based on this analysis, option A is the only one with correct probabilities listed.