HEREDITY
MONOHYBRID CROSS
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
2:4 FF 2:4 Ff4:4 free ear lobes
|
|
|
2:4 Ff 2:4 ff2:4 free ear lobes 2:4 attached ear lobes
|
|
|
3:4 FF 1:4 ff3:4 free ear lobes 1:4 attached ear lobes
|
|
|
1:4 FF 2:4 Ff 1:4 ff3:4 free ear lobes 1:4 attached ear lobes
|
Detailed explanation-1: -If a person has a free earlobe, then its genotype would be either UU or Uu. If a person has an attached earlobe then its genotype would be uu. So, if parents (male as well as female) have free earlobes and offspring have attached earlobes, then surely both parents would be heterozygous for this trait.
Detailed explanation-2: -The answer is c) 50%. This can be visualized with a Punnett square. The individual with attached earlobes has the genotype ee and can only produce e alleles. The individual that is heterozygous with free earlobes has the genotype Ee and can produce both E and e alleles.
Detailed explanation-3: -A single autosomal gene with two alleles determines whether you have attached earlobes or free-hanging earlobes. The allele for free-hanging earlobes (F) is dominant to the allele for attached earlobes (f). Other single-gene autosomal traits include widow’s peak and hitchhiker’s thumb.
Detailed explanation-4: -This means that it isn’t uncommon for parents with attached earlobes to have kids with unattached lobes. Or even for parents to have kids with one attached and one unattached earlobe!