Solve
Guides
0
You visited us 0 times! Enjoying our articles? Unlock Full Access!
Standard XII
Biology
Question

In humans, the ability to taste the chemical PTC is inherited as a single gene dominant trait represented by the allele T. A couple who are both tasters have four children, one of which is a nontaster.
Which of the following best predicts what genotypes the parents of these children possess?

  1. Both parents are homozygous dominant for the taster trait (TT).
  2. One parent is homozygous dominant (TT) and the other is heterozygous (Tt).
  3. One parent is homozygous dominant (TT) and the other is homozygous recessive (tt).
  4. One parent is homozygous recessive (tt) and the other parent is heterozygous (Tt).
  5. Both parents are heterozygous (Tt).

A
One parent is homozygous dominant (TT) and the other is heterozygous (Tt).
B
One parent is homozygous recessive (tt) and the other parent is heterozygous (Tt).
C
Both parents are homozygous dominant for the taster trait (TT).
D
Both parents are heterozygous (Tt).
E
One parent is homozygous dominant (TT) and the other is homozygous recessive (tt).
Open in App
Solution
Verified by Toppr

Taste blindness of PTC is a genetic trait. PTC (Phenyl Thiocarbamide) is a compound of nitrogen, carbon and sulphur with sour taste. This trait is transmitted by a dominant gene T. The genotypes TT and Tt are tasters of PTC, while tt are non tasters or taste blind persons.
In the question it is given that the couple are both tasters. This means their genotype could be either TT or Tt. But one of their four children is non taster i.e. his genotype is tt. For this genotype, the t allele is inherited from both the parents. So, both the parents have to be heterozygous for PTC i.e. they should have the genotype Tt. The cross can be represented as shown in the figure.
So, the correct answer is 'Both parents are heterozygous (Tt)'.

831922_532233_ans_51d69556b6f541ae955a1c5aad4e557f.jpg

Was this answer helpful?
4
Similar Questions
Q1
In humans, the ability to taste the chemical PTC is inherited as a single gene dominant trait represented by the allele T. A couple who are both tasters have four children, one of which is a nontaster.
Which of the following best predicts what genotypes the parents of these children possess?

View Solution
Q2
In a typical Mendelian cross which is a dihybrid cross, one parent is homozygous for both dominant traits and another parent is homozygous for both recessive traits. In the F2 generation, both parental combinations and recombinations appear. The phenotypic ratio of parental combinations to recombinations is
View Solution
Q3
In a pedigree of a family given below, the trait denoted by A is inherited as dominant, autosomal trait. What will be the genotype of mother and father?
Note: AA- Homozygous dominant, aa- Homozygous recessive, Aa- Heterozygous dominant


View Solution
Q4
How many different types of genotypes are formed in the second generation of a cross between a homozygous dominant parent and a homozygous recessive parent?
View Solution
Q5

A round seeded plant ( R ) is dominant to a wrinkled seeded plant ( r). What parental genotypes will produce offspring that are 50% homozygous dominant and 50% heterozygous dominant ?


View Solution