Make a Punnett square and find out the genotypic and phenotypic ratios of F₂ generations in the progeny of a genetic cross between:

(a) A pure tall (TT) pea plant with a pure dwarf (tt) pea plant.

(b) Red flower variety of pea (RR) with white flower variety of pea (rr).

Mendel crossed a homozygous pea plant having round seeds (RR) with a homozygous pea plant having wrinkled seeds (rr). He got different results. On the basis of it, answer the following questions:

(a) Which character of seed is studied in the experiment?

(b) Which of the above two traits is dominant ?

(c) Write the phenotype and genotype of F₁ offspring.

(d) Mention and state the Mendel’s law shown in the above cross.

(e) Make a Punnett square for F₂ generation when two plants of F₁ offspring are crossed with each other.

(f) Write the phenotypic ratio of F₂ progeny.

(g) What will be the genotypic ratio of F₂ offsprings ?

(h) What are the two traits of seed colour ? Also mention which is dominant and recessive ?

(i) Write the scientific name of garden pea.

(j) Write two main features of pea plant due to which Mendel had selected it for his hybridisation studies.

A homozygous plant having round (R) and yellow (Y) seed is crossed with another homozygous plant having wrinkled (r) and green (y) seeds. Answer the following questions :

(a) Give the genotype of the F₁ generation.

(b) Mention the phenotype of the F₁ offsprings.

(c) Give the possible combinations of gametes that can be obtained from F₁ hybrids.

(d) Give the dihybrid phenotypic ratio and the phenotype of the offsprings of the F₂ generation when two plants of F₁ generation are crossed.

(e) Name and state the law which explains the dihybrid phenotypic ratio.

Rohan, a colour blind man is married to Aashima, a carrier woman with normal vision. Colour blindness is a genetic disorder in which people are not able to distinguish between red and green colours. Rohan and Aashima are scared about the possibilities of the transmission of this disorder in their children.

(i) The defective gene of colour blindness is located on the X-chromosome which can be found in both- male and female sex chromosomes. Which of the following statements is/are incorrect ?

1. Colour blindness is a recessive sex-linked disorder.
2. It is caused by a dominant allele, located on all sex chromosomes, when a person is colourblind.
3. It is more common in females.
4. Both (2) and (3)

(ii) Aashima delivered a baby girl via her first pregnancy. Which of the following features are not possible in her daughter ?

1. The daughter may be colourblind.
2. The daughter may be carrier with normal vision.
3. The daughter has a normal vision without the defective gene on the chromosomes.
4. Both (1) and (2)

(iii) After three years, Aashima conceived and delivered a baby boy. The couple was very happy because they heard that the disorder is X-linked and would not pass down to their son. Choose the correct option from the following statements :

1. Males do not suffer from colour blindness as the male gametes contain only Y-chromosome.
2. Males have one X-chromosome and one Y-chromosome. So even if one X-chromosome has the defective gene of colour blindness, it would be insignificant.
3. Their son may be colour blind, if he receives the X-chromosome with the defective gene from his mother.
4. None of these.