Question

A homozygous dominant tall pea plant bearing red flowers (TTRR) is crossed with a homozygous recessive dwarf pea plant bearing white flowers (ttrr).

1. What is the phenotype and genotype of F₁ individuals?
2. Write the possible combination of gametes that are obtained when two F₁ hybrid plants are crossed.
3. Mention the phenotypic ratio of the F₂ generation.
4. State Mendel’s Law of Independent Assortment.
5. Name two X-linked disorders found in humans.

Answer 1

1. Phenotype: All plants will be tall and will bear red flowers.
   Genotype: TtRr
2. TR, Tr, tR, tr
3. 9 : 3 : 3 : 1
4. Mendel’s law of independent assortment states that when the parents differ in two or more alleles, then the inheritance of one pair of alleles does not depend on the other pair.
5. Colour-blindness and haemophilia.