Question

In a homozygous plant round seeds (R) are dominant over wrinkled seeds (r):

1. Draw a Punnett square to show the gametes and offsprings when both the plants have heterozygous round seeds (Rr).
2. Mention the phenotype and genotype ratios of the offsprings in F₂ generation.
3. Name the sex chromosomes in human males and females.
4. Briefly explain the term ‘Mutation’.
5. What is the number of chromosomes in the gametes of human beings?

Answer 1

1. 
   

   Gamets	R	r
   R	RR	Rr
   r	Rr	rr

2. Phenotypic ratio: 3 : 1
   Genotypic ratio: 1 : 2 : 1
3. Sex chromosomes in human males are XY and in human females are XX.
4. A mutation is a sudden change in one or more genes, or in the number or structure of chromosomes. Mutation alters the hereditary material of an organism's cells and results in a change in certain characters or traits in an entire population, and such changes can persist for years.
5. Human gametes have 23 chromosomes.