Mendel worked out the rules of heredity by working on garden pea using a number of visible contrasting…
Mendel worked out the rules of heredity by working on garden pea using a number of visible contrasting characters. He conducted several experiments by making a cross with one or two pairs of contrasting characters of pea plant. On the basis of his observations he gave some interpretations which helped to study the mechanism of inheritance.
(i) When Mendel crossed pea plants with pure tall and pure short characteristics to produce F1 progeny, which two observations were made by him in F1 plants?
(ii) Write one difference between dominant and recessive trait.
(iii) (A) In a cross with two pairs of contrasting characters
RRYY × rryy
(Round Yellow) (Wrinkled Green)
Mendel observed 4 types of combinations in F2 generation. By which method did he obtain F2 generation ? Write the ratio of the parental combinations obtained and what conclusions were drawn from this experiment.
Solution
(i) In F1 generation, all plants were tall / No short plants were observed
No medium height plants / No halfway characteristics were observed / Only dominant parental traits were seen and not the mixture of the two.
(ii)
Dominant trait: Single copy of dominant trait is enough to get it expressed/always expressed
Recessive trait: Only expressed when present in pair.
(Any other point)
(iii)(A) Self-pollination / Self-fertilisation / Selfing of F1 plants
Ratio – Round Yellow : Wrinkled Green
9 : 1
Traits are inherited independently.