Question 2 - Past Year - 5 Mark Questions - Chapter 9 Class 10 - Heredity and Evolution

(a) Why did Mendel choose garden pea for his experiments? Write two reasons.

(b) List two contrasting visible characters of garden pea Mendel used for his experiment.

(c) Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.

Answer:

(a)

Mendel chose garden pea for his experiments because:

• They are small and easy to grow.
• They are self-pollinating and thus, self and cross-pollination can be easily performed.
• Flowers are bi-sexual.
• They have a shorter life-span.

(b)

Contrasting visible characters of garden pea Mendel used for his experiment are:

• Round / Wrinkled seeds
• Tall / short plants
• White / Purple flowers
• Green / yellow seeds

(c)

Mendel crossed two pea plants with two contrasting characters, only one character appeared in the F ₁ progeny and the other character remained hidden.

On self-crossing plants in the F ₁ progeny, 

• The hidden character appeared in the F ₂ progeny but only 25% of the F ₂ progeny members had the hidden character. 
• The other 75% had the character all the plants had in the F ₁ progeny.

Thus, Mendel concluded that character which expressed itself in the F ₁ progeny and 75% of the F ₂ progeny is the dominating character whereas the character which expressed itself in 25% of the F ₂ progeny is the recessive character.