Question

Mendel took garden pea plants with different characteristics, such as height to study the inheritance pattern of factors (genes). He crossed tall pea plant with short pea plant and obtained all the tall plants in the F1 generation.

Answer the following questions:

(a) Why only tall pea plants were observed in F₁ progeny?    [1]

(b) By which method did Mendel obtain F₂ progeny?    [1]

(c) (i) Write one difference between dominant and recessive trait.    [2]

OR

(c) (ii) Write two observations made by Mendel about F₁ progeny.    [2]

Answer 1

(a) Only tall plants were observed because the trait for tallness is dominant over the trait for shortness in pea plants.

(b) Mendel obtained F₂ progeny by allowing the F₁ hybrid plants to undergo self-pollination.

(c) (i) Dominant trait: It is a trait that expresses itself even when only one copy of the allele is present (e.g., TT or Tt both result in tall plants).

Recessive trait: It is a trait that is expressed only when both alleles are identical and recessive (e.g., tt results in short plants). It remains hidden in the presence of a dominant allele.

OR

(c) (ii) Mendel’s observations regarding the F₁ progeny were:

1. Uniformity of Phenotype: In the F₁ generation, all plants inherited the Tallness trait from a single parent. None of the plants was short.
2. Absence of Blending: There were no plants of middle or intermediate heights. This study demonstrated that features are inherited as distinct “factors,” rather than “mixing” like paint.