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 :
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
(a) In the F₁ generation, only tall plants were observed because tallness is the dominant trait. When a tall plant (TT) is crossed with a short plant (tt), all F₁ offspring are Tt. Since a single copy of 'T' is enough to make the plant tall, all plants appeared tall.
(b) Mendel obtained F₂ progeny by self-pollination of the F₁ tall plants.
(c)
| Dominant Trait | Recessive Trait |
|---|---|
| The trait that expresses itself in the presence of even one copy of the factor (e.g., tallness – T). | The trait that expresses itself only when both copies of the factor are the same recessive type (e.g., shortness – tt). |
Source: Chapter 8, Section 8.2.2
---
Explanation
- (a) Always mention the genotypes (TT × tt → Tt) and state that one copy of 'T' is sufficient for expression — this earns full marks.
- (b) The key term is self-pollination — do not write "cross-pollination."
- (c) Two marks means two distinct points — one for dominant, one for recessive. Using a table format is clear and saves time. The examiner looks for the idea that dominant is expressed with one copy, recessive needs two copies of the recessive allele.