- A Having largely separate male and female plants existing individually within the same breeding population in general practice as frequently described
- B Having morphologically distinct flower types (pin and thrum) where stamens of one type are at the same height as stigma of other type, promoting cross-pollination
- C Relying mainly upon chemical self-incompatibility reactions occurring specifically at the receptive stigma surface itself in most textbook accounts during normal conditions
- D Temporal separation occurring mainly between the timing of pollen release and the period of stigma receptivity, as observed in typical laboratory settings
Correct answer: B. Having morphologically distinct flower types (pin and thrum) where stamens of one type are at the same height as stigma of other type, promoting cross-pollination
Explanation: Heterostyly (distyly/tristyly): flowers differ in position of stamens and stigma. Pin (long style, low anthers) x Thrum (short style, high anthers) ensures pollen lands on stigma of opposite type -- mechanical self-incompatibility.
Concept context
Flower structure, pollination, double fertilization, and seed/fruit development — the highest-scoring Class 12 biology chapter in NEET.
Read the full Sexual Reproduction in Flowering Plants notes →