Question

In Castor and Maize plants

• A. Both autogamy and geitonogamy are prevented
  
• B. Autogamy is prevented but not geitonogamy
  
• C. Male and female flowers are borne by different plants
  
• D. Anthers and stigma are placed
  at different positions to
  encourage cross-pollination
  

Answer 1

The correct option is B Autogamy is prevented but not geitonogamy


Castor and Maize plants
Castor and Maize are monoecious plants, i.e., unisexual male and female flowers are borne on the same plant. Thus, these plants can exhibit geitonogamy as the pollen from the anther of the male plant can be transferred to the stigma of the female flower on the same plant.
However, autogamy is not possible as the flowers on these monoecious plants are unisexual, i.e., bearing either the male reproductive part or the female one. Thus, pollen grains cannot be transferred from the anther to the stigma of the same flower.
Different position of anther and stigma
As maize and castor are monoecious plants, they bear unisexual flowers and hence an individual flower does not possess both anther and stigma.
Final answer
(A) Autogamy is prevented but not geitonogamy