(a) How does cleistogamy ensure autogamy?
(b) State one advantage and one disadvantage of cleistogamy to the plant.

Explanation

(a) Cleistogamous flowers are those which do not open at all and pollen from other plants cannot land on the stigma of these flowers. Thus, in such plants cross pollination cannot occur and only autogamy occurs. Therefore, cleistogamy ensures autogamy.
(b) Cleistogamy has this advantage that the plant produces assured seed set even in the absence of pollinators and disadvantage is that self pollination occur which reduces that chances of variation and evolution of genetically superior progeny.