Which of the following statements are incorrect?
(A) Transfer of pollen grains (shed from the anther) to the stigma of a pistil is termed pollination.
(B) In a normal flower which opens and exposes the anthers and the stigma, complete autogamy is rather rare.
(C) Continued cross-pollination results in inbreeding depression.
(D) Geitonogamy is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → C and D only
(A) Transfer of pollen grains (shed from the anther) to the stigma of a pistil is termed pollination. — True. This is the definition of pollination. It brings the non-motile male gametes close to the female gamete.
(B) In a normal flower which opens and exposes the anthers and the stigma, complete autogamy is rather rare. — True. Autogamy in an open flower needs pollen release and stigma receptivity at the same time, and anthers lying close to the stigma. These conditions are seldom met, so complete autogamy is rare.
(C) Continued cross-pollination results in inbreeding depression. — False. Inbreeding depression comes from continued self-pollination. Cross-pollination is the cure; that is why plants have outbreeding devices.
(D) Geitonogamy is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma. — False. In geitonogamy the pollen comes from another flower of the same plant, so genetically it is like autogamy. Only xenogamy, with pollen from a different plant, brings genetically different pollen.
NCERT Extract:
Pollination – “… Transfer of pollen grains (shed from the anther) to the stigma of a pistil is termed pollination. … (i) Autogamy : In this type, pollination is achieved within the same flower. Transfer of pollen grains from the anther to the stigma of the same flower (Figure 1.9a). In a normal flower which opens and exposes the anthers and the stigma, complete autogamy is rather rare.”
Pollination – “… (ii) Geitonogamy – Transfer of pollen grains from the anther to the stigma of another flower of the same plant. Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy since the pollen grains come from the same plant. (iii) Xenogamy – Transfer of pollen grains from anther to the stigma of a different plant (Figure 1.9b). This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.”
Pollination – “… Continued self-pollination result in inbreeding depression.”