Question

Which one of them cannot exhibit both autogamy and geitonogamy?
A. Castor
B. Maize
C. Papaya
D. Cucumber

Answer 1

Hint: As we already know in the reproduction of the flowering plants, the zygote is formed by the union of ovule and pollen grain. Both autogamy and geitonogamy could be found by the transfer of the pollen grains. Here, we are going to find the correct one which does not exhibit both autogamy and geitonogamy through some information. Based on that it could be found and analyzed.

Complete answer:
    Autogamy is the fusion of the gametes that forms an individual. This is the predominant form of self-pollination and also the type of self-pollination. This is also known as self-fertilization. This is the reproductive mechanism that is employed by the flowering plants. This is the transfer of pollen grains from the anther to stigma by itself within the same flower of the same plant. Here, the word autogamy is formed by combining two Greek words, Auto + gamy = Autogamy, Auto means self and gamy means union. The following are some of the points that come under autogamy. They are as follows:
The flowers which come under this pollination are maybe brightly colored or colorless.
This does not require any agents for pollination.
These have low biological fitness because these occur in the same flower.
The open flower here is chasmogamy and the closed flower is cleistogamy.
                  Geitonogamy is also the type of self-pollination where it is formed by combining two Greek words, Geitono + gamy = Geitonogamy, Geitono means neighbor and gamy means union. This is the transfer of pollen to another of the one flower to the stigma of another flower. The following are some of the points that come under geitonogamy. They are as follows:
> These need pollinating agents for pollination.
> The flowers which come under this pollination are brightly colored.
> Here it has high biological fitness.
So, in papaya both of these types of pollination are not possible. All the others come under these kinds. The female plants produce fruits and they are cross pollinated with others by the agents like insects and wind. Only in papaya, both male and female flowers are present in different plants.

So, the correct answer is Option C.

Note: Autogamy and geitonogamy are the two ways of self-pollination. In autogamy the genetic variation is not produced but in geitonogamy there is the energy wastage of the pollinator attractants. This is the major disadvantage of both. These produce genetically identical offspring. These do not contribute to the process of evolution.