Self pollination - class-XII

self-pollination causes an increase in homozygosity in progeny in every generation of selfing up to approximately 96% in the F5, and selfing of homozygous line produce genetically similar progeny with negligible or little variability. So, the correct option is C. ( Yields progeny which are not genetically variable )

Homogamy is the condition in flowers where the anthers (male) and stigma (female) mature at the same time, which facilitates self-pollination.

XX X Xx ...      Parents

I

XX Xx Xx xx ...     Fl hybrid

In Fl generation half of the total offsprings represent 
parental genotype i.e., Xx. Therefore out of 1200 seedling 600 will have parental genotype.

Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Since geitonogamy is the fertilization of a flower by pollen from another flower on the same (or a genetically identical) plant and geitonogamy is the fertilization of a flower by pollen from a flower on a genetically different plant and it is known that a cleistogamous flower is unable to pollinate via any of these methods. So, the correct option is "A" (Both geitonogamy and xenogamy are not possible).

Repeated self-pollination leads to inbreeding depression, where the accumulation of homozygous recessive deleterious alleles results in reduced fitness and vigor. This process is commonly used in breeding to create pure lines, but it often manifests as weak progeny.

Metaxenia refers to the effect of pollen on maternal tissues like the pericarp and seed coat, which are outside the embryo and endosperm. Xenia refers to the effect of pollen on the endosperm itself.

Cleistogamous flowers remain closed throughout their development, which physically forces the pollen to land on the stigma of the same flower, ensuring autogamy. Chasmogamous flowers are open and can facilitate either self or cross-pollination.

Cleistogamy is the type of automatic self-pollination of certain plants. This is a form that is used to propagate plants by using self-pollinating flowers in bud state. This is also known as bud pollination.

•           Geitonogamy is the process for which the fertilization of a flower by pollen from another flower on the same plant.

•           Entomophily is the process in which pollinations are carried out by insects.

•           Xenogamy is the process of transfer of pollen grains to the stigma of a different plant. This process is cross-pollination.

Thus, the correct answer is option C.

Geitonogamy: The transfer of pollen grains from the anther of a flower to the stigma of another flower borne by the same plant.

Xenogamy: Transfer of pollen grains from the anther of a flower to the stigma of another flower borne on a different plant but belonging to the same species.

Allogamy is the deposition of pollen grains from the anther of the one flower on the stigma of another flower, either in the same plant or in a different plant of the same species.

Homogamy: It is the condition in which flowers are bisexual anther and stigma mature at the same time to make self-pollination possible. Under this condition, the stigma receives the pollen grains from the anthers of the same flower by the agency of wind or insects.

 So, the correct answer is D.

Protogyny is the maturation of the stigma (female part) before the anthers (male part) in the same flower. Protandry is the opposite, where anthers mature first.

Self-incompatibility is a mechanism to prevent self-fertilization, but it can often be bypassed by techniques like bud pollination or high salt concentrations on the stigma. Thus, it is not an absolute barrier.

In Sporophytic Self-Incompatibility (SSI), pollen is typically 2-celled and rejected on the stigma. In Gametophytic Self-Incompatibility (GSI), pollen is typically 2-celled and rejected in the style.