Reproduction In Plants - SS2 Biology Past Questions and Answers - page 2

Self-pollination

Parietal

Ovary

Dioecious

Apocarpous

Insects

A typical flower consists of several essential parts. The outermost whorl is composed of sepals, which protect the developing bud. Inside the sepals, the next whorl consists of colorful petals, which attract pollinators. The male reproductive organs, called stamens, are composed of anthers that produce pollen and filaments that support the anthers. The central whorl contains one or more female reproductive organs called carpels, which consist of a stigma, style, and ovary. The stigma receives pollen, the style connects the stigma to the ovary, and the ovary houses the ovules, which contain the female gametes.

Flowers can be categorized based on their reproductive organs. Perfect flowers have both male and female reproductive organs (stamens and carpels) within the same flower. Imperfect flowers, on the other hand, possess either stamens or carpels, but not both. Monoecious plants have separate male and female flowers on the same plant, while dioecious plants have distinct male and female flowers on separate plants.

Placentation refers to the arrangement of ovules within the ovary of a flower. Axile placentation occurs when the ovules are attached to a central column in the ovary. Parietal placentation involves ovules attached to the inner wall of the ovary. Free-central placentation occurs when ovules are attached to a central axis, with no connection to the ovary wall. Basal placentation involves ovules attached at the base of the ovary.

Pollination is the transfer of pollen from the male reproductive organs to the female reproductive organs of a flower. It can be achieved through various agents. Wind pollination occurs when pollen is carried by the wind to reach the stigma of a receptive flower. Insect pollination involves insects, such as bees or butterflies, transferring pollen while visiting flowers for nectar. Bird pollination occurs when birds, such as hummingbirds, carry pollen between flowers. Other animals, such as bats or small mammals, can also act as pollinators. Each agent plays a crucial role in the reproductive success and genetic diversity of flowering plants.