What do you understand by pollination? Outline five causes of self-pollination in flowers. State five advantages and five disadvantages of self-pollination.

Here are the solutions to your biology questions.

1. Seed bearing plants

• a) What do you understand by pollination? Pollination is the transfer of pollen grains from the anther (male reproductive part) to the stigma (female receptive part) of a flower. This process is crucial for sexual reproduction in flowering plants, leading to fertilization and subsequent seed formation.

• b) Outline five causes of self-pollination in flowers.

  1. Bisexual flowers: The flower contains both functional male (stamens) and female (pistil) reproductive organs.
  2. Homogamy: The anthers and stigma of the same flower mature simultaneously, allowing pollen to be transferred directly.
  3. Cleistogamy: Flowers remain closed, preventing cross-pollination and ensuring self-pollination (e.g., in some violets).
  4. Position of anthers and stigma: The anthers are positioned directly above or very close to the stigma, facilitating pollen transfer within the same flower.
  5. Wind or insect absence: In environments where pollinators are scarce or wind is minimal, self-pollination becomes a more reliable reproductive strategy.

• c) State five advantages and five disadvantages of self-pollination.

  • Advantages:
    1. Ensures seed production even when pollinators are scarce or absent.
    2. Preserves desirable traits in a lineage, as there is no genetic mixing.
    3. Requires less energy from the plant for producing nectar, scent, or large petals.
    4. More reliable in certain environments, as it doesn't depend on external agents.
    5. Helps maintain genetic purity over generations.
  • Disadvantages:
    1. Leads to reduced genetic variation, making the population less adaptable to environmental changes.
    2. Increases the risk of inbreeding depression, where harmful recessive traits become more common.
    3. Reduces vigor and fertility over successive generations.
    4. Limits the ability of the species to evolve and adapt to new conditions.
    5. May lead to accumulation of deleterious mutations.