Biological Reproduction: Asexual and Sexual Processes

Reproduction

• Asexual reproduction: Requires only one parent.
• Sexual reproduction: Requires two parents, female and male.

Asexual Reproduction in Plants

1. Spore formation: The plant produces small unicellular structures called spores that become new individuals without attaching themselves to other cells.
2. Vegetative reproduction:
   • Bulbs: Underground stems (e.g., onion or garlic).
   • Stolons: Aerial stems that root when they touch the ground and produce new stems (e.g., strawberry).
   • Stem tubers: Subterranean stems (e.g., potato).

Asexual Reproduction in Animals

• Gemmation or Budding: A small bump or bud appears on the body of the progenitor; it grows and takes on the form of the adult (e.g., sponges).
• Fragmentation: A new organism grows from a fragment of the parent's body (e.g., starfish).

Sexual Reproduction in Plants

1. Female part (Carpel): Female gametes (ovules) are produced in the ovary inside the carpel.
2. Male part (Stamen): Pollen grains are produced in the anther.
3. Petals: Attract animals and protect the flower; they form the corolla.
4. Sepals: Cover and protect the other parts of the flower; they form the calyx.

Flowering Plant Reproduction Steps

1. Pollination: Pollen is transferred from the male stamen to the female stigma by insects or wind.
2. Fertilization: When pollen lands on a stigma of the same species, the pollen grain grows a tube to join with the female gamete (ovule).
3. Seed dispersal: After fertilization, petals fall off, a fruit usually forms from the ovary, and fertilized ovules become seeds. Seeds are dispersed by wind or animals.
4. Seed germination: Seeds start to grow when temperature, air, and water conditions are right.

Sexual Reproduction in Animals

• Gametogenesis: Reproductive cells or gametes are made in the sexual organs.
• Copulation: The process in which sperm from a male is inserted into the female’s body.
• Fertilization: The fusion of male and female gametes.
• Embryonic development: The period when the embryo develops.
• Birth or hatching: Birth is the process of expelling the new being from the mother’s body; hatching is the breaking of the egg and the emergence of the new being.