Sexual Reproduction

                                                                              

                                                                  

1. Sexual Reproduction

• Definition: The process involves the union of male and female gametes (sperm and egg).

• Fertilization: Fertilisation can take place outside the organism (external) for instance, female fish release eggs and male fish releases their sperm upward into the water or within the organism (internal) these fusions occur.

• Genetic Variation: Since the offspring receive the genes from both parents, it increases the diversity of the offspring which increases their chance of survival in the environments.

2. Asexual Reproduction

• Binary Fission: A single organism divides to produce two genetically identical organisms. This is common in bacteria organisms.

• Budding: Outgrowth and eventual splitting off of a new organism from the parent organism. For example yeast and hydra.

• Vegetative Propagation: Plants that reproduce asexually from the peripheries of the parent plant. For example roots, stems or leaves are used for propagation as in strawberries and potatoes.

• Cloning: This is another mode of asexual reproduction whereby copies of an organism, with identical genes, are made naturally as in plants and/or artificially such as through laboratory methods.

3. Parthenogenesis

• Definition: Is the phenomenon where the egg develops without fertilization.

• Examples: Occurs in insects such as aphids, among reptiles such as the obeying lizards and certain plants.

• Benefits: It can help to sustain a rapid growth of population under favorable condition although generally results in low genetic variability.