Reproduction in Organisms

Study Notes

Asexual reproduction is the production of new organisms from a single parent without the involvement of sex cells (gametes).
Methods of asexual reproduction include fission, budding, spore formation, vegetative propagation, and fragmentation.

Sexual reproduction is the production of new organisms by two parents making use of their gametes.

Feature	Asexual Reproduction	Sexual Reproduction
Number of parents	One parent	Two parents
Sex cells	No sex cells involved	Sex cells (gametes) involved
Variation	Little or no variation among offspring	Significant variation among offspring
Speed	Faster	Slower
Energy requirement	Less energy required	More energy required

Fission: A single organism divides into two identical organisms, e.g. bacteria, Amoeba.
Budding: A new organism develops from an outgrowth or bud from the parent body, eventually separating to become independent, e.g. hydra, yeast.
Spore Formation: Specialized reproductive cells (spores) develop under favorable conditions from the parent body, then germinate to form new organisms, e.g., fungi, bread molds.
Vegetative Propagation: A new plant grows from a vegetative part of the parent plant, e.g., runners, tubers, rhizomes, bulbs, suckers, etc., in various plants.
Fragmentation: A multicellular organism breaks into fragments (pieces), and each fragment develops into a complete organism, e.g., Planaria, some algae/fungi.

Regeneration is when an organism can regrow lost body parts.
Regeneration is a specific type of asexual reproduction in certain organisms like Planaria.
Complex multicellular organisms generally cannot regenerate entire bodies.

Many plants exhibit vegetative propagation; from roots, stems, or leaves.
Examples include runners (strawberries), tubers (potatoes), bulbs (onions), rhizomes (ginger), suckers (mint), etc.
Plants can be propagated artificially by methods like cutting, layering, grafting, tissue culture, and parthenogenesis.