Cell Division and Reproduction

Study Notes

Fission and Fragmentation

In unicellular organisms, cell division leads to the creation of new individuals.
Fission patterns vary, with some bacteria and protozoa splitting into two equal halves during cell division.
In organisms like Amoeba, cell division can occur in any plane.

Fragmentation in Multi-Cellular Organisms

In multi-cellular organisms with simple body organisation, simple reproductive methods can still work.
Fragmentation occurs in organisms like Spirogyra, where the organism breaks into smaller pieces that grow into new individuals upon maturation.

Reproduction in Multi-Cellular Organisms

Multi-cellular organisms with complex body organisation cannot simply divide cell-by-cell.
This is because specialised cells are organised as tissues, and tissues are organised into organs, requiring precise placement in the body.
Reproduction is the function of a specific cell type in multi-cellular organisms.

Why Organisms Reproduce

Reproduction is not necessary for an individual organism's survival, unlike essential life processes like nutrition, respiration, or excretion.
Organisms reproduce, despite expending energy, for reasons that are still debated.
Reproduction allows organisms to create new individuals, leading to large numbers of organisms belonging to a single species.

Species Identification

We identify organisms as belonging to the same species based on their similar appearance.
Reproducing organisms create new individuals that resemble themselves.

Description

Learn about the different methods of cell division and reproduction in unicellular and multi-cellular organisms, including fission and fragmentation. Understand the various patterns of fission and how they occur in different organisms.