REPRODUCTION
What is reproduction?
* The process by which organisms produce offspring that are similar or identical to themselves. Can be sexual or asexual.
* Asexual reproduction involves a single parent producing new offspring identical to itself.
* Sexual reproduction involves the fusion of male and female sex cells to produce an individual that is similar but not identical.
ASEXUAL REPRODUCTION
Advantages
* Reproduction is faster. Does not require searching for a mate
* Multiple offspring can be produced at any given time. Useful in a catastrophe and in agriculture (propagation)
* Allows for continuation of beneficial or desirable traits. A farmer can choose to propagate plants that are larger, desirable flavor etc.
Disadvantages
* No genetic variation.
* Prone to extinction. They don't adapt or change so changes in the environment can kill them.
* Increased competition for resources. Offspring stay in the same location; overcrowding.
Asexual reproduction in unicellular organisms
Budding in yeast
Yeast is a single celled fungus that reproduces asexually by budding. The parent sends out a bud. When it is large enough, the nucleus splits and migrates to the bud, which then breaks off, making a new cell.
Binary fission
Unicellular organisms like amoeba and bacterium split into 2 in a process called binary fission.
Amoeba takes 1 hour, bacteria within 20 mins.
Asexual reproduction in flowering plants
* Vegetative reproduction (propagation) occurs naturally. Some plants use storage organs that allow them to go dormant during unfavorable conditions. These are known as perennating organs. Eg:
* Corm- short, swollen underground stem that produces buds at the top, roots at the bottom, and new shoots in the wet season.
* Bulb - underground stem that is totally surrounded by large fleshy and scaly leaves. Onion and garlic are good examples.
* Rhizome - underground swollen stem that grows horizontally. Terminal buds give rise to new plants. Ginger is a good example.
* Stem tuber -
* Root tuber -
* Tap roots -