Reproduction

Step 1: Sexual reproduction involves male and female gametes. Step 2: These gametes combine genetic information from two parents. Step 3: This creates new combinations and increases variation among offspring.

Step 1: One organism can live for some time without reproduction. Step 2: But new offspring are needed to maintain the species after organisms die. Step 3: So understand reproduction as the process that continues a species.

Step 1: A new cell or organism needs information to form. Step 2: Without copying genetic information that information cannot pass on. Step 3: Therefore copying is a base of reproduction.

Step 1: Small differences can arise during copying. Step 2: These differences can produce variation in offspring. Step 3: Variation may be useful for organisms in changing environments.

Step 1: Only one parent participates in asexual reproduction. Step 2: The offspring receives information from that parent. Step 3: Therefore offspring are very similar to the parent.

Step 1: Sexual reproduction forms male and female gametes. Step 2: These gametes may carry information from two different parents. Step 3: Fusion makes new combinations and increases variation.

Step 1: In binary fission one cell usually divides into two parts. Step 2: In multiple fission one cell can form many daughter cells. Step 3: Therefore the main difference is the number produced.

Step 1: Amoeba has an irregular shape. Step 2: Leishmania has a whip like structure at a definite position. Step 3: Therefore the plane of division is more definite in Leishmania.

Step 1: In Rhizopus spores are formed in sac like structures. Step 2: Spores can remain protected in some difficult conditions. Step 3: Under favourable conditions they can form a new organism.

Step 1: A small bud forms on the body of Hydra. Step 2: The bud grows and can become a new Hydra. Step 3: Thus it is an example of asexual reproduction from one parent.

Step 1: In fragmentation the body breaks into pieces. Step 2: Each piece can form a new organism. Step 3: In regeneration special cells rebuild lost parts.

Step 1: Planaria has special cells. Step 2: These cells can divide and form different tissues. Step 3: Therefore a complete organism can develop from a cut piece.

Step 1: In vegetative propagation a new plant forms from parts like root stem or leaf. Step 2: Information from one parent plant is passed on. Step 3: Therefore new plants can have traits like the parent.

Step 1: Some plants form few seeds or no seeds. Step 2: New plants can be grown from their stem root or leaf. Step 3: Thus vegetative propagation is useful in farming.

Step 1: Tissue culture uses a small part of a plant. Step 2: In a proper nutrient medium cells can divide and form new plants. Step 3: This gives many similar plants in less time.

Step 1: Self pollination mainly involves information from the same plant. Step 2: Cross pollination can involve two different plants of the same species. Step 3: Therefore cross pollination can increase variation more.

Step 1: After reaching stigma a pollen grain can germinate. Step 2: A pollen tube is formed. Step 3: The pollen tube carries the male gamete to the ovule.

Step 1: Reaching the stigma is only the first step for pollen. Step 2: The male gamete needs a path to reach the ovule. Step 3: Without pollen tube this path is not available.

Step 1: After fertilisation an embryo can develop inside the ovule. Step 2: The ovule becomes the seed. Step 3: The ovary grows and becomes the fruit.

Step 1: Fruit forms from the ovary. Step 2: Seeds can remain protected inside the fruit. Step 3: Many fruits also help disperse seeds over distances.