Reproduction

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

Step 1: Planaria has special cells in its body. Step 2: These cells can divide and form different types of cells. Step 3: Therefore a complete organism can form from cut pieces.

Step 1: In vegetative propagation a new plant forms from a plant part. Step 2: The new plant often has traits similar to the parent. Step 3: Thus useful plants can be multiplied quickly.

Step 1: In sugarcane and rose a new plant can grow from a stem part. Step 2: It does not require seeds or gamete fusion. Step 3: Therefore it is an example of vegetative propagation.

Step 1: Tissue culture uses a small tissue of a plant. Step 2: The same tissue can produce many new plants. Step 3: Therefore produced plants may be similar to the parent plant.

Step 1: Pollen grains are related to male gametes. Step 2: They must reach the stigma. Step 3: Then a pollen tube can carry the male gamete to the ovule.

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

Step 1: After pollen lands on stigma it can germinate. Step 2: A pollen tube is formed. Step 3: The pollen tube carries the male gamete to the ovule.

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

Step 1: Water activates the seed. Step 2: Air is needed for respiration of the seed. Step 3: Suitable temperature is also needed for growth.

Step 1: Testes are main organs of the male reproductive system. Step 2: Sperms are produced in them. Step 3: They also produce male hormone related to puberty changes.

Step 1: Sperms are produced in testes. Step 2: Slightly lower temperature is useful for sperm production. Step 3: Therefore testes are located in a sac outside the body.

Step 1: Sperms are produced in testes. Step 2: They need to reach the passage for exit. Step 3: The sperm duct carries sperms forward.

Step 1: Ovaries are main organs of the female reproductive system. Step 2: Eggs are produced in them. Step 3: They also produce female hormones that help body changes.

Step 1: The egg is released from the ovary. Step 2: It enters the fallopian tube. Step 3: Fusion with sperm usually occurs there.

Step 1: Fusion of sperm and egg forms the zygote. Step 2: The zygote divides to form a group of cells. Step 3: This group develops further as an embryo.

Step 1: The embryo needs nutrients and oxygen to grow. Step 2: Attachment to the uterine wall allows exchange of materials. Step 3: This supports safe development of the embryo.

Step 1: The embryo cannot eat food by itself. Step 2: It needs nutrients and oxygen from the mother. Step 3: Placenta helps exchange these materials and also removes wastes.

Step 1: The uterus prepares an inner lining for possible pregnancy. Step 2: If fertilisation and pregnancy do not occur this lining is not used. Step 3: It comes out with blood and is called menstruation.

Step 1: During adolescence hormonal influence increases in the body. Step 2: Hormones help reproductive organs mature. Step 3: They also cause secondary sexual characters to appear.