🐾 Reproduction in Animals
1. Reproduction is the biological process by which new individual organisms are produced.
2. All living things reproduce to ensure the continuity of their own kind.
3. Cells are the basic building blocks of life. All living things are made up of one or many cells that contain genetic information which determines their traits. Different types of cells perform different functions.
4. Both humans and plants have male reproductive cells and female reproductive cells that are responsible for sexual reproduction.
1. Sexual reproduction is the mode of reproduction where the offspring arises from the fusion of a male and female reproductive cell (→ fertilisation).
- The male reproductive cell is known as the sperm.
- The female reproductive cell is known as the egg.
2. During fertilisation, the sperm fuses with the egg to form a fertilised egg. The fertilised egg undergoes cell division and eventually grows into an offspring.
3. This offspring will have traits inherited from both parents, as the genetic information stored in the sperm and egg are passed on from the parents to the offspring.
| Part | Characteristics and functions |
|---|---|
| Penis | Male reproductive organ which ejects sperm and deposits them in the vagina of the female reproductive system. |
| Testis (plural: testes) | Male reproductive organs that produce the sperm. |
| Part | Characteristics and functions |
|---|---|
| Ovary (plural: ovaries) | Female reproductive organs that produce eggs. |
| Womb (Uterus) | A pear-shaped structure made up of a thick wall of muscle. This is the place where the fertilised egg will be implanted and where the fertilised egg/foetus develops. |
| Vagina | A muscular tube which receives sperm. It is also the birth canal for the baby. |
1. Fertilisation is the process where the sperm and the egg fuse, producing a fertilised egg.
2. Although females usually release one egg from either ovary each time, males release a large number of sperm each time to increase the chances of a sperm reaching the egg for fertilisation to occur.
One egg can only be fertilised by one sperm at a time. The large number of sperm released is what increases the chances of fertilisation occurring.
1. After fertilisation, the fertilised egg will develop in the womb to form a foetus.
2. This process will take about 40 weeks or 9 months until the baby is ready to be born.
3. This period of time where the fertilised egg develops into a young individual ready to be born is known as the gestation period.
| Sperm | Egg | |
|---|---|---|
| Reproductive cell | The sperm is the male reproductive cell. | The egg is the female reproductive cell. |
| Where it is produced | The sperm is produced in the testes. | The egg is produced in the ovaries. |
| Genetic information | It contains genetic information from the father. | It contains genetic information from the mother. |
| Amount | Large amounts of sperm are released at one time. | Only one egg is usually produced at a time. |
| Fertilisation: One egg can only be fertilised by one sperm at a time. | ||
1. Heredity is the passing of traits from parents to their offspring through their genetic material.
2. Some traits that we inherit from our parents include hair colour, eye colour, skin colour and blood type.
3. The sperm and the egg contain genetic information from the father and the mother respectively. When the sperm and egg fuse during fertilisation, the genetic information stored in the cells is passed on from parents to the offspring. Hence, the offspring will have traits from both parents.
| Hereditary | Non-hereditary |
|---|---|
| Double or single eyelids | Length of hair |
| Ability to roll tongue | Length of fingernails |
| Presence or absence of dimples | Fingerprints |
| Detached or attached earlobes | Iris pattern |
| Colour of eyes/skin/hair | Moles on skin |