Cell Division

• Growth can be defined as a permanent increase in size. Cells are constantly being used. These cells must be replaced periodically.

Species Number

• Each species has a particular number of chromosomes which can be found in the nucleus of all cells.
• Note that red blood cells do not have a nucleus.
• Humans (Homo Sapiens) have 46 chromosomes.
• The full compliment of chromosomes in the body cells of a human is 23 pairs/46 chromosomes. This number represents the Diploid Number.

Diploid Number

• Can be found in all cells except sex cells/gametes.

Mitosis

• This type of cell division is responsible for growth, repairing cells and a-sexual reproduction.

Asexual Reproduction

• This is where one organism is involved, it does not involve the fusion of gametes (sex cells).
• Produces identical copies or clones.

The Amoeba

• This is able to undergo asexual reproduction.

What are Cuttings?

• These are identical copies of the parent plants, they have the same genetic makeup, same number of chromosomes and they have the same genes. The cuttings and the new plant is identical in every way.
• THE IS NO VARIATION IN MITOSIS.

Advantages of Asexual Reproduction

1. There is no time wasted looking for a mate.
2. Advantageous qualities will be passed on.
3. Time taken to develop from a seed is reduced.

Disadvantages of Asexual Reproduction

1. Negative/Bad qualities can also be passed on.
2. There is no variation. There may be no change to combat issues. (If a disease is spread through a field, there is no variation to combat these issues).

Meiosis

• This type of cell division takes place in the formation of your sex cells. It is in this type of cell division that the chromosome number is reduced to the Haploid Number.

Homologous

• These are chromosomes which are the same shape, length and the same genes along the length.

Sex Chromosomes

Alelles

• Different forms of genes.

Josiah Renne (PC)