Additinal science Biology

Comptition In Plants

A number of FACTORS limit the growth in plants: Light, Nutrient availability, Tempreature, Carbon dioxide, Oxygen, Hormone levels and avaliable space.

In plant FERTILISATION, the male gemete (POLLEN) lands on the STIGMA. From here, a long tube grows down into the plant OVUM where it fertilises the female (OVUM).

After fertilisation, the petals fall off. Fruit is the swollen OVARY wall.

SEEDS can be transported by: Animals and Insects, the wind and water.

The way the seed is DISPERSED affects how far the plant is DISTRTBUTED.

Selective Breeding

SELECTIVE BREEDING has been used to create organisms that are more useful to humans.

For example, we have bred horses that are taller and faster, cows that produce more milk, sheeps that produce better wool and crops that produce a greater yield.

Organisms are chosen according to desired features and are bred together.

Dolly The Clone

A CLONE is an organism genetically identical to its parent.

A clone is made by taking an egg cell and a normal body cell from an organism.

The nucleus from the egg cell is removed. This neclus is HAPLOID and has insufficient genetic material to create life.

The nucleus fromt he body cell (DIPLOID) is then placed into the egg cell.

The egg is encouraged to divide by being shocked with electric shocks.

Once the cell has started to divide, it is placed into the womb of the mother oganism.

Treating Genetic Disorders

The potential to treat genetic disorders such as cancer and cystic fibrosis is becoming more of a reality.

Cells affected by the disorder can be 'infected' with genes that do not have the mutation.

There are many potential ethical dilemmas for such genetic treatment. Some people feel that we have been assigned our own unique genetic code and this should not be tampered with.

GENETIC THERAPY would not necssarily eradicate genetic deisorders. Sex cells will still contain the mutation and also spontaneous mutations will still occur.