Selective breeding (artificial selection) and its uses and risks, the process and uses of genetic engineering including genetically modified crops and bacteria producing insulin, the benefits, risks and ethics of genetic modification, and an outline of tissue culture and cloning.

What this dot point is asking

OCR wants you to describe selective breeding (artificial selection) and its risks, describe the process and uses of genetic engineering including GM crops and bacteria making insulin, evaluate the benefits, risks and ethics of genetic modification, and outline cloning.

Selective breeding (artificial selection)

The process is the same whatever the organism:

1. From a population, select the individuals with the desired characteristic.
2. Breed these individuals together.
3. From the offspring, again select those with the best form of the characteristic and breed them.
4. Repeat over many generations until the characteristic is strongly expressed.

Useful characteristics chosen include higher crop yields, disease resistance in crops, more milk or meat from animals, gentle temperament in pets, and large or unusual flowers.

Genetic engineering

A classic example is engineering bacteria to make human insulin for people with diabetes:

1. The gene for human insulin is cut out of human DNA using enzymes.
2. The same enzymes cut open a small ring of bacterial DNA called a plasmid.
3. The insulin gene is inserted into the plasmid, which acts as a vector (a carrier).
4. The plasmid is put back into a bacterium, which then reproduces and makes human insulin, which is collected and purified.

This produces large amounts of insulin quickly and cheaply, identical to human insulin and without using animals.

Uses, benefits and risks of GM

Genetic engineering has many uses you can quote:

• GM crops engineered for higher yields, resistance to pests, herbicides or disease, or added nutrients (for example "golden rice" with extra beta-carotene to reduce vitamin A deficiency).
• Bacteria engineered to make medicines such as insulin and other proteins.

The benefits include more food, less use of pesticides, and cheaper medicines. The risks and ethical concerns that OCR expects you to discuss include:

• Possible effects on human health that are not yet fully known.
• Effects on the environment, for example GM genes spreading to wild plants, or harming insects such as pollinators, and reducing biodiversity.
• Ethical and economic worries, for example farmers depending on companies that own the GM seeds.

OCR rewards a balanced answer that weighs benefits against risks rather than only one side.

Cloning

A clone is a genetically identical copy of an organism. In plants, tissue culture grows many identical plants from a few cells of a parent plant, which is useful for mass-producing a plant with desirable characteristics or for preserving rare species. In animals, cloning can copy an animal with useful characteristics. Because clones are genetically identical, cloning, like selective breeding, produces no genetic variation.