Not only is it possible to see differences between plants and animals but it’s also possible to observe differences between the same species; this is known as variation. This is down to two main reasons: what they inherited from their parents and the environment in which they live. Asexual reproduction, on the other hand, can be used to create individuals which are genetically identical to their parent. Today, scientists are able to manipulate genes so that they can create exactly the plant or animal they want.

By the end of this section you should understand:

• about cloning and genetic engineering techniques
• the economic, social and ethical implications surrounding cloning and genetic engineering with an emphasis on genetically modified crops

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Why organisms are different

The reason why plants and animals have similar characteristics to their parents is because of genes. Genes make up chromosomes which are found in the nucleus of cells. However, sexual reproduction is able to produce offspring which are very similar to the parents but not identical.

Genetic information

Chromosomes are found in the nucleus of a cell. Each chromosome is composed of a number of genes. In turn, each gene is a piece of DNA which has instructions for specific proteins. As each gene creates a specific protein so each is in charge of particular characteristics that make up an organism. This means that for a whole organism a lot of genes are required.

Variations

Despite the fact that each member of the same species looks alike they don’t tend to be exactly the same. This is known as variation and there are two main ways in which this can occur.

Inherited genes

One way is because of the genes an individual inherited. Humans are a good example of this. A child won’t look exactly like their father or their mother because they inherited genes from both of their parents. For example, people may comment that a child has got their mother’s eyes and their father’s nose.

Environmental causes

Variations can also be caused by the conditions in which an individual grew up in. Both animals and plants can be affected by a number of factors including:

• nutrition
• diet
• climate
• accidents
• pollution

Humans are affected by a range of other external factors:

• culture
• lifestyle
• religion

A combination

Sometimes an individual can be affected by both genetic and environmental factors.