GCSE Biology/Diversity of Life
Variation
editWithin any species there is room for variation. Not all the organisms will look the same because of different factors. Within species we can see variation in many ways, for example in humans we see variation in hair colour, eye colour and height. This variation is caused by two classes of factors, which are environmental and genetic. Environmental variations are different to genetic variations.
Environmental Variation
editMany features we see in organisms are caused by the environment in which they live. For example, environmental variations in humans could be:
- Hair length: what length you choose to have your hair
- Scars caused by accidents personal to you
- Muscle strength - dependent on how much exercise you do
- Piercings - whether you choose to have piercings or not
These forms of variation are caused by factors found in the environment. The most important of these factors include lifestyle (diet and exercise), temperature, and water level. For plants, light levels could also be included.
Genetic Variation
editMany features we see in organisms are caused by the genes with which they are born. These are passed on from their parent organisms. For example, genetic variations in humans could be:
- Eye color
- Blood group: either group AB, A, B or O
- Maximum potential height is determined by genetics, but whether this height is reached is due to environmental factors, like diet
- Earlobe attachment: earlobe attached or not
These forms of variation are caused by the sequences of genes. When a male sex cell joins a female sex cell, two opposite sets of genetic material are joined together to create a new, unique individual. This is called sexual reproduction, and creates much variation within a population.