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When it comes to AS/A-level Biology, do you know what are the causes of variation?
Variation
- The presence of variety - the differences between individuals.
(1) Intraspecific variation – variation between members of the same species.
(2) Interspecific variation – the differences between species.
(3) Continuous variation – variation where there are two extremes and a full range of values in between.
(4) Discontinuous variation – variation where there are distinct categories and nothing in between.
Causes of Variation
(1) Inherited or genetic variation
- This includes the combination of alleles that is inherited from our parents which is completely unique to us (unless there is an identical twin).
(2) Environmental variation
- Many characteristics are brought out by environmental changes.
- E.g. An overfed pet can become obese and a person’s skin tone may change due to exposure to the sun.
(3) Combined effects
- Humans have become taller as the result of a better overall diet but however well your diet, you are unlikely to grow as tall as other people if your family is short.
- Not all genes are active at any one time
- E.g. Puberty is a time when many different genes are activating.
- Changes in the environment can also directly affect which genes are active.
That's the end of the topic!
Drafted by Bonnie (Biology)