1.2.11

Variation

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Natural Selection

Natural selection is the process by which the least-well adapted organisms die, and the best-adapted organisms survive, breed and pass their advantageous genes onto the next generation.

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Continuous vs discontinuous variation

  • Continuous - this type of variation is difficult to group. There are some extreme examples and most people fall in the middle. Some examples are height and weight.
    • Continuous data can be represented on a line graph.
  • Discontinuous - this type of variation is easier to group. Groups have hard borders and you cannot fall between groups. Some examples are sex and blood group.
    • Discontinuous data can be represented on a bar or pie chart.
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Why do animals vary?

  • Animals within the same species vary from one another.
    • This is because of their slightly different genes.
    • For example, not all cheetahs can run at the same speed. Some are slightly faster and some are slower than others.
  • This is to do with the genes that control muscles size, aerodynamic head shape and so on.
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Competition

  • Because of these differences, or variation, some cheetahs are better adapted to survive.
    • They find it easier to hunt, eat and live to an older age so that they can breed.
  • If they are more likely to breed, those genes that made them such good hunters will be passed onto their offspring.
  • The cheetahs that were slow don’t survive and don’t pass on the genes for slowness or poor aerodynamics.
  • Over time, the cheetah population is refined and becomes better suited to its environment.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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