Biology KS3/4: Size and heat

Professor Brian Cox explores the relationship between an organism's body size and its metabolic rate.

He explains that smaller animals have a larger surface to volume ratio compared to larger animals. This means they lose heat at a much quicker rate.

To combat this, smaller animals are forced to maintain a high metabolic rate, to keep a constant body temperature; their heart beats at a faster pace and they breathe much quicker, as such smaller animals do not tend to live as long.

This clip is from the series Wonders of Life.

Teacher Notes

This clip could be used to consider how the size of an animal determines its metabolic rate, which in turn determines its life span. This could be determined by providing data on animals so their surface area to volume ratio can be calculated and a correlation either determined or predicted based upon its life span.

Curriculum Notes

This clip will be relevant for teaching Biology at KS3 and KS4/GCSE in England, Wales and Northern Ireland and SQA National 3/4/5 in Scotland.

More from Wonders of Life:

Bacteria and the development of an oxygen rich atmosphere
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Conservation of energy
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How has life on Earth become so varied?
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Lemurs: Evolution and adaptation
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Jellyfish and photosynthesis
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The arrival of water on Earth
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The origins of life on Earth
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Evolution of hearing
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Evolution of sight
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Evolution of the senses
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Gravity, size and mass
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