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Excretion in plants and humans
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Excretion is removing the waste products of metabolism. Plants and humans both do it.
What excretion is
Excretion is the removal of waste products made by chemical reactions in cells (metabolism).
It is different from egestion, which is getting rid of undigested food as faeces.
It is different from egestion, which is getting rid of undigested food as faeces.
Excretion in plants
Plants make carbon dioxide in respiration and oxygen in photosynthesis.
When these are not needed, they are waste products. They diffuse out of the leaves through the stomata.
When these are not needed, they are waste products. They diffuse out of the leaves through the stomata.
Excretion in humans
Is getting rid of faeces an example of excretion? Explain.
- Faeces are mostly undigested food.
- Undigested food was never made by the body's cells, so it is not a metabolic waste product.
Answer: No. It is egestion, because faeces are undigested food, not waste from metabolism.
Excretion removes metabolic waste. Plants lose waste carbon dioxide and oxygen through stomata. Human lungs excrete carbon dioxide, kidneys excrete urea, water and ions, and skin excretes sweat.
The interactive lesson includes the diagrams for this topic.
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