Page 26 - 新思维科学学生用书8 样章

1.4 Respiration

Questions

1 Neurones contain more mitochondria than cheek cells. Suggest why.
2 Look at the word equation for aerobic respiration.
a What are the reactants in this reaction?

b What are the products of this reaction?
3 Use the equation for aerobic respiration to explain why the air that you breathe out contains more
carbon dioxide than the air that you breathe in.

Respiration and heat production

In Stage 7, you learned that every time energy is transferred or transformed, some of it is changed to
heat energy.

In respiration, chemical energy stored in glucose is transferred to other substances, so that cells can
use it. In this process, some of the energy is changed to heat energy. So respiring cells get a little bit
warmer than their surroundings.

Think like a scientist

Investigating respiration in peas
All living things need energy. So all living things respire. Even seeds respire.

Seeds respire especially quickly when they are germinating, because they need a lot
of energy to do this. You can make pea seeds start to germinate by soaking them in
water for about an hour.

You will need:

• two thermometers • cotton wool • two flasks
• insulating material to wrap round the outside of the flasks
• some dead peas • the same number of live, germinating peas

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