Other than the thermometer, explain how two features of the calorimeter shown in Figure 2 would enable a valid measurement of the total heat energy released.

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A 2 g sample of biomass was fully combusted in a calorimeter.

The volume of water in the calorimeter was 100 cm3

The increase in temperature recorded was 15.7 °C

4.18 J of energy are needed to increase the temperature of 1 cm3 of water by 1 °C

Use this information to calculate the heat energy released in kJ per g of biomass.

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In natural ecosystems, most of the light falling on producers is not used in photosynthesis.

Suggest two reasons why.

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The light absorbed by chlorophyll is used in the light-dependent reaction.

Name the two products of the light-dependent reaction that are required for the light-independent reaction.

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Chlorella cells can divide rapidly. A culture of 2000 Chlorella cells was set up in a fermenter. The cells divided every 90 minutes.

You can assume that there were no limiting factors and that no cells died during the 24 hours.

Calculate the number of cells in the culture after 24 hours.

Give your answer in standard form.

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