The carbon cycle is fundamental to all ecosystems. Carbon is continuously cycled between living organisms and the atmosphere, as shown in Fig. 7.1. [Figure 7.1]

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

1. [1] carbon dioxide in atmosphere absorbed by producers / plants / chloroplasts / chlorophyll ;
2. [1] photosynthesis ;
3. [1] production of carbohydrates / glucose ;
4. [1] used to make other organic substances / named example ;
5. [1] eaten by / transferred to animals ;
6. [1] respiration ;
7. [1] releases carbon dioxide ;
8. [1] burning max two from: releases carbon dioxide ;
9. [1] greenhouse gas / global warming / greenhouse effect ;
10. [1] climate change / example of change ;
11. [1] made into objects max two from: object acts as a carbon store / locks up carbon ;
12. [1] tree removed from ecosystem so nutrients removed AW ;
13. [1] left in ecosystem max two from: fed on by decomposers / fungi / bacteria / decomposed ;
14. [1] nutrients returned to soil ;
15. [1] respiration of decomposers releases carbon dioxide gradually ;
16. [1] dead trees / logs act as a habitat ;