O-LevelBiologyEcology & Environment5090/22 · May/June 2019 · Q59 Marks

The diagram shows the carbon cycle. [Figure 5.1: Diagram showing the carbon cycle with interconnected boxes for fossil fuels, carbon dioxide in the atmosphere, living plants, living animals, and dead plants and animals, linked by processes K, L, M, N.]

(a)Name each of the processes K to N. K L M N[4]
(b)(i)The diagram shows two locations, X and Y, on the Earth. [Figure 5.2: Diagram showing locations X and Y on the Earth relative to the equator.] The table shows the length of daylight at each location during a year. | | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Jan | Feb | |------------|-----|-----|-----|------|------|------|-----|-----|-----|------|------|------| | length of | | | | | | | | | | | | | | daylight at| medium | | | long | | | medium | | | short| | | | location X | | | | | | | | | | | | | |------------|-----|-----|-----|------|------|------|-----|-----|-----|------|------|------| | length of | | | | | | | | | | | | | | daylight at| medium | | | short| | | medium | | | long | | | | location Y | | | | | | | | | | | | | The graph shows the change in carbon dioxide concentration in the atmosphere measured during one year at location X. [Figure 5.3: Graph showing carbon dioxide concentration in the atmosphere at location X from March to February, with a trough around August/September and a peak around February/March.] Suggest an explanation for the pattern of changes in the concentration of carbon dioxide in the atmosphere shown in the graph.[3]
(b)(ii)Draw a line on the graph to suggest the change in carbon dioxide concentration in the atmosphere during the year at location Y.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[4] (K) combustion / burning;
[4] (L) respiration ;
[4] (M) photosynthesis ;
[4] (N) decomposition / decay / rotting / respiration ;
[3] (for May to Sep / long days) falls AW / low / lowest / more removed from air; more + leaves / foliage; more / long(er) + light / daylight ; more / fast(er) + photosynthesis ; carbon dioxide + used in photosynthesis ; photosynthesis faster than respiration ;
[3] (for Sep to May / short days) rises AW / high / highest / more released into air; less + leaves / foliage; less / short(er) + light / daylight; less / slow(er) + photosynthesis ; carbon dioxide + produced in respiration; respiration faster than photosynthesis ;
[2] line drawn from y-axis to middle of grid + shows only a trough ;
[2] line drawn from middle of grid to end of grid + shows only a peak ;
[2] (Note for b(ii): Graph for X has a trough in northern summer and peak in northern winter. Location Y has reversed seasons compared to X. So, for Y, the trough should be in southern summer (Dec-Feb) and peak in southern winter (Jun-Aug). The line drawn should reflect this reverse pattern.)

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.