| Date | November 2016 | Marks available | 3 | Reference code | 16N.3.SL.TZ0.12 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 12 | Adapted from | N/A |
Question
The climograph shows the distribution of biomes according to the temperature and rainfall of land areas on Earth.
Identify the ecosystem with the appropriate numeral from the climograph.
Referring to the climograph, explain reasons that the nutrient store in the litter layer of the taiga is greater than in the tropical rainforest.
Markscheme
Award [2] if all three are correct, [1 max] if one or two are correct and [0] if none correct.
a. litter is dead plant material on the ground
b. conditions in tropical rainforests are ideal to decompose plant material
OR
conditions in taiga do not favour decomposition of litter
c. decomposition returns nutrients to soil
OR
nutrients in taiga remain in the litter and not in the soil
d. tropical rainforests have more saprotrophs/decomposers
OR
taiga have fewer saprotrophs/decomposers
Numbers alone do not constitute an explanation.
