| Date | May 2010 | Marks available | 1 | Reference code | 10M.3.SL.TZ2.20 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Describe | Question number | 20 | Adapted from | N/A |
Question
List four factors that affect the distribution of plant species.
[4]
a.
Describe one effect of plants on an abiotic factor in a pioneer community.
[1]
b.
Markscheme
pH of soil;
water /humidity;
light;
temperature;
salinity;
mineral nutrients;
competition;
altitude;
pollinating agents;
predators / parasites;
slope;
a.
adds humus to soil;
breaks down rock (through roots, chemicals, rhizoids);
holds soil/prevents erosion;
aerates soil;
provides shade;
reduces water content;
b.
Examiners report
Most candidates listed the abiotic factors affecting the distribution of plant species and were able to score full marks, making it easy to score 4 marks in this option.
a.
N/A
b.
Syllabus sections
Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.1 Species and communities
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