Edaphic, topographic and biotic factors
Answers are for parents and teachers.
1
The valley at 500 m has +34 °C. With −6 °C per 1000 m, about what is the temperature on a pasture at 2500 m?
22
2
What is slope exposure? Illustrate its effect on a plant community with one example.
The orientation of slopes toward compass directions; xerophytes on the south slope, juniper and moist grasses on the north.
3
Give symbols: (a) a beetle living in a rat’s burrow, neither harming nor helping its host; (b) wheat and wild oat growing in one field; (c) codling-moth caterpillar–apple tree; (d) hummingbird–nectar-bearing flower.
(a) (+ 0); (b) (– –); (c) (+ –); (d) (+ +).
4
Which relationship between organisms is the discovery of antibiotics based on? Explain.
Amensalism (– 0): the Penicillium mould releases a substance that stops bacterial growth, while the mould itself neither gains nor loses; A. Fleming observed this in 1928 and discovered penicillin.
5
Explain the ecological basis of rotating legumes in crop rotation.
Nodule bacteria fix atmospheric nitrogen, enriching the soil, so the following crop grows well with less fertiliser.