Question 1
Which is the best definition of an adaptive feature?
- A feature an organism learns during its life
- An inherited feature that helps an organism to survive and reproduce in its environment
- A feature that only appears in a mutated organism
- Any difference between two species
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Answer: B (1)
Question 2
A polar bear has white fur and a thick layer of fat under its skin. Describe how each feature helps the polar bear to survive in the Arctic.
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- white fur gives camouflage (1)
- against the snow, so prey cannot see it / the bear can hunt (1)
- fat is insulation / reduces heat loss (1) ignore keeps it warm on its own
Question 3
A cactus lives in a hot desert. Its leaves are reduced to spines and its stem is thick. Suggest how these features help the cactus to survive.
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- spines have a small surface area, so less water is lost (by transpiration) (1)
- thick stem stores water (1)
- spines protect the cactus from being eaten by animals (1)
- Max 2
Question 4
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanMarram grass is a xerophyte. Its leaves roll up and have hairs that trap air, and its stomata are in pits. Explain how these features help marram grass to survive in dry, windy sand dunes.
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- rolled leaves reduce the exposed surface area (1)
- trap a layer of humid air / water vapour (1)
- which reduces the concentration gradient of water vapour out of the leaf (1)
- stomata in pits reduce water vapour loss / transpiration (1)
- hairs reduce air movement over the stomata (1)
- Max 4
Question 5
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanA water lily is a hydrophyte. It has floating leaves with stomata only on the upper surface and large air spaces in the leaves. Explain how each feature helps the water lily to survive in water.
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- stomata on the upper surface because the lower surface is in contact with water (1)
- so gas exchange can occur with the air (1)
- air spaces make the leaf float / provide buoyancy, so it receives more light (1)
- air spaces store oxygen or carbon dioxide for gas exchange (1)
- Max 3
Question 6
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanWhich feature is found in a xerophyte but not in a hydrophyte?
- Large air spaces in the leaf
- Stomata on the upper surface of a floating leaf
- Thick waxy cuticle
- Little or no xylem
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Answer: C (1)