IGCSE · Practice questions · Adaptive features

Feature, problem, benefit.

Six original Cambridge-style questions on adaptive features: the arctic fox, unfamiliar animals from descriptions, and the leaves, stems and roots of xerophytes and hydrophytes.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

Keep these straight

Link every feature to the habitat.

Adaptive feature: inherited, helps survival and reproduction in the environment.
Answer frame: name the feature, say what it does, say why that matters in this habitat.
Xerophytes (Extended): reduce water loss (spines, thick cuticle, sunken stomata, rolled leaves, hairs) and store or find water.
Hydrophytes (Extended): air spaces, stomata on the upper surface, large floating leaves, flexible stems.

Recall

[2 marks]

Define the term adaptive feature.

An inherited feature, ✓
that helps an organism to survive and reproduce in its environment. ✓

Explain

[4 marks]

The arctic fox lives in a cold, snowy habitat. Explain how two of its features help it to survive there.

Thick fur traps a layer of air, which insulates and reduces heat loss. ✓
White fur camouflages it against snow, so it can approach prey without being seen. ✓
Small ears have a small surface area, so less heat is lost. ✓
A layer of fat insulates and stores energy for when food is scarce. (Any two features, each with an explanation.) ✓

Data

[3 marks]

The fennec fox lives in hot deserts. It has very large ears, pale sandy fur and furry soles on its feet. It hunts at night. Suggest how each feature helps it survive.

Large ears: a large surface area to lose heat (and to hear prey). ✓
Pale sandy fur: camouflage against sand, so it is hidden from predators and prey. ✓
Furry soles: insulate the feet from hot sand (and grip on loose sand); hunting at night avoids the heat of the day. ✓

Explain

[4 marks]

Extended. Explain how three features of a cactus help it survive in a desert.

Leaves reduced to spines: a very small surface area, so little water is lost by transpiration (and they deter animals). ✓
Thick waxy cuticle: reduces evaporation of water from the surface. ✓
Swollen stem: stores water and carries out photosynthesis in place of leaves. ✓
Few, sunken stomata (often open only at night) or wide shallow roots and a deep root. (Any three, each explained.) ✓

Explain

[4 marks]

Extended. A water lily is a hydrophyte. Explain the advantage of each of these features: (a) large air spaces in the stem, (b) stomata on the upper surface of the leaf, (c) large flat leaves, (d) flexible stems.

(a) Air spaces keep the leaves afloat and allow oxygen to diffuse to the submerged stems and roots. ✓
(b) The upper surface is in contact with the air, so gases can be exchanged through the stomata. ✓
(c) A large surface area spread on the water absorbs as much light as possible for photosynthesis. ✓
(d) Flexible stems bend with water currents without breaking; the water supports the plant. ✓

Analysis

[3 marks]

Extended. Marram grass grows on sand dunes. Its leaves roll up in dry weather, with hairs and sunken stomata on the inner surface. Explain how these features reduce water loss.

Rolling the leaf traps moist (humid) air inside the roll. ✓
Hairs trap a further layer of moist air, and sunken stomata sit in pits of humid air. ✓
The water vapour concentration gradient between the inside of the leaf and the air is reduced, so less water vapour diffuses out (and wind cannot blow the moist air away). ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.