1. 1
   A biology field trip visits a freshwater pond and an adjoining sand dune. In the pond, students observe water lilies with broad, flat floating leaves. On the sand dune, they observe marram grass, a plant with narrow, tightly rolled leaves and a thick waxy cuticle.

   (a)

   A water lily has broad, flat leaves that float on the surface of a pond, with tiny pores (stomata) mostly on the upper surface of the leaf. The water lily is an example of which type of plant?

   [1 mark]

   • AHydrophyte
   • BXerophyte
   • CHalophyte
   • DEpiphyte

   (b)

   On the sand dune, students observe marram grass, which has narrow, tightly rolled leaves and a thick waxy cuticle. Marram grass is an example of which type of plant?

   [1 mark]

   • AHydrophyte
   • BXerophyte
   • CProducer only, not adapted to water availability
   • DA plant with no special adaptations

   (c)

   Explain how the leaf features of marram grass (narrow, tightly rolled leaves and a thick waxy cuticle) help it survive in the dry conditions of a sand dune.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A wildlife documentary compares two animals adapted to extreme environments: the polar bear, which has a thick layer of fatty tissue and a compact body shape with small ears, and the fennec fox, a desert-dwelling animal with unusually large ears and pale, sandy-coloured fur.

   (a)

   A polar bear has a thick layer of fatty tissue beneath its skin and a compact body shape with small ears. Which environment is the polar bear adapted to survive in?

   [1 mark]

   • AHot, dry desert
   • BCold polar region
   • CTropical rainforest
   • DFreshwater lake

   (b)

   The fennec fox, which lives in hot desert regions, has unusually large ears compared with foxes living in colder climates. What is the main adaptive advantage of large ears in a hot desert environment?

   [1 mark]

   • AThey reduce surface area to conserve heat
   • BThey increase surface area for heat loss, helping the fox stay cool
   • CThey store extra fat as an energy reserve
   • DThey improve camouflage against predators

   (c)

   Explain how the polar bear's compact body shape with small ears helps it to survive in a cold environment, in terms of surface area to volume ratio.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A comparative ecology study examines two xerophytic (dry-adapted) plants growing in the same desert: a cactus with a thick, swollen, spiny stem and no leaves, and a species of desert grass with sunken stomata located in deep pits on the underside of narrow, rolled leaves.

   (a)

   A cactus growing in a hot, arid desert has a thick, swollen stem, a waxy cuticle, sunken stomata and spines instead of leaves. Explain how each of the stem and spine adaptations helps the cactus survive with very little water.

   [3 marks]

   (b)

   The desert grass has sunken stomata located in deep pits on the underside of its narrow, rolled leaves. Explain how sunken stomata and rolled leaves reduce water loss in this plant, and explain why reducing water loss is important for its survival.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A tropical botanical garden compares two very different aquatic and terrestrial plants for a school project. The first is water hyacinth, a hydrophyte with broad floating leaves, air-filled leaf stalks and stems, and roots that hang freely in the water. The second is a barrel cactus, a xerophyte with a thick barrel-shaped stem, a deep and extensive root system, and stomata that open only at night.

   (a)

   Water hyacinth is a hydrophyte that floats freely on the surface of ponds and slow-moving rivers. It has broad, flat leaves held above the water surface, large air-filled spaces (aerenchyma) in its leaf stalks and stems, and roots that hang freely in the water rather than anchoring in soil. Explain how each of these features is adaptive for a plant living in an aquatic environment.

   [6 marks]

   (b)

   A barrel cactus has a thick barrel-shaped stem, a deep and extensive root system spreading widely below and around the plant, and stomata that open only during the cooler night hours rather than during the day. Explain how each of these features helps the barrel cactus survive in a hot, dry desert environment.

   [6 marks]

   Total for question 4: 12 marks

End of questions