Biology 9700 · AS & A Level · Control and coordination in plants

Control and coordination in plants — practice question

The Venus fly trap, Dionaea muscipula, is a plant capable of catching insects. Each leaf of a Venus fly trap is changed so that it has 2 lobes. Fig. 7.1 shows the Venus fly trap leaf in a folded (closed) position after an insect has been caught.
(a(i))[1]

Suggest a reason why the Venus fly trap needs to capture insects, even though it carries out photosynthesis.

(a(ii))[1]

The leaves are adapted to become 2 lobes. The upper surface of the lobes is red. Suggest why the lobes are red.

(a(iii))[1]

The lobes have sensory hairs. Touching 1 sensory hair will not make the leaf respond. At least 2 sensory hairs must be touched within 20 seconds to trigger a response in the leaves. State the advantage to the plant of producing a response only when 2 sensory hairs are touched within 20 seconds.

(a(iv))[1]

After an insect has been trapped, the leaves must stay closed for several days. Suggest why this needs to happen.

(b)[3]

Action potentials are produced by the Venus fly trap during the closing of a leaf. Each action potential is also linked to a refractory period. This is similar to the action potential and refractory period seen in a mammalian neurone during nerve impulse transmission. Explain the role played by the refractory period in the transmission of an impulse in a mammalian neurone.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Soil contains few named mineral ions OR plant is in shaded areas/areas of low light intensity

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI