AQA GCSE Biology

Transpiration & translocation

AQA GCSE Biology revision on Transpiration & translocation. Aligned to the AQA GCSE Biology 8461 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Which environmental factor directly increases the rate of transpiration by reducing the water potential gradient between the leaf and the surrounding air?

    • A) High light intensity
    • B) Low humidity levels
    • C) Increased air speed
    • D) Higher temperature
    Show answer

    Answer: Low humidity levels

    Transpiration occurs via diffusion of water vapour out of the stomata. When the surrounding air is dry (low humidity), the water potential gradient is steeper, which promotes faster water loss from the leaf surface.

  2. Question 2

    What is the primary function of the companion cells located adjacent to the sieve tube elements in phloem tissue?

    • A) Provide energy for transport
    • B) Storage of excess sucrose
    • C) Support structural integrity
    • D) Active transport of water
    Show answer

    Answer: Provide energy for transport

    Sieve tube elements have limited cytoplasm and organelles to allow for the flow of sap. Companion cells provide the metabolic support, specifically the energy needed to load sugars into the phloem.

  3. Question 3

    Which tissue is responsible for the unidirectional transport of water and mineral ions from the roots to the leaves?

    Show answer

    Answer: xylem

    The xylem is composed of hollow, dead cells reinforced with lignin to withstand the tension generated by transpiration. This unidirectional flow is essential for photosynthesis and cooling.

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