IGCSE Biology: Transport in plants — Practice Questions (Cambridge 0610)

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — Cambridge International holds copyright in its own papers. Use these alongside the official past papers available from your board.

Each question practises a skill tested in the June 2024 Paper 42. After each answer there is an examiner insight, a mark-scheme insight or a tip, and (where a close match exists) the real question to try next. Questions marked (Extended) test Supplement content.

Tier note: questions marked (Extended) go beyond 0610 Core: the structure of xylem vessels (8.1), the transpiration pull and the effect of humidity (8.3), and translocation (8.4 is Supplement only). All other questions are answerable by a 0610 Core candidate.

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Questions

1. Plants have two transport tissues, xylem and phloem.

(a) State two functions of xylem.

(b) Name the two substances that phloem transports. [3]

2. (Extended) Explain how three features of xylem vessels make them suited to their function. [3]

3. A bean seedling absorbs water from the soil.

(a) Explain how root hair cells are adapted for taking up water.

(b) Put these in order to show the pathway of water through the plant: mesophyll cells, root cortex cells, root hair cells, xylem. [2]

4. (Extended) Explain how water moves up the xylem from the roots to the leaves of a tall tree. [3]

5. (Extended) The same pot plant is placed outside on two different days with the same temperature. Day 1 is humid and still. Day 2 is dry and windy. Explain why the plant loses water vapour faster on day 2. [3]

6. (Extended) In summer, a potato plant sends sucrose from its leaves to its growing underground tubers. The next spring, a tuber sprouts and sends sucrose to its new shoots.

(a) Describe what is meant by translocation.

(b) Explain why the tuber is described as a sink in summer but a source in spring. [3]

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Answers

1. (a) Transport of water and mineral ions [1] and support for the plant [1].

(b) Sucrose and amino acids [1 for both].

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 4(c)(i)): Most candidates knew that phloem carries sucrose, though some wrote xylem or a blend of the two words. Many knew amino acids are also carried, but a wide range of wrong molecules was seen. Spell xylem and phloem clearly and keep their jobs separate.

Source for the examiner insights on this page: Cambridge IGCSE Biology 0610 June 2024 Principal Examiner Report for Teachers, Paper 0610/42 section, paraphrased.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 4(c)(i).

2. (Extended) Thick walls strengthened with lignin, which support the plant and stop the vessel collapsing [1]; no cell contents, so water flows through without obstruction [1]; cells joined end to end with no cross walls, forming a long continuous tube [1].

Tip: The command word is “explain”, so give each structural feature and how it helps. A list of features on its own gets fewer marks.

3. (a) Root hairs give a large surface area for the uptake of water (and mineral ions) [1].

(b) Root hair cells → root cortex cells → xylem → mesophyll cells [1].

Tip: Water enters at the root hairs and ends in the leaf mesophyll, where it evaporates. If you are unsure of the order, trace the route from the soil inwards and then upwards.

4. (Extended) Water evaporates from the mesophyll cells in the leaves and is lost by transpiration, creating a transpiration pull [1]. This pull draws up a continuous column of water in the xylem [1], because water molecules are held together by forces of attraction between water molecules [1].

Tip: The pull starts at the top, in the leaves. Answers that say water is “pushed up” from the roots, or that the xylem pumps it, do not describe the mechanism in the syllabus.

5. (Extended) In dry air (low humidity) there is less water vapour outside the leaf, so there is a steeper concentration gradient for water vapour to diffuse out through the stomata [1]. The wind carries away water vapour from around the leaf surface [1], which keeps the concentration gradient high [1]. So water vapour diffuses out faster on day 2.

Tip: Link each factor to the concentration gradient for diffusion. “Wind blows the water off the leaf” is wrong: the water leaves as vapour through the stomata.

6. (Extended) (a) The movement of sucrose and amino acids in the phloem [1] from sources to sinks [1].

(b) In summer the tuber stores the sucrose (as starch), so it is a sink; in spring the stored starch is broken down and the tuber releases sucrose to the growing shoots, so it is a source [1].

Tip: Whether a part is a source or a sink depends on what it is doing at the time: releasing sucrose or amino acids (source) or using or storing them (sink).

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 4(c)(i).

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Where marks are usually lost

• Mixing up xylem and phloem, or writing a blend of the two words.
• Naming the wrong molecules carried in phloem: it is sucrose and amino acids.
• Listing features of xylem vessels without explaining how each helps.
• Saying water is pushed up from the roots instead of pulled up by transpiration.
• Forgetting that a plant part can be a source at one time and a sink at another.