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A-LevelBiologyTransport in plantsMay/June 2012Paper 1 Q261 Mark

Sucrose is transported in solution in the phloem of plants. Transport takes place from sources to sinks. The process depends on differences in hydrostatic pressure between the sources and the sinks. [Figure 26.1] Which tissues are either a source or a sink and what is the hydrostatic pressure at X and Y within the phloem?

Aleaf: sink, root: source; high hydrostatic pressure: X, low hydrostatic pressure: Y
Bleaf: sink, root: source; high hydrostatic pressure: Y, low hydrostatic pressure: X
Cleaf: source, root: sink; high hydrostatic pressure: X, low hydrostatic pressure: Y
Dleaf: source, root: sink; high hydrostatic pressure: Y, low hydrostatic pressure: X

✓ Correct Answer

The correct answer is C: leaf: source, root: sink; high hydrostatic pressure: X, low hydrostatic pressure: Y

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Biology Question

Topic

This multiple-choice question tests Transport in plants in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology May/June 2012 examination, Paper 1 Variant 2.

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