A-LevelBiologyTransport in plants9700/12 · Oct/Nov 2020 · Q261 Mark

ATP is used in companion cells to provide the energy for loading a sieve tube element with sucrose. How does the co-transporter mechanism use this energy?

Ato pump hydrogen ions into the sieve tube element

Bto pump hydrogen ions out of the companion cell

Cto pump sucrose into the sieve tube element

Dto pump sucrose out of the companion cell

✓ Correct answer

B: to pump hydrogen ions out of the companion cell

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Topic: Transport in plants, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, Oct/Nov 2020 Paper 1 Variant 2, question 26.

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