Biology A-Level
companion cells
What companion cells means in Biology A-Level, as defined for AQA.
Definition of companion cells
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Reference: AQA
Cells adjacent to sieve tube elements, packed with mitochondria, that keep the elements alive and use ATP to pump hydrogen ions out.
Topics that use companion cells
- Mass transport in plants (AQA A-Level)
Related terms
- cohesion
- Hydrostatic pressure gradients
- Mass flow hypothesis
- Ringing experiments
- Tracer experiments
- Transpiration
- adhesion to the wall
- sieve tube elements and sieve plates
Using companion cells in the exam
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