Flashcards
Mass flow evidence
Cards in this deck (6)
- 1In supportIf a ring of bark is removed from a woody stem, a bulge forms above the ring. The fluid from the bulge has a higher concentration of sugars than the fluid below the ring. This is because the sugars can't move past the area where the bark has been removed. Evidence that there can be a downward flow of sugars.
- 2In supportCan be investigated using aphids - they pierce the phloem, then their bodies are removed leaving the mouthparts behind, allowing the sap to flow out. The sap flows out quicker nearer the leaves than further down the stem - evidence that there is a pressure gradient
- 3In supportA radioactive tracer can be used to track the movement of organic substances in a plant. The results demonstrate the translocation of substances from source to sink over time.
- 4In supportIf a metabolic inhibitor is put into the phloem, then translocation stops - evidence that active transport is involved
- 5AgainstSugar travels to many different sinks, not just the one with the highest water potential as this model would suggest
- 6Againstthe sieve plates would create a barrier to mass flow. A lot of pressure would be needed for the solutes to get through at a reasonable rate.
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- As-Level AS-Level Biology (Topic 3B: More Exchange and Transport Systems) Flashcards on Mass flow evidence, created by Heather Jones on 08/05/2016.
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- Heather Jones
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