7.9- Investigating transport in plants

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  • Created by: Megan2413
  • Created on: 09-05-17 17:21
Whta two experiments can be done to prove that the translocation of sugars takes places place in the phloem?
Ringing and tracer experiments
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What happens in the ringing experiment?
- A section of the outer layers (protective layer and phloem) is removed around the complete circumference of a woody stem whilst still attached to the rest of the plant - After a period of time the section above the region with missing tissue swells
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What does the swelling show?
The sugars from the phloem have accumulated above the ring, leading to swelling which shows an interruption of flow of sugars to the region below the ring and the death of tissues in this region
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How is a radioactive isotope of 14C used to prove phloem is involved in translocation?
14C can be used to create radioactively marked 14CO2 to grow the plant in, so the 14C will be incorporated into the sugars produced during photosynthesis. They can then be traced by autoradiography
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How is autoradiography carried out?
Thin cross-sections of the plant with incorporated 14C sugars is cut and placed on X-ray film. The film becomes blackened wherever it has been exposed to 14C in the sugars.
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How was translocation in the phloem proven by autoradiography?
The blackened regions only occurred where the phloem ocurred
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Other cards in this set

Card 2

Front

What happens in the ringing experiment?

Back

- A section of the outer layers (protective layer and phloem) is removed around the complete circumference of a woody stem whilst still attached to the rest of the plant - After a period of time the section above the region with missing tissue swells

Card 3

Front

What does the swelling show?

Back

Preview of the front of card 3

Card 4

Front

How is a radioactive isotope of 14C used to prove phloem is involved in translocation?

Back

Preview of the front of card 4

Card 5

Front

How is autoradiography carried out?

Back

Preview of the front of card 5
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