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Chapter 9

Three techniques are described to show translocation in plants: bark ringing, using radioactive carbon dioxide with potted plants, and allowing aphids to feed then analyzing their sap. The document also summarizes that phloem transports sucrose from source to sink tissues through sieve tubes and plates, with loading by active transport, water entry by osmosis, and pressure flow aided by companion cells.

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85 views1 page

Chapter 9

Three techniques are described to show translocation in plants: bark ringing, using radioactive carbon dioxide with potted plants, and allowing aphids to feed then analyzing their sap. The document also summarizes that phloem transports sucrose from source to sink tissues through sieve tubes and plates, with loading by active transport, water entry by osmosis, and pressure flow aided by companion cells.

Uploaded by

api-304486052
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Describe a technique to show translocation

Bark ringing method


- Remove a ring of bark from stem
- Leave for a minimum of one day
- Analyse content of tissue above ring
Labelled carbon dioxide and potted plant
- Supply plant with radioactive CO2
- Allow to photosynthesises
- Use autoradiography to identify substances
Aphids
- Allow aphids to feed on stem
- Cut off proboscis and collect sap
- Use chromatography to identify substances

Describe the transport of organic compounds in vascular plants


- Phloem transports sucrose
- From sources to sinks
- Sources are the photosynthetic tissues/leaves
- Sinks are fruits, seeds, roots
- Through sieve tubes with sieve plates
- Loading of sucrose into phloem by active transport
- High solute concentration causes water to enter by osmosis
- High hydrostatic pressure causes flow from source to sink
- Companion cells help with loading
- Translocation/Mass flow

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