Chapter 3 (3.4) Flashcards

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1
Q

Explain the phenomenon of plant wilting. (5)

A
  • excessive use of fertilisers may cause wilting in plants
  • dissolved fertiliser causes soil water to be hypertonic to the sap cell of roots
  • water diffuse by osmosis from the roots’ cell sap to the soil
  • cells become plasmolysed
  • if period of plasmolysis is prolonged, wilted plants will eventually die
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2
Q

What are the applications of movement of substances across a plasma membrane in our daily life? (4)

A
  • rehydration drinks help to recover loss of water & electrolytes in individuals with diarrhoea
  • isotonic drinks help athletes recover water loss & electrolytes through perspiration
  • saline solutions are isotonic to the blood plasma
  • liposomes (vesicles that contain aqueous solution surrounded by phospholipid bilayer membrane) are used to protect drug/active substances taken orally from being destroyed by gastric juices. Hence, drugs can reach they’re target cells
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3
Q

What is reverse osmosis & how is it done? (4)

A
  • a technology used to extract fresh water from seawater using desalination process
  • pressure is applied to push the seawater through a semi-permeable membrane
  • the membrane allows water particles to pass through it but not foreign particles, salt & microorganisms
  • Hence, only pure fresh water is released
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