B3 AQA Further Biology

Notes on Exchange of Substances.

Covers Active Trasport, Diffusion, Osmosis, Human exchanges (breathing, diffusion of oxygen into the blood stream, diffusion of food into the blood stream) and Plant exchanges (transpiration, osmosis of water and minerals into plant roots and active trasport of nitrate ions into plant roots) 

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  • Created by: Aparna
  • Created on: 17-12-12 10:52
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Further Biology: B3
Exchanges
Type of exchange Type of Molecules Concentration Energy
Gradient
Diffusion Small, dissolved (O2, CO2) Down (high to low) Kinetic
Osmosis Mainly water, solvent Down (high to low) Kinetic
Active Transport small (e.g. glucose), ions Up (low to high) ATP (from
respiration)

Diffusion

DIFFUSION IS THE RANDOM…

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Active Transport

THE TRANSPORTATION OF MOLECULES FROM A LOW CONCENTRATION TO A HIGH CONCENTRATION (AGAINST THE CONCENTRATION
GRADIENT) USING ATP (ENERGY FROM RESPIRATION)


Energy is required as carrier
proteins pick up specific
molecules and take them
through the cell membrane.
Therefore, cells using active
transport have lots of
mitochondria as…

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It's important for the body parts to be highly
specialised as the size and complexity of an
organism increases the difficulty of exchanging
materials.

Sports Drinks

If the water and ions lost are not replaced, the
ion/water balance of the body is disturbed.
Sweating releases more water than ions…

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All drinks help to rehydrate the body (replace lost water)
Soft drinks contain water, sugar, ions and flavourings but concentrations can vary greatly.
Sport drinks contain sugar to replace the glucose lost during exercise and water and ions.



Gaseous exchange in Humans: Ventilation

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Ventilators

Devices that help patients breathe who cannot automatically do so due to disease or injury.

Negative-Pressure Ventilators

E.g. the iron lung, developed for use during epidemics of poliomyelitis as breathing muscles stopped
functioning, was a large tank enclosing the whole patient's body except the head and neck. A pump…

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