Biology unit 3 topic 1

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Osmosis
the diffusion of water through a partially permeable membrane, moving from a high concentration (dilute solution) to a low concentration (concentrated solution).
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Active transport
Cells use active transport to absorb substances across partially permeable membranes against the concentration gradient. This requires energy. A transport protein is used to carry across the useful molecule(s).
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Sports drinks
when exercising, you sweat, which contains water and mineral ions. To replenish these we drink sports drinks. – If the drink concentration matches the body fluids the solution is called isotonic.
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Exchanging materials
Efficient exchange surfaces have a large surface area, thin walls or a short diffusion path, and an efficient transport system- the blood supply in animals
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Exchange in the lungs
The lungs contain the gaseous exchange surface. The surface area is increased by the alveoli (air sacs). They have thin walls, a large surface area and a good blood supply. Oxygen diffuses into capillaries surrounding alveoli, and CO2 diffuses out
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The Lungs
- Lungs contain the exchange surface of the breathing system & situated in thorax inside the ribcage and above the diaphragm which separates them from the abdomen. The movement of air in + out of lungs known as ventilation.
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When we breathe in:
- Intercostal muscles (between ribs) contract, ribcage moves up and out + diaphragm flattens. Volume of thorax increases & pressure in thorax decreases and air moves in.
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When we breathe out:
- The intercostal muscles of ribcage and diaphragm relax. Ribcage moves down and in + diaphragm becomes domed. The volume of the thorax decreases and pressure increases and air is forced out.
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Artificial breathing aids
Iron lung- air drawn out of cylinder persons chest moved up + out so breathed in, air pushed back in, pressure pushes chest down so breathes out. Breathing aids – bags of air linked to mask forced down trachea, smaller easier to manage
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Exchange in gut
Food digested into smaller soluble molecules. These are absorbed into the blood in the small intestines. The walls of the villi are very thin & have many capillaries close to the wall.
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Exchange in plants
- Gases (e.g Oxygen,CO2) diffuse in + out of leaves through stomata. The size of the hole controlled by guard cells. Plants lose water vapour due to evaporation.
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Transpiration
movement of water through plant called the transpiration stream. Evaporation more rapid in hot, dry, windy and bright conditions. Guard cells close to prevent excessive water loss. Wilting also deceases surface area of leaves reducing water loss
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Card 2

Front

Cells use active transport to absorb substances across partially permeable membranes against the concentration gradient. This requires energy. A transport protein is used to carry across the useful molecule(s).

Back

Active transport

Card 3

Front

when exercising, you sweat, which contains water and mineral ions. To replenish these we drink sports drinks. – If the drink concentration matches the body fluids the solution is called isotonic.

Back

Preview of the back of card 3

Card 4

Front

Efficient exchange surfaces have a large surface area, thin walls or a short diffusion path, and an efficient transport system- the blood supply in animals

Back

Preview of the back of card 4

Card 5

Front

The lungs contain the gaseous exchange surface. The surface area is increased by the alveoli (air sacs). They have thin walls, a large surface area and a good blood supply. Oxygen diffuses into capillaries surrounding alveoli, and CO2 diffuses out

Back

Preview of the back of card 5
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