GCSE A* REVISION NOTES


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B3


B3.1: Movement of molecules in and out of cells

B3.1.1: dissolved substances

Diffusion – The net movement of particles from an area of high concentration to an area of low concentration

Active Transport – The movement of particles from an area of low concentration to an area of high concentration using energy across at partially permeable membrane containing carrier proteins

Osmosis – The net movement of water from an area of high concentration of water to an area of low concentration of water across a membrane

Hypotonic – Solution surrounding cell is less concentrated (ions) that solution in cell causing water to move into cell

Isotonic – Solution surrounding cells is the same concentration of the solution in the cells causing no net movement

Hypertonic – Solution surrounding cell is more concentrated that solution in cell causing water to move out of cell

B3.1.2: Gaseous Exchange

B3.1.3: Exchange systems in plants

Light

Transpiration Rate increases

Stomata are open because photosynthesis needs more CO2

Temperature

Transpiration Rate increases

Stomata are open because photosynthesis needs more CO2

Water evaporates quicker

Diffusion is quicker

Wind

Transpiration Rate increases

Water molecules evaporate quicker maintaining concentration gradient

Humidity

Decreases transpiration rate

Lower concentration gradient

 

 

B3.2: Transport systems in plants and animals

B3.2.1: The blood system

B3.2.2: The blood

B3.2.3: Transport systems in plants

B3.3: Homeostatis

B3.3.1 Removal of waste and water control

Stages of urine production

  1. Ultrafiltration occurs due to the high blood pressure in the glomerulus. Small molecules (glucose, water, urea and salt ions) are forced out of the blood into the Bowmans Capsule. Large molecules (proteins and blood cells remain in the blood)
  2. All of the glucose is reabsorbed, initially through diffusion and later via active transport
  3. Water is reabsorbed by osmosis producing a more concentrated solution
  4. Some salt ions are reabsorbed through either diffusion or active transport depending on the concentration difference between the fluid and surrounding cells
  5. Selective reabsorptions has occurred forming a solution containing no glucose, some water, ions and urea
  6. Urine drains into the ureter before being stored in the bladder

Dialysis and Transplants

B3.3.2 Temperature control

 

B3.3.3 Sugar control

 

B3.4: Humans and their enviroment

B3.4.1 Waste from human activity

B3.4.2 Deforestation and the destruction of areas of peat

B3.4.3 Biofuels

B3.4.4 Food production

 


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