AQA A-LEVEL BIOLOGY - EXCHANGE SYSTEMS Questions With
Accurate Answers
How is tissue fluid formed? (2) - Accurate answers - Overall outward pressure of (value) from
capillaries
- Forces small molecules out of the capillaries
The hydrostatic pressure falls from the arteriole end to the venule end of the capillary. Give one reason
why. (1) - Accurate answers - Loss of fluid/loss of water
- Friction against capillary lining
High blood pressure leads to an accumulation of tissue fluid. Explain how. (3) - Accurate answers -
High blood pressure means high hydrostatic pressure
- Increases outward pressure from the arteriole end of the capillary
- More tissue fluid is formed
- Lymph system not able to drain tissues fast enough
The water potential of the blood plasma is more negative at the venule end of the capillary than the
arteriole end of the capillary. Explain why. (3) - Accurate answers - Water has left the capillary
- Proteins in the blood are too large to leave the capillary
- Concentration of proteins in the blood increases
Name the monosaccharides sucrose and lactose are composed of. (2) - Accurate answers -
Sucrose: glucose and fructose
- Lactose: glucose and galactose
Some people cannot digest lactose when they are an adult. They could digest lactose when they were
children.
Use your knowledge of water potential to explain why these adults get diarrhoea when they drink milk.
(2) - Accurate answers - water potential in the gut is lower than than the water potential outside
the gut
Accurate Answers
How is tissue fluid formed? (2) - Accurate answers - Overall outward pressure of (value) from
capillaries
- Forces small molecules out of the capillaries
The hydrostatic pressure falls from the arteriole end to the venule end of the capillary. Give one reason
why. (1) - Accurate answers - Loss of fluid/loss of water
- Friction against capillary lining
High blood pressure leads to an accumulation of tissue fluid. Explain how. (3) - Accurate answers -
High blood pressure means high hydrostatic pressure
- Increases outward pressure from the arteriole end of the capillary
- More tissue fluid is formed
- Lymph system not able to drain tissues fast enough
The water potential of the blood plasma is more negative at the venule end of the capillary than the
arteriole end of the capillary. Explain why. (3) - Accurate answers - Water has left the capillary
- Proteins in the blood are too large to leave the capillary
- Concentration of proteins in the blood increases
Name the monosaccharides sucrose and lactose are composed of. (2) - Accurate answers -
Sucrose: glucose and fructose
- Lactose: glucose and galactose
Some people cannot digest lactose when they are an adult. They could digest lactose when they were
children.
Use your knowledge of water potential to explain why these adults get diarrhoea when they drink milk.
(2) - Accurate answers - water potential in the gut is lower than than the water potential outside
the gut
