Paper 2 Exchange Flashcards
Name one human organ that is specially adapted for exchanging substances with the environment. [1]
lungs (alveoli)
small intestine, kidney
A flatworm is multicellular but does not have an exchange system or a transport system.
Explain why. [3]
can rely on diffusion alone because the flatworm is very flat and thin
large surface area to volume ratio
every cell in the flatworm is close to the surface
In some lung infections, fluid builds up inside the alveoli. Explain why this makes it harder for the person to breathe properly. [3]
- this reduces the surface area of the alveoli over which diffusion can take place
- so decreases the rate of gas exchange
State one way in which the air breathed out is different from the air breathed in. [1]
less oxygen
more CO2
more water
Explain why you breathe faster when you exercise. [2]
- more oxygen needed for respiration
- more carbon dioxide to breathe out
Explain the advantage of the alveoli having many capillaries around them. [2]
- maintains a concentration gradient
- larger surface area for exchange
People who smoke develop a disease in which the walls of the alveoli break down. These people become breathless easily. Explain why. [3]
- fewer alveoli in their lungs
- lower surface area for diffusion
- rate of diffusion of oxygen into their blood is lower
Explain why an extensive capillary network and ventilation of the lungs helps to maximise the effectiveness of gas exchange. [4]
- capillaries deliver blood that has high CO2 levels and low O2 levels
- take away blood that has high O2 levels and low CO2 levels
- this means that there is always a concentration gradient between the blood and the air in the lungs
- ventilation of the lungs replaces air with higher concentration of CO2 and lower concentration of O2 with air that has a higher concentration of O2 and a lower concentration of CO2
- these factors maintain a high concentration gradient between the body and air for the two gases
Describe what would happen to the rate of diffusion if:
a) the surface area of an amoeba was halved [1]
b) the concentration difference was increased [1]
a) the rate of diffusion would halve/decrease by a factor of 2
b) the rate of diffusion would increase
Explain how the structure of a red blood cell (erythrocyte) is related to its function [4]
red blood cells contain haemoglobin, which carries oxygen
the bioconcave shape means it has a large surface area, making it easier for oxygen to diffuse into and out of the cell
the cell has no nucleus, so there is room for more haemoglobin to carry more oxygen
Respiring cells need oxygen and glucose. State which parts of the blood carry each of these substances [2]
oxygen in red blood cells
glucose in plasma
Describe two ways in which white blood cells help to protect the body against disease [2]
some white blood cells surround and destroy pathogens
other white blood cells produce antibodies that destroy pathogens
Explain how platelets help to protect the body against infection [3]
platelets respond to a break/wound in a blood vessel by triggering the blood clotting process
the clot blocks the wound
this prevents pathogens getting into the body
