Q4: Some small organisms do not have a specialised gas exchange system like humans. Instead they absorb oxygen through their skin. What is this process called? • Transpiration • Respiration • Diffusion • Photosynthesis

The answer is Diffusion.This is random movement of a substance from an area of high concentration (the air) to a region of low concentration (inside the organism). In this case, the substance diffusing would be oxygen. Transpiration is the loss of water from plants by evaporation on the underside of the plants' leaves. Respiration is the process which allows organisms to release energy for their living processes e.g. growth, division. Photosynthesis is a process carried out by plants - they use chlorophyll (the green pigment) to absorb light energy and use this to fuel reactions inside the plant. It can be thought of as the way plants make 'food' for themselves.