Explain what is meant by each of the following terms and describe one example of each in either a plant or an animal: diffusion, active transport.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

1. [7] (diffusion) 1 movement + particles / molecules / ions ; 2 down concentration gradient / from high to low concentration ; 3 named molecule or ion ; 4 (ONLY if point 3 awarded) context for example named in point 3 ; e.g. oxygen / carbon dioxide / glucose e.g. out of blood / into leaf / into villi (active transport) 5 movement + particles / molecules / ions ; 6 against concentration gradient / from low to high concentration ; 7 energy ; 8 respiration ; 9 membrane / carrier proteins ; 10 named molecule or ion moved by active transport ; 11 (ONLY if point 10 awarded) context for example named in point 10 ; e.g. nitrate ion / glucose e.g. into root hair / into villi
2. [3] points referring to why starch is more suitable: insoluble ; molecule + large / compact / complex OR polysaccharide ; remains inside cell / cannot cross membrane / grains ; does not change water potential inside cell ; prevents gain of water by cells ; osmosis OR diffusion + water ; A reverse argument for all points if reference made to why glucose would be less suitable