2020_AQA_Biology_Paper_1_Mark Scheme.

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1. (ATP to ADP + Pi ) Releases energy; 2. (energy) allows ions to be moved against a concentration gradient OR (energy) allows active transport of ions; 2 1. Reject ‘produces/makes/creates en... ergy’. 2. For ‘ions’ accept Na+ or K + . 2. Do not accept if this movement is of glucose not ions. 01.2 1. (Maintains/generates) a concentration/diffusion gradient for Na+ (from ileum into cell); 2. Na+ moving (in) by facilitated diffusion, brings glucose with it OR Na+ moving (in) by co-transport, brings glucose with it; 2 1. Accept ‘(Maintains/generates) a lower concentration of Na+ inside the cell compared with outside the cell’. 2. Accept ‘co-transporter’ for ‘co-transport’. 01.3 1. Folded membrane/microvilli so large surface area (for absorption); 2. Large number of co-transport/carrier/channel proteins so fast rate (of absorption) OR Large number of co-transport/carrier proteins for active transport OR Large number of co-transport/carrier/channel proteins for facilitated diffusion; 3. Large number of mitochondria so make (more) ATP (by respiration) OR Large number of mitochondria for aerobic respiration OR Large number of mitochondria to release energy for active transport; 4. Membrane-bound (digestive) enzymes so maintains concentration gradient (for fast absorption); 2 max 1. Reject references to ‘villi’. 1. Accept ‘brush border’ for ‘microvilli’. 4. Accept named examples of digestive enzymes. [Show More]

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