2020 AQA Biology Paper 1 MS.

Question Marking Guidance Mark Comments 01.1 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 ‘p ...

Question Marking Guidance Mark Comments 01.1 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 energy’. 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. 01.4 1. Phospholipids drawn with head and two tails; 2. Correctly positioned as a bilayer on either side of SGLT1; 2 2. Some of every ‘head’ must extend into the hydrophilic region and some of every ‘tail’ must extend into the hydrophobic region. 2. Reject phospholipids drawn within the protein. 01.5 1. One amine/NH2 group joins to a carboxyl/COOH group to form a peptide bond; 2. (So in chain) there is a free amine/NH2 group at one end and a free carboxyl/COOH group at the other OR Each amino acid is orientated in the same direction in the chain; 2 Accept on diagram, for example (at least) two amino acids joining by a correctly drawn peptide bond (MP1) with NH2 at one end and COOH at the other (MP2). 1. Ignore incorrect names of NH2 and COOH groups. 2. Allow ECF for incorrect naming of groups. ...................................................................................continued...............................................................................