58. (i) 46/23 1 (ii) mitosis; R 1 any possible confusion with meiosis [2] 59. (a) (i) 5:1; 1 (ii) 7 [× smaller]/AW; 1 (b) 0.5; 1 (c) surface area relative to volume too small/AW; diffusion too slow/AW; idea of speed needed distance too great/some cells deep in body/not all cells in contact with environment/AW; R large if unqualified insufficient/AW, oxygen/(named) nutrient, supplied/(named) waste removed; idea of linking (named) areas; look for with an ‘from…’ ‘to…’ implication of organs, not just over body’ ‘all (may be,) more (metabolically) active/AW/, homoiothermic; R 3 max just more energy’ ‘need [6] 60. (i) alveolus/alveolar air, sac/space; A A 1 alveoli/air sac squamous epithelium (ii) large surface area to volume (ratio)/AW; R large area unqualified thin/one cell thick, wall/short diffusion distance/AW; A appropriate figures for width squamous epithelium; permeable; blood supply, qualified; elastic tissue/recoil (after expansion); surfactant; 3 max error carried forward mark (ii) independently. E.g. candidates who – put in (i) could still get points 1 to 4 in (ii) ‘capillary’ – [4] 61. H; C/G; A either or both E; I; D; F; 6 [6]
58. (i) 46/23 1 (ii) mitosis; R any possible confusion with meiosis 1 [2] 59. (a) (i) 5:1; 1 (ii) 7 [× smaller]/AW; 1 (b) 0.5; 1 (c) surface area relative to volume too small/AW; diffusion too slow/AW; idea of speed needed distance too great/some cells deep in body/not all cells in contact with environment/AW; R large if unqualified insufficient/AW, oxygen/(named) nutrient, supplied/(named) waste removed; idea of linking (named) areas; look for ‘from…’ ‘to…’ with an implication of organs, not just ‘all over body’ (may be,) more (metabolically) active/AW/, homoiothermic; R just ‘need more energy’ 3 max [6] 60. (i) alveolus/alveolar air, sac/space; A alveoli/air sac A squamous epithelium 1 (ii) large surface area to volume (ratio)/AW; R large area unqualified thin/one cell thick, wall/short diffusion distance/AW; A appropriate figures for width squamous epithelium; permeable; blood supply, qualified; elastic tissue/recoil (after expansion); surfactant; 3 max error carried forward – mark (ii) independently. E.g. candidates who put ‘capillary’ in (i) – could still get points 1 to 4 in (ii) [4] 61. H; C/G; A either or both E; I; D; F; 6 [6]
unit-1-answers.docx