AQA_A Level Biology Paper 2_Mark Scheme 2022 | Practice Paper 2

AQA A Level Biology Paper 2 Mark Scheme 2022 - - - - 1 (a) Prevents oxygen being taken up / entering / being absorbed; 1 Accept: any idea of no contact with oxygen. Neutral: for anaerobic respiration / anaerobic ...

AQA A Level Biology Paper 2 Mark Scheme 2022 - - - - 1 (a) Prevents oxygen being taken up / entering / being absorbed; 1 Accept: any idea of no contact with oxygen. Neutral: for anaerobic respiration / anaerobic conditions. Neutral: prevents entry of air. Reject: prevents entry of oxygen and another named gas. (b) (i) 0.0155 / 0.016 = 2 marks;; 2 0.0775 / 0.077 / 0.078 / 0.08 = 1 mark / 0.62 = 1 mark (ii) Glucose decreases / is a limiting factor / increase in ethanol / yeast / 1 cells die / toxins build up; Accept: glucose is used up. (iii) 1. (Stays the) same / level / (relatively) constant; 2 2. Same volume / amount of oxygen uptake and carbon dioxide release; Note: if m.p.1 is awarded m.p 2 can be obtained without referring to ‘same volume / amount’. (c) 1. Oxygen is final / terminal (electron) acceptor / oxygen combines 2 with electrons and protons; 2. Oxidative phosphorylation / electron transport chain provides (most) ATP / only glycolysis occurs without oxygen / no Krebs / no link reaction; [Total 8 marks] 2 (a) 1. (In myelinated) action potential / depolarisation only at node(s); 3 2. (In myelinated, nerve impulse) jumps from node to node / saltatory; 3. (In myelinated) action potential / impulse does not travel along whole length; The question is about speed of transmission, not repolarisation or related matters Accept converse for non-myelinated (b) 1. Probability of obtaining this difference by chance; 2 max Reject ‘results’ once only/ This statement often split round 2. 2. Is less than 5% / less than 0.05 / less than one in twenty; Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047 Accept correct greater than 95% / greater than 0.95 arguments 3. Difference is significant; 1 max for 'the probability that the results are due to chance is less than 5% - - - AQA A Level Biology Paper 2 Mark Scheme 2022 - - - - 1 (a) Prevents oxygen being taken up / entering / being absorbed; 1 Accept: any idea of no contact with oxygen. Neutral: for anaerobic respiration / anaerobic conditions. Neutral: prevents entry of air. Reject: prevents entry of oxygen and another named gas. (b) (i) 0.0155 / 0.016 = 2 marks;; 2 0.0775 / 0.077 / 0.078 / 0.08 = 1 mark / 0.62 = 1 mark (ii) Glucose decreases / is a limiting factor / increase in ethanol / yeast / 1 cells die / toxins build up; Accept: glucose is used up. (iii) 1. (Stays the) same / level / (relatively) constant; 2 2. Same volume / amount of oxygen uptake and carbon dioxide release; Note: if m.p.1 is awarded m.p 2 can be obtained without referring to ‘same volume / amount’. (c) 1. Oxygen is final / terminal (electron) acceptor / oxygen combines 2 with electrons and protons; 2. Oxidative phosphorylation / electron transport chain provides (most) ATP / only glycolysis occurs without oxygen / no Krebs / no link reaction; [Total 8 marks] 2 (a) 1. (In myelinated) action potential / depolarisation only at node(s); 3 2. (In myelinated, nerve impulse) jumps from node to node / saltatory; 3. (In myelinated) action potential / impulse does not travel along whole length; The question is about speed of transmission, not repolarisation or related matters Accept converse for non-myelinated (b) 1. Probability of obtaining this difference by chance; 2 max Reject ‘results’ once only/ This statement often split round 2. 2. Is less than 5% / less than 0.05 / less than one in twenty; Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047 Accept correct greater than 95% / greater than 0.95 arguments 3. Difference is significant; 1 max for 'the probability that the results are due to chance is less than 5% - - - AQA A Level Biology Paper 2 Mark Scheme 2022 - - - - 1 (a) Prevents oxygen being taken up / entering / being absorbed; 1 Accept: any idea of no contact with oxygen. Neutral: for anaerobic respiration / anaerobic conditions. Neutral: prevents entry of air. Reject: prevents entry of oxygen and another named gas. (b) (i) 0.0155 / 0.016 = 2 marks;; 2 0.0775 / 0.077 / 0.078 / 0.08 = 1 mark / 0.62 = 1 mark (ii) Glucose decreases / is a limiting factor / increase in ethanol / yeast / 1 cells die / toxins build up; Accept: glucose is used up. (iii) 1. (Stays the) same / level / (relatively) constant; 2 2. Same volume / amount of oxygen uptake and carbon dioxide release; Note: if m.p.1 is awarded m.p 2 can be obtained without referring to ‘same volume / amount’. (c) 1. Oxygen is final / terminal (electron) acceptor / oxygen combines 2 with electrons and protons; 2. Oxidative phosphorylation / electron transport chain provides (most) ATP / only glycolysis occurs without oxygen / no Krebs / no link reaction; [Total 8 marks] 2 (a) 1. (In myelinated) action potential / depolarisation only at node(s); 3 2. (In myelinated, nerve impulse) jumps from node to node / saltatory; 3. (In myelinated) action potential / impulse does not travel along whole length; The question is about speed of transmission, not repolarisation or related matters Accept converse for non-myelinated (b) 1. Probability of obtaining this difference by chance; 2 max Reject ‘results’ once only/ This statement often split round 2. 2. Is less than 5% / less than 0.05 / less than one in twenty; Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047 Accept correct greater than 95% / greater than 0.95 arguments 3. Difference is significant; 1 max for 'the probability that the results are due to chance is less than 5% - - -