In respiration, most ATP is synthesised during oxidative phosphorylation. Some ATP is made by substrate-linked reactions in glycolysis and Krebs cycle.

1. (a)Describe how ATP is made by substrate-linked reactions.[2]
2. (b)(i)Lipids can be metabolised to provide ATP. • The enzyme lipase hydrolyses lipids to glycerol and fatty acids. • The hydrocarbon chain of the fatty acid breaks down into smaller, 2C compounds. • Each 2C compound reacts with coenzyme A to form acetyl coenzyme A. (i) Name the covalent bond in lipids that is hydrolysed by lipase.[1]
3. (b)(ii)State the role of acetyl coenzyme A in respiration.[1]
4. (b)(iii)Explain why lipids have a higher energy value than carbohydrates.[2]
5. (c)(i)The respiratory quotient, RQ, is used to show which substrate is being metabolised by cells. It can be determined using the equation below. RQ = molecules of carbon dioxide released / molecules of oxygen taken in Lauric acid is a saturated fatty acid found in coconuts and has a chain of 12 carbon atoms. (i) Complete the equation below which outlines the aerobic respiration of lauric acid. C₁₂H₂₄O₂ + ........O₂ → 12CO₂ + 12H₂O[1]
6. (c)(ii)Calculate the RQ value for lauric acid. Show your working. Give your answer to 2 decimal places. answer =[2]