Practise ATP, respiratory substrates and aerobic or anaerobic pathways while calculating RQ, analysing respirometers and tracking carbon and reduced coenzymes.
There are many mitochondria located in the presynaptic knobs of neuromuscular junctions and in the sarcomeres of muscle fibres of striated muscle.
Explain the need for many mitochondria in the presynaptic knobs and in the sarcomeres.
ATP is the universal energy currency which provides the immediate source of energy for cellular processes.
Fig. 2.1 shows some ways in which ATP may be synthesised and used in cells.
Fig. 2.1
Complete Fig. 2.1 by writing correct terms or examples on the three dotted lines provided.
Name the molecule that is required to react with ATP in order to convert ATP into ADP and an inorganic phosphate.
Name the membrane-bound enzyme responsible for phosphorylating ADP to make ATP.
During a sporting event an athlete may have to carry out respiration in anaerobic as well as aerobic conditions to produce sufficient ATP.
Fig. 2.2 outlines both processes in a muscle cell and shows how a liver cell is linked to these processes.
Fig. 2.2
You may refer to Fig. 2.2 in answering questions (i) to (v).
Glucose produced in the liver cell can be released into the blood to maintain blood glucose concentration.
State one use of glucose within the liver cell.
Suggest why respiration is said to be less efficient in anaerobic conditions than in aerobic conditions.
Complete the table to indicate, within the muscle cell, the exact locations of glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation.
Additional oxygen is required in the metabolic pathways involved in the conversion of lactate to glucose.
State the term given to this additional oxygen.
In aerobic respiration，most ATP is produced by oxidative phosphorylation．
Outline the features of ATP that make it suitable as the universal energy currency．
Rotenone is a compound that affects oxidative phosphorylation．
Rotenone disrupts the first carrier in the electron transport chain by stopping the transfer of electrons from this carrier．
Suggest and explain how rotenone reduces the production of ATP and water in aerobic respiration．
In respiration, most ATP is synthesised during oxidative phosphorylation. Some ATP is made by substrate-linked reactions in glycolysis and Krebs cycle.
Describe how ATP is made by substrate-linked reactions.
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 2 C compound reacts with coenzyme A to form acetyl coenzyme A.
State the role of acetyl coenzyme A in respiration.
Explain why lipids have a higher energy value than carbohydrates.
The respiratory quotient, RQ, is used to show which substrate is being metabolised by cells. It can be determined using the equation below.
Lauric acid is a saturated fatty acid found in coconuts and has a chain of 12 carbon atoms.
Complete the equation below which outlines the aerobic respiration of lauric acid.
Calculate the RQ value for lauric acid.
Show your working. Give your answer to 2 decimal places.
answer =