A nerve cell is supplied with glucose. During each nerve impulse, ions move across its cell membrane. The cell transmits many impulses, but its ATP concentration stays nearly constant while its rate of respiration is high.
Which statement explains this observation?
Energy from glucose pumps the ions back directly, so no ATP is used by the cell.
Ions moving back across the membrane join ADP and phosphate together to rebuild ATP.
Respiration transfers energy to rebuild ATP from ADP and phosphate as fast as ATP is used.
Respiration makes new energy during each impulse, so ions are pumped back without ATP.
113 exam-style questions on OCR GCSE Biology 1.3 Respiration, covering 1.3.1 Cellular respiration supplies ATP, 1.3.2 Aerobic and anaerobic respiration, 1.3.3 Sugars and carbohydrates, 1.3.4 Amino acids and proteins, and 1.3.5 Fatty acids and lipids. Each one has a worked solution and a mark scheme showing where the marks go.