ATPAQA A-Level Biology: Subtopic test

1. 1
   The hydrolysis of ATP to ADP and inorganic phosphate (Pi) releases about 30 kJ of energy per mole of ATP.

   (a)

   How much energy is released by the hydrolysis of 0.25 mol of ATP?

   [1 mark]

   • A120 kJ
   • B0.0083 kJ
   • C7.5 kJ
   • D30 kJ

   (b)

   Which row correctly gives the components of an ATP molecule?

   [1 mark]

   • ADeoxyribose, adenine and three phosphate groups
   • BRibose, adenine and two phosphate groups
   • CRibose, thymine and three phosphate groups
   • DRibose, adenine and three phosphate groups

   (c)

   Describe the hydrolysis of ATP.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   In the first step of glycolysis, glucose reacts with ATP to form glucose phosphate and ADP. Glucose phosphate is more reactive than glucose, and the reaction is catalysed by an enzyme.

   (a)

   Which statement describes the role of ATP in this reaction?

   [1 mark]

   • AATP supplies water to hydrolyse glucose
   • BATP donates a phosphate group to glucose, making it more reactive
   • CATP is hydrolysed to adenosine and three phosphate groups
   • DATP acts as the enzyme that catalyses the reaction

   (b)

   Which row correctly describes the formation of ATP from ADP and Pi?

   [1 mark]

   • AA condensation reaction, catalysed by ATP synthase
   • BA hydrolysis reaction, catalysed by ATP synthase
   • CA condensation reaction, catalysed by ATP hydrolase
   • DA hydrolysis reaction, catalysed by ATP hydrolase

   (c)

   Explain how the hydrolysis of ATP makes the formation of glucose phosphate possible.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   During intense exercise the muscles of an athlete hydrolyse ATP at a rate of 0.80 mol per minute, but the muscles contain only about 0.10 mol of ATP at any one time. Assume that 30 kJ of energy is released per mole of ATP hydrolysed.

   (a)

   Suggest why ATP, rather than glucose, is the immediate source of energy for muscle contraction.

   [3 marks]

   (b)

   Calculate how long the ATP in the muscles would last at this rate, and the energy released per minute. Explain why the athlete can nevertheless keep exercising.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   In a leaf cell, ATP is made in chloroplasts during photosynthesis and in mitochondria during respiration. ATP from the chloroplasts is used to build sugars. ATP from the mitochondria is used for processes such as the active transport of ions into the cell. Both organelles contain the enzyme ATP synthase.

   (a)

   Describe the structure of ATP and explain how its hydrolysis can drive the active transport of ions.

   [6 marks]

   (b)

   Explain how a leaf cell resynthesises ATP in the light and in the dark.

   [6 marks]

   Total for question 4: 12 marks

End of questions