GlycolysisAQA A-Level Biology: Subtopic test

1. 1
   Glycolysis was investigated in a cell-free extract of yeast, supplied with glucose, ATP, ADP, NAD and inorganic phosphate, in a sealed tube containing no oxygen.

   (a)

   What is the end product of the glycolysis of one glucose molecule?

   [1 mark]

   • ATwo molecules of pyruvate
   • BOne molecule of pyruvate
   • CTwo molecules of acetyl coenzyme A
   • DSix molecules of carbon dioxide

   (b)

   In which part of a eukaryotic cell does glycolysis take place?

   [1 mark]

   • AMitochondrial matrix
   • BInner mitochondrial membrane
   • CCytoplasm
   • DNucleus

   (c)

   Explain why glycolysis begins with the phosphorylation of glucose using ATP.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A biochemist measures the ATP and reduced NAD produced when glucose is converted to pyruvate in a cell-free extract, with all the enzymes and cofactors in excess.

   (a)

   What is the net gain of ATP from the glycolysis of one glucose molecule?

   [1 mark]

   • A4
   • B0
   • C6
   • D2

   (b)

   How many molecules of reduced NAD are formed in the glycolysis of one glucose molecule?

   [1 mark]

   • A1
   • B4
   • C2
   • D6

   (c)

   Explain how glycolysis gives a net gain of two ATP per glucose molecule.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   The metabolic poison iodoacetate inhibits the enzyme that oxidises triose phosphate during glycolysis. Cultured human cells in which glucose is the only respiratory substrate are treated with iodoacetate and supplied with glucose and oxygen.

   (a)

   Predict and explain the effect of iodoacetate on the concentration of triose phosphate and on the production of ATP and reduced NAD in the cells.

   [3 marks]

   (b)

   Explain why the cells would die even though oxygen is plentiful and their mitochondria are intact.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Glycolysis occurs in the cytoplasm of yeast cells, of bacteria and of human cells, using very similar enzymes.

   (a)

   Describe the stages of glycolysis, from glucose to pyruvate, and state its net yield.

   [6 marks]

   (b)

   Explain what the presence of glycolysis in yeast, bacteria and humans suggests about evolution, and why this is only indirect evidence.

   [6 marks]

   Total for question 4: 12 marks

End of questions