Respiration

Question 1

Where does glycolysis take place?

Answer 1

The cytoplasm.

Question 2

Describe what happens during glycolysis?

Answer 2

Glucose is phosphorylated into glucose phosphate using an Inorganic phosphate released by the hydrolysis of ATP. Glucose phosphate is phosphorylated into hexose biphosphate. The hexose biphosphate breaks down into two triose phosphate molecules. Triose phosphate is oxidised into pyruvate. This releases 2 hydrogen molecules, which are taken in by NAD to make 2 NADH molecules, and it releases energy that is needed to make 4 ATP molecules. There is a net gain of two ATP molecules.

Question 3

What happens during anaerobic respiration in plants?

Answer 3

Pyruvate loses a carbon dioxide molecule and is reduced by NADH to form NAD and produce ethanol.

Question 4

What happens during anaerobic respiration in mammals?

Answer 4

Pyruvate is reduced into lactate and NAD is reproduced so it can be reused in glycolysis.

Question 5

Where does the link reaction take placee?

Answer 5

The matrix of the mitochondria.

Question 6

Describe the link reaction.

Answer 6

1. The pyruvate is actively transported into the matrix of the mitochondria.
2. The pyruvate is decarboxylated and releases the hydrogen. The hydrogen is used to reduce NAD and form NADH.
3. The acetate combines with coenzyme A to form acetyl-Coa.

Question 7

What happens during the Krebs cycle?

Answer 7

1. The acetyl coenzyme A combines with a 4-carbon molecule to make a 6-carbon molecule.
2. The 6-carbon molecule is decarboxylated and releases hydrogen, which is used to reduce NAD. This produced NADH and a 5-carbon molecule.
3. The 5-carbon molecule is further oxidised and decarboxylated to produce a 4-carbon molecule, a NADH molecule, two FADH molecules and the Inorganic phosphate released is used to make ATP.

Question 8

Describe what happens during oxidative phosphorylation?

Answer 8

1. The FADH and NADH carry the electrons and protons to the electron transport chain in the cristae.
2. As the electrons move down the electron transport chain, they release energy, which is used to transport protons from the matrix to the intermembrane space.
3. This created an electron gradient. The protons diffuse down that gradient and back into the matrix.
4. The energy released from this allows ATP synthase to make ATP from ADP and organic phosphate.