Respiration

Question 1

What is repiration?

Answer 1

The process by which organisms release chemical energy from food through controlled oxidative breakdown of food. Some of the energy released is used to form ATP.

Question 2

Role of ATP in metabolism

Answer 2

Energy carrier - when it’s broken down into ADP and a phosphate, energy is released and is readily usable by the cell for metabolic activities.

Question 3

Relationship between photosynthesis and respiration

Answer 3

Allows a CYCLING of MATERIALS and a FLOW of ENERGY in ecosystems.

Question 4

Organic compounds

Answer 4

Compound containing carbon atoms covalently bonded to hydrogen atoms

Question 5

Structure of a mitochondrion

Answer 5

1. Inner membrane
2. Outer membrane
3. Mitochondrial matrix
4. Cristae

Question 6

Adaptation of cytoplasm for respiration

Answer 6

The cytoplasm contains enzymes for catalysing the reactions in respiration

Question 7

Adaptive feature of double membrane in repiration

Answer 7

Inner membrane is high folded to form cristae. Cristae are packed with enzymes involved in reactions of respiration

Question 8

Adaptive features of mitochondrial matrix

Answer 8

Fills the space enclosed by the inner membrane.
Contains enzymes involved in the reactions of repiration.
Provides a fluid medium for reactions to take place

Question 9

Respiration that requires oxygen is called

Answer 9

Aerobic rspiration

Question 10

Main stages of aerboic repiration

Answer 10

1. Glycolysis
   1b. Bridging between glycolysis and Krebs cycle
2. Krebs cycle
3. Oxidative phosphorylation

Question 11

Site for glycolysis

Answer 11

Cytoplasm

Question 12

Final product of glycolysis

Answer 12

2 Pyruvate (3-C compound), net amount of 2 ATP, 2 NADH

Question 13

How is glucose broken down in glycolysis

Answer 13

Glucose is first activated by ATP, 2 molecules of ATP are used. The activated glucose molecule is then broken down to 2 molecules of triose phosphate.

Question 14

How is triose phosphate converted to pyruvate?

Answer 14

Triose phosphate molecules lose hydrogen (oxidised) to form pyruvate.

Question 15

What’s the fate of the hydrogen atoms released?

Answer 15

Hydrogen is accepted by carrier molecule called NAD. NAD is reduced to form NADH

Question 16

Significance of bridging between glycolysis and Krebs cycle

Answer 16

Pyruvate formed in glycolysis enters the mitochondria, the conversion process in catalysed by enzymes in the mitochondrial matrix.

Question 17

What’s the bridging process

Answer 17

A carbon atom is removed from pyruvate and released as carbon dioxide.
The remaining 2-C compound loses hydrogen which is accepted by NAD to form NADH.
2-C compound then combines with coenzyme A to form acetyl-CoA. It carries the acetyl group into Krebs cycle.

Question 18

Where does Krebs cycle occur?

Answer 18

Mitochondrial matrix

Question 19

What are the two main stages of Krebs cycle?

Answer 19

1. Combination of acetyl-CoA with 4-C compound
2. Regeneration of 4-C compound

Question 20

Combination of acetyl-CoA with 4-C compound

Answer 20

Acetyl-CoA combines with a 4-C compound already present in the mitochondrial matrix. The 2-C acetyl group is then donated to the 4-C compound to form a 6-C compound. Coenzyme A is released. and regenerated continually.

Question 21

Regeneration of 4-C compound

Answer 21

6-C compound loses 2 carbon atoms which are released as carbon dioxide. 6-C compound is oxidised, losing 2 hydrogen atoms which are accepted by NAD and FAD to form NADH and FADH. The energy released is used to make one molecule of ATP.

Question 22

Where does oxidative phosphorylation occur?

Answer 22

On the inner membrane of mitochondrion

Question 23

Where does the energy for forming ATP come from

Answer 23

Oxidation of NADH and FADH