BY4 - Respiration

Question 0

Where does the link reaction and the Kreb’s cycle take place?

Answer 0

In the matrix of the mitochondria

Question 1

Where does glycolysis take place?

Answer 1

In the cytoplasm of the cell

Question 2

Where does the electron transport chain take place?

Answer 2

At the cristae of the mitochondria

Question 3

Give three roles of ATP

Answer 3

Metabolic processes
Active transport
Movement
Nerve transmission
Secretion

Question 4

Define activation energy

Answer 4

The minimum energy required to start a chemical reaction

Question 5

Define phosphorylation

Answer 5

The addition of phosphate (Pi) and ADP

Question 6

What are the three forma of phosphorylation?

Answer 6

Oxidative phosphorylation
Substrate-level phosphorylation
Photophosphorylation

Question 7

Give the uses and advantages of ATP

Answer 7

Hydrolysis of ATP to ADP is a single reaction that releases immediate energy
Only one enzyme required to release energy
Energy released in small amounts
Is the universal energy currency in organisms

Question 8

Why is ATP described as the universal energy currency?

Answer 8

Universal because it is a common source of energy for all reactions in all cells
Energy currency because it transfers small packets of energy from the place of release to energy requiring reactions

Question 9

Give the disadvantages of glucose as an energy source

Answer 9

Requires many enzymes to release energy
Has many intermediates to release energy
Takes a long time to release energy
Releases a large amount of energy that may not be needed immediately
Release large amounts of heat energy that can damage the cell and enzymes

Question 10

What is oxidation?

Answer 10

Is the loss of electrons/hydrogen
Catabolism
Exergonic

Question 11

What is reduction?

Answer 11

The gain of electrons/hydrogen
Anabolism
Endergonic

Question 12

Give the two coenzymes and their reactions

Answer 12

NAD and FAD
NAD + 2H+ + 2e- —-> NADH/H+
FAD + 2H+ + 2e- —-> FADH2

Question 13

What is the role of coenzyme A?

Answer 13

Transports the acetyl group to the next stage of reaction as acetyl coenzyme A

Question 14

Define dehydrogenation

Answer 14

The removal of hydrogen

Question 15

Define carboxylation

Answer 15

The removal of carbon dioxide

Question 16

What is the Chemiosmotic theory?

Answer 16

A model to explain the synthesis of ATP. It proposes that the energy for ATP synthesis originates from the electrochemical gradient of protons across a membrane.

Question 17

What is referred to as the final electron acceptor?

Answer 17

Oxygen

Question 18

During anaerobic respiration what acts as the final hydrogen acceptor in animals? Consequently what is it converted to?

Answer 18

Pyruvate is the final hydrogen acceptor. It is reduced to lactic acid.

Question 19

What is the final hydrogen acceptor in plants? What is it converted into?

Answer 19

(Pyruvate is decarboxylated to produce ethanal). Ethanal is the final hydrogen acceptor. It is then reduced to form ethanol. This process is called fermentation.

Question 20

Define a respiratory substance

Answer 20

Organic molecules that can be respired to release energy to make ATP

Question 21

How can lipids be used as a respiratory substance?

Answer 21

It is hydrolysed into glycerol and fatty acids. The glycerol is then converted into a three carbon sugar which enters glycolysis via triose phosphate, this yields ATP molecules. The fatty acid chains are split into two carbon fragments which enter the pathway as acetyl coenzyme A. Very large molecules of ATP can be built up depending on the hydrocarbon chain length of the fatty acids. 1g of fat releases 2x more energy than carbohydrates.

Question 22

When are proteins used as a respiratory substance?

Answer 22

Only when an individual is suffering from starvation. Usually only when reserves of carbohydrates and lipids have been used up.

Question 23

How can proteins be used as a respiratory substance? Where does it take place?

Answer 23

Protein is hydrolysed into its amino acids. Amino acids are deaminated to form urea and residue. Urea is excreted. The residue is then converted into acetyl coA or pyruvate to enter the Krebs Cycle.
This takes place in the liver.