Respiration

Question 1

Describe and explain the process of glycolysis.

Answer 1

-glucose is phosphorylated and converts to 2x triose phosphate (TP)
-2x ATP –> 2x ADP +2x Pi
-2x TP is oxidised into 2x pyruvate
-4x ADP –> 4x ATP
-2x NAD –> 2x NADH
-net gain for 2x ATP

Question 2

What is the net gain of ATP in glycolysis?

Answer 2

2x ATP

Question 3

Where does glycolysis occur?

Answer 3

Cytoplasm

Question 4

By what process is pyruvate and NADH transported to the matrix?

Answer 4

Active transport

Question 5

Describe and explain the process of link reaction.

Answer 5

-pyruvate loses a carbon atom and hydrogen atom and converts to acetate
-CO2 produced and NAD –> NADH
-coenzyme A is added to acetate and makes Acetyl coenzyme A

Question 6

What does link reaction produce per glucose molecule?

Answer 6

2x CO2
2X NADH
2X Acetyl coenzyme A

Question 7

Where does the link reaction occur?

Answer 7

Mitochondrial matrix

Question 8

Describe and explain the Kreb cycle?

Answer 8

-Acetyl coenzyme A reacts with a 4-carbon compound to form a 6-carbon compound
-coenzyme A is removed and reused in link reaction
- 2x CO2 lost
-redox reactions occur where: 3x NAD –> 3x NADH, 1x FAD –> 1x FADH2
-substrate level phosphorylation occurs where ADP + Pi –> ATP

Question 9

What does the Kreb cycle produce per glucose molecule?

Answer 9

4x CO2
2X ATP
6X NADH
2X FADH2

Question 10

Where does the Kreb cycle occur?

Answer 10

Mitochondrial matrix

Question 11

Describe the process of oxidative phosphorylation.

Answer 11

-reduced NAD oxidised by Complex I and reduced FAD oxidised by Complex II
NADH –> NAD + H+ + e-
FADH2 –> FAD + 2H+ + 2e-
-electrons pass along Electron Transport Chain (ETC) and release energy
-energy used to actively transport H+ against concentration gradient from matrix to Inter Membrane Space
-creates electrochemical gradient in IMS
-H+ travels down concentration gradient by facilitated diffusion through ATP synthase
-results in synthesis of ATP
ADP + Pi –> ATP
-oxygen (final electron acceptor) picks up electrons after being travelled through ETC and combines to form water
2H+ + 2e- + 1/2 O2 –> H2O

Question 12

How many ATP molecules is made from 1x NADH?

Answer 12

3x ATP

Question 13

How many molecules of ATP can be made from 1x FADH2?

Answer 13

2x ATP

Question 14

What are the two types of fermentation in anaerobic respiration?

Answer 14

Lactic fermentation and alcoholic fermentation

Question 15

Describe lactate fermentation.

Answer 15

pyruvate reduced to lactate by gaining hydrogen atom from NADH

Question 16

What happens to NADH when it’s oxidised in lactic fermentation?

Answer 16

converts into NAD and reused in glycolysis

Question 17

What is lactate called when it’s dissolved in water?

Answer 17

Lactic acid

Question 18

Where does lactic fermentation occur?

Answer 18

Animal cells and some bacteria

Question 19

Why is lactate not kept for long periods of time?

Answer 19

It’s toxic and after some time it would denature enzymes involved in glycolysis and all respiration would stop.

Question 20

Describe alcoholic fermentation.

Answer 20

-pyruvate converts to ethanal by losing a carbon atom and producing CO2
-Ethanal is reduced to ethanol by gaining hydrogen atom from NADH

Question 21

Why can ethanol not be kept for long periods of time?

Answer 21

It’s toxic and eventually will denature enzymes involved in glycolysis and all respiration would stop.

Question 22

Where does alcoholic fermentation occur?

Answer 22

Yeast and plants

Question 23

How are lipids used instead of glucose during respiration?

Answer 23

Lipids are hydrolysed to glycerol and fatty acids.
Glycerol is phosphorylated to triose phosphate which would enter the Kreb cycle.

Question 24

How are amino acids used instead of glucose during respiration?

Answer 24

Amino acids are hydrolysed and amino group would be removed.
Carbon compound left would enter Kreb cycle.