Unit 5: Respiration

Question 1

How much ATP is produced from Aerobic respiration?

Answer 1

• Involves the complete breakdown of glucose
• releases more energy and produces much more ATP

Question 2

What is the equation for Aerobic respiration?

Answer 2

C6H12O6 + 6O2 > 6CO2 + 6H2O + (~36ATP)

glucose + oxygen > carbon dioxide + water + energy

Question 3

How much ATP is produced from Anerobic respiration?

Answer 3

glucose isn’t completely broken down

produces only 2 ATP

Question 4

What is the equation for Anaerobic respiration in animals

Answer 4

C6H12O6 > 2C3H6O3 + (2ATP)
Glucose > Lactate + Energy

Question 5

What is the equation for Anaerobic respiration in Yeast?

Answer 5

C6H12O6 > 2C2H5OH + (2ATP)
Glucose > Ethanol + 2CO2 + Energy

Question 6

Where does Glycolysis occur

Answer 6

Cytoplasm

Question 7

Where does the link reaction occur

Answer 7

Matrix

Question 8

Where does the Krebs cycle occur?

Answer 8

Matrix

Question 9

Where does Oxidative Phosphorylation occur

Answer 9

Cristae

Question 10

What are cristae

Answer 10

folds of the inner membrane of the mitochondria

Question 11

Which processes only occur in aerobic respiration?

Answer 11

• Link reaction
• Krebs cycle
• Oxidative Phosphorylation

Question 12

What happens during glycolysis

Answer 12

Glucose(6C) is split into 2 pyruvate(3C) molecules

Glucose first converted into triose phosphate (3C)

Question 13

Outline glycolysis

Answer 13

1. Two ATP molecules are used to phosphorylate glucose to make it more reactive &Triose phosphate is formed
2. TP is oxidised (H+ removed) into pyrvate, releasing energy
3. Hydrogen atoms are accepted by coenzyme NAD forming 2 reduced NAD
4. ATP is produced by substrate-level phosphorylation
5. 4 ATP molecules are produced for every phosphate
6. Net gain of 2 ATP molecules per glucose
7. Pyrvate it then actively transported into the mitochondria

Question 14

What is NAD

Answer 14

a coenzyme and it transports hydrogen to the electron transfer chain and more ATP can be produced by oxidative phosphorylation

Question 15

What happens during glycolysis if oxygen isn’t present

Answer 15

anaerobic respiration will occur
- glycolysis still occurs but the pyrvate remains in the cytoplasm and and is converted into different products

Question 16

Outline the Link reaction

Answer 16

• Pyruvate is oxidised and carbon dioxide is removed
• 2 hydrogen atoms are accepted by NAD to form Reduced NAD
• Acetate (2C) is produced and Coenzyme A is added to form Acetyl Coenzyme A

Question 17

What happens during the Krebs cycle

Answer 17

a series of oxidation-reduction reactions

Question 18

Outline the Krebs cycle

Answer 18

• AcetylCoA (2C) combines with a 4C molecule to form a 6C molecule which then enters the Krebs cycle
• CoA is removed and the 6C enters a cycle of reactions resulting in the reformation of the 4C
• The cycle involves the removal of CO2 and Hydrogen
• H atoms are removed and passed to NAD and FAD to formed 2 reduced NAD and reduced FAD
• These reduced coenzymes pass the hydrogen atoms to the ETC producing ATP via oxidative phosphorylation
• Each cycle produced 1 ATP via substrate level phosphorylation

Question 19

How many times does the link reaction and Krebs cycle occur

Answer 19

The link reaction and Krebs cycle occur twice per glucose molecule as 2 pyruvate molecules ae produced in glycolysis

Question 20

What are other respiratory substrates?

Answer 20

• fatty acids and glycerol
• amino acids where the amino group has been removed
• these also enter the Krebs cycle

Question 21

What are the two main methods of producing ATP during aerobic respiration?

Answer 21

• substrate level phosphorylation
• oxidative phosphorylation

Question 22

What is substrate level phosphorylation

Answer 22

occurs during Krebs cycle and Glycolysis

• Certain reactions release sufficient energy for the direct formation of ATP from ADP and Pi
• the ETC is NOT involved

Question 23

Why is oxygen important

Answer 23

It is the final electron acceptor without it the ETC can’t function, aerobic respiration would stop and no ATP would be produced from so O.P

Question 24

Outline oxidative phosphorylation

Answer 24

1. Reduced NAD and FAD are oxidised releasing hydrogen to the first electron carrier of the ETC.
2. Hydrogen splits into an electron and proton
3. Electrons pass down carriers at decreasing energy levels. The energy released is used to actively pump the protons across the inner membrane to the intermembrane space. some energy is released as heat
4. A proton gradient is established, theres a higher conc or protons in the intermembrane space than the matrix
5. the gradient means the protons diffuse back across the inner membrane into the matrix via ATP synthase
6. The movement of protons through ATP synthase releases energy whihc is used to from ATP from ADP and Pi
7. At the end of the chain the electrons combine with protons and O2 to form water, O2 is the terminal electron acceptor

Question 25

What is oxidation

Answer 25

the removal of a hydrogen atom from respiratory substances

Question 26

What is phosphorylation

Answer 26

the formation of ATP by the addition of phosphate to ADP

Question 27

What happens during Anaerobic respiration

Answer 27

involves glycolysis and production of pyruvate - however the pyruvate doesnt enter the mitochondria but remains in the cytoplasm

Question 28

What is produced during Aerobic respiration?

Answer 28

pyruvate is reduced using reduced NAD produced in glycolysis enables the regeneration of NAD as the reduced NAD is converted to NAD this ensures a continual supply of NAD so gycolysis can continue

Question 29

What is the equation for the reduction of pyruvate in animals

Answer 29

Pyruvate+ Red NAD > Lactate + Ox NAD

Question 30

What is the equation for the reduction of pyruvate in plants/fungi

Answer 30

Pyruvate + Red NAD > Ethanol + CO2 + Ox NAD

Question 31

What happens if NAD is not regenerated

Answer 31

glycolysis would eventually stop as all the NAD would be reduced and there would be no NAD available to allow the oxidation of triose phosphate

Question 32

What is a respirometer?

Answer 32

a device used to measure the rate of respiration of a living organism by **measuring the uptake of oxygen or the release of CO2**

Question 33

What is the control variable when using a respirometer?

Answer 33

the mass of the organism

Question 34

What is the purpose of the spring clip in a respirometer

Answer 34

allows the pressure throughout the apparatus to equilibrate with atmospheric pressure

Question 35

Where is the coloured fluid in a respirometer?

Answer 35

In a narrow bone capillary tube to ensure max movement of fluid with any change of volume

Question 36

What is the purpose of the rubber stopper in a respirometer?

Answer 36

airtightness this can be improved by smearing vaseline along the seal between the chamber and stopper

Question 37

What is the purpose of the respiratory chamber in a respirometer?

Answer 37

has a low volume to ensure that volume changes due to respiratory activity are significant enough to be measured

Question 38

What is the purpose of the Filter paper wick in a respirometer?

Answer 38

ensures max surface area of potassium hydroxide solution is available to the contents of the chamber

Question 39

What is the purpose of Potassium hydroxide solution in a respirometer?

Answer 39

to absorb CO2 evolved during respiration

Question 40

What is the purpose of the Graduated scale in a respirometer?

Answer 40

measures movement of the coloured liquid

Question 41

What is the purpose of the gauze basket in a respirometer?

Answer 41

holds respiring material must be porous to permit free exchange of gases

Question 42

What is the purpose of the Glass rod in a respirometer?

Answer 42

to keep the respiring material out of direct contact with the potassium hydroxide solution

Question 43

How does the respirometer work to measure the uptake of O2?

Answer 43

- when organisms in the respirometer **respire aerobically O2 is absorbed** - **CO2 given off in respiration is **absorbed by potassium hydroxide** - therefore the **volume inside the respirometer decreases meaning the pressure decreases** so the bubble/coloured fluid moves to the left

Question 44

What do you need to know in order to calculate the rate of O2 consumption?

Answer 44

*Distance travelled by dye* **(d)** in mm/cm *Radius of tube* - allows you to convert distance moved into volume **(πr²d)** *Time* - to calculate rate *O2 consumption* - can then be expressed as rate (e.g volume per time, cm3 min-1

Question 45

What other equipment is needed for the respirometer?

Answer 45

Ruler - to measure distance travelled by fluid Stopwatch - to measure time

Question 46

How does the respirometer work to measure the uptake of CO2?

Answer 46

Exact same way as O2 **without the potassium hydroxide** (its often replaced by water) - the movement of the coloured fluid is recorded - any **difference between movement with KOH and without must be due to the production of CO2**

Question 47

How do you calculate the volume of CO2

Answer 47

volume of O2 consumed **with** KOH - movement of fluid **without** KOH