C1.2 (Cell respiration)

Question 1

What life processes within cells are supplied with ATP energy?

Answer 1

• Active transport
• Anabolism

Question 2

How is energy released and stored by ATP?

Answer 2

Energy is released when ATP is hydrolyzed to ADP and phosphate

Question 3

Simple discription of cell respiration

Answer 3

Biochemical process that produces ATP by releasing energy from carbon compounds such as glucose and fatty acids

Question 4

Anaerobic vs Aerobic in Humans

Answer 4

Anaerobic
- No oxygen
- Produces less ATP
- Yields lactic acid as waste product
- Mainly in Cytoplasm

Aerobic respiration
- Requires oxygen
- Occurs in mitochondria
- Produces more ATP
- CO2 and H2O as waste

Question 5

What variables affect CR?

Answer 5

• Temperature
• Availability of substrates
• Oxygen concentration

Question 6

What is the role of NAD in cell respiration

Answer 6

• Acts as a hydrogen carrier
• When hydrogen (and it’s electron) is removed oxidation occurs

Question 7

NAD is reduced when…

Answer 7

NAD is reduced when it gains hydrogen

Question 8

What is the process used to convert glucose to pyruvate in and what are the products? (8)

Answer 8

1. Glucose is substrate of glycolysis
2. Glycolysis has 4 main events, Phosphorylation, lysis, oxidation, and ATP formation
3. Phosphorylation 2 ATP used to phosphorylate glucose
4. lysis Glucose is broken down into three carbon Pyruvate molecules
5. Oxidation of glucose removing of hydrogen and adding to NAD
6. NAD going to NADH is a Reduction
7. Different enzymes used for each step
8. Net yield of 2 pyruvate, 2 ATP, and 2 NADH

Question 9

How is pyruvate converted to lactate in anaerobic respiration, and why is this significant?

Answer 9

Pyruvate being converted to lactate to regenerate NAD allows glycolysis to continue
- Net yield of 2 ATP
- Essential for energy production when oxygen is not available

Question 10

What is the link reaction? (6)

Answer 10

1. Pyruvate enters mitochondria
2. Happens in the matrix
3. Carbon removed by decarboxylation
4. NAD is reduced to NADH
5. Remaining 2 carbon molecules bind with CoA to form Acetyl CoA
6. Acetyl CoA prepars to enter Krebs cycle

Question 10

What is the role of anaerobic respiration in yeast, and how is it utilized in brewing and baking?

Answer 10

• Not used to regenerate NAD
• Pyruvate is further broken down, producing carbon dioxide + alcohol
• CO2 = bubbles for brewing and makes bread rise

Question 11

What happens during the Krebs cycle? (5)

Answer 11

1. Acetyl CoA enters krebs cycle
2. 6C sugar is turned into a 5C sugar by oxidative decarboxylation
3. oxidation removes hydrogen from `citrate
4. Hydrogen added to NAD and FAD, resulting in reduced NAD + FAD
5. Decarboxylation produces CO2

Question 12

Net field of Krebs cycle

Answer 12

• 2 CO2
• 3 reduced NAD
• 1 reduced FAD
• 1 ATP
  Per molecule of pyruvate

Question 13

How is energy transferred to the electron transport chain in the mitochondrion?

Answer 13

Energy is transferred when reduced NAD passes a pair of electrons to First carrier in ETC.

Question 14

What is energy from electrons used to do in the electron transport chain?

Answer 14

(Energy comes from oxidation reactions from Krebs cycle and glycolysis)

• Energy is released and passes from carrier to carrier
• Release of energy is coupled to proton pumping
  -Protons are pumped into inter-membrane space creating a proton gradient

Question 15

What is chemosmosis and how is it linked to ATP production?

Answer 15

• Protons diffuse down their concentration gradient
• Protons pass through ATP synthase
• Protons returns to matrix
• Flow of protons provide enough energy to produce ATP

Question 16

What is oxygens role in aerobic respiration?

Answer 16

• It acts as the terminal electron acceptor
• It accepts electrons+protons from matrix to produce metabolic water
• This allows the continuous flow
• Otherwise there would be a buildup

Question 17

Lipids vs carbohydrates as respiratory substrates

Answer 17

lipids
- Yield more energy
- Usually used during long, low-intensity exercise
- Aerobic respiration not possible as it starts at Krebs cycle

Carbohydrates
- Both Aerobic and anaerobic respiration is possible
- Broken down quickly for faster energy
- Used first as easier to metabolise

Question 18

How does ATP release energy?

Answer 18

When it’s phosphate bonds are hydrolysed

Question 19

What is Ethanol?

Answer 19

Alcohol formed by microbial fermentation of carbohydrates`

Question 20

Describe fermentation?

Answer 20

Anaerobic breakdown of glucose with end products of ethanol and CO or lactic acid

Question 21

What is yeast

Answer 21

Unicellular fungus that lives in liquid/ moist habitats

Question 22

What is the cristae?

Answer 22

Series of inner membranes in mitochondria where cell respiration occurs

Question 23

What is pyruvate?

Answer 23

3 - carbon compound that forms as end product of glycolysis

Question 24

Cellular respiration equation (chemical)

Answer 24

C6 H12 O6 + 6O2 -> 6CO2 + 6H2O

Question 25

Cellular respiration equation (written)

Answer 25

Glucose + oxygen -> Carbon dioxide + water

Question 26

Anaerobic equation (animals)

Answer 26

Glucose -> Lactic acid + 2 ATP

Question 27

Anaerobic respiration equation (plants)

Answer 27

Glucose -> Ethanol + 2CO2 + 2 ATP

Question 28

What is oxidation

Answer 28

- Addition of oxygen atoms - Removal of hydrogen atoms - Loss of electrons

Question 29

4 main steps of Glycolysis

Answer 29

1. Phosphorylation 2. Lysis 3. Oxidation 4. ATP formation

Question 30

How does the ETC works?

Answer 30

1. Takes place in inner mitochondrial membrane 2. Series of electron carriers comes and drops off its protons and electrons 3.Electrons pass through a series of protein complexes 4. H+ ions are pumped into the **intermembrane space** 5. A high concentration of H+ builds up in the intermembrane space 6. Chemiosmosis occurs, ATP synthase 7. Flow of h+ drives ATP sunthesis 8. Oxygen acts as the final electron acceptor

Question 31

Difference between Reduced FAD and reduced NAD

Answer 31

**Reduced NAD** - Higher electron energy - Enters at first protein complex - Has a higher ATP yield **Reduced FAD** - Lower electron energy - Enters later in the chain (Complex II) - Has a lower ATP yield

Question 32

Structure of the Mitochondria

Answer 32

- Contains mitochondrial DNA that has it's own genetic material - Has the **cristae**, a tubular projection of inner membrane that increases surface area - Has an intermembrane space in which protons are pumped into by the ETC - Has an outer mitochondrial membrane, separating the mitochondria from the rest of the cell

Question 33

What is Gas exchange?

Answer 33

**Gas exchange** is a physical process by which gases move in and out of an organism/ cell (such as oxygen moving into blood during inhalation and CO2 moves out)

Question 34

What are variables to **consider** affecting the rate of cell respiration

Answer 34

- Ethical implications - Method to measure dependent variable - Controlled variables

Question 35

How a respirometer functions

Answer 35

- Living functions are placed in a sealed container while a **capillary tube** conects chamber to external fluid - As oxygen respires, it usese oxygen - This creates a preasure drop, pulling fluid **towards** the tube - KOH is used to **absorb CO2)

Question 36

Dependent variable of respirometer:

Answer 36

Rate of oxygen uptake

Question 37

Independent variable in Respirometer:

Answer 37

Temperature/ number of organisms/ age/ species...