Respiration

Question 1

🔴️Anaerobic respiration in animals

Answer 1

• Pyruvate is converted to Lactate
• NADH releases H to Pyruvate
• NAD reformed
• NAD can be reused to oxidise more respiratory substrate, so glycolysis can continue

Question 2

🔴️Similarities in anaerobic respiration in yeast and muscle cells

Answer 2

• ATP formation
• Glycolysis is involved in both
• Pyruvate is reduced in both
• NAD reformed

Question 3

🔴️Differences in anaerobic respiration in yeast and muscle cells

Answer 3

• Ethanol made in yeast whereas lactate is made by muscle cell
• CO2 is released by yeast but not by muscle cell

Question 4

🔴️How ATP is generated by reactions in the mitochondria

Answer 4

• ATP made in Krebs cycle
• NADH made in Krebs and Link reaction
• NADH and FADH release H+ and e-‘s
• Electrons passed to the ETC, located in the inner membrane (cristae)
• Electron carrier arranged in order of decreasing energy level
• Energy is lost by movement along ETC
• Energy is used to AT H+ into intermembranal space
• Protons diffuse through ATP synthase into matrix, leading to ADP + Pi→ ATP

Question 5

🔴️Explain why the CO2 production will be higher when Apple decomposes in pure Nitrogen

Answer 5

• Anaerobic respiration occurs
• This is less efficient as less ATP is produced
• More respiratory substrate must be respired to make the same amount ATP, so more CO2 is made

Question 6

🔴️Why do humans need to make loads of ATP daily?

Answer 6

• ATP is unstable
• It can’t be stored as it is an immediate source of energy
• Used for active transport and muscle contraction etc
• ATP releases energy in small chunks

Question 7

Explain why respiration produces more ATP per molecule of glucose under aerobic conditions

Answer 7

• Only glycolysis occurs without oxygen as there is no Krebs or ETC
• Only 2 ATP are made per glucose
• krebs cycle and the Electron transport chain produces ATP
• Oxygen is final electron acceptor as it combines with electrons and protons to make water

Question 8

Explain why glucose can’t be used as a respiratory substrate for mitochondria.

Answer 8

• Glucose cannot cross mitochondrial membrane but pyruvate can.
• This means Glucose has to be broken down during glycolysis in cytoplasm;

Question 9

3 ways ATP can be formed?

Answer 9

• photophosphorylation: light dependent stage of photosynthesis
• substrate-level phosphorylation: glycolysis and krebs cycle of respiration
• oxidative phosphorylation: electron transport chain of respiration

Question 10

Glycolysis

Answer 10

• Glucose is phosporylated as 2 ATP molecules are hydrolysed
• Phosphorylated glucose is split into 2 Triose Phosphate
• The 2 TP molecules are oxidised as the NAD molecules accepts a H.The NADH goes to the ETC
• Enzyme-controlled reactions convert the oxidated TP into Pyruvate which enters link reaction
• All of this occurs in the cytoplasm
• 1 glucose makes 2 ATP, 2 Pyruvate, 2 NADH

Question 11

Link reaction

Answer 11

• Pyruvate is dehydrogenated and decarboxylated. NAD accepts the H, then goes to ETC
• The acetyl groups reacts with CoA, forming acetyl coenzyme A
• Acetylcoenzyme A used in krebs cycle
• CO2 released as waste

Question 12

Krebs Cycle

Answer 12

• Acetyl coenzyme A, reacts with a 4-C oxaloacetate, forming a 6-C Citrate
• Citrate releases 2 CO₂ and H, reforming a oxaloacetate which recombines with the acetyl
• The H are accepted by NAD and FAD, forming FADH,FADH₂ , NADH
• ATP is made
• CO₂ given off as waste

Question 13

How does converting pyruvate to lactate allows continued production of ATP during anaerobic respiration

Answer 13

• Pyruvate accepts H from NADH
• NAD Regenerated
• NAD is used to accept H from TP in glycolysis

Question 14

When there’s sufficient O_{2 ,} why is lactate converted to pyruvate in the muscles.

Answer 14

• Lactic acid causes muscle fatigue
• Pyruvate can enter link reaction and continue aerobic respiration

Question 15

Describe how water is formed at the end of aerobic respiration.

Answer 15

• oxygen is the final acceptor of electrons ;
• O₂ combines with electron and hydrogen, forming water

Question 16

How many molecules of ATP are produced from each glucose molecule in anaerobic respiration ?

Answer 16

2

Question 17

Things produced from anaerobic respiration in muscle

Answer 17

• lactate
• ATP;

Question 18

Explain why most of the energy provided is by anaerobic respiration rather than aerobic respiration during a 100m sprint

Answer 18

• energy demand is very high so high respiration rate;
• insufficent oxygen supplied to muscles
• insufficient time for oxygen to reach muscles

Question 19

Why do athletes pant after a race

Answer 19

• oxidise lactate;
• converting it to pyruvate,
• aerobic respiration can now occur so CO₂ + H₂O made

Question 20

Benefits of having many cristae

Answer 20

• larger surface area for oxidative phosphorylation;
• more ATP can be made
• which is needed to supply the energy for muscle contraction, AT etc;

Question 21

If glycolysis is inhibited how will this affect the ATP production in the electron transfer chain

Answer 21

1. No NADH released
2. So no pyruvate formed, so no link reaction or Krebs cycle ;
3. Movement of electrons down the chain stops;
4. No energy is released for protons to be AT across membrane
5. No energy is released to phosphorylate ADP

Question 22

How does lactic acid production lead to muscle fatigue during anaerobic resp

Answer 22

• Lactic acid lowers pH
• It increases conc of H+ by dissociating to produce lactate and H+;
• This decrease enzyme activity and stops muscle proteins working effectively

Question 23

Difference between how ATP is made in glycolysis and the ETC

Answer 23

• In glycolysis no oxygen required (substrate level phosphorylation)
• oxidative phosphorylation in ETC

Question 24

Uses of ATP in cells

Answer 24

• Active transport;
• Synthesis of: glycogen/ protein

Question 25

Explain how ATP is useful in biological processes

Answer 25

* Releases energy in small **suitable** chunks * Broken down in a one step (single bond broken) * Immediate energy source so energy rapidly available * Can Phosphorylate molecules * Makes phosphorylated substances (e.g glucose) more reactive * Rapidly reformed during **_glycolysis_**

Question 26

Benefits of carb loading for marathon

Answer 26

* More glycogen stored in the liver/muscles * Releases many glucose * Glucose can be respired so energy is released

Question 27

Explain why respiration produces less ATP in the absence of oxygen

Answer 27

* Incomplete breakdown of glucose in glycolysis; * No Krebs cycle; * No electron transport chain * As oxygen is terminal electron acceptor; * Most ATP formed along electron transfer chain

Question 28

Explain how carbon dioxide is produced during aerobic respiration.

Answer 28

* **_Decarboxylation_** during link reaction * Conversion of pyruvate to acetylcoenzyme A * During the Krebs cycle; * Conversion of 6C (citrate) 5C * Conversion of 5C to 4C

Question 29

Describe what happens to this lactate made in muscle

Answer 29

* Passes into the blood; * Transported to the liver * Some is converted to pyruvate; * Which undergoes aerobic respiration * To form carbon dioxide and water;

Question 30

Why should all respiration experiments be done at the same temperature?

Answer 30

* respiration involves enzymes (2m)