Exam (elaborations)
3.3.3 RESPIRATION QUESTIONS AND ANSWERS 2024
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Exam of 54 pages for the course Aerobic Respiration at Aerobic Respiration (3.3.3 RESPIRATION)
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3.3.3 RESPIRATIONCompare aerobic and anaerobic respiration. - answer- Aerobic need oxygen, anaerobic
doesnt
- Aerobic is more effecient as produced more ATP per molecule than anaerobic
- Aerobic has a complete breakdown of glucose to form CO2 and lots of ATP, anaerobic
is incomplete and makes harmful waste products (animals and bacteria = lactic acid,
plants and yeast = ethanol)
- Aerobic is slow and anaerobic is fast
Name all the stages of aerobic respiration and where they take place. - answer1.
Glycolysis → cytoplasm
2. Link reaction → matrix of mitochondria
3. Kreb cycle → matrix of mitochondria
Oxidative phosphorylation → intermembrane space of mitochondria (cristae)
Name all the stages of anaerobic respiration. - answer1. Glycolysis ONLY → takes
place in the cytoplasm
Where does glycolysis take place? - answer Glycolysis takes place in the cytoplasm,
NOT the mitochondria.
Describe and summarise glycolysis (aerobic respiration). - answer- Anaerobic → no
oxygen involved
- Net yield: 2ATP, 2 NADH
- Glucose is phosphorylated by adding ATP
- Triose phosphate is oxidised to form pyruvate
- Pyruvate is actively transported into the mitochondria for link reaction.
Describe the stages of glycolysis for aerobic respiration. - answerFirst, Phosphorylation
of glucose: adding phosphate using ATP
1. Glucose [6C] is phosphorylated into glucose phosphate [6C] from the energy of ATP
breaking down to ADP + Pi, Pi is taken in.
2. Glucose phosphate [6C] is phosphorylated into hexose bisphosphate [6C] from
energy of ATP breaking down to ADP + Pi, Pi is taken in.
3. Hexose biphosphate [6C] splits into two molecules of triose phosphate [TP → 3C]
(x2)
Second, Oxidation: losing hydrogen
,4. Each triose phosphate [TP][3C] is converted into pyruvate [3C] using 2(ADP + Pi) and
forming 2ATP for each molecule, overall 4ATP is produced. Simultaneously, each TP is
oxidised as each has one NAD molecule being reduced to NADH when making
pyruvate, overall 2 NADH produced. There is a net yield of 2 ATP (2 in, 4 out)
5. Pyruvate goes to the matrix of the mitochondria for the link reaction.
Draw the diagram with all the stages of glycolysis in aerobic respiration. - answerLook
at image.
What is a co-enzyme? - answerA molecule that aids the function of an enzyme by
transferring a chemical group from one molecule to another
What are the products of glycolysis (aerobic respiration) and where do they go? -
answer- 2 reduced NAD: to oxidative phosphorylation
- 2 pyruvate: actively transported into the mitochondrial matrix for use in the link reaction
- 2 ATP (net gain): used for energy
Describe all the stages of anaerobic respiration for mammals and bacteria.[lactate
fermentation] - answer1. Glucose [6C] is phosphorylated into glucose phosphate [6C]
from the energy of ATP breaking down to ADP + Pi, Pi is taken in.
2. Glucose phosphate [6C] is phosphorylated into hexose bisphosphate [6C] from
energy of ATP breaking down to ADP + Pi, Pi is taken in.
3. Hexose biphosphate [6C] splits into two molecules of triose phosphate [TP → 3C]
(x2)
4. Each triose phosphate [TP][3C] is converted into pyruvate [3C] using 2(ADP + Pi) and
forming 2ATP for each molecule, overall 4ATP is produced. Simultaneously, each TP is
oxidised as each has one NAD molecule being reduced to NADH when making
pyruvate [3C], overall 2 NADH produced. There is a net yield of 2 ATP (2 in, 4 out)
5. NAD eventually runs out, so pyruvate [3C] is reduced into lactate (lactic acid), as
pyruvate is reduced, this oxidises NADH back to NAD so more ATP can be made in the
conversion of TP to pyruvate as glycolysis continues.
What organisms anaerobically respire to produce lactate fermentation? -
answerMammals and bacteria.
What organisms anaerobically respire to produce alcoholic fermentation? -
answerPlants and yeasts.
Describe all the stages of anaerobic respiration for plants and yeasts [alcoholic]. -
answer1. Glucose [6C] is phosphorylated into glucose phosphate [6C] from the energy
of ATP breaking down to ADP + Pi, Pi is taken in.
2. Glucose phosphate [6C] is phosphorylated into hexose bisphosphate [6C] from
energy of ATP breaking down to ADP + Pi, Pi is taken in.
3. Hexose biphosphate [6C] splits into two molecules of triose phosphate [TP → 3C]
(x2)
,4. Each triose phosphate [TP][3C] is converted into pyruvate [3C] using 2(ADP + Pi) and
forming 2ATP for each molecule, overall 4ATP is produced. Simultaneously, each TP is
oxidised as each has one NAD molecule being reduced to NADH when making
pyruvate [3C], overall 2 NADH produced. There is a net yield of 2 ATP (2 in, 4 out)
5. Pyruvate [3C] is converted to ethanal [2C] as CO2 is released (decarboxylation).
6. Ethanal [2C] is reduced into ethanol [2C] where NADH is oxidised to NAD
(regenerated) which goes back to react with TP and forms pyruvate.
Draw a diagram that displays the stages of glycolysis in anaerobic respiration in
mammals and bacteria. - answerLook at image.
Draw aa diagram that displays the stages of glycolysis in anaerobic respiration in plants
and yeasts. - answerLook at image.
Why is less ATP produced in anaerobic respiration in comparison to aerobic
respiration? - answer- Products (Lactate/ethanol) not respired → still have chemical
energy
- No oxygen as the final electron acceptor → no link reaction / Krebs cycle / Oxidative
Phosphorylation, the majority of ATP is formed in oxidative phosphorylation
Describe and explain what happens in The Link Reaction. - answer2x Pyruvate [3C] is
received from glycolysis and actively transported into the mitochondrial matrix.
1. Each pyruvate [3C] is oxidised by NAD to reduced NAD (NADH) to form acetate [2C],
in doing so it loses/releases CO2 [1C] as well. (pyruvate is dehydrogenated and
decarboxylated)
2. Acetate combines with Coenzyme A to form Acetyl Coenzyme A
What are the products of the link reaction? - answer- Per reaction: 1CO2 + 1NADH + 1
Acetyl Coenzyme A
- Per glucose: 2CO2 + 2NADH + 2 Acetyl Coenzyme A
Define dehydrogenation. - answerLoss of a hydorgen atom / ion
Define decarboxylation. - answerLoss of a carbon atom
Describe the Krebs Cycle. - answer2 x Acetyl Coenzyme A continues to react in the
mitochondrial matrix.
1. Acetyl Coenzyme A [2C] combines with a [4C] compound to form a [6C] compound.
Coenzyme A is released and recycled back to the link reaction.
2. [6C] compound loses/releases CO2 [1C] (decarboxylation) and becomes oxidised
(dehydrogenation) as NAD is reduced to NADH to form a [5C] compound.
2. [5C] compound loses CO2 [1C], as well as is oxidised as 2NAD is reduced to
2NADH. ADP + Pi combines to form ATP (substrate level phosphorylation). [5C]
compound is further oxidised as FAD is reduced to FADH.
, Draw a diagram with all the stages of the link reaction. - answerLook at image.
Draw a diagram with all the stages of the Krebs Cycle. - answerLook at image.
What is substrate level phosphorylation? - answerCreation of ATP without ATP
synthase, phosphate is added directly to ADP from intermediate compound.
What are the products of The Krebs Cycle. - answerPer cycle: 3NADH, ATP, FADH,
2CO2
What can be respired aerobically besides glucose? - answerLipids/proteins can also be
respired aerobically --> Broken down into Acetyl Coenzyme A to enter Krebs cycle.
Where does oxidative phosphorylation occur? - answerTakes place on the cristae of
mitochondria (inner membrane)
Describe oxidative phosphorylation and all its stages. - answer1. NADH and FADH are
oxidised back into FAD and NAD in the inner membrane of the mitochondria, releasing
atoms of hydrogen which split into protons (H+) and electrons. E.g:
- NADH → e- + H+ + NAD
- FADH → e- + H+ + FAD
2. The electrons (e-) enter the membrane and are transferred down the electron
transport chain in a series of redox reactions, losing/releasing energy at each carrier.
This energy is used the actively pump/transport protons (H+) from the matrix to the
inter-membrane space, creating a proton gradient (chemiosmosis).
3. Protons (H+) move down the proton/electrochemical gradient through ATP synthase
(embedded in membrane), back into the matrix. This movement provides the energy
needed to combine ADP with Pi to form ATP.
4. Oxygen is the final electron acceptor, ½ O2 + 2e- + 2H+ → H2O (combines with
electrons from electron transport chain and protons to form water)
What stage of respiration makes the most ATP? - answerOxidative phosphorylation
What is the mitochondria. - answerThe site of aerobic respiration in a eukaryote, e.g.
link reaction, Krebs cycle, oxidative phosphorylation
What is the cristae? - answerA fold in the inner membrane of a mitochondrion to
increase the surface area for oxidative phosphorylation
How can ATP production be affected by mitochondrial diseases? - answerMitochondrial
diseases affect the functioning of mitochondria. They can affect how proteins involved in
oxidative phosphorylation or the Krebs cycle function, reducing ATP production. This
may cause anaerobic respiration to increase, to try and make up some of the ATP
shortage. Thai results in lots of lactate being produced, which can cause muscle fatigue
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