5.2 - Respiration Flashcards
Describe the process of glycolysis. (4)
- Phosphorylation of glucose using ATP
- Oxidation of triose phosphate to pyruvate
‘accept removal of hydrogen from triose phosphate for oxidation’ - Net gain of 2 ATP with 4 produced, 2 used
- NAD reduced
Malonate inhibits a reaction in the Krebs cycle. Explain why malonate would decrease the uptake of oxygen in a respiring cell. (2)
- Less/no reduced NAD/coenzymes
/ Fewer/no hydrogens/electrons removed (and passed to
electron transfer chain)
‘accept less/no FAD reduced’ - Oxygen is the final/terminal (electron) acceptor
In muscles, pyruvate is converted to lactate during prolonged exercise. Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. (2)
- Regenerates/produces NAD / oxidises reduced NAD
‘accept descriptions of oxidation e.g. loss of hydrogen’ - (So) glycolysis continues
Where in the cell does glycolysis occur? (1)
- Cytoplasm
Explain how anaerobic respiration enables glycolysis to continue. (2)
- Regenerates/produces NAD / oxidises reduced NAD
- NAD reduced in glycolysis / NAD accepts hydrogen glycolysis
Aerobic respiration produces more ATP per molecule of glucose than anaerobic respiration. Explain why. (2)
- Oxygen is final/terminal (electron) acceptor / oxygen combines with electrons and protons
- (Aerobic respiration) oxidative phosphorylation / electron transfer chain
- Anaerobic (respiration) only glycolysis occurs / no Krebs / no link reaction
Describe how acetyl coenzyme A is formed in the link reaction. (2)
- Oxidation of / hydrogen removed from pyruvate and carbon dioxide released
- Addition of coenzyme A
Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration. (2)
- Regenerates / produces NAD / oxidises reduced NAD
- (NAD used) in glycolysis
In muscles, some of the lactate is converted back to pyruvate when they are well supplied with oxygen. Suggest one advantage of this. (1)
- (Pyruvate used) in aerobic respiration / (lactate / lactic acid) is toxic / harmful / causes cramp / (muscle) fatigue
‘(pyruvate) can enter link reaction’
‘accept reduces cramp / (muscle) fatigue’
Describe the mechanism in which ATP is formed in the mitochondria. (6)
- Substrate level phosphorylation / ATP is produced in the Krebs cycle
- The Krebs cycle / link reaction produces reduced coenzyme/NAD/FAD
- Electrons are released from reduced coenzymes NAD/FAD
- Electrons pass along the electron carriers / through the electron transport chain releasing energy
- Allowing protons to move into intermembrane space
- Protons re-enter the matrix via ATP synthase along the proton/chemiosmotic gradient
- ATP forms from ADP + Pi (in oxidative phosphorylation)
- Oxygen is the final electron acceptor
Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP. (4)
- NAD/FAD are reduced / hydrogen attached to NAD/FAD
- H+ ions / electrons transferred in a series of redox reactions
- Energy made available as electrons passed on
- Energy used to synthesise ATP from ADP and phosphate
- H+/protons passed into intermembrane space
Explain why oxygen is referred to as the ‘terminal electron acceptor’ in aerobic respiration. (3)
- Oxygen has a high electronegativity / attracts electrons
- Oxygen combines with protons and electrons to form water
- Protons produced in glycolysis and the Krebs cycle
- Electrons passed down the electron transport chain / oxidative phosphorylation chain
Molecules other than carbohydrates are, under certain circumstances, used as respiratory substrates. Name two main groups of molecules that are used in this way and describe how their catabolic products join the main pathways of respiration. (6)
- Lipids / fats
- Proteins
- Glycerol from lipids converted to triose phosphates / enter glycolysis
- Fatty acids broken down / converted to acetyl CoA
- Amino acids deaminated
- 3-C and 5-C compounds converted to pyruvate / 5-C intermediates in Krebs cycle
Describe the production of ATP in aerobic respiration. (6)
- Substrate level phosphorylation / ATP produced in Krebs cycle
- Krebs cycle / link reaction produces reduced coenzyme / reduced NAD / reduced FAD
- Electrons released from reduced coenzymes / reduced NAD / reduced FAD
- (Electrons) pass along the electron transport chain / oxidative phosphorylation / via a series of redox reactions
- Energy is released
- ADP / ADP + Pi /inorganic phosphate
- Protons move into intermembrane space
- Via ATP synthase / ATPase
Mitochondrial diseases in humans cause their mitochondria to malfunction. Individuals that suffer from mitochondrial disease are only able to endure intense exercise for a short period of time. Explain why. (2)
- (Mitochondria) is the site of aerobic respiration
- Mitochondria produce ATP / release energy that is required for muscles (to contract during exercise)
