Core L - Respiration Flashcards
Explain why, in the absence of oxygen, pyruvate needs to be converted to lactate. (2)
- NAD regenerated
- So glycolysis can continue
- To produce ATP
Name the part of the cell where glucose is converted to pyruvate. (1)
Cytoplasm.
Name the enzyme responsible for the conversion of pyruvate to lactate. (1)
Lactate dehydrogenase.
Name the type of reaction and the type of bonds formed when glucose molecules are used to make glycogen. (2)
- Condensation / polymerisation
* Glycosidic bonds
Describe how anaerobic respiration in yeast cells differs from anaerobic respiration in mammalian cells. (4)
- Pyruvate decarboxylated
- Produce ethanal
- Reduced to ethanol
- Two steps from pyruvate
- Ethanol dehydrogenase
- Not a reversible reaction (ethanol cannot be converted back to pyruvate)
- Less energy efficient
State how RQ is calculated. (2)
Volume of carbon dioxide produced divided by volume of oxygen consumed.
Suggest what would happen to the RQ value when respiration becomes anaerobic. (1)
Above one / infinity.
Explain why ATP is needed at the start of glycolysis. (1)
Raise chemical PE of glucose (provide activation energy)
State the role of NAD in glycolysis. (1)
Removes hydrogen / hydrogen carrier / coenzyme
Name the two types of reaction that occur during the conversion of pyruvate to acetyl CoA in the link reaction. (2)
- Dehydrogenation
* Decarboxylation
Describe what happens to the hydrogen released during the link reaction. (2)
- Accepted by NAD
- Passed to ETC
- For oxidative phosphorylation
- Proton pump / chemiosmosis
Explain why ATP is regarded as the universal energy currency in organisms. (5)
- Found in all organisms
- Loss of phosphate (hydrolysis) leads to 30.6 kJ of energy release
- Reversible reaction
- Small packets of energy
- Small, water soluble so can move around cell
- Used by cells as immediate energy donor
- Link between energy yielding and energy requiring reactions
- High turnover
- Active transport, muscle contraction, Calvin Cycle
Describe how anaerobic respiration in mammalian cells differs from anaerobic respiration in yeast cells. (3)
- Lactate produced / no ethanol produced
- No decarboxylation
- Single step
- Lactate dehydrogenase
- Reversible
Explain why anaerobic respiration results in a small yield of ATL compared with aerobic respiration. (3)
- Only glycolysis occurs
- Glucose not fully broken down (still contains energy)
- Pyruvate does not enter mitochondrion
- No oxygen so no final electron acceptor in ETC
- ETC stops
- No oxidative phosphorylation
Explain why glucose needs to be converted to hexose bisphosphate. (2)
- Provide activation energy
* For it to split
Describe what happens to pyruvate in a yeast cell when oxygen is not present. (4)
- Decarboxylated
- Ethanal produced
- Ethanal reduced
- By reduced NAD
- To ethanol
- Dehydrogenase
The mitochondria take up oxygen. Explain how this oxygen, plus the succinate, ATP and inorganic phosphate, are used by the mitochondria. (4)
- Succinate converted to oxaloacetate
- Dehydrogenation
- NAD is reduced (accepts hydrogen)
- Hydrogens move to ETC
- Hydrogen split into protons and electrons
- Electrons pass along ETC
- ADP + Pi –> ATP
- Oxygen receives protons and electrons (final electron acceptor)
- Form water
Suggest why membranes in cells lose their normal structure when the water potential is low. (3)
- Water leaves mitochondrion
- By osmosis
- Mechanical disruption to membranes
- Membranes made of phospholipid bilayer
- Hydrophilic heads / glycoproteins / glycolipids form fewer hydrogen bonds with water
- Reduces stability / fluidity of membrane
Describe the structure of ATP and the role of ATP as the energy currency in all living organisms. (8)
- Nucleotide
- Adenine + ribose + three phosphates
- Hydrolysis releases 30.6 kJ
- Reversible reaction
- Small packets of energy
- Small / water soluble so can move around the cell
- Used by cells as immediate energy donor
- Link between energy yielding and energy requiring reactions
- High turnover
- Active transport / muscle contraction
- Protein synthesis
Outline anaerobic respiration in mammalian cells and describe how it differs from anaerobic respiration in yeast cells. (7)
- Pyruvate cannot enter mitochondrion
- Becomes hydrogen acceptor (reduced)
- By reduced NAD
- From glycolysis
- Converted to lactate
- Lactate dehydrogenase
- Allows glycolysis to continue
- No decarboxylation
- Single step
- Reversible reaction (converted back to pyruvate)
- By oxidation
- Oxygen debt
- Ethanol produced in yeast
Outline the need for energy in living organisms using named examples. (9)
- ATP as universal energy currency
- Light energy needed for photosynthesis
- ATP used conversion of GP to GP
- ATP used to regenerate RuBP
- Energy needed for anabolic reactions
- Protein synthesis / starch formation / triglyceride formation
- Activation energy
- Activate glucose in glycolysis
- Active transport
- Sodium potassium pump
- Movement / locomotion
- Muscle contraction / cilia beating
- Endocytosis / exocytosis / pinocytosis / bulk transport
- Temperature regulation
Explain the different energy values of carbohydrate, lipid and protein as respiratory substrates. (6)
- Lipid has more energy than either protein or carbohydrate
- 39.4, 17.0, 15.8
- Per unit mass
- More hydrogen atoms in molecule, more energy
- Lipid have more hydrogen atoms / C-H bonds
- Most energy comes from oxidation of hydrogen to water
- Using reduced NAD / FAD
- In ETC
- Chemiosmosis
- ATP production
Outline the main features of the Krebs cycle. (9)
- Acetyl CoA combines with oxaloacetate
- To form citrate
- 4C to 6C
- Decarboxylation
- Dehydrogenation
- Reduced NAD produced
- Reduced FAD produced
- ATP produced
- Substrate level phosphorylation
- Series of steps
- Enzyme catalysed reactions
- Oxaloacetate regenerated
- Occurs in mitochondrial matrix
Explain the role of NAD in aerobic respiration. (6)
- Coenzyme
- For dehydrogenase
- Reduced
- Carries electrons and protons
- From Krebs cycle
- And glycolysis
- To ETC
- Reoxidised / regenerated (hydrogen removed)
- ATP produced
