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Biology > Core L - Respiration > Flashcards

Core L - Respiration Flashcards

0
Q

Explain why, in the absence of oxygen, pyruvate needs to be converted to lactate. (2)

A
  • NAD regenerated
  • So glycolysis can continue
  • To produce ATP
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1
Q

Name the part of the cell where glucose is converted to pyruvate. (1)

A

Cytoplasm.

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2
Q

Name the enzyme responsible for the conversion of pyruvate to lactate. (1)

A

Lactate dehydrogenase.

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3
Q

Name the type of reaction and the type of bonds formed when glucose molecules are used to make glycogen. (2)

A
  • Condensation / polymerisation

* Glycosidic bonds

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4
Q

Describe how anaerobic respiration in yeast cells differs from anaerobic respiration in mammalian cells. (4)

A
  • 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
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5
Q

State how RQ is calculated. (2)

A

Volume of carbon dioxide produced divided by volume of oxygen consumed.

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6
Q

Suggest what would happen to the RQ value when respiration becomes anaerobic. (1)

A

Above one / infinity.

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7
Q

Explain why ATP is needed at the start of glycolysis. (1)

A

Raise chemical PE of glucose (provide activation energy)

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8
Q

State the role of NAD in glycolysis. (1)

A

Removes hydrogen / hydrogen carrier / coenzyme

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9
Q

Name the two types of reaction that occur during the conversion of pyruvate to acetyl CoA in the link reaction. (2)

A
  • Dehydrogenation

* Decarboxylation

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10
Q

Describe what happens to the hydrogen released during the link reaction. (2)

A
  • Accepted by NAD
  • Passed to ETC
  • For oxidative phosphorylation
  • Proton pump / chemiosmosis
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11
Q

Explain why ATP is regarded as the universal energy currency in organisms. (5)

A
  • 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
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12
Q

Describe how anaerobic respiration in mammalian cells differs from anaerobic respiration in yeast cells. (3)

A
  • Lactate produced / no ethanol produced
  • No decarboxylation
  • Single step
  • Lactate dehydrogenase
  • Reversible
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13
Q

Explain why anaerobic respiration results in a small yield of ATL compared with aerobic respiration. (3)

A
  • 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
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14
Q

Explain why glucose needs to be converted to hexose bisphosphate. (2)

A
  • Provide activation energy

* For it to split

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15
Q

Describe what happens to pyruvate in a yeast cell when oxygen is not present. (4)

A
  • Decarboxylated
  • Ethanal produced
  • Ethanal reduced
  • By reduced NAD
  • To ethanol
  • Dehydrogenase
16
Q

The mitochondria take up oxygen. Explain how this oxygen, plus the succinate, ATP and inorganic phosphate, are used by the mitochondria. (4)

A
  • 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
17
Q

Suggest why membranes in cells lose their normal structure when the water potential is low. (3)

A
  • 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
19
Q

Describe the structure of ATP and the role of ATP as the energy currency in all living organisms. (8)

A
  • 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
20
Q

Outline anaerobic respiration in mammalian cells and describe how it differs from anaerobic respiration in yeast cells. (7)

A
  • 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
21
Q

Outline the need for energy in living organisms using named examples. (9)

A
  • 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
22
Q

Explain the different energy values of carbohydrate, lipid and protein as respiratory substrates. (6)

A
  • 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
23
Q

Outline the main features of the Krebs cycle. (9)

A
  • 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
24
Q

Explain the role of NAD in aerobic respiration. (6)

A
  • Coenzyme
  • For dehydrogenase
  • Reduced
  • Carries electrons and protons
  • From Krebs cycle
  • And glycolysis
  • To ETC
  • Reoxidised / regenerated (hydrogen removed)
  • ATP produced

Biology (10 decks)

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