Lab 8: Energetics, Fermentation, and Respiration.

What is glycolysis?

• An anaerobic process that occurs in the cytoplasm of both aerobic and anaerobic organisms.

• A process that only occurs in the mitochondria of plant cells.

• A type of photosynthesis in green plants.

• A process that produces oxygen in animal cells.

Answer explanation

Glycolysis is an anaerobic process that breaks down glucose in the cytoplasm, producing energy. It occurs in both aerobic and anaerobic organisms, making the first answer choice correct.

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What is the end product of glycolysis?

• 2 Pyruvate.

• 2 Acetyl-CoA.

• 2 Lactate.

• 2 Glucose.

Answer explanation

The end product of glycolysis is 2 pyruvate molecules. This process occurs in the cytoplasm and is crucial for cellular respiration, leading to further energy production in the presence or absence of oxygen.

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What is anaerobic?

• A process that can proceed in the absence of oxygen.

• A process that requires sunlight to occur.

• A process that only happens in water.

• A process that needs oxygen to proceed.

Answer explanation

Anaerobic refers to processes that can occur without oxygen. This distinguishes it from aerobic processes, which require oxygen. Therefore, the correct choice is that anaerobic is a process that can proceed in the absence of oxygen.

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What is aerobic?

• A process that requires oxygen.

• A process that produces carbon dioxide only.

• A process that occurs without any gas exchange.

• A process that requires sunlight.

Answer explanation

Aerobic refers to processes that require oxygen for cellular respiration, making 'A process that requires oxygen' the correct choice. The other options incorrectly describe processes that do not involve oxygen or gas exchange.

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What is fermentation?

• An anaerobic process that oxidizes NADH back to NAD.

• A process that produces oxygen from glucose.

• A method of breaking down proteins into amino acids.

• A reaction that requires sunlight to occur.

Answer explanation

Fermentation is an anaerobic process that converts NADH back to NAD, allowing glycolysis to continue. This is essential for energy production in the absence of oxygen, making the first answer choice correct.

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What is fermentation?

• This is the conversion of glucose to pyruvate as a major source of energy.

• This is the process of breaking down proteins into amino acids.

• This is the conversion of fats to fatty acids and glycerol.

• This is the process of photosynthesis in plants.

Answer explanation

Fermentation is the metabolic process where glucose is converted to pyruvate, primarily for energy production. This distinguishes it from other processes like protein breakdown or fat conversion.

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What is lactic acid fermentation?

• The second type of fermentation process that metabolizes pyruvate and produces lactic acid.

• A process that produces ethanol from glucose in plants.

• A method of photosynthesis in bacteria.

• A type of aerobic respiration that uses oxygen to produce energy.

Answer explanation

Lactic acid fermentation is a process that converts pyruvate into lactic acid, occurring in anaerobic conditions. It is distinct from alcoholic fermentation, which produces ethanol, and is not related to photosynthesis or aerobic respiration.

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What is lactic acid fermentation? (b) For example, when oxygen in the muscles is depleted, what happens?

• Lactic acid is produced and eventually resynthesized into pyruvate once oxygen becomes available again.

• Glucose is directly converted into ATP without any byproducts.

• Oxygen is produced in the muscles to continue aerobic respiration.

• Fatty acids are immediately broken down to supply energy.

Answer explanation

Lactic acid fermentation occurs when oxygen is low, leading to the production of lactic acid from glucose. Once oxygen is available again, lactic acid can be converted back into pyruvate, allowing for aerobic respiration to resume.

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What is pyruvate oxidation?

• Included in when pyruvate enters the mitochondria, the second stage of glucose oxidation.

• A process that occurs during photosynthesis in plants.

• A reaction that takes place in the cytoplasm during glycolysis.

• A step involved in the breakdown of fatty acids.

Answer explanation

Pyruvate oxidation occurs when pyruvate enters the mitochondria, marking the second stage of glucose oxidation. This process is crucial for converting pyruvate into acetyl-CoA, which then enters the citric acid cycle.

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What happens to glucose at the end of the Krebs Cycle?

• Glucose is completely oxidized, releasing its carbon atoms as CO₂.

• Glucose is converted into lactic acid.

• Glucose is stored as glycogen.

• Glucose is released into the bloodstream.

Answer explanation

At the end of the Krebs Cycle, glucose is completely oxidized, resulting in the release of carbon atoms as CO₂. This process is crucial for energy production in cellular respiration.

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