Cellular Respiration 1 - Higher Level

What is the definition of oxidation in cellular respiration?

• Oxidation refers to the production of ATP in cellular respiration.

• Oxidation is the process of breaking down glucose without oxygen.

• Oxidation is the loss of electrons or hydrogen atoms during cellular respiration.

• Oxidation is the gain of electrons during cellular respiration.

Answer explanation

Oxidation in cellular respiration specifically refers to the loss of electrons or hydrogen atoms. This process is crucial for energy production, as it allows for the transfer of energy from glucose to ATP.

How does reduction differ from oxidation?

• Reduction occurs only in acidic conditions.

• Reduction and oxidation are the same process.

• Reduction involves gaining electrons; oxidation involves losing electrons.

• Reduction involves losing electrons; oxidation involves gaining electrons.

Answer explanation

Reduction is the process of gaining electrons, while oxidation is the process of losing electrons. This distinction is fundamental in redox reactions, making the correct choice clear.

What role does NAD play in cellular respiration?

• NAD is involved in protein synthesis during respiration.

• NAD is a source of energy in cellular respiration.

• NAD acts as a structural component of the cell membrane.

• NAD serves as an electron carrier in cellular respiration.

Answer explanation

NAD serves as an electron carrier in cellular respiration, facilitating the transfer of electrons during metabolic reactions, which is crucial for ATP production.

What happens to NAD when it accepts hydrogen atoms?

• NAD remains unchanged when it accepts hydrogen atoms.

• NAD is oxidized to NADH when it accepts hydrogen atoms.

• NAD is converted to ATP when it accepts hydrogen atoms.

• NAD is reduced to NADH when it accepts hydrogen atoms.

Answer explanation

When NAD accepts hydrogen atoms, it undergoes reduction, forming NADH. This process involves the gain of electrons and hydrogen, which is why the correct answer is that NAD is reduced to NADH.

Describe the process of glycolysis in brief.

• Glycolysis occurs only in the mitochondria and produces carbon dioxide.

• Glycolysis is the process of breaking down glucose into pyruvate, producing ATP and NADH.

• Glycolysis converts pyruvate into glucose, using ATP and NADH.

• Glycolysis is the process of synthesizing glucose from fatty acids.

Answer explanation

Glycolysis is a metabolic pathway that breaks down glucose into pyruvate, generating ATP and NADH in the process. This distinguishes it from the incorrect options that misrepresent the function and location of glycolysis.

What are the end products of glycolysis?

• 2 pyruvate, 2 ATP, 2 NADH

• 2 glucose, 4 ATP, 1 NADH

• 2 acetyl-CoA, 2 FADH2, 1 ATP

• 1 pyruvate, 3 ATP, 2 NADH

Answer explanation

Glycolysis breaks down one glucose molecule into 2 pyruvate, producing 2 ATP and 2 NADH in the process. Thus, the correct answer is 2 pyruvate, 2 ATP, 2 NADH.

How does anaerobic respiration differ in humans and yeast?

• Humans produce ethanol; yeast produces lactic acid.

• Both humans and yeast produce carbon dioxide only.

• Humans produce glucose; yeast produces oxygen.

• Humans produce lactic acid; yeast produces ethanol and carbon dioxide.

Answer explanation

In humans, anaerobic respiration results in the production of lactic acid, while yeast produces ethanol and carbon dioxide. This distinction is crucial in understanding how different organisms metabolize energy without oxygen.

What is the link reaction in cellular respiration?

• The link reaction occurs in the cytoplasm of the cell.

• The link reaction produces glucose from acetyl-CoA.

• The link reaction converts ATP into ADP.

• The link reaction converts pyruvate into acetyl-CoA.

Answer explanation

The link reaction is a crucial step in cellular respiration where pyruvate, produced from glycolysis, is converted into acetyl-CoA. This process occurs in the mitochondria and is essential for entering the citric acid cycle.

How does the link reaction connect glycolysis to aerobic respiration?

• The link reaction produces ATP directly from glucose.

• The link reaction converts pyruvate from glycolysis into acetyl-CoA, connecting it to aerobic respiration.

• The link reaction converts glucose into lactate for energy.

• The link reaction occurs in the cytoplasm and does not involve mitochondria.

Answer explanation

The link reaction converts pyruvate, produced during glycolysis, into acetyl-CoA. This conversion is essential for connecting glycolysis to the Krebs cycle in aerobic respiration, allowing for further energy production.

What are the main stages of cellular respiration?

• Glycolysis, Lactic Acid Cycle, Citric Acid Cycle

• Glycolysis, Krebs Cycle, Electron Transport Chain

• Krebs Cycle, Oxidative Phosphorylation, Fermentation

• Photosynthesis, Fermentation, Calvin Cycle

Answer explanation

The main stages of cellular respiration are Glycolysis, Krebs Cycle (also known as Citric Acid Cycle), and Electron Transport Chain. These processes convert glucose into ATP, the energy currency of the cell.