Free Biochemistry Integration of Metabolism Questions and Answers — Questions and Answers
Question 1: Which hormone primarily regulates the metabolic processes in the fed state?
- Glucagon
- Cortisol
- Insulin (Correct answer)
- Epinephrine
Correct answer: Insulin
Insulin is the primary hormone that regulates metabolic processes in the fed state, when blood glucose levels are elevated after a meal. It promotes the uptake of glucose by cells, stimulates the synthesis of glycogen in the liver and muscles, and encourages fat storage. Insulin effectively lowers blood glucose and directs nutrients towards storage.
Question 2: During fasting, which process provides glucose for the body when glycogen stores are depleted?
- Glycogenesis
- Lipogenesis
- Gluconeogenesis (Correct answer)
- Ketogenesis
Correct answer: Gluconeogenesis
During fasting, when the body's glycogen stores are depleted, gluconeogenesis becomes the primary process to synthesize new glucose. This pathway, mainly in the liver, produces glucose from non-carbohydrate precursors like amino acids, lactate, and glycerol. Gluconeogenesis is vital for maintaining blood glucose levels to supply energy to glucose-dependent tissues, such as the brain.
Question 3: Which metabolic pathway is activated during prolonged starvation to supply energy to the brain?
- Glycolysis
- Citric acid cycle
- Ketogenesis (Correct answer)
- Beta-oxidation
Correct answer: Ketogenesis
During prolonged starvation, the body activates ketogenesis to provide an alternative energy source for the brain when glucose reserves are severely depleted. The liver produces ketone bodies from fatty acids, which can then be utilized by the brain for energy. This metabolic adaptation helps conserve muscle protein by reducing the need for gluconeogenesis from amino acids.
Question 4: Which of the following statements about the Cori cycle is TRUE?
- It occurs between the liver and brain.
- Lactate produced in the muscles is converted back to glucose in the liver. (Correct answer)
- It only operates in the presence of oxygen.
- It involves the direct synthesis of ATP in muscle cells.
Correct answer: Lactate produced in the muscles is converted back to glucose in the liver.
The Cori cycle describes the metabolic pathway where lactate produced during anaerobic glycolysis in active muscles is transported to the liver. In the liver, this lactate is converted back into glucose through gluconeogenesis. This newly synthesized glucose can then be released into the bloodstream to be used by muscles or other tissues, effectively recycling the lactate.
Question 5: In the integration of metabolism, which pathway is the primary source of ATP during intense physical activity?
- Oxidative phosphorylation
- Glycolysis (Correct answer)
- Fatty acid oxidation
- Pentose phosphate pathway
Correct answer: Glycolysis
During intense physical activity, oxygen supply to muscles can become limited, leading to anaerobic conditions. In this scenario, glycolysis becomes the primary source of ATP, rapidly producing a small amount of energy without requiring oxygen. While less efficient than oxidative phosphorylation, it provides the quick bursts of energy necessary for high-intensity exercise.
Free Biochemistry Integration of Metabolism Questions and Answers
Which hormone primarily regulates the metabolic processes in the fed state?