ATP is made of adenine, the sugar ribose, and three phosphate groups.
Correct Answer
True
True. ATP consists of adenine bonded to ribose and a chain of three phosphates. Breaking the bond to the last phosphate releases usable energy and leaves ADP and inorganic phosphate.
Category: Metabolic Reactions
Question 2
Cortisol is classified as an anabolic hormone.
Correct Answer
False
False. Cortisol is a catabolic hormone that promotes breakdown of stored fuels such as protein and fat. Anabolic hormones include insulin, growth hormone, testosterone and estrogen.
Category: Metabolic Reactions
Question 3
NADH and FADH2 carry high-energy electrons to the electron transport chain.
Correct Answer
True
True. NAD+ and FAD are coenzymes that accept hydrogen atoms during glycolysis, the Krebs cycle and beta-oxidation. In their reduced forms they deliver those electrons to the electron transport chain, where the energy is used to make ATP.
Category: Metabolic Reactions
Question 4
The Krebs cycle takes place in the cytoplasm of the cell.
Correct Answer
False
False. The Krebs cycle runs in the mitochondrial matrix. Glycolysis is the stage of glucose breakdown that occurs in the cytoplasm.
Category: Carbohydrate Metabolism
Question 5
Hexokinase phosphorylates glucose to glucose-6-phosphate, which traps the glucose inside the cell.
Correct Answer
True
True. Adding a phosphate gives glucose a charge that keeps it from crossing back out through the plasma membrane. This is the first step of glycolysis and it uses one ATP.
Category: Carbohydrate Metabolism
Question 6
ATP synthase uses the flow of hydrogen ions back across the inner mitochondrial membrane to make ATP.
Correct Answer
True
True. The electron transport chain pumps hydrogen ions into the space between the mitochondrial membranes. As they flow back through ATP synthase, the complex turns like a turbine and joins ADP and phosphate into ATP.
Category: Carbohydrate Metabolism
Question 7
Glycogenolysis is the synthesis of glycogen from glucose.
Correct Answer
False
False. Glycogenolysis is the breakdown of glycogen into glucose. The synthesis of glycogen from glucose is called glycogenesis.
Category: Carbohydrate Metabolism
Question 8
In the Cori cycle, the liver converts lactate produced by muscle back into glucose.
Correct Answer
True
True. Lactate from anaerobic muscle activity travels in the blood to the liver, which converts it to glucose. That glucose can then return to the muscle as fuel.
Category: Carbohydrate Metabolism
Question 9
Bile salts emulsify dietary fats so that pancreatic lipase can digest them.
Correct Answer
True
True. Bile salts break large fat droplets into tiny droplets, greatly increasing the surface area available to water-soluble lipase. Lipase then splits triglycerides into fatty acids and monoglycerides.
Category: Lipid Metabolism
Question 10
Lipogenesis occurs mainly when blood glucose is low.
Correct Answer
False
False. Lipogenesis, the synthesis of fatty acids and triglycerides, occurs mainly when glucose is plentiful and excess acetyl CoA is available. When glucose is low, the body breaks down fat instead.
Category: Lipid Metabolism
Question 11
Ketone bodies are produced mainly in the kidneys.
Correct Answer
False
False. Ketone bodies are produced mainly in liver mitochondria from excess acetyl CoA. Other tissues, including the heart and the brain during starvation, then take them up and use them as fuel.
Category: Lipid Metabolism
Question 12
Pepsin is a protein-digesting enzyme produced by the pancreas.
Correct Answer
False
False. Pepsin is produced in the stomach, released as inactive pepsinogen and activated by hydrochloric acid. The pancreas produces other proteases such as trypsin and chymotrypsin.
Category: Protein Metabolism
Question 13
Chymotrypsinogen is converted to its active form by trypsin.
Correct Answer
True
True. Once enterokinase activates trypsin in the small intestine, trypsin activates chymotrypsinogen and other pancreatic protease precursors. Releasing these enzymes in inactive form protects the pancreas from digesting itself.
Category: Protein Metabolism
Question 14
Insulin is released by the alpha cells of the pancreatic islets.
Correct Answer
False
False. Insulin is released by pancreatic beta cells. The alpha cells release glucagon.
Category: Metabolic States
Question 15
The postabsorptive state occurs when the digestive tract is empty and the body draws on stored fuels.
Correct Answer
True
True. Once a meal has been digested and absorbed, such as overnight, the body maintains blood glucose by breaking down liver glycogen and making new glucose. This contrasts with the absorptive state, when nutrients from the gut are being stored.
Category: Metabolic States
Question 16
During the absorptive state, glucagon secretion rises to promote storage of nutrients.
Correct Answer
False
False. In the absorptive state after a meal, insulin rises and drives storage of glucose as glycogen and fat. Glucagon secretion falls then and rises instead between meals.
Category: Metabolic States
Question 17
Evaporation of sweat is the main way the body loses heat during exercise.
Correct Answer
True
True. During exercise the body produces sweat, and as it evaporates it removes large amounts of heat from the skin. Evaporation works less well in humid air, which slows the change from liquid to vapor.
Category: Energy and Heat Balance
Question 18
Basal metabolic rate generally increases with age.
Correct Answer
False
False. Basal metabolic rate generally decreases with age, largely because lean muscle mass declines. More lean mass and more physical activity raise energy use.
Category: Energy and Heat Balance
Question 19
Thyroid hormone increases the metabolic rate and heat production of cells throughout the body.
Correct Answer
True
True. Thyroid hormones raise oxygen and energy use in most tissues, which increases heat production. This is why excess thyroid hormone causes heat intolerance and too little causes cold intolerance.
Category: Energy and Heat Balance
Question 20
A deficiency of vitamin C causes rickets.
Correct Answer
False
False. Vitamin C deficiency causes scurvy, marked by bleeding gums and poor wound healing because collagen is not formed properly. Rickets is caused by vitamin D deficiency in children.
Category: Nutrition