Hormones such as growth hormone, testosterone and estrogen that stimulate the synthesis of larger molecules are classified as anabolic hormones.
Missing Word
anabolic
Anabolic describes building reactions that join small molecules into larger ones using energy from ATP. Growth hormone, testosterone and estrogen promote tissue building, unlike catabolic hormones such as cortisol.
Category: Metabolic Reactions
Question 2
In a redox reaction, the molecule that gains electrons undergoes reduction.
Missing Word
reduction
Reduction is the gain of electrons, and it always pairs with oxidation, the loss of electrons, by another molecule. NAD+ undergoing this change to NADH is a key example in metabolism.
Category: Metabolic Reactions
Question 3
Glycolysis splits one glucose molecule into two molecules of the three-carbon compound pyruvate.
Missing Word
pyruvate
Pyruvate is the end product of glycolysis. With oxygen it is converted to acetyl CoA and enters the Krebs cycle, and without oxygen it is converted to lactate.
Category: Carbohydrate Metabolism
Question 4
Between meals, glucagon stimulates the liver to release glucose by breaking down its stored polysaccharide, a process called glycogenolysis.
Missing Word
glycogenolysis
Glycogenolysis is the breakdown of glycogen into glucose. The liver uses it to release glucose into the blood during the postabsorptive state.
Category: Metabolic States
Question 5
Lipolysis splits each triglyceride into three fatty acids and one molecule of glycerol.
Missing Word
glycerol
Glycerol is the three-carbon backbone of a triglyceride. After lipolysis it can enter glycolysis or be used by the liver for gluconeogenesis, while the fatty acids undergo beta-oxidation.
Category: Lipid Metabolism
Question 6
The liver process that turns excess acetyl CoA into acetoacetate during prolonged fasting is called ketogenesis.
Missing Word
ketogenesis
Ketogenesis is the formation of ketone bodies in liver mitochondria when acetyl CoA builds up faster than the Krebs cycle can use it. It increases in starvation and uncontrolled diabetes.
Category: Lipid Metabolism
Question 7
Fatty acids are carried into the mitochondrial matrix for beta-oxidation with the help of the transport molecule carnitine.
Missing Word
carnitine
Carnitine binds fatty acyl groups and shuttles them across the mitochondrial membranes. Without it, long-chain fatty acids cannot reach the matrix where beta-oxidation occurs.
Category: Lipid Metabolism
Question 8
Chylomicrons leaving intestinal cells enter lymphatic capillaries inside the villi called lacteals.
Missing Word
lacteals
Lacteals are the lymphatic capillaries of the intestinal villi. Chylomicrons are too large to enter blood capillaries, so they travel through the lymph before reaching the bloodstream.
Category: Lipid Metabolism
Question 9
Nitrogen removed from amino acids is converted by the liver into urea, which the kidneys excrete.
Missing Word
urea
Urea is the main nitrogenous waste in humans. The liver forms it from ammonium and carbon dioxide in the urea cycle, which keeps ammonia from reaching toxic levels.
Category: Protein Metabolism
Question 10
In the stomach, hydrochloric acid converts an inactive precursor secreted by chief cells into the active protein-digesting enzyme pepsin.
Missing Word
pepsin
Pepsin is the main protease of the stomach. Chief cells secrete its inactive precursor, pepsinogen, and stomach acid converts that precursor into active pepsin, which cuts proteins into smaller polypeptides.
Category: Protein Metabolism
Question 11
The hormone released by pancreatic beta cells after a meal, which promotes glucose uptake by cells, is insulin.
Missing Word
insulin
Insulin is the main hormone of the absorptive state. It lowers blood glucose by promoting glucose uptake and storage as glycogen and triglycerides.
Category: Metabolic States
Question 12
Heat lost from the skin as infrared energy to cooler objects in the surroundings is called radiation.
Missing Word
radiation
Radiation transfers heat as infrared waves between objects at different temperatures without direct contact. At rest in a cool room it accounts for much of the body's heat loss.
Category: Energy and Heat Balance
Question 13
A core body temperature that falls well below the normal range is called hypothermia.
Missing Word
hypothermia
Hypothermia is an abnormally low core temperature, which occurs when heat loss outpaces heat production, as in cold water. The hypothalamus responds by triggering shivering and skin vasoconstriction.
Category: Energy and Heat Balance
Question 14
Vitamin D deficiency in children softens the developing bones, causing a condition called rickets.
Missing Word
rickets
Rickets is softening and deformity of growing bones caused by too little vitamin D, which is needed for calcium absorption. In adults, the comparable condition is osteomalacia.
Category: Nutrition
Question 15
Dietary deficiency of the trace mineral iodine can lead to an enlarged thyroid gland called a goiter.
Missing Word
iodine
Iodine is a trace mineral required to make thyroid hormones. Without enough of it, thyroid hormone levels fall and the gland enlarges into a goiter.
Category: Nutrition