Negative feedback counteracts a change, returning a variable such as blood glucose toward its set point.
Correct Answer
True
True. In negative feedback, a rise in a variable triggers responses that lower it and a fall triggers responses that raise it, keeping conditions near the set point.
Category: Homeostasis and Kidneys
Question 2
Ectotherms keep a constant body temperature by generating large amounts of internal heat.
Correct Answer
False
False. That description fits endotherms, such as mammals and birds. Ectotherms have body temperatures that follow the environment and rely mostly on behavior, such as basking or seeking shade, to adjust them.
Category: Homeostasis and Kidneys
Question 3
Shivering generates heat that helps an endotherm raise its body temperature.
Correct Answer
True
True. Shivering is rapid, involuntary muscle contraction, and the extra metabolic activity releases heat. It is one of the responses triggered when body temperature falls below its set point.
Category: Homeostasis and Kidneys
Question 4
Urine travels from each kidney to the urinary bladder through the urethra.
Correct Answer
False
False. Urine moves from each kidney to the bladder through a ureter. The single urethra carries urine from the bladder out of the body.
Category: Homeostasis and Kidneys
Question 5
The pyloric sphincter controls the passage of chyme from the stomach into the esophagus.
Correct Answer
False
False. The pyloric sphincter controls the passage of chyme from the stomach into the duodenum, the first part of the small intestine. Food enters the stomach from the esophagus through a different sphincter at the top of the stomach.
Category: Digestion and Nutrition
Question 6
The large intestine reabsorbs water and mineral salts and compacts the remaining waste into feces.
Correct Answer
True
True. By the time material reaches the large intestine, most nutrients have been absorbed. The colon recovers water and salts, and its resident bacteria help break down some remaining material.
Category: Digestion and Nutrition
Question 7
The contents of the human stomach are normally slightly basic, with a pH of about 8.
Correct Answer
False
False. Stomach contents are strongly acidic, with a pH of about 1.5 to 2.5. This acidity kills many microbes, helps break down food and activates pepsin.
Category: Digestion and Nutrition
Question 8
Humans cannot digest cellulose, although gut bacteria can extract some nutrition from it.
Correct Answer
True
True. Human enzymes cannot break the bonds of cellulose, so plant fiber passes through largely undigested. Bacteria living in the large intestine can break some of it down.
Category: Digestion and Nutrition
Question 9
Veins contain internal valves that help keep blood from flowing backward.
Correct Answer
True
True. Blood pressure in veins is low, so one-way valves prevent backflow as blood returns to the heart. Vein walls are also thinner than artery walls.
Category: Circulation and Respiration
Question 10
In humans, the right atrium receives oxygen-poor blood from the superior and inferior venae cavae.
Correct Answer
True
True. The superior vena cava returns blood from the head and arms, and the inferior vena cava returns blood from the lower body. Both empty into the right atrium.
Category: Circulation and Respiration
Question 11
Arteries carry blood toward the heart, and veins carry it away from the heart.
Correct Answer
False
False. Arteries carry blood away from the heart and veins return blood to the heart. The direction of flow, not oxygen content, defines the two types of vessels.
Category: Circulation and Respiration
Question 12
A hormone affects only the cells that have receptors specific to that hormone.
Correct Answer
True
True. Hormones circulate throughout the body, but only target cells with matching receptors, either on the cell surface or inside the cell, respond to them.
Category: Endocrine System
Question 13
Endocrine glands, like sweat glands, release their products through ducts.
Correct Answer
False
False. Endocrine glands release hormones directly into body fluids, usually the blood. Glands that release products through ducts, such as sweat glands, are exocrine glands.
Category: Endocrine System
Question 14
The kidneys release erythropoietin in response to low oxygen levels, which stimulates red blood cell production.
Correct Answer
True
True. Erythropoietin (EPO) signals the bone marrow to make more red blood cells, increasing the blood's oxygen-carrying capacity.
Category: Endocrine System
Question 15
Glucagon lowers blood glucose by promoting glucose uptake into body cells.
Correct Answer
False
False. Glucagon, released by pancreatic alpha cells when blood glucose falls, raises blood glucose by causing the liver to release glucose. Insulin is the hormone that promotes glucose uptake by cells.
Category: Endocrine System
Question 16
Skeletal muscle is striated and under voluntary control.
Correct Answer
True
True. Skeletal muscle fibers show a striped pattern from their regularly arranged filaments and are consciously controlled. Cardiac muscle is also striated but involuntary, and smooth muscle is neither striated nor voluntary.
Category: Bones and Muscles
Question 17
The adult human skeleton typically has 306 bones.
Correct Answer
False
False. The adult human skeleton typically has 206 bones, divided between the axial skeleton and the appendicular skeleton.
Category: Bones and Muscles
Question 18
The myelin sheath around many axons is produced by glial cells.
Correct Answer
True
True. Glial cells such as oligodendrocytes wrap axons in myelin, an insulating layer that keeps the electrical signal from fading and speeds its conduction.
Category: Nervous System
Question 19
The inside of a resting neuron is positively charged relative to the outside, at about +70 mV.
Correct Answer
False
False. The inside of a resting neuron is negative relative to the outside, at about -70 mV. This resting potential results from uneven ion distribution maintained by the sodium-potassium pump and ion channels.
Category: Nervous System
Question 20
Sensory neurons carry movement commands from the central nervous system to skeletal muscles.
Correct Answer
False
False. Motor neurons carry commands from the central nervous system to skeletal muscles. Sensory neurons carry information in the opposite direction, from the skin, muscles and sense organs to the central nervous system.
Category: Nervous System