In a homeostatic feedback loop, which component carries out the response that moves a variable back toward its set point?
Effector
✓
Receptor
Control center
Stimulus
Correct Answer
Effector
The effector, such as a muscle or gland, produces the change that restores the variable toward its set point. A receptor detects the change. The control center, often the brain, processes the information and sends signals to the effector. The stimulus is the change in the internal or external environment that starts the loop.
Category: Homeostasis and Kidneys
Question 2
At which kidney structure is blood first filtered, so that water, wastes and small solutes pass into the nephron tubule?
Renal pelvis
Glomerulus
✓
Ureter
Urethra
Correct Answer
Glomerulus
The glomerulus is a ball of capillaries where blood pressure pushes water, wastes, ions, glucose and other small molecules into the start of the nephron. The renal pelvis is the funnel-shaped region that collects urine before it leaves the kidney. A ureter carries urine from a kidney to the bladder. The urethra carries urine from the bladder out of the body.
Category: Homeostasis and Kidneys
Question 3
Which brain region maintains the body's temperature set point and triggers responses such as shivering and sweating?
Cerebellum
Thalamus
Hypothalamus
✓
Occipital lobe
Correct Answer
Hypothalamus
The hypothalamus acts as the body's thermostat, comparing body temperature to its set point and triggering heat-gaining or heat-losing responses. The cerebellum coordinates movement and balance. The thalamus relays sensory and motor information to the cerebral cortex. The occipital lobe processes vision.
Category: Homeostasis and Kidneys
Question 4
Salivary amylase in the mouth begins the chemical digestion of which nutrient?
Protein
Fat
Cellulose
Starch
✓
Correct Answer
Starch
Salivary amylase breaks starch into the disaccharide maltose, so carbohydrate digestion begins in the mouth. Protein digestion begins in the stomach with pepsin. Fat digestion begins with lipase and is completed in the small intestine with the help of bile. Cellulose cannot be digested by human enzymes.
Category: Digestion and Nutrition
Question 5
Which enzyme, released in an inactive form and activated in the acidic stomach, begins the digestion of proteins?
Pepsin
✓
Amylase
Lipase
Lactase
Correct Answer
Pepsin
Pepsin is a protein-digesting enzyme that becomes active in the low pH of the stomach. Amylase digests starch. Lipase digests fats. Lactase breaks down the milk sugar lactose and acts in the small intestine.
Category: Digestion and Nutrition
Question 6
Which organ produces bile, which helps break down fats in the duodenum?
Gallbladder
Liver
✓
Pancreas
Stomach
Correct Answer
Liver
The liver makes bile, whose salts emulsify fats so enzymes can digest them in the small intestine. The gallbladder stores and concentrates bile but does not produce it. The pancreas secretes bicarbonate and digestive enzymes. The stomach secretes acid and pepsin.
Category: Digestion and Nutrition
Question 7
What is the main role of the villi and microvilli that line the small intestine?
Secreting bile into the gut
Churning food into a liquid
Increasing surface area for absorption
✓
Storing feces before elimination
Correct Answer
Increasing surface area for absorption
Villi are finger-like projections of the intestinal lining and microvilli are tiny projections on their cells; together they greatly enlarge the surface through which nutrients pass into the blood. Secreting bile into the gut is done by the liver and gallbladder through a duct. Churning food into a liquid happens in the stomach. Storing feces before elimination is the job of the rectum.
Category: Digestion and Nutrition
Question 8
In the human respiratory system, where does the exchange of oxygen and carbon dioxide with the blood take place?
Bronchi
Trachea
Larynx
Alveoli
✓
Correct Answer
Alveoli
Alveoli are tiny thin-walled air sacs surrounded by capillaries, and their huge combined surface area allows oxygen and carbon dioxide to diffuse between air and blood. The bronchi are airways that carry air into each lung. The trachea is the cartilage-ringed windpipe leading to the bronchi. The larynx is the voice box above the trachea.
Category: Circulation and Respiration
Question 9
Which chamber of the human heart pumps oxygenated blood into the aorta for delivery to the body?
Left ventricle
✓
Right ventricle
Left atrium
Right atrium
Correct Answer
Left ventricle
The left ventricle has the thickest wall of the heart and pumps oxygen-rich blood into the aorta and out to the body. The right ventricle pumps blood to the lungs. The left atrium receives oxygenated blood from the lungs and passes it to the left ventricle. The right atrium receives oxygen-poor blood returning from the body.
Category: Circulation and Respiration
Question 10
Which heart valve keeps blood from flowing back from the right ventricle into the right atrium?
Bicuspid valve
Tricuspid valve
✓
Aortic semilunar valve
Pulmonary semilunar valve
Correct Answer
Tricuspid valve
The tricuspid valve sits between the right atrium and right ventricle and closes when the ventricle contracts. The bicuspid valve sits between the left atrium and left ventricle. The aortic semilunar valve guards the exit from the left ventricle into the aorta. The pulmonary semilunar valve guards the exit from the right ventricle into the pulmonary artery.
Category: Circulation and Respiration
Question 11
What is the phase of the cardiac cycle called in which the heart muscle relaxes and the chambers fill with blood?
Systole
Fibrillation
Diastole
✓
Repolarization
Correct Answer
Diastole
Diastole is the relaxation phase of the cardiac cycle, when the chambers fill with blood. Systole is the contraction phase that pushes blood out of the heart. Fibrillation is an abnormal, uncoordinated quivering of heart muscle. Repolarization is the electrical recovery of a cell membrane after it fires, not a filling phase of the cycle.
Category: Circulation and Respiration
Question 12
Which hormone do pancreatic beta cells release when blood glucose rises after a meal?
Glucagon
Cortisol
Epinephrine
Insulin
✓
Correct Answer
Insulin
Insulin promotes the uptake of glucose by body cells, lowering blood glucose back toward its set point. Glucagon comes from pancreatic alpha cells and raises blood glucose. Cortisol is a glucocorticoid from the adrenal cortex that helps maintain blood glucose during stress. Epinephrine comes from the adrenal medulla and raises blood glucose during the fight-or-flight response.
Category: Endocrine System
Question 13
Which hormone, released from the posterior pituitary, increases water reabsorption by the kidneys?
Antidiuretic hormone
✓
Oxytocin
Prolactin
Growth hormone
Correct Answer
Antidiuretic hormone
Antidiuretic hormone (ADH) makes the kidneys return more water to the blood, producing less and more concentrated urine. Oxytocin is also released by the posterior pituitary but stimulates uterine contractions during childbirth. Prolactin comes from the anterior pituitary and stimulates milk production. Growth hormone comes from the anterior pituitary and promotes growth and protein synthesis.
Category: Endocrine System
Question 14
Which hormone, secreted by the thyroid gland when blood calcium rises, lowers blood calcium levels?
Parathyroid hormone
Calcitonin
✓
Aldosterone
Glucagon
Correct Answer
Calcitonin
Calcitonin is released by the thyroid gland when blood calcium is high and acts to bring it back down. Parathyroid hormone has the opposite effect, raising blood calcium when it falls. Aldosterone from the adrenal cortex raises blood sodium. Glucagon from the pancreas raises blood glucose.
Category: Endocrine System
Question 15
In the sliding filament model, which protein makes up the thick filaments whose heads bind and pull on the thin filaments?
Actin
Tubulin
Myosin
✓
Collagen
Correct Answer
Myosin
Myosin forms the thick filaments of a sarcomere, and its heads use energy from ATP to bind, bend and pull the thin filaments past them. Actin is the main protein of the thin filaments. Tubulin builds microtubules of the cytoskeleton. Collagen is a structural protein of connective tissues such as tendons and bone.
Category: Bones and Muscles
Question 16
Which type of joint has a fluid-filled cavity and allows the greatest range of movement, as in the knee and shoulder?
Fibrous joint
Cartilaginous joint
Suture joint
Synovial joint
✓
Correct Answer
Synovial joint
A synovial joint has a fluid-filled cavity, cartilage-covered bone ends and a surrounding capsule, which together allow free movement. A fibrous joint holds bones together with dense connective tissue and allows little or no movement. A cartilaginous joint, such as those between vertebrae, joins bones with cartilage and allows only slight movement. A suture joint is a type of fibrous joint found between skull bones and is essentially immovable in adults.
Category: Bones and Muscles
Question 17
Which part of a neuron carries the electrical signal away from the cell body to the terminals that release neurotransmitter?
Axon
✓
Dendrite
Myelin sheath
Synaptic cleft
Correct Answer
Axon
The axon conducts the action potential away from the cell body to its terminals, where neurotransmitter is released. A dendrite receives incoming signals and carries them toward the cell body. The myelin sheath insulates the axon but does not itself carry the signal. The synaptic cleft is the gap between one neuron and the next cell.
Category: Nervous System
Question 18
Which ions rush into a neuron through voltage-gated channels to depolarize the membrane during an action potential?
Potassium ions
Sodium ions
✓
Chloride ions
Calcium ions
Correct Answer
Sodium ions
When voltage-gated sodium channels open, sodium ions flood into the axon and the membrane potential swings from negative to about +30 mV. Potassium ions leave the cell afterward, which repolarizes the membrane. Chloride ions do not drive depolarization in this process. Calcium ions enter at the axon terminal to trigger neurotransmitter release, not to depolarize the axon.
Category: Nervous System
Question 19
Which part of the brain controls balance, coordinates movement and supports motor learning?
Thalamus
Amygdala
Cerebellum
✓
Corpus callosum
Correct Answer
Cerebellum
The cerebellum, at the back of the brain below the cerebrum, fine-tunes movement and keeps the body balanced. The thalamus relays sensory and motor input to the cortex. The amygdala is part of the limbic system involved in fear. The corpus callosum is a band of nerve fibers that connects the two cerebral hemispheres.
Category: Nervous System
Question 20
Which division of the peripheral nervous system produces the fight-or-flight response, raising heart rate and dilating the pupils?
Parasympathetic division
Sensory-somatic system
Central nervous system
Sympathetic division
✓
Correct Answer
Sympathetic division
The sympathetic division of the autonomic nervous system prepares the body for danger by speeding the heart, dilating the pupils and bronchi and inhibiting digestion. The parasympathetic division does the reverse, supporting rest and digestion. The sensory-somatic system carries sensory information and controls voluntary skeletal muscle. The central nervous system is the brain and spinal cord, not a division of the peripheral system.
Category: Nervous System