MDCAT Biology chapter 5: Biology · Coordination and control MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
57 exam-style questions on Biology · Coordination and control, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten Biology · Coordination and control questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. A frog kept on a dark background slowly turns darker as pigment spreads out through the pigment cells of its skin. Which pituitary hormone brings about this change?
A
calcitonin
B
melatonin
C
prolactin
D
melanocyte-stimulating hormone (MSH)
Show answer
Answer: D. MSH from the intermediate lobe of the pituitary makes melanin granules spread through the pigment cells, so the skin darkens. Melatonin, from the pineal gland, has the opposite effect in amphibians and lightens the skin, while prolactin is a pituitary hormone that acts on milk production.
2. The resting membrane potential of a typical neuron is about
A
−70 mV
B
+70 mV
C
−7 mV
D
0 mV
Show answer
Answer: A. At rest the inside of the axon is about 70 mV negative with respect to the outside, written −70 mV. The inside becomes positive only briefly, at the peak of an action potential.
3. Which sequence shows the correct path of impulses in a spinal reflex arc?
Answer: D. A stimulus at the receptor starts impulses in a sensory neuron, which passes them through an interneuron in the spinal cord to a motor neuron and so to the effector, a muscle or gland.
4. A child has had too little thyroxine since birth. He is short, his mental development is slow and his face is puffy. The condition is
A
cretinism
B
myxoedema
C
pituitary dwarfism
D
acromegaly
Show answer
Answer: A. Lack of thyroxine from birth causes cretinism, with stunted growth and poor mental development. Myxoedema is thyroxine deficiency in adults, and pituitary dwarfism (lack of growth hormone) gives short stature with normal intelligence.
5. Several hours after a meal the blood glucose level starts to fall. Which hormone is then secreted to raise it, and how does it act?
A
glucagon, which makes the liver break down glycogen
B
insulin, which makes the liver break down glycogen
C
glucagon, which makes muscles store more glycogen
D
insulin, which makes the liver convert glucose to glycogen
Show answer
Answer: A. Glucagon from the α cells acts mainly on the liver, which breaks down glycogen and releases glucose into the blood. Insulin has the opposite effect, lowering blood glucose by promoting glucose uptake and glycogen formation.
6. Compared with nervous coordination, coordination by hormones is generally
A
slower, longer-lasting and carried in the blood to many targets
B
faster, shorter-lasting and carried along neurons to precise targets
C
faster, longer-lasting and carried in the blood to many targets
D
slower, shorter-lasting and carried along neurons to precise targets
Show answer
Answer: A. Hormones travel in the blood, so they act more slowly than impulses but can reach cells all over the body, and their effects usually last longer. Nervous messages travel along neurons to particular effectors and act within milliseconds, briefly.
7. The depolarisation (rising phase) of an action potential is caused mainly by
A
rapid diffusion of K+ ions out of the axon
B
rapid diffusion of Na+ ions into the axon
C
active pumping of Na+ ions out of the axon
D
slow diffusion of Cl− ions into the axon
Show answer
Answer: B. A stimulus opens voltage-gated sodium channels and Na+ floods in down its concentration gradient, making the inside positive. Outward diffusion of K+ causes the later fall (repolarisation).
8. At rest, the inside of a neuron is negative compared with the outside mainly because its plasma membrane is
A
equally permeable to Na+ and K+, so both ions leak out at the same rate
B
far more permeable to Na+ than to K+, so Na+ floods in and makes the inside positive
C
permeable only to Cl−, which the pump carries in to make the inside negative
D
far more permeable to K+ than to Na+, so K+ leaks out faster than Na+ leaks in
Show answer
Answer: D. Open potassium leak channels greatly outnumber sodium channels, so K+ diffuses out faster than Na+ diffuses in; more positive charge leaves than enters and the inside settles at about −70 mV. The sodium-potassium pump keeps the two gradients going and adds a little to the negativity.
9. Which sense receptor is correctly matched with its class?
A
hair cells of the inner ear: chemoreceptors
B
taste buds of the tongue: chemoreceptors
C
rods and cones of the retina: mechanoreceptors
D
pain receptors of the skin: thermoreceptors
Show answer
Answer: B. Taste buds respond to chemicals dissolved in saliva, so they are chemoreceptors. Hair cells for hearing are mechanoreceptors bent by vibrations, rods and cones are photoreceptors, and pain receptors are nociceptors.
10. Pacinian corpuscles, found deep in the dermis of the skin, are receptors that respond to
A
light touch
B
deep pressure
C
changes in temperature
D
chemical stimuli
Show answer
Answer: B. Pacinian corpuscles are large, layered mechanoreceptors in the deep dermis that respond to pressure. Light touch is sensed by Meissner's corpuscles, which lie just below the epidermis.
Biology · Coordination and control: questions students ask
How many Biology · Coordination and control MCQs are there?
57, each with the answer and a short explanation, across 3 topics: Neurons and the nerve impulse, The nervous system, Chemical coordination. Every chapter test draws ten of them, so you can take it many times.
Is the MDCAT Biology chapter 5 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
