Free Coordination and Control MCQs with Answers

21. Which of the following is NOT an effect of adrenaline?

• A. Increased heart rate
• B. Conversion of glycogen to glucose in the liver
• C. Dilation of the bronchioles
• D. Increased peristalsis and secretion in the gut

Explanation: Adrenaline prepares the body for fight or flight, so it diverts blood and resources to the heart, muscles and lungs and slows digestion rather than speeding it up. Raising heart rate, releasing glucose for respiration and widening the airways all fit that pattern, which is the quickest way to answer this kind of question. It is secreted by the adrenal medulla and acts within seconds.

22. Receptors that respond to changes in temperature are called

• A. photoreceptors
• B. thermoreceptors
• C. chemoreceptors
• D. mechanoreceptors

Explanation: Thermoreceptors in the skin and hypothalamus detect heat and cold and feed the thermoregulatory centre. Photoreceptors respond to light, chemoreceptors to chemicals and mechanoreceptors to pressure and touch, so each stimulus has its own receptor family.

23. The structure of the human eye that adjusts the amount of light entering it is the

• A. retina
• B. iris
• C. lens
• D. cornea

Explanation: Muscles of the iris widen or narrow the pupil, letting more light in during darkness and less in bright sun. The lens focuses light and the cornea refracts it, but neither controls the quantity of light entering the eye.

24. Colour vision in bright light is provided by the retinal receptors called

• A. rods
• B. bipolar cells
• C. cones
• D. ganglion cells

Explanation: Cones, concentrated in the fovea, work in bright light and distinguish colours in three types. Rods are far more light sensitive and serve dim vision but give no colour, which is why colours fade at dusk.

25. The sense of balance and the detection of head rotation depend on receptors located in the

• A. cochlea of the inner ear
• B. eardrum
• C. auditory canal
• D. semicircular canals of the inner ear

Explanation: The three semicircular canals, set at right angles, contain fluid that moves when the head turns, stimulating hair cells that report position and rotation. The cochlea, by contrast, converts sound vibrations into nerve impulses.

26. The receptors responsible for the senses of taste and smell are

• A. mechanoreceptors
• B. chemoreceptors
• C. photoreceptors
• D. thermoreceptors

Explanation: Taste buds and the olfactory epithelium respond to dissolved or volatile chemicals, which is the defining feature of chemoreceptors. Both senses feed closely into each other, which is why food seems tasteless when the nose is blocked.

27. The blind spot of the eye is the region where

• A. the optic nerve leaves the retina and no photoreceptors are present
• B. the lens focuses light most sharply
• C. the iris meets the cornea
• D. rods are most densely packed

Explanation: At the optic disc the axons of ganglion cells gather to form the optic nerve, leaving no space for rods or cones, so light falling there is not seen. The point of sharpest vision is the opposite, the fovea.

28. Neurons that carry impulses from receptors towards the central nervous system are called

• A. motor neurons
• B. interneurons
• C. sensory neurons
• D. glial cells

Explanation: Sensory, or afferent, neurons bring information in from receptors, while motor neurons carry commands out to effectors. Interneurons connect the two within the CNS, so direction of travel is the key to naming each type.

29. The myelin sheath around peripheral nerve fibres is produced by

• A. astrocytes
• B. microglia
• C. ependymal cells
• D. Schwann cells

Explanation: Schwann cells wrap themselves repeatedly around the axon, their membranes forming the insulating myelin. In the central nervous system the same job is done by oligodendrocytes, a distinction examiners like to test.

30. The gaps between successive Schwann cells along a myelinated axon are called

• A. nodes of Ranvier
• B. synaptic clefts
• C. dendritic spines
• D. neurofibril nodes

Explanation: At the nodes the axon membrane is exposed and rich in ion channels, so the action potential jumps from node to node in saltatory conduction. This jumping is what makes myelinated fibres conduct many times faster than unmyelinated ones.