CBSE Questions for Class 11 Medical Biology Neural Control And Coordination Quiz 13 - MCQExams.com

• The dendrites accept signals generated by other neurons. These signals may be excitatory or inhibitory. All signals present at the dendrites of a neuron are combined and the result will determine whether or not that neuron will fire. If a neuron fires, an electrical impulse is generated. 
• An axon, or nerve fibre, is a long slender projection of a nerve cell or neuron, that conducts electrical impulses away from the neuron's cell body or soma. 
• Axon terminals have knob-like swellings at the very end called synaptic knobs. The function of a synaptic knob is to change the action potential that is carried by axons into a chemical message. 

• Hair cells (sense cells) are the sound receptors of the auditory system. 
• In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear. 
• Cochlea produces nerve impulses in response to the sound vibration.
• The vestibular labyrinth of mammals comprises the utricle (utriculus), the saccule (sacculus), and the semicircular canals (ductus semicirculares), which are filled with a fluid, the endolymph.
  
• Semicircular canals are three tiny, fluid-filled tubes in the inner ear that help you keep your balance along with sacculus & utriculus.
  

• The eustachian tube is a canal, which connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity. 
• It regulates the pressure within the middle ear, equalizing it with the air pressure outside the body.
• So, the correct answer is option D.

A medullated nerve fiber is also called as myelinated nerve fiber. The nerve fibers, which are covered by the myelin sheath are called as medullated nerve fibers. Myelin sheath is derived from Schwann cells. Myelin sheath is made up of alternate concentric layers of lipids and proteins. Myelinated nerve fiber also shows the presence of neurolemma. It covers the nerve fiber.

So, the correct answer is 'Both A and B'

• The pupillary light reflex is a reflex that controls the diameter of the pupil, in response to the intensity of light that falls on the retina of the pupil and the eye. 
• Parasympathetic nerve fibres from the third (oculomotor) cranial nerve innervate the muscle that causes constriction of the pupil, whereas sympathetic nerve fibres control dilation. 
• The increase in respiration rate and heartbeat is done by the stimulation from the Sympathetic nervous system. Also, the sympathetic nervous system inhibits sweat secretion.

• The space between the cornea and the lens is called the aqueous chamber and contains a thin watery fluid called aqueous humour.
•  It Maintains the intraocular pressure and inflates the globe of the eye. It is this hydrostatic pressure which keeps the eyeball in a roughly spherical shape and keeps the walls of the eyeball stretched. 
• Hence, the option which gives correct identification along with its functions/characteristics is C- Aqueous chamber - increase pressure inside the eye. 
• So, the correct answer is 'C- Aqueous chamber - increase pressure inside the eye'.

• The malleus is a hammer-shaped small bone or ossicle of the middle ear, which connects with the incus and is attached to the inner surface of the eardrum. 
• It transmits the sound vibrations from the eardrum to the incus.