Test: The Eye & Ear - 2 - A Level MCQ

Cochlea of the mammalian ear is concerned with Hearing.
Cochlea is a part of the inner ear. It is shaped like a snail shell. It is also called as organ of hearing. It receives sound in the form of vibrations and converts it into the perception of hearing. Vestibule is a part of inner ear which  plays major role in balancing the body. Auditory tube helps to keep air pressure in the middle ear at equilibrium with atmospheric pressure by interpreting the atmospheric pressure.

The pupil is a hole or aperture in the middle of the iris. Iris is the colored part of the eye that controls the amount of light entering the eye by adjusting the size of the pupil. The point of exit of optic nerve from eye forms a “blind spot” in the retina. The sclera is the white and opaque outer layer of the eyeball.

Myopia is a defect in the human eye in which the image is formed in front of the retina and can be corrected by using a concave lens.
Myopia (nearsightedness) is a refractive error, which means the eye does not bend or refract light properly. With myopia, close objects look clear but distant ones are blurred. The images are focused in front of the retina rather than on it. This occurs when the eyeball becomes too long and prevents incoming light from focusing directly on the retina. It may also be caused by an abnormal shape of the cornea or lens. It is corrected with a spherical concave lens.

Photopsins are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the visual purple rhodopsin that is used in night vision.

The malleus is one of three ossicles in the middle ear, which transmit sound from the tympanic membrane (ear drum) to the inner ear. The malleus receives vibrations from the tympanic membrane and transmits this to the incus.

Colour blindness and haemophilia are both X-linked recessive disorders. 

Red-green colour blindness, a very common trait in humans affects between 7% and 10% of men and 0.49% to 1% of women. 

Hemophilia A, a blood clotting disorder is caused by a mutation of the factor VIII gene and hemophilia B, also known as 'Christmas disease', is a blood clotting disorder, caused by a mutation of the factor IX gene. 

The photoreceptor cells convert the light into electrical impulses which are transmitted to the brain through the nerve cells.
The retina converts the light energy into electrical impulse.
The electrical impulse is then carried to the brain by the optic nerve.
So, the correct answer is 'Biological process'

Connecting the ear to the pharynx. The structure of this tube is very different in mammals compared to most reptiles, with mammals having a narrow tube, known as the Eustachian tube, while reptiles have a wide-open connection between the pharynx and ear.

The membranous labyrinth contains fluid called endolymph. The membranous labyrinth is also the location for the receptor cells found in the inner ear.

Six extraocular muscles facilitate eye movement. These muscles arises from the common Tendinous ring in the orbit. The eye cavity and attached to the eye ball. The six muscles are lateral, medial, inferior and superior rectus muscles and the inferior and superior are oblique muscles. The muscles when contracting, causes movement of eye ball. By pulling the eye ball towards the muscles.

A monocular vision is a type of vision found mainly in animals with eyes placed on the opposite side of their head such as fish , rabbits and birds of their prey. In the areas to the sides of rabbits can only see through one eye at once. This is known as Monocular vision. 

The meibomian glands (or tarsal glands) are a special kind of sebaceous gland at the rim of the eyelids inside the tarsal plate, responsible for the supply of meibum, an oily substance, that prevents evaporation of the eye's tear film. Meibum prevents tear spillage onto the cheek, trapping tears between the oiled edge and the eyeball, and makes the closed lids airtight. There are approximately 50 glands on the upper eyelids and 25 glands on the lower eyelids. Dysfunctional meibomian glands often cause dry eyes.

The harderian gland is a gland found within the eye's orbit, which occurs in tetrapods (reptiles, amphibians, birds and mammals) that possess a nictitating membrane. The gland can be compound tubular or compound tubuloalveolar, and the fluid it secretes (mucous, serous or lipid) varies between different groups of animals. In some animals it acts as an accessory to the lacrimal gland, secreting fluid that eases movement of the nictitating membrane.

Sacculus (saccule) is a chamber of the inner ear from which the cochlea arises in reptiles, birds, and mammals. It bears patches of sensory epithelium concerned with balance.

Three semicircular canals are present in labyrinth of rabbit's ear that serve to detect the angular motion. These canals lie at right angle to each other in vestibular apparatus of inner ear and are filled with endolymph, this arrangement senses the change in movement (acceleration or deceleration) or position. So, the correct answer is option B.

An otolith, also called statoconium or otoconium, is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. They are sensitive to gravity and linear acceleration. In mammals, otoliths are small particles, composed of a combination of a gelatinous matrix and calcium carbonate in the endolymph of the saccule and utricle. The inertia of these small particles causes them to stimulate hair cells, when the head moves.

The stapes is a stirrup-shaped bone in the middle ear for the conduction of sound vibration to the middle ear. It rests on the oval window, to which it is connected by an angular ligament.
So, the correct answer is 'Stapes'.

Presbyopia is caused by an age related process. It occurs due to a gradual thickening and loss of flexibility of the natural lens inside the eye. These age related changes occur within the proteins in the lens, making the lens harder and less elastic over time. Age related changes also take place in the muscle fibers surrounding the lens. Changes in the lens curvature progressively cause diminished ability to focus on near objects. 

So, the correct answer is option C.