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CBSE Questions for Class 11 Medical Biology Neural Control And Coordination Quiz 3 - MCQExams.com
CBSE
Class 11 Medical Biology
Neural Control And Coordination
Quiz 3
The size of pupil is controlled by the
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Ciliary muscles
0%
Suspensory ligaments
0%
Cornea
0%
Iris muscles
Explanation
The pupil is the opening in the centre of the iris
.
The size of the pupil determines the amount of light, that enters the eye.
The pupil size is controlled by the dilator and sphincter muscles of the iris.
Match the following and choose the correct option.
Column I
Column II
A
Fovea
1
Provides opening for entry of light
B
Iris
2
Maximum visual acuity
C
Pupil
3
Transmits information to CNS
D
Lens
4
Controls amount of light entering
E
Optic nerve
5
Focuses light on the retina
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(A)- 4, (B)- 1, (C)- 5, (D)- 2, (E)- 3
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(A)- (5), (B)- (1), (C)- (4), (D)- (3), (E)- (2)
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(A)- (3), (B)- (1), (C)- (4), (D)- (5), (E)- (2)
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(A)- (1), (B)- (2), (C)- (3), (D)- (4), (E)- (5)
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(A)- (2), (B)- (4), (C)- (1), (D)- (5), (E)- (3)
Explanation
The fovea centralis is the central portion of the human retina, that has the most acute vision and the best color perception.
The cones have 3 types of specific photopigments - red, green and blue, or
RGB
. Most of the color sensitive cones are packed in the
fovea centralis.
The colored part of the eye is called as the iris. It controls light levels inside the eye similar to the aperture on a camera. The round opening in the center of the iris is called as the pupil. The iris is embedded with tiny muscles, that dilate (widen) and constrict (narrow) the pupil size.
The lens, by changing shape, functions to change the focal distance of the eye, so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina, which is then transmitted to the brain by the optical nerve.
Sensory neurons of retina of eye are
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Rods and cones
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Maculae and cristae
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Pacinian and Ruffini's corpuscles
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All of the above
Explanation
Rods and cones are the photoreceptors present in retina of the eye. They have their own bipolar neurons and photo-sensitive pigments.
Iris of an eye is an extension of
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0%
Cornea
0%
Sclerotic
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Retina
0%
Both choroid and retina
Explanation
The choroid is continuous with the iris; together the choroid and iris are called the uvea.
The posterior surface of the iris is covered by the retina. The inner layer of the retina, i.e., the layer facing the posterior chamber, is called the posterior epithelium of the iris.
Both layers of the retina are pigmented, but the pigmentation is heavier in the inner layer. In the region of the central opening of the iris, the pupil, the retina extends for a very short distance onto the anterior surface of the iris.
So, the correct answer is option D.
Fovea in the eye is a central pit in the yellowish pigmented spot called
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Blind spot
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Retina
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Cornea
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Macula lutea
Explanation
The choroid is a dark brown membrane that is rich with blood vessels, located between the sclera and the retina. It supplies blood and nutrients to the retina and nourishes all of the other structures within the eye. The retina is comprised of photoreceptors.
The macula lutea is the small, yellowish central portion of the retina. It is about 5.5 mm in diameter and is the area providing the clearest, most distinct vision.
The fovea is located in the center of the macula and provides the sharpest detail vision. The beginning of the optic nerve in the retina is called the optic nerve head or optic disc, which lacks photoreceptors and
cannot respond to light stimulation. As a result, it is known as the blind spot.
So, the correct answer is option D.
Cornea transplant in humans is almost never rejected. Because
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It is composed of enucleated cells.
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It is a non-living layer.
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Its cells are least penetrable by bacteria.
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It has no blood supply.
Explanation
Correct option: D
Explanation:
Cornea transplant in humans is almost never rejected because it has no blood supply.
Rejection of transplanted organs is caused by the immune system which links the transplant as a foreign body and triggers response against the organ or tissue leading to rejection in most organs.
Since cornea absorbs oxygen directly from air and is not involved in immune system due to lack of blood supply, Cornea transplants in humans is never rejected. Option D is correct.
The movement of eye ball is brought about by the
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Adductor muscle
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Rectus muscle
0%
Biceps
0%
Peroneus
Explanation
Adductor group muscles are located in different parts of the body. They are located on the medial thigh and are involved in thigh movement. Biceps is the muscle of arm while peroneus muscles are found on lateral side and leg and serve in the movement of ankle and foot. There are two pairs of rectus muscles: superior and inferior rectus muscles involved in the upward and downward rolling of eyes respectively and lateral and medial rectus muscles that turn the eye outward and inward respectively.
Thus, the correct answer is option B.
If the circular ciliary muscles of the eye are unable to contract, the
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Lens will become more convex
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Lens will be thin and stretched
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Vision will be lost completely
0%
Bright light will have no adverse effect on retina
Explanation
Ciliary body and the attached suspensory ligament change the shape (flattened or round) of the lens through relaxation and contraction of ciliary muscles and thereby the focal length to focus on the distant and near object. Contraction of ciliary muscles releases the suspensory ligaments and allow the lens to become round (convex) while relaxation of these muscles makes the lens taut. Since ciliary muscles are involved in accommodation required for close vision, loss of their contraction would not cause loss of vision but would affect the close vision only. The amount of light entering retina is controlled by the iris.
So, the correct answer is option B.
The number of occipital condyles in man is / are
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One
0%
Two
0%
Three
0%
Four
Explanation
The protrusion on the occipital bone of the skull, that forms a joint with the first cervical vertebra, enabling the head to move relative to the neck is an occipital condyle. Humans have
two occipital condyles, that are large rounded kidney-shaped projections of occipital bone, that are located contralateral to the foramen magnum and that articulate with the superior facets of the atlas
cervical vertebra.
The central opening of iris is called as
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0%
Pupil
0%
Cornea
0%
Lens
0%
Fovea centralis
Explanation
The pupil is a hole or opening in the middle of iris that controls the amount of light entering the eye. The cornea is the transparent anterior window of an outer layer of the eyeball located within otherwise opaque sclera. Fovea centralis is the part of the retina that has densely packed cones. The lens is attached to the ciliary body by ligaments and divides the eye into anterior and posterior compartments. Thus, the correct answer is option A.
Function of ciliary muscles is
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To contract pupil when one move in sunlight
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To keep valve in position
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To rotate eye ball
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To change shape of lens
Explanation
Muscles of the ciliary body of the eye, located between the sclera and the fine ligaments suspends the lens. They are composed of both longitudinal and circular fibres, that change the shape of the lens, enabling the eye to focus upon near or distant objects.
In the retina of human eye, the cones are concentrated more at the
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0%
Blind spot
0%
Edges of retina
0%
Fovea
0%
Choroid
Explanation
The point of exit of optic nerve from eye forms a “blind spot” in the retina which is devoid of both rods and cones and hence no image is formed on it. Rods and cones are the secondary photoreceptors that are presently buried under the layer of blood vessels and nerve fibers throughout the retina. Rod cells are mostly concentrated near the edges of retina while densely packed cones are present in the fovea. The choroid is a dark pigmented thin vascular layer and is characterized by the presence of many blood vessels but no cones and rods.
So, the correct answer is option C.
Rhodopsin pigment is found in
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0%
Bile juice
0%
Retinal cells
0%
RBC
0%
Skin
Explanation
Rhodopsin is a photochemical
pigment found in
the rods of the retina of the vertebrate eye.
It
is extremely sensitive to light, and thus enables vision in low-light conditions.
Hence, the correct answer is option B.
Human eye lens is
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Spherical and can be moved forward.
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Biconvex and cannot be moved forward.
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Spherical and cannot be moved forward.
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Biconvex and can be moved forward.
Explanation
At rest, the lens in the normal eye focuses images of distant objects on the retina.
It acts in much the same way as a biconvex optical glass lens, however, it cannot be moved forward.
Thus, the refractive power of the lens is a function of the curvature of the lens surfaces, as well as the refractive index of the cell mass.
The closely packed, highly ordered array of lens cells is essential for optical quality, and even small defects in lens fibre cell anatomy can cause detectable spherical aberration.
So, the answer is - 'B
iconvex and cannot be moved forward'.
Eye balls will not be moved inwards on the damage of which of following muscles?
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Inferior rectus
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Inferior oblique
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Both A and B
0%
Medial rectus
Explanation
The medial rectus is an adductor, and functions along with the lateral rectus which abducts the eye. These two muscles allow the eyes to move from side to side.
So, option D is the correct option.
In the chemistry of vision in mammals, the photosensitive substance is called as
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0%
Sclera
0%
Retinol
0%
Rhodopsin
0%
Melanin
Explanation
Rhodopsin
, also known as visual purple, is a light-sensitive receptor protein. It is a biological pigment in photoreceptor cells of the retina.
Rhodopsin
is the primary pigment found in rod photoreceptors.
Rhodopsins belong to the G-protein-coupled receptor (GPCR) family.
This protein is necessary for normal
vision, particularly in low-light conditions. It
allows night vision
and is extremely sensitive to light. Exposed to a spectrum of light, the pigment immediately bleaches, and it takes about 30 minutes to regenerate fully, but most of the adaptation occurs within the first five or ten minutes in the dark.
The human eye is sensitive only to light having wave length ranging from
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80 to 280 nanometres
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380 to 760 nanometres
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780 to 870 nanometres
0%
880 to 980 nanometres
Explanation
The human eye is sensitive to violet (400 nm) to red (700 nm ) light only that can generate photometric effect i.e. visual sensation on an eye. So, the correct answer is option B.
A 22 years student goes to his ophthalmologist. He has problem in reading books, because he is not able to contract his
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0%
Suspensory ligament
0%
Pupil
0%
Iris
0%
Ciliary muscles
Explanation
The ciliary muscle is located in the eye and surrounds the lens. It is smooth
circular muscle, that relaxes or tightens the zonules to enable the lens to change shape for focusing.
When it contracts, it pulls forward, moving to a frontal portion to relax the fibers, that hold the lens in place; this process also allows it to take on a more spherical shape to provide short range focus.
Macu lalutea is located
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Below the lens
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Below the pupil
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Below the iris
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In the middle of the retina
Explanation
Macula lutea, in anatomy, the small yellowish area of the retina,
near the optic disk, that provides central vision. When the gaze is fixed on any object, the centre of the macula, the centre of the lens, and the object are in a straight line. In the centre of the macula is a depression, called as the fovea
, which contains specialised nerve cells, that are exclusively of the type known as cones. Cones are associated with colour vision and perception of fine detail. Toward the centre of the macula there are no blood vessels to interfere with vision; thus, in this area, vision in bright light and colour perception are keenest.
Choroid is
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Middle layer of ear
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Innermost layer of eye
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Innermost layer of ear
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Middle layer of eye
Explanation
The choroid is a layer of eyeball. The eyeball has three coats namely sclera, choroid, and retina. The choroid is middle dark pigmented thin vascular layer of the eyeball and is characterized by the presence of many blood vessels. Retina forms the innermost layer of the eye.
Which of the following have "ommatidia" as unit of eye?
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Pheretima
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Housefly
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Pila
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Sepia
Explanation
Compound eyes are the characteristic feature of insects. The compound eye of insects consists of many ommatidia, each of which is a separate visual unit that portrays each object into several broken pieces. This type of vision is called as mosaic vision. Among the given options, housefly is an insect and has ommatidia as a unit of an eye. Pheretima (annelid) and pila and sepia (molluscs) do not have compound eyes.
So, the correct answer is option B.
The black pigment in the eye, which reduces the internal reflection is located in
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0%
Retina
0%
Iris
0%
Choroid
0%
Cornea
Explanation
The choroid is the part of the vascular coat in the eyes.
It also contains blood vessels that provide nourishment to the eye.
It is pigmented towards the rear of the eye and absorbs light.
It is dark brown in colour. It darkens the cavity o
f the eyeballs to prevent internal reflection of light that might blur the image.
Thus, the correct answer is C.
The function of iris in the eyes of frog is to
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Refract the light rays
0%
Alter the size of the pupil
0%
Move the nictitating membrane
0%
Move the lens forward and backward
Explanation
Smooth muscle cells of the frog iris sphincter contain rhodopsin and contract in response to light.
It is the colored part of the eye, which regulates the size of the pupil controlling the entry of light into the eye.
The purplish red pigment, rhodopsin contained in the rods type of photoreceptor cells of the human eye, is a derivative of
Report Question
0%
Vitamin A
0%
Vitamin B
0%
Vitamin C
0%
Vitamin D
Explanation
Rhodopsin is the pigment of rod cells which absorbs green-blue part of the spectrum. Therefore, rod cells detect the dim light and respond to light intensity. Rhodopsin consists of the protein opsin and retinal.
Retinal
is a vitamin A derivative.
So, the correct answer is option
A.
Retina is most sensitive at
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Optic disc
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Periphery
0%
Macula lutea
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Fovea centralis
Explanation
Correct option: D
Explanation:
Retina is most sensitive at Fovea centralis.
It is a thin layer of tissue present at the back of the inner-eye, near the optic nerve. It contains two visual pigments called cones and rods.
Fovea centralis provides sharp vision and
contains only cones
which are responsible for
vision during the day and also aid in colour vision
. So, retina is most sensitive at this point.
Optic disc is the area inside the eye, where optic nerves and blood vessels are connected to the retina.
Peripheral vision provided by rods which controls night vision and low light vision and is insensitive to colour.
Macula lutea is a small yellowish area near the optic disc, which provides central and detailed vision.
Thus, Option D is correct.
Which function will be lost due to damage of occipital lobe?
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Hearing
0%
Speech
0%
Vision
0%
Memory
Explanation
The occipital lobe
is one of the four major lobes of the cerebral cortex in the brain of mammals. The
occipital lobe
is the visual processing center
So, the correct answer is '
Vision'
Photosensitive pigment is
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Similar in all eyes
0%
Similar in all vertebrate eyes
0%
Variable in all eyes
0%
Variable in all vertebrate eyes
Explanation
A common visual pigment is found in all kinds of photoreceptors. a mixture of a vitamin A-based chromophore known as Retinal and a seven-transmembrane-helix apoprotein called Opsin. Together, they form rhodopsin. The pigments belong to a special class of receptors called G protein-coupled receptors, characterized by signaling through heterotrimeric G proteins. Rhodopsin is thermally unstable, breaking down with light into the opsin and chromophore in vertebrates. Those are maintained by an enzymatic process. Invertebrate rhodopsins are stable, although renewal also must take place there. The amount of this pigment sometimes varies within species.
So the correct option is B.
Human eyes are most sensitive to the wavelength of
Report Question
0%
1000$$A^{\circ}$$
0%
5000$$A^{\circ}$$
0%
7000$$A^{\circ}$$
0%
20$$A^{\circ}$$
Explanation
The human eye can see lights present only in the visible range of wavelength. The visible range 400 nm (blue light) to 700 nm (red light). But the human eye is most sensitive to green color and the wavelength is 500-555 nm or 5000-5550 Angstrom. That's why we can green as the brightest color.
So the correct option is B.
Who got the Nobel prize for describing in detail the visual
cycle
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Wald
0%
Sherrington
0%
Young
0%
Henson
Explanation
George Wald got the Nobel prize for describing the visual cycle. He proposed that vitamin A is an important component in rhodopsin, a light-sensitive compound in the retina, and explained in a series of studies from the 1930s to the 1960s that how light causes rhodopsin to change form and be converted. This conversion gives rise to signals in a complicated network of nerve cells by which a number of reconnections and transformations occur before the signals eventually are transformed into visual impressions in the brain.
So, the correct option is A.
The malleus, incus, and stapes are the modified bones of
...................respectively
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Articular, hyomandibular and quadrate
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Quadrate, articular and hyomandibular
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Articular, quadrate and hyomandibular
0%
Quadrate, hyomandibular and articular
Explanation
C. Atricular, quadrate and hyomandibular
Reason: There are three small bones present between the tympanic membrane and oval window that are collectively referred to as ossicles. These are malleus, incus and stapes. In mammals, ossicles are originated from earlier jawbones. Malleus is modified articular while incus is modified quadrate. Modified hyomandibular forms stapes.
Adaptation of eyes in dark is due to
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Depletion of vision pigment in rod
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Depletion of vision pigment in cones
0%
Repletion of vision pigment in rods
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Repletion of vision pigment in cones
Explanation
C. Repletion of vision pigment in rods
Reason:Adaption by eyes means to the ability of the eye to adjust with the amount of light. There are three most important factor regarding the vision adaptation in dark. Those are the pupil, the cone cells, and the rod cells. The pupil allows the light into the eye, cone cells along the retina are responsible for color vision and the rod cells are responsible for black and white vision. Both Cones and rods contain rhodopsin, a common biological pigment that is a highly sensitive photoreceptor. The pigment get dissociated into retinal and opsin in presence of light. Rods are more sensitive to light and take longer to fully adapt to the change in light. Besides, the photopigment in the rods regenerate more slowly, thus do not reach their maximum sensitivity while cone cells take just 10 minutes. However, since there are far more rods in the retina than cone cells it is the repletion of visual pigment in rods that help in the adaptation of eyes to dark. So the correct option is C.
In a mammal, the eyes are lubricated by the secretion of
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0%
Harderian glands
0%
Nictitating membrane
0%
Meibomian glands
0%
Lacrimal glands
Explanation
Meibomian glands are tiny oil glands that are situated in the margin of the eyelids. These glands secrete oil that coats the surface of our eyes and keeps the water component of our tears from evaporating (drying out). Together, the water and the oil layer make up the tear film. This tear film lubricates and keeps the surface of our eyes healthy. It also affects how clearly we see.
So the correct option is C.
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Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
0%
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
0%
Assertion is correct but Reason is incorrect
0%
Both Assertion and Reason are incorrect
Explanation
The wall of each eyeball is made up of three concentric layer-sclerotic, choroid and retina. The choroid is a highly vascular pigmented layer separating the sclerotic from the inner layer of the eyeball. It is connected in front to a thick structure called ciliary body. Iris is a pigmented, muscular, opaque diaphragm which extends from the ciliary body in front of a biconvex transparent lens. Iris has a small central aperture called pupil. Light passing through the cornea enters through the pupil to fall on the lens behind it. The iris has two sets of smooth muscles arranged circularly and radially around the pupil. The pupil gets constricted by the contraction of circular muscles to reduce the amount of light falling on the lens. On the contrary, the pupil gets dilated by the contraction of radial muscles to increase the amount of light falling on the lens.
So, the correct answer is 'Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion'.
If the light source infront of an eye becomes bright suddenly
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0%
Focus of lens will change
0%
Retinal blood supply will cut
0%
Vitreous humour becomes fluid
0%
Pupil will contract
Explanation
In response to sudden bright light, pupil constricts by
the constriction of sphincter papillae muscles through
parasympathetic nervous system, in order to protect
retina from possible injury against bright light.
In which direction cristae of rabbit ear helps in maintaining
balance
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Circular position of longitudinal axis of semi circular
canals
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Transverse position of longitudinal axis of semi circular
canals
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Parallel to longitudinal axis of semi circular canals
0%
All of the above
Explanation
The cristae of rabbit ear help sin maintaining balance in
transverse position of longitudinal axis of semicircular
canals.
Ear drum is known as
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0%
Tympanic membrane
0%
Tensor tympani
0%
Scala tympani
0%
Scala vestibuli
Explanation
The tympanic membrane also called the eardrum is a membrane in the human ear, that receives sound vibrations from the outer air and transmits them to the auditory ossicles in the tympanic (middle ear) cavity.
How many eye muscles are present which control all types
of eye movement
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3
0%
4
0%
5
0%
6
Explanation
Eye can be moved by 6 extrinsic ocular muscles attached
to its posterior wall. Two are external and internal
oblique muscle while the other four are rectus muscles.
The human hindbrain comprises of three parts one of which is
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0%
Spinal cord
0%
Corpus callosum
0%
Cerebellum
0%
Hypothalamus
Explanation
The hindbrain is the part of the brain which consists of three parts pons, the cerebellum and the medulla oblongata.
They form the brainstem and medulla extends to the spinal cord.
Cerebellum mainly maintains body balance and coordination.
So, the correct answer is option C.
Nissl granules are absent in
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Axon
0%
Cyton
0%
Dendron
0%
Both A and B
Explanation
Correct option: A
Explanation:
Nissl granules are absent in Axon.
The neuron is made up of a cell body (cyton), dendrites (dendron), axons and axon terminals. Nissl granules are discrete structures, which consist rough endoplasmic reticulum and free ribosomes. It is the main site for synthesize of proteins in neurons.
These are found in somata and dentrites region of the neuron, and not in the axon or axon hillock regions.
Thus, Option A is correct.
The vibrations of the tympanic membrane are amplified approximately ............... times in the oval window.
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0%
5
0%
20
0%
40
0%
55
Explanation
The ear ossicles cause the oval window to vibrate; this is a small membrane-covered opening directly below the stapes. Since the ear ossicles amplify the vibrations of the tympanic membrane and since the oval window is much smaller than this membrane, the waves are amplified 15 to 20 times their original amount.
The kind of tissue that forms the supportive structure in our pinna (external ears) is also found in
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0%
Vertebrae
0%
Nail
0%
Ear ossicles
0%
Tip of the nose
Explanation
Pinna is provided with voluntary muscle and is supported by elastic fibrocartilage. Nose cartilage includes the lateral nasal cartilages, the lesser alar cartilages, the greater alar cartilages, and the septal cartilage.
So, the correct answer is option D.
Which of the following parts of a neuron is covered by fatty sheath?
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Axon
0%
Cyton
0%
Dendrite
0%
Node of Ranvier
Explanation
Myelin sheath is a fatty acid containing a white creamy layer that forms cover the axons of myelinated fibers. Cyton is the metabolic center of the nerve cell where the metabolic contents are manufactured. Dendrites are the small extension of nerve cells that receives signals from sensory receptors or other neurons. Dendrites and cyton are not involved in nerve impulse conduction. The node of Ranvier is the site of myelinated fibres where axons are not covered with the myelin sheath. Thus, the correct answer is option A.
The bony labyrinth is filled with
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0%
Endolymph
0%
Synovial fluid
0%
Perilymph
0%
Humour
Explanation
The bony labyrinth is the cavity of the inner ear. It consists of the central vestibule, the semicircular canals, and the cochlea. Inside the bony labyrinth lies a complicated membranous sac called the membranous labyrinth. The small space between the wall of the bony labyrinth and the wall of the membranous labyrinth is filled with a fluid called perilymph. The space within the membranous labyrinth is filled with endolymph.
In a neuron, conversion of electrical signal to a chemical signal occurs at
Report Question
0%
Cell body
0%
Axonal end
0%
Dendritic end
0%
Axon
Explanation
Signals are transferred from one neuron to another.
The electrical signals are very fast as compared to that of chemical signals. Myelinated sheath present on the surface of neurons helps in better conduction of signals.
At the end of the axon (axonal end),
the electrical signal
is
converted into
a
chemical
signal, and the axon releases
chemical
messengers called neurotransmitters (acetylcholine) which are received by their receptors on the dendrites of the subsequent neuron. This region is called synapse.
So, the correct answer is '
Axonal end'
Percentage of nerve cells deteriorated till the age of 70 years is __________.
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0%
10%
0%
20%
0%
30%
0%
35%
Explanation
As the age of a person advances, the Brain and spinal cord lose nerve cells and undergoes atrophy. By the age of 70 years, approximately 10% of nerve cells undergo atrophic changes.
So, the correct answer is 'Option A-10%'.
Four healthy people in their twenties got involved in injuries resulting in damage and death of a few cell of the following. Which of the
cells are least likely to be replaced by new cells -
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Osteocytes
0%
Liver cells
0%
Neurons
0%
Malpighian layer of the skin
Explanation
So the correct option is C.
Which cells do not form layer and remains structurally separate?
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Epithelial cells
0%
Muscle cells
0%
Nerve cells
0%
Gland cells
Explanation
Never cells do not form layer and remains structurally separate. These are specialized cells to carry impulse conduction. They originate from neural plate of embryonic ectoderm. They are the structural and functional units of nervous system. Epithelial cells are made up of few layers of compactly arranged cells on a basement membrane. Muscles cells are made up of elongated contractile cells. Glands cells are type of epithelial cells.
Thus, the correct answer is 'Nerve cells.'
What used to be described as Nissel granules in a nerve cell are now identified as : -
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0%
Cell metabolites
0%
Fat granules
0%
Ribosomes
0%
Mitochondria
Explanation
The cell body of a nerve cell contains basophilic granules called Nissl's granules. These granules appear to be cisternae of rough endoplasmic reticulum with numerous attached and free ribosomes. They probably synthesize proteins for the cell.
So, the correct answer is 'Ribosomes'.
Which is the correct combination about the figure?
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(a) Dendrite, (b) Cell body, (c) Dendron, (d) Synaptic knob
0%
(a) Dendrite, (b) Cell body, (c) Axon, (d) Synaptic knob
0%
(a) Synaps, (b) Cell body, (c) Axon, (d) Synaptic knob
0%
(a) Dendrite, (b) Myelin sheath, (c) Axon, (d) Synaptic knob
Explanation
Dendrites receive impulses. It is represented by (a).
The cell body or cyton contains the nucleus and cell organelles. It is represented by (b).
Axon (It is represented by (c)) is an elongated dendron that transfers the impulse to another nerve through a knob-like structure which is known as a synaptic knob that contains neurotransmitters (chemical transmission of signal). It is represented by (d).
So, the correct answer is option B.
Which of the following statement is correct for node of Ranvier of nerve?
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Neurilemma is discontinuous
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Myelin sheath is discontinuous
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Both neurilemma and Myelin sheath are discontinuous
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Covered by myelin sheath
Explanation
The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. This provides faster transmission of electrical impulses through axon.
So, the correct option is 'Myelin sheath is discontinuous'.
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Practice Class 11 Medical Biology Quiz Questions and Answers
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