The part of an eye which acts like a diaphragm of a photographic

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 Multiple Choice QuestionsMultiple Choice Questions

251.

Cochlea of mammalian internal ear is concerned with

  • hearing

  • balance of body posture

  • both (a) and (b)

  • perception changes of atmospheric pressure


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252.

The part of an eye which acts like a diaphragm of a photographic camera is

  • pupil

  • iris

  • lens

  • cornea


B.

iris

The iris of the eye is the thin, circular structure made of connective tissue and muscle that surrounds the pupil. The color of our eyes is determined by the amount of pigment in the iris apart from this  the iris acts like the diaphragm of a camera and controls the size of the pupil. One muscle within the iris constricts the pupil in bright light (full sunlight, for example), and another iris muscle dilates (enlarges) the pupil in dim lighting and in the dark.


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253.

The dendrite carries impulses

  • towards the cyton

  • away from cyton

  • across the body

  • from one neuron to another


254.

Cerebrospinal fluid is present

  • beneath the pia mater

  • between piamater and arachnoid

  • between arachnoid and duramater

  • between duramater and cranium


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255.

Cranium is made up of

  • 8 bones

  • 12 bones

  • 10 bones

  • 16 bones


256.

Arbor-vitae is composed of

  • grey matter

  • neurogleal cells

  • white matter

  • all of the the above


257.

Human brain has greater development of

  • cerebrum

  • cerebellum

  • optic lobes

  • medulla oblongata


258.

The 'end organs of Ruffini' are receptors of :

  • heat

  • cold

  • pressure

  • touch


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259.

Which of the following part of human brain is associated with integration of sympathetic and parasympathetic activities ?

  • Cerebrum

  • Neopallium

  • Hypothalamus

  • Medulla oblongata


260.

The unidirectional transmission of a nerve impulse through nerve fibre is due to :

  • neurotransmitters are released by axon endings

  • neurotransmitters which are released by dendrites

  • nerve fibre which is insulated by a medullary sheath

  • sodium pump which starts operating into the nerve fibre


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