Tag: introduction to sense organs

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Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

The function of iris in the eyes of frog is to

  1. Refract the light rays

  2. Alter the size of the pupil

  3. Move the nictitating membrane

  4. Move the lens forward and backward
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

The iris of eye is 

  1. Photosensitive

  2. Chemoreceptor

  3. Both A and B

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The colored part of the eye is called as the iris. It controls light levels inside the eye. The round opening in the center of the iris is called as the pupil. It is photosensitive in nature and is embedded with tiny muscles that dilate (widen) and constrict (narrow) the pupil size depending on the presence or absence of light.
Therefore, the correct answer is option A.

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

In the chemistry of vision in mammals, the photosensitive substance is called as

  1. Sclera

  2. Retinol

  3. Rhodopsin

  4. Melanin
Reveal answer Fill a bubble to check yourself
C Correct answer
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. 

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

A 22 years student goes to his ophthalmologist. He has problem in reading books, because he is not able to contract his

  1. Suspensory ligament

  2. Pupil

  3. Iris

  4. Ciliary muscles
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

Where is the image of an object formed in human eye?

  1. Iris

  2. Pupil

  3. Retina

  4. Cornea
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.
  • The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create the visual perception.
  • The retina serving a function analogous to that of the film or image sensor in a camera. Hence, the retina  is the image of an object formed in the human eye.
So, the correct answer is 'retina'.

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

Which of the following is transparent in nature?

  1. Conjuctiva

  2. Cornea

  3. Iris

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A. Conjunctiva is a transparent membrane that lines the eyelids. It protects the delicate cornea.
B. Cornea is a transparent layer that forms the front of eyes. It is the anterior portion of sclera, a dense connective tissue which maintains the shape of eye and also protects it.
C. Iris is an opaque and pigmented structure in the eye. It controls the size of pupil and thus, regulates amount of light entering the eye.
Hence, conjunctiva and cornea are transparent. So, both options A and B are correct.
So, the correct answer is 'Both A and B'.
Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

Anterior chamber of the eye is the space between

  1. Lens and iris

  2. Cornea and iris

  3. Lens and retina

  4. Cornea and lens
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • The anterior chamber of the eyeball is the part of the human eye with the chamber at right.
  • The anterior chamber is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.
So, the correct option is 'lens and iris'.

Multiple choice biology human brain and sense organs introduction to sense organs eyes and their function the structure and function of the eye

Which of the following is the clean window in the sclera in front of iris ?

  1. $Conjuctiva$
  2. $Pupil$
  3. $Cornea$
  4. $Choroid$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The cornea is the clear, dome-shaped outer surface of the eye covering the front of the iris, pupil, and anterior chamber, functioning as a clean window that helps focus light.