TEST PAPER HUMAN EYE and COLOURFUL WORLD

1.      The change in focal length of an eye lens to focus the image of objects at varying distances is done by the action of ________.

1.	pupil
2.	ciliary muscles
3.	retina
4.	blind spot

2.      Far point of a normal eye is situated at _________.

1.	25 cm
2.	infinity
3.	50 cm
4.	400 cm

3.      A long-sighted person cannot see objects nearer to his eye than 50 cm. To enable him to read a book 25 cm away, he should use spectacle lenses whose power in dioptres is

1.	-6
2.	-4
3.	-2
4.	+ 4

4.      The process by which a beam of white light splits into its constituent colours is known as _________.

1.	reflection
2.	dispersion
3.	divergence
4.	convergence

5.      The band of colours obtained due to dispersion is known as ______________.

1.	spectrum
2.	rainbow
3.	image
4.	mirage

6.      Power of a lens is expressed in

1.	dioptre
2.	cm
3.	metre
4.	millimetre

7.      1 D is the power of a lens of focal length ______ cm.

1.	100
2.	10
3.	1/100
4.	1/10

8.      Hypermetropia is rectified by using

1.	convex lens
2.	concave lens
3.	cylindrical lens
4.	progressive lens

9.      Reciprocal of focal length in metres is known as the ______ of a lens.

1.	focus
2.	power
3.	power of accommodation
4.	far point

10.  The power of a convex lens of focal length 50 cm is ______.

1.	+ 2 D
2.	- 2 D
3.	50 D
4.	- 5 D

11.  Two lenses having powers +2D and -4D respectively are put together. Power of the combination would be

1.	-2 D
2.	+2 D
3.	-4 D
4.	+4 D

12.  The fluid between the retina and the lens is called _______.

1.	aqueous humour
2.	vitreous humour
3.	aqua
4.	humus

13.  Two thin lenses of power +5D and -2D are put in contact with each other. Focal length of the combination is

1.	+3 m
2.	-3 m
3.	0.33 m
4.	-0.33 m

14.  The least distance of distinct vision for infants is _________.

1.	15 cm
2.	20 cm
3.	25 cm
4.	5 cm

15.  The focal length of a lens whose power is -1.5 D is _______.

1.	-66.66 cm
2.	+ 1.5 m
3.	+ 66.66 cm
4.	-1.5 m

SECTION-B (5 CHOICE QUESTIONS)

1 In the figure of the human eye, which of the following labels are correct? 

 a) "A" is the blind spot 
 b) "B" is the pupil 
 c) "C" is the main refractive element 
 d) "D" is the fovea 
 e) all of the above

2 The reason we cannot see light that falls on the blind spot is

 a) photoreceptor cells in that region of the retina are light adapted 
 b) photoreceptor cells in that region of the retina are dark adapted 
 c) photoreceptor cells in that region of the retina are covered by blood vessels 
 d) the cortex suppresses vision in this area 
 e) none of the above

3 An ophthalmoscope is

 a) a device for measuring how far you can see in each direction 
 b) a device for looking at electrical waveforms 
 c) a device for looking into eyes 
 d) specifically for testing children's vision 
 e) a tube inserted into eyes through the pupil

4  A person suffering from short-sightedness has

 a) an eye that is too long and needs a convex lens to focus distant objects 
 b) an eye that is too long and needs a concave lens to focus distant objects 
 c) an eye that is too short and needs a convex lens to focus near objects 
 d) an eye that is too short and needs a concave lens to focus near objects 
 e) none of the above

5 An animal that lives under water (eg. a fish)

 a) cannot use the cornea to refract light into a sharp image 
 b) needs a stronger lens than a land-dwelling animal 
 c) needs a weaker lens than a land-dwelling animal 
 d) a and b 
 e) a and c

6 An ELECTRODE

 a) is part of a nerve cell 
 b) is a device for measuring electrical events 
 c) is the junction between nerve cells 
 d) is another name for ACTION POTENTIAL 
 e) none of the above 

7 Rods and cones

 a) have different physical shapes 
 b) have different distributions across the retina (more cones in foveal region) 
 c) have different distributions across the retina (more rods in foveal region) 
 d) a and b 
 e) a and c 

8 The visual receptive field of a cell is

 a) that area of the image from which light will have an influence on that cell 
 b) any area on the retina 
 c) the visual area that the person can see (from about 110 degrees to the left to about 110 degrees to the right) 
 d) the entire retina 
 e) the entire image 

9 The relay station between the retina and the cortex is

 a)   the optic chiasm 
 b)   the visual cortex 
 c)   the superior colliculus 
 d) the lateral geniculate nucleus of the thalamus 
 e)   the vestibular nucleus 

10 A simple cell in the visual cortex

 a) has a receptive field shape similar to retinal ganglion cells (ie. circular) 
 b) responds best to corners 
 c) responds best to bars 
 d) is not fussy about orientation 
 e) all of the above