A person is wearing spectacles with concave lenses for correcting vision. While not using the glasses, the image of a distant object in his case will be formed
on the blind spot
behind the retina
in front of the retina
on the yellow spot
C.
in front of the retina
As the person uses spectacles having concave lens, he must be suffering from myopia or short-sightedness. Here the eyeballs become elongated, so that parallel rays are focussed in front of retina.
Myopia is an eye disorder where light focuses in front of retina. This causes distant objects appear normal. It is also known as short- sightedness.
Examine the diagram of the two cell types A and B given below and select the correct option
A B
Cell A is the rod cell found evenly all over retina
Cell A is the cone cell more concentrated in the fovea central is
Cell B is concerned with colour vision in bright light
Cell A is sensitive to low light intensities
The total number of nitrogenous bases in human genome is estimated to be about
3.5 million
35 thousand
35 million
3.1 billion.
Given below is a table comparing the effects of sympathetic and parasympathetic nervous system
for four feature (a-d). Which one feature is correctly described
Feature | Sympathetic nervous system | Parasympathetic nervous system |
a) Salivary glands | Stimulate Secretion | Inhibit Secretion |
b) Pupil of the eye | Dilate | Constricts |
c) Heart rate | Decreases | Increases |
d) Intestinal peristalsis | Stimulates | Inhibits |
Unidirectional transmission of a nerve impulse through nerve fibre is due to the fact that
nerve fibre is insulated by a medullary sheath
sodium pump starts operating only at the cyton and then continues into the nerve fibre
neurotransmitters are released by dendrites and not by axon endings
neurotransmitters are released by the axon endings and not by dendrites.
Cochlea of mammalian internal ear is concerned with
hearing
balance of body posture
both (a) and (b)
perception changes of atmospheric pressure
Cerebrospinal fluid is present
beneath the pia mater
between piamater and arachnoid
between arachnoid and duramater
between duramater and cranium
A person who shows unpredictable moods, outbursts of emotion, quarrelsome behaviour and conflicts with others is suffering from
borderline personality disorder (BPD)
mood disorder
addictive disorder
schizophrenia.
The dendrite carries impulses
towards the cyton
away from cyton
across the body
from one neuron to another