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प्रश्न
Which part of the eye contains cells which are sensitive to light?
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उत्तर १
The retina of an eye contains light-sensitive cells.
उत्तर २
The retina is the part of the eye which contains cells that are sensitive to light.
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संबंधित प्रश्न
Name one gustatory receptor and one olfactory receptor present in human beings.
The diagram given below shows the internal structure of a spinal cord depicting a phenomenon. Study the diagram and answer the questions:
1) Name the phenomenon that is depicted in the diagram. Define the phenomenon.
2) Give the technical term for the point of contact between the two nerve cells.
3) Name the parts numbered 1, 2 and 3.
4) How does the arrangement of neurons in the spinal cord differ from that of the brain?
5) Mention two ways by which the spinal cord is protected in our body.
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the smell of the food?
What is a reflex action? Explain with the help of an example.
Which of the following cannot be considered a receptor?
(a) ear
(b) nose
(c) muscle
(d) eye
The involuntary actions in the body are controlled by :
(a) medulla in forebrain
(b)medulla in hindbrain
(c) medulla in spinal cord
(d) medulla in midbrain
When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers and impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.
(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
(b) What is (i) neuron S, and (ii) neuron T?
(c) Name the tissue U.
(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
(e) Name the effector in this whole process.
A cylindrical structure P in our body begins in continuation with medulla and extends downwards. It is enclosed in a bony cage Q and surrounded by membranes R. As many as x pairs of nerves arise from the structure P. The structure P is involved in the reflex actions of our body and conduction of nerve impulses to and from another organ S of our body with which it forms CNS.
(a) Name the structure P.
(b) Name (i) bony cage Q, and (ii) membranes R.
(c) How much is x?
(d) Name the organs S.
(e) What are the reflexes involving structure P only known as?
With the help of suitable example, describe reflex action.
Note the relationship between the first two words and suggest the suitable word/words for the fourth place.
Stimulus : Receptor :: Impulse : ______.
State whether the following is simple reflex, conditioned reflex or neither of the two.
Contraction of eye pupil
Define the following:
Reflex action
State whether the following is
The sudden application of brakes without thinking
State whether the following is
Cleaning
What type of reflex is the following?
Solving mathematical sums
Complete the following sentence with appropriate Word
A reflex arc in man is best described as movement of stimuli from:
Reflex arc allows the rapid response of the body to a stimulus.
The given diagrammatic representation of reflex action shows knee jerk reflex.
Identify the parts labeled as A to E and select the correct option.
Categorise the following under stimulus and response.
Withdrawal of hand on touching a hot plate
