Q2 of 102 Page 118

Given below are a few common reflexes in humans. Write against each the kind of reflex it is (simple or conditioned).

(i) Knee-jerk ___________


(ii) Watering of mouth on seeing a favourite dish ___________


(iii) Tying of shoelaces while talking ___________


(iv) The closing of eyelids if a strong beam of light is flashed across ___________

(i) Knee-jerk: Simple reflex


Explanation: Knee jerks is when the leg is involuntarily extended as a result of a sharp tap below the kneecap in a relaxed leg rested on the other leg while sitting.


(ii) Watering of mouth on seeing a favourite dish: Conditioned reflex


Explanation: When we see our favourite food, our brain remembers the taste of that food and starts working in an unconscious manner. This reflex is not inborn, it has developed over a period of time when we first tasted this food and liked it.


(iii) Tying of shoelaces while talking: Conditioned reflex


Explanation: Tying of shoelaces needs a lot of practice, it is not an inborn talent. As time passes, we learn how to tie shoelaces while talking as it would have become a habit to tie laces every day before work.


(iv) Closing of eyelids if a strong beam of light is flashed across: Simple reflex


Explanation: When the light intensity falling on the eyes suddenly increases due to light being flashed across the eyelids, in order to protect the pupil from sudden contraction, one will quickly close the eyelids.


More from this chapter

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2

Categorize the following under stimulus and response.


(i) Withdrawal of hand on touching a hot plate ____________


 


(ii) Seeing a green light turning red at a road crossing before applying the brakes ____________


 


(iii) Pain in the eye if something falls into it. ____________

 1

Fill in the blanks by choosing the correct alternative given for each.


(i) Brain and spinal cord are the parts of __________ nervous system (central/peripheral/autonomous)


 


(ii) __________ is the largest part of the brain. (Cerebellum/cerebrum/medulla oblongata).


 


(iii) White matter consists mainly of __________ (axons/dendrites/cytons)


 


(iv) The part of the brain concerned with body balance is __________ (cerebrum, cerebellum, medulla oblongata).

 3

Given alongside is a partial diagrammatic representation of a certain phenomenon pertaining to the nervous system.


(i) Name the parts numbered 1-7


(ii) What phenomenon does the diagram represent? ____________


(iii) Name the parts not shown in the diagram that should be included to complete the pathway of the phenomenon. ______________

 1

The insulating sheath covering the neural axon is called