responding for the external stimuli by a fraction of second are due to reflex action.
- Reflex actions are very important as they save us from painful or dangerous stimuli.
- Reflex actions or reflexus are fast, immediate automatic and involuntary responses of the body.
- They help in the body as they save us from painful or dangerous stimuli.
- Reflexes occur without our thinking.
- Brain is not involved in the execution of several reflexes.
Ex: Withdrawing our hand when we touch hot subject.
State whether the following actions are voluntary action, reflex action or conditioned reflex.
- Cleaning the table
- Playing on the key board
- Salivating when food is put in the mouth
- We close our ears when we hear unbearable sound
- Blinking: Involuntary action or reflex action.
- Cleaning the table: Voluntary action.
- Playing on the keyboard: Conditioned reflex.
- Salivating when food is put in the mouth: Involuntary or Reflex action.
- We close our ears when we hear unbearable sound: Involuntary or reflex action.
What will happen to the potted plant kept near window in the room?
Draw a diagram of a plant showing phototropism. Explain why plants possess such type of response.
A plant which grows near a window bends towards sun light. Write the reason for it.
- The potted plant which is kept near the window in the room, grows towards light.
- Auxins acts on bending of stem of show a response to the sun light.
- More auxin collects on the light illuminated side of the stem. So cells on that side grow faster.
- On opposite side cells grow slow to make the stem bend.
- Auxins are the plant hormones responsible for the growing of the stem towards light.
- Auxins are synthesized at the tip of the stem (meristematic tissue).
- Bending of the plant towards light is called phototropism.
What happens if all the functions of the human body are controlled only by brain?
Brain controls all the functions of the human body. Comment on it.
- If all actions of the human body are controlled by brain, our body will get harm in dangerous situations.
- Some actions may be delayed and our brain could not conduct reflex actions, which require immediate action to a stimulus.
- For example, when we touch a hot object, we require an immediate response to save our hand. If the brain controls this action, the time taken will be more and our hand will burn.
- So, it is controlled by spinal cord, the response will be quick, and we may escape the danger.
- Nerves can not reach the every corner of the body, whereas hormones of endocrine glands can do that.
- So it’s not good that all functions are controlled by brain.
If you visit a doctor, what doubts you would like to clarify about pancreas?
- What is pancreas?
- Where is pancreas located in our body?
- Why is it called mixed gland?
- What is the exocrine part of pancreas?
- What is the endocrine part of pancreas?
- What are the cells that secrete hormone insulin?
- What is the function of insulin?
- What happens if required amounts of insulin is not produced?
- What are the symptoms of diabetes?
- How can diabetes be controlled?
Take a small potted plant. Cover base portion of the plant tightly and hang the part upside down. Observe the plant for a week. Based on your observation how can you support phototropism?
Aim: To prove that phototropism is a character that is carried by stem.
Apparatus: Potted plant, a strong small rope.
Procedure : Take a small potted plant. Cover the base portion of the plant tightly so that the plant along with soil do not fell down. Now take a rope and hang the potted plant upside down to a support firmly.
Observe the plant after a week.
Observation: We observe that the end of the stem which is upside down takes ‘U’ turn and grows towards light.
Conclusion: Phototropism is a response of plants towards light. That the stem grows towards light that is negatively to gravitation. Auxins are responsible for phototropism.
Take a cock feather touch smoothly at different parts of your body. Findout which portion of the body has high sensation. Is this similar during sleeping ? Prepa