Notes

Coordination in Plants:
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- The biochemical substance which is produced in plants and regulates growth and development of the plant is known as "phytohormone" or hormone.
- Every cell of a plant has the ability to produce hormones.
- The main natural phytohormones are auxin, gibberellin, cytokinin
- The hormones which cannot be identified or separated are known as postulated hormones

Nervous System:
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- The tissue that can receive stimulus from the environment and transmit accordingly to make an appropriate response is known as Nervous Tissue.
- Neuron is the basic functional unit of nervous system.
- Neuron is composed of two parts:
(1) Cell Body (2) Processes
- The part of the neuron which contains the nucleus, surrounded by cytoplasm, round, oval or star shaped is known as "Cell Body".
- Cell body contains the mitochondria and golgi bodies.
- A variable number of nerve fibres extend from the cell body which are known as "processes". They are of 2 types:
(1) Dendrite (2) Axon
- The small branch like fibres which are around the cell body are known as dendrites. The number of dendrites may be from zero to a few.
- The long unbranched structure which originates from the cell body is known as Axon.
- Numerous dendrites and axons together form a nerve.
- Main function of neuron is to conduct nerve impulses
- The neurons do not connect with each other directly
- There is a gap between the neurons of a nervous system
- The dendrites of one neuron connects with axon of another neuron and this is known as "Synapse".
- Nerve impulses transmit stimuli from one neuron to another through the dendrite through an electrochemical process.
- In this way, stimuli travels from one neuron to another in one direction only.

Reflex Action:
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- The immediate response to a specific stimulus which is not controlled by the brain, rather the spinal cord is known as Reflex Action.