Write notes on : Transpiration, Nerve
cell,
Human brain, Reflex action
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Answer:
The process by which plants lose water from the leaves and aerial parts in the form of water vapour is called transpiration. It is essential in bringing rain because when plants transpire they increase the amount of water molecules in the air which results in rainfall. It also provides a cooling effect to the plants. It also creates a transpirational pull which results in the absorption of water and minerals from the soil.
A neuron (or neurone) is a nerve cell that carries electrical impulses. Neurons are the basic units of our nervous system. Neurons have a cell body (soma or cyton), dendrites and an axon. Dendrites and axons are nerve fibers.
It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses. The brain is made up of many specialized areas that work together: The cortex is the outermost layer of brain cells.
A reflex action is an automatic , rapid response to the stimulus. i.e coughing, sneezing, blinking of eyes,etc.It protects the body from damage and does not involve conscious thought. In a reflex action, the message is passed straight to the motor neurones through a relay neurones. They are controlled by spinal cord.