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Tissues
What is nervous tissue?
Nervous Tissue. Nervous tissue is made up of nerve cells or neurons.
Each neuron has a single long part called the axon and many short branches celled the dendrites.
The cell body contains a distinct nucleus and has a special kind of granule, called Nissl’s granule in the cytoplasm.
In some nerve cells the axon has a thick white covering called medullary sheath. These are called medullated fibres. When this sheath is absent, it is called non-medullated fibres.
In the medullated fibres, the sheath is not continuous—there are gaps along the entire length. Each gap is called Nodes of Ranvier.
The terminal end of axon is without sheath and branched. The axon of one neuron remains in contact with the branches of dendrites from another neuron. The region of contact is called synapse.
Each nerve cell receives message through the dendrites and sends message through the axon.
Nerve cell.
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Make a comparison and write down ways in which plant cells are different from animal cells?
How is a prokaryotic cell different from a eukaryotic cell?
What would happen if the plasma membrane ruptures or breaks down?
What would happen to the life of a cell if there was no Golgi apparatus?
Which organelle is known as the powerhouse of the cell? Why?
Where do the lipids and proteins constituting the cell membrane get synthesized?
How does an Amoeba obtain its food?
What is osmosis?
Carry out the following osmosis experiment:
Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) keep cup A empty
(b) put one teaspoon sugar in cup B
(c) put one teaspoon salt in cup C
(d) put one teaspoon sugar in boiled potato cup D.
Keep this setup for two hours. Then observe the four potato cups and answer the following :
(i) Explain why water gathers in the hollowed portion of B and C?
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
By which instrument you can see internal structure of onion peel cell?
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