Question

1. Describe the process of double circulation in human beings.
2. What are the methods used by plants to get rid of their waste products ?
3. Give reason for the following : (a) Arteries are thick walled blood vessels.
(b) Veins are thin walled blood vessels.
(c) Veins have valves in them.
these are board questions for class 10 bio life process.......

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Answer 1

In double circulation, blood passes through the heart twice in order to supply oxygen once to the body.
Plants get rid of waste by transpiration, or they store it in leaves which later falls off, or in form of resins, gums and lenticles.
(a) Artries are thick walled because blood in them flows with high pressure, so in order to reduce the pressure they are thickk walled.
(b) Veins are thin walled because they contain blood flowing with less pressure.
(c) As the veins contain blood with low flowing pressure, they contain valves to prevent its back flow while moving against the gravity or moving upward. 
ANSWER.
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