Life Processes — Science STD 10 — Question

What are the various ways in which a chemical equation can be made more informative? Give examples to illustrate your answer.

1. Given below are the steps for extraction of copper from its ore. Write the reaction involved.
   1. Roasting of copper (1) sulphide.
   2. Reduction of copper (1) oxide with copper (1) sulphide.
   3. Electrolytic refining.
2. Draw a neat and well labelled diagram for electrolytic refining of copper.

Write down the differences between AC and DC generators.

i. Define a reflex arc. Why have reflex arcs evolved in animals? Trace the sequence of events which occur, when you suddenly touch a hot object.
ii. Name the part of nervous system which helps in communication between the central nervous system and other parts of the body. What are the two components of this system?

The gland X which is located just below the brain in the human head secretes a chemical substance Y which controls the development of ones and muscles in the body of a person. Secretion of too little of substance Y as well as the secretion of too much of substance Y by the gland X leads to abnormal development of the body of a person.

1. Name the gland X.
2. What is the chemical substance Y?
3. What happens if too little of substance Y is secreted?
4. What happens if too much of substance Y is secreted?
5. Name the system of glands in the human body of which gland X is a part.

A student wants to project the image of a candle flame on the walls of the school laboratory by using a mirror.

1. Which type of mirror should he use and why?
2. At what distance, in terms of focal length 'f' of the mirror, should he place the candle flame to get the magnified image on the wall?
3. Draw a ray diagram to show the formation of the image in this case.
4. Can he use this mirror to project a diminished image of the candle flame on the same wall? State 'how' if your answer is 'yes' and 'why not' if your answer is 'no.'

The pancreas is made up of two parts A and B. The part A secretes insulin whereas part B secretes pancreatic juice.

1. Which part is functioning as an endocrine gland? Why?
2. What is insulin and what effect does it have in the body?
3. Name the disease which can be treated by giving insulin injection.
4. What does pancreatic juice contain? Where does pancreatic juice go?
5. Name the life process in which pancreatic juice is made use of.

It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm.

1. What should be the range of distance of an object placed in front of the mirror?
2. Will the image be smaller or larger than the object. Draw ray diagram to show the formation of image in this case.
3. Where will the image of this object be, if it is placed 24 cm in front of the mirror? Draw ray diagram for this situation also to justify your answer.

Show the positions of pole, principal focus and the centre of curvature in the above ray diagrams.

At what distance from a concave mirror of focal length 10cm should an object be placed so that:

1. Its real image is formed 20cm from the mirror?
2. Its virtual image is formed 20cm from the mirror?

Describe the alimentary canal of man.