Life Processes — Science STD 10 — Question

How do we decide that a given material is a good conductor of electricity or is an insulator?

Write short notes: Chipko Movement of Bishnoi.

Write short note :
Structure of the Modern Periodic table.

Write Short note: Seed germination.

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

1. What is metal M?
2. What is solution S? Is it acidic or alkaline?
3. What is gas G?
4. Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
5. Is this reaction exothermic or endothermic?

Construction of a compound microscope:
(1) A compound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens (the lens directed towards the object) and the eyepiece (the lens directed towards the eye). Both the lenses are small in size, but the cross section of the objective lens is less than that of the eyepiece. The objective lens has a short focal length. The focal length of the eyepiece is more than that of the objective lens.(2) The metal tube is mounted on a stand. The principal axes of the objective lens and the eyepiece are along the same line. The distance between the object and the objective lens can be changed with a screw. It is possible to change the distance between the objective lens and the eyepiece.
Working:
(1) The object to be observed is illuminated and placed in front of the objective lens, slightly beyond the focal length of the objective lens. Its real, inverted and enlarged image is formed by the, objective lens on the other side.
(2) This intermediate image lies within the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope. The final image is virtual, highly enlarged and inverted with respect to the original object. It can be formed at the minimum distance of distinct vision from the eyepiece. The final image is observed by keeping the eye close to the eyepiece.
Use: This microscope is used to observe blood cells, microorganisms, etc.
1.In a compound microscope, which lens has greater focal length?
2.Where do you place the object to be observed with a compound microscope?
3.State which distance is adjusted to observe the object with a compound microscope.
4.State the nature of the final image in compound microscope relative to the object.
5.State the use of a compound microscope.

A scientist removed some cells from the growing point of a plant and placed it in a suitable medium leading to the formation of a shapeless lump of mass X. X is then transferred to another medium which stimulates it to develop roots. When X with developed roots is placed in a yet another medium, then it develops shoots to form tiny plantlets. These plantlets can then be transplanted in pots or soil where they can grow to form mature plants.

1. What is the shapeless lump of mass X known as?
2. What name is given to this method of producing new plants?
3. The growth medium used in this method contains plant nutrients in the form of a 'jelly'. Name this jelly.
4. What is the general name of chemicals used to stimulate the growth of plant cells and development of roots and shoots?
5. Name any two plants which are produced by this method.
6. State any two advantages of this method of producing plants.
7. What is the other name of this method [other then that given in (b) above]?

What are abiotic factors? Write examples.