Management of Natural Resources — Science STD 10 — Question

The organs A of a person have been damaged completely due to which too much of a poisonous waste material B has started accumulating in his blood, making it dirty. In order to save this person's life, the blood from an artery in the person's arm is made to flow into long tubes made of substance E which are kept in coiled form in a tank containing solution F. This solution contains three materials G, H and I in similar proportions to those in normal blood. As the person's blood passes through long tubes of substance E, most of the wastes present in it go into solution. The clean blood is then put back into a vein in the arm of the person for circulation.

1. What are organs A?
2. Name the waste substance B.
3. What are (i) E and (ii) F? Name G, H and I.
4. What is the process described above known as?

1. Explain the role of placenta in the development of human embryo.
2. Give example of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents spread of such diseases.

If the teeth are not cleaned regularly, they become covered with a sticky yellowish layer W of food particles and bacteria. Since layer W covers the teeth, the alkaline liquid X secreted by glands Y inside the mouth cannot reach the teeth surface to neutralise the acid formed by the action of organisms Z on sugary food, and hence tooth decay sets in.

1. What is W known as?
2. What is (i) X, and (ii) Y?
3. What are organisms Z?
4. State one way of removing layer W from the teeth.

Two lamps, one rated 40W at 220V and the other 60W at 220V, are connected in parallel to the electric supply at 220V.

1. 10 Draw a circuit diagram to show the connections.
2. Calculate the current drawn from the electric supply.
3. Calculate the total energy consumed by the two lamps together when they operate for one hour.

What is meant by power of a lens? Define its S.I. unit. You have two lenses A and B of focal lengths +10cm and -10cm respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8cm from the lens? Draw a ray diagram to justify your answer.

Suppose you have three concave mirrors A, B and C of focal lengths 10cm, 15cm and 20cm. For each concave mirror, you perform the experiment of image formation for three values of object distance of 10cm, 20cm and 30cm. Giving reason answer the following:

1. For the three object distances, identify the mirror/ mirrors which will form an image of magnification - 1.
2. Out of the three mirrors identify the mirror which would be preferred to be used for shaving purposes/ makeup.
3. For the mirror B draw, ray diagram for image formation for object distances 10cm and 20cm.

1. Explain the following terms related to spherical lenses:

1. Optical centre.
2. Centres of curvature.
3. Principal axis.
4. Aperture.
5. Principal focus.
6. Focal length.

2. A converging lens has focal length of 12 cm. Calculate at what distance should the object be placed from the lens so that it forms an image at 48 cm on the other side of the lens.

The farmers have been cultivating a food plant X for over two thousand years and have produced as many as five entirely different looking vegetables A, B, C, D and E from it.

1. What could the plant X be?
2. What are A, B, C, D and E?
3. What is the process of evolution involved in this example known as?

Two lamps, one rated 40W at 220V and the other 60W at 220V, are connected in parallel to the electric supply at 220V.

1. 10 Draw a circuit diagram to show the connections.
2. Calculate the current drawn from the electric supply.
3. Calculate the total energy consumed by the two lamps together when they operate for one hour.