MODEL PAPER 1 — Science STD 10 — Question

Give two differences between food chain and food web.

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.

Explain why, though both a plane mirror and a sheet of paper reflect light but we can see the image of our face in a plane mirror but not in a sheet of paper.

1. What is dispersion of white light? What is the cause of such dispersion? Draw a diagram to show the dispersion of white light by a glass prism.
2. A glass prism is able to produce a spectrum when white light passes through it but a glass slab does not produce any spectrum. Explain why it is so.

1. What is (i) phototropism and (ii) geotropism? With labelled diagrams describe an activity to show that light and gravity change the directions that plant parts grow in.
2. Mention the role of each of the following plant hormones:

1. Auxin.
2. Abscisic acid.

Explain the phenomenon of dispersion of white light through a glass prism, using suitable ray diagram.

A liquid X of colour Y circulates in the human body only in one direction: from body tissues to the heart. Among other things, liquid X contains germs from cells and dead cells. The liquid X is cleaned of germs and dead cells by a special type of white blood cells called Z. This cleaned liquid is then put into blood circulatory system in subclavian veins.

1. What is (i) liquid X and (ii) colour Y?
2. What are Z.
3. The liquid X is somewhat similar to a component of blood. Name this component.
4. Why is liquid X not red?

In what ways damages are caused to the environment?

When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?

What is the importance of forest as a resource?