Answer briefly:
(a) Why are villi present in the intestine and not in the stomach?
(b) How does pepsinogen change into its active form?
(c) What are the basic layers of the wall of alimentary canal?
(d) How does bile help in the digestion of fats?

Answer briefly : (a) How do you perceive the colour of an object ? (b) Which part of our body helps us in maintaining the body balance ? (c) How does the eye regulate the amount of light that falls on the retina.

The image given below indicates a particular medical technique done for a pregnant woman. (a) Name the medical technique carried out in the image. (b) At which period of gestation does this procedure is generally performed? (c ) What is the objective of performing this procedure? (d) How this procedure was misused by certain people in society?

(a) What is the picture about? (b) What does the picture of the last man indicate to us and what was he called? (c ) How did the change happen from first man to the last man as shown in the figure?

The picture given below is an organelle of plant cell . Identify the picture and answer then questions . (a) Name the organelle . (b) Mention the role of the organelle in the cell . (c) How do you call the stack of coin like structures present on it ? (d) Whether is shows semi - autonomy ?If yes how ? If no , why ?

A car moves with a speed of 54 kmh^-1 towards a cliff. The horn of the car emits sound of frequency 400 Hz at a speed of 335 m s^-1 . (a) Find the wavelength of the sound emitted by the horn in front of the car. (b) Find the wavelength of the wave reflected from the cliff (c) What frequency does a person sitting in the car hear for the reflected sound wave ? (d) How many beats does he hear in 10 seconds between the sound coming directly from the horn and that coming after the reflection ?

i. Will the velocity of a stone thrown vertically upwards remian constant or will it change with time? How will it change? ii. Why doesn't the stone move up all the time? Why does it fall down after reaching a certain height? iii. What does its maximum height depend on?