Saurabh@educational

The Solar System   Q. Write a short note on each: I) Sun The sun is at the centre of solar system. It is the nearest star from us. Like all the stars the sun produces energy by transforming hydrogen into helium. Through a series of complex nuclear reactions, two hydrogen protons combine to form a helium atom. This reaction produces an enormous amount of energy. Hence, the Sun is the main source of heat and light for all the planets. The diameter of sun is 109 times the diameter the diameter of Earth. In volume it is 1.3 million times bigger than earth. Gravitational pull of the sun is 28 times the gravity of the Earth. A body weighing 1 kg on the Earth will weigh 28 Kg on the Sun. The sun rotates on its axis as the earth does. The sun completes one rotation in about 25 days. It also revolves around the centre of galaxy once in 225 million years. II) Mercury (Budh) It is nearest planet to the Sun and the smallest planet present in our solar system. It is very difficult t

 Reproduction in Plants (Extra questions) Q.1. What is the importance of reproduction? Ans. Biological process which involves production of new organism from existing species is called reproduction. Importance: *It ensures continuity of life on earth. *It is essential for survival of species on earth and ensures their stability. *Reproduction helps in maintaining a proper balance among various biotic constituents of ecosystem. *It also facilitates evolution because variation comes through reproduction over several generations. Q.2.  What happens when bryophyllum falls on moist soil? Ans. Bryophyllum (sprout leaf plant) has buds in the margins of leaves. If a leaf of this plant falls on a moist soil, leaf buds at its notches develop into new plants. Q.3. What is the importance of notches (eyes) in a potato? Ans. Potato  tuber has depressions called "eyes" on its surface. These eyes have vegetative buds in them which germinate to produce a new potato plant.  Q.4.