Universe It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist. The Universe contains billions of galaxies, each containing millions or billions of stars. The space between the stars and galaxies is largely empty. Astronomy Astrono . . .
Galaxy Constellation It is a collection of billions of stars. It does not form any fixed pattern of any animal or an object. There are around 1011 galaxies in the universe. It is a group of only few stars. It forms the shape of an animal or an object. . . .
Stars are cosmic energy engines that produce heat, light, ultraviolet rays, x-rays, and other forms of radiation. They are composed largely of gas and plasma, a superheated state of matter composed of subatomic particles. Though the most familiar star, our own sun, stands alone, about three of every four stars exist as part of a binary system conta . . .
Some stars have always stood out from the rest. Their brightness is a factor of how much energy they put out–known as luminosity–and how far away from Earth they are. Stars in the heavens may also appear to be different colors because their temperatures are not all the same. Hot stars are white or blue, whereas cooler stars appear to ha . . .
Positively charge Negatively charge Glass rod Woollen cloth Carpet Nylon Dry hair Woollen coat Silk cloth Plastic sheet Comb Amber Ebonite Rubber Cotton cloth . . .
Q. Which organelle is known as the powerhouse of the cell? Why? Ans. Mitochondria are known as the powerhouse of cell. Mitochondria contain enzymes for catalysing biochemical reactions involved in respiration. Energy in the form of ATP is produced in the process. For this reason, mitochondria are generally called powerhouses of cell. . . .
Q. Explain the structure and the functions of the nucleus. Ans. Nucleus is the largest cell organelle. Most of the cells have single nucleus. It is spherical or oval in shape. It is surrounded by double membrane called nuclear membrane and contains a colourless, dense fluid called nucleoplasm. In nucleoplasm, some spherical bodies are embedded called . . .
Q. What is classification? Classify the plants on the basis of size and shape. Answer: Classification: Classification means grouping things together on the basis of certain common features. It is actually the method of putting similar things into one group. On the basis of their size and shape, plants have been divided into the following three cat . . .
Q. What is the difference between diffusion and osmosis? Ans: Diffusion: Diffusion is the movement of solute molecules (eg: sugar molecules in water) from higher concentration to the region of lower concentration without using any energy. This is also called passive transport. Osmosis: Diffusion of solvent molecules (water) through a . . .
Q. Write the functions and sources of nutrients. Answer: There are five types of nutrients in food: Carbohydrates Proteins Fats Vitamins Minerals Nutrient Function Source (Food it is found in) Carbohydrates Sugar Starch Cellulose (fibre) . . .
What is symbiosis? Give one example. Answer: Symbiosis -A Special Mode of Nutrition-: When two organisms live together and share shelter and nutrients, their association is called symbiosis or symbiotic relationship, and the organisms are called symbionts. They mutually help each other. Lichen is an example of symbiotic relationship bet . . .
Living and Non-living things Q.1 Give differences between Living and Non-living things: Answer: Characteristics Living Things Non-living Things 1. Cellular Structure Made of tiny units called cells. Not made of cells. 2. Movemen . . .
Structure The sun, like others stars, is a ball of gas. In terms of the number of atoms, it is made of 91.0% hydrogen and 8.9% helium. By mass, the sun is about 70.6% hydrogen and 27.4% helium. The sun's enormous mass is held together by gravitational attraction, producing immense pressure and temperature at its core. The sun has six regions . . .
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Since the galaxies in the universe are racing away from each other, it is believed that they may have originated from a single point in the space. This led to the most widely accepted theory about the origin of the universe- THE BIG BANG THEORY. According to this theory, the total matter in the space was initially concentrated into a mass of about 100 m . . .