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  Charles Darwin gave the theory of Natural Selection that is applicable to both plants and animals.  Darwin's theory of evolution Charles Robert Darwin ( 1809-1882 ) was a British naturalist who made significant discoveries of biology. He became the unpaid naturalist in 1831 and set out on a voyage when he was 22 years old. He developed the idea of organic evolution by natural selection on his five-year expedition around the world. When he returned to England, he didn't leave again and stayed at home. He conducted various experiments and formulated the hypothesis stating that evolution occurred due to natural selection.  Darwin gave the theory of evolution called The Theory of Natural Selection in his book The Origin of Species. The Theory of Natural Selection in his book The Origin of Species. The Theory of Natural Selection suggests that the best adapted organisms are naturally selected to pass on their traits to the offsprings. Darwin's theory of evolution can be explai

Biodegradable and Non-Biodegradable Wastes The material that becotablemes useless after being used and needs to be discarded is called waste. Everday, we generate a lot of waste through our activities. This waste can be domestic, municipal, agricultural, hospital or industrial. All the waste materials can be classified into two main categories. 1- Biodegradable wastes  2- Non-biodegradable wastes Biodegradable Wastes biodegradable and non biodegradable wastes The waste materials that can be broken down into simple harmless substances by biological processes are called biodegradable wastes. In biological processes, various microorganisms such as bacteria and fungi decompose biodegradable waste. These microorganisms release enzymes that act on waste and break it down into smaller harmless substances. All the enzymes are specific in their action and they can only break down the natural materials or the products made from natural materials. Enzymes cannot breakdown various human made mater

Fission: 1- Occurrence of fission is only in unicellular organisms.  2- New organisms are formed as a result of parent cell dividing into two daughter cells. Thus, identity of parent is lost in fission. 3- Nuclear division is followed by cytoplasmic division.  4- Examples: Amoeba, Paramecium.  Budding: 1- Occurrence of budding is in both unicellular and multicellular organisms.  2- Parent gives new outgrowth to form new individual. Parent does not divide so its identity is retained in budding. 3- Cellular outgrowth is followed by the division of nucleus. 4- Examples: Planaria, Hydra.

Arteries  1- Arteries carry blood away from the heart. 2- These carry oxygenated blood (except pulmonary artery). 3- Arteries walls are thick. 4- These are highly elastic in nature. 5- These do not collapse when empty. 6- These do not have any valves. Veins 1- Veins carry blood towards the heart. 2- These carry deoxygenated blood (except pulmonary vein). 3- Walls of veins are thin. 4- These are less elastic than arteries. 5- These collapse easily when empty.  6- These have a series of valves that prevent backflow of blood. 

Paramecium is also a unicellular organisms. It has a definite shape and food is taken in at a specific spot called oral groove. Food is moved to the oral groove by the movement of cilia which are hair-like structures that cover the entire body surface of Paramecium.  Once the food enters the cell, it is surrounded by a food vacuole. Digestive enzymes come in contact with food vacuole and carry out the process of digestion as in case of Amoeba.

The process involved in the basic necessary activities and function for the survival or maintenance of a living body are called life processes or maintenance processes. A living body needs continuous repair and maintenance whether we are active, sitting or sleeping. It means that the maintenance processes should occur continuously to repair the damage or worn out cells or tissues. Hence, these processes are termed as life processes as they work in coordination to support the body to be in a living state. Let's understand some important life processes.  1- Nutrition: All the maintenance processes need a regular supply of energy to occur. The living organism derive this energy from the food they eat. So the process of taking in food and obtaining energy from it for growth, repair and metabolism is called nutrition. The nutrients obtained through food are essential for an organism to grow and develop. As life on earth depends mainly on Carbon-based molecules such as fats and proteins,