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STD :- VII SUBJECT :- GENERAL SCIENCE MAHATMA GANDHI VIDYALAYA, MANCHAR STD :- VII SUBJECT :- GENERAL SCIENCE Smt. Chikhale A.S.

ISAAC NEWTON ....

Sir Isaac Newton was an English physicist and mathematician who is widely recognized as one of the most influential scientists of all time and as a key figure in the scientific revolution. His book Philosophic Naturalism Principal Mathematical first published in 1687, laid the foundations for classical mechanics. Newton made seminal contributions to optics, and he shares credit with Gottfried Leibniz for the development of calculus. Newton's Principia formulated the laws of motion and universal gravitation, which dominated scientists' view of the physical universe for the next three centuries. By deriving Kepler's laws of planetary motion from his mathematical description of gravity, and then using the same principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the Solar System. This work also demonstrated that the motion of objects on Earth and of celestial bodies could be described by the same principles. His prediction that Earth should be shaped as an oblate spheroid was later vindicated by the measurements of Maupertuis, La Condamine, and others, which helped convince most Continental European scientists of the superiority of Newtonian mechanics over the earlier system of Descartes. Newton built the first practical reflecting telescope and developed a theory of colour based on the observation that a prism decomposes white light into the many colours of the visible spectrum. He formulated an empirical law of cooling, studied the speed of sound, and introduced the notion of a Newtonian fluid. In addition to his work on calculus, as a mathematician Newton contributed to the study of power series, generalised the binomial theorem to non-integer exponents, developed a method for approximating the roots of a function, and classified most of the cubic plane curves.

EFFORTS BY PRATHAMESH RITESH ROHAN CHAKRADHAR JAY YASH 37 38 39 40 41 42

REPRODUCTION IN PLANTS….. The life span of all living things is limited. Living things produce other organisms like themselves and thus ensure the continuity of their species. This process is called as reproduction. It is a natural process due to which the species continues to exist even if individual plants or animals of that type die. There are two important modes of reproduction:- Asexual reproduction. Sexual reproduction. The male female distinction can be seen in many species of living things. A new individual of a species is created through the union of their gametes. Such reproduction is called sexual reproduction. Reproduction without the union of gametes is called asexual reproduction. Plants like grape vine, sugarcane, rose are produced from their vegetative parts. This is called asexual reproduction. However, in flowering plants, fruits and seeds are produced. This sexual reproduction.

ASEXUAL REPRODUCTION IN PLANTS….

VEGETATIVE REPRODUCTION…. Reproduction from parts of plants such as the root or stem or leaf is called vegetative reproduction. This is a natural method. The new plant that grow by this method is exactly like the parent plant. When branches of pants like the rose, hibiscus are panted in the ground they take root and a new plant grows from them.

FROM THE ROOT AND STEM:- When we bury a potato, sweet potato, onion, turmeric in he ground, a new plant begins to grow from them. Potato, turmeric, onion or chrysanthemum are under ground Stem. Sweet potato is a root. They carry out the function of vegetative reproduction. Leaves Buds grow on the margins of the bryophyllum leaf .hey take root when he leaf Falls on the ground and a new plant grows from them .

CELL DIVISION Unicellular living things reproduce by cell division .When the cell has grown , The nucleus in the cell division and forms a nuclei .After that , the protoplasm also divides and two independent cells are formed . The new cells also divides in the same way when it has grown . This kind of reproduction is seen in bacteria , algae and chlorella.

BUDDING This kind of reproduction is seen in the living things like yeast . In this , the original cell gets a little swelling . Soon a part of its nucleus enters the swelling and a bud is formed . The bud grows and in time becomes a cell . This original is called the parent cell . The nucleus of the parent cell divides to form two nuclei . One nucleus and some protoplasm enters the swelling or bud . Later this bud separates from the parent cell . It becomes an independent organism . Reproduction from buds is called budding .

SPOROGENESIS Reproduction from spores is called sporogenesis . You must have seen the fungus that grows on bread or pickles . spores begin to grow when they find favourable condition , that is ,when they get enough moisture, warmth and oxygen . Then a new plant grows from each spore.

SEGMENTATION In algae [spirogyra] small pieces or segments are formed due to decomposition or Some other reason. An independent plant grows from every segment.

SEXUAL REPRODUCTION IN PLANTS In flowering plants, flowers are the organ of reproduction . The androecium And gynoecia in the flower are important for reproduction. The androecium is the Male part and gynoecia is the female part. When the pollen grains from the androecium fall on the stigma of the gynoecia they begin to grow there.This is Called pollination. As the pollen tube grow from thepollen grain,male are formed in it. Hey uni with the femalke gamate in rthe overy . This unionis called Fertiliesion.

PERPETUATION OF SPECIES A cat young one is like the cat itself . When a mango seed takes root in he soil, it is a mango tree that grows from it . After a period of time mangoes will grow on the New tree. When a rose branch is planted in the soil a rose bush grows from it. It means That a species of animal or plant continues to exit through reproduction. In other Words, the species is perpetuated.

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