Q.6. Answer the following. [3 marks each] (any six) [18 marks]
(37) State the medicinal use of microorganisms
(38) State for physical changes seen in boys during puberty
(39) What is force? explain with the help of some example.
(40) Explain why sportsmen use shoes with spikes
(41) How do pathogens enter our body?
(42) Give scientific reason : The nail is pushed into a wooden plank from its pointed end.
(43) Give scientific reason: we cannot hear the explosion taking place on the sun
Answers
Answer:
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Explanation:
(37) They are used in various therapeutic purposes such as production of vaccines of rabies, influenza, polio, small pox, hepatitis B etc. and production of antibiotics such as penicillin, cephalosporin, chloramphenicol, tetracycline etc.
The most wonderful usage of microorganisms is in cancer treatment.
(38) In boys, the first puberty change is the enlargement of the scrotum and testes.At this point, the penis does not enlarge. As the testes and scrotum continue to grow, the penis grows. The first growth of pubic hair produces long, soft hair that is only in a small area around the genitals.
(39) Force is an external influence (push or pull) on a body that tends to either change the state of a body or its shape.
Actions like pushing, pulling, picking, hitting, lifting, running and bending are some of the examples of force.
(40) Sportsmen use shoes with spikes so as to have a better grip while running. This is because the force of friction between theshoes and the ground increases with the help of spikes.
(41) Microorganisms capable of causing disease—pathogens—usually enter ourbodies through the mouth, eyes, nose, or urogenital openings, or through wounds or bites that breach the skin barrier. Organisms can spread—or be transmitted—by several routes.
(42)The area of the pointed end of the nail is much smaller than that of its head. The same force, therefore, produces a pressure sufficient to push the pointed end of the nail into the wooden plank. ... So, the pressure on their head is reduced and they find it easier to carry the load.
(43)Sound is a form of mechanical energy,it requires medium for the propagation. But there is no medium in between sun and earth.So we can not hear the sounds of explosions that take place on the surface of sun.