Question

Prachi math book class 8th chapter 2 Exponents (powers) exercise 2.1 5th part solutions​

Answer 1

Answer:

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Step-by-step explanation:

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Answer 2

Answer:

1. Fill in the blanks. (a) Microorganisms can be seen with the help of  Microscope (b)Blue-green algae fix Nitrogen directly from the air and enhance the fertility of the soil. (c) Alcohol is produced with the help of Yeast (d) Cholera is caused by  Bacteria- Vibrio cholera   2. Tick the correct answer. (a) Yeast is used in the production of (i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen   (b) The following is an antibiotic (i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast   (c) Carrier of malaria-causing protozoan is (i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly   (d) The most common carrier of communicable diseases is (i) ant (ii) housefly (iii) dragonfly (iv) spider   (e) The bread or idli dough rises because of (i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading   (f) The process of conversion of sugar into alcohol is called (i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection                                                                                                     4. Can microorganisms be seen with the naked eye? If not, how can they be seen? → No, microbes are invisible to the naked eye, because they are very small in size.Some of these, such as fungus growing on bread, can be seen with a magnifying glass. Others cannot be seen without the help of a microscope.That is why these are called microorganisms or microbes.   5. What are the major groups of microorganisms? →These groups are bacteria, fungi, protozoa and some algae   6. Name the microorganisms which can fix atmospheric nitrogen in the soil. →Rhizobium can fix atmospheric nitrogen in the soil.   7. Write 10 lines on the usefulness of microorganisms in our lives. They are used in winemaking, baking, pickling and other food-making processes.Alcoholic fermentation by yeast is widely used in the preparation of wine and bread.A bacterium Lactobacillus promotes the formation of curd.Microbes are used to reduce pollution.They are used to increase soil fertility