Production of Food and its Management — BIOLOGY STD 8 — Question
ICSE BoardEnglish MediumSTD 8BIOLOGYProduction of Food and its Management4 Marks
Question
How are bacteria useful to human beings ?
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Answer
$a.$ Saprophytic bacteria decompose excretory products and dead remains of plants and animals into simple substances. Thus, they clear the earth of all the waste. These bacteria are called decomposers. They are the natural scavengers which help in cleaning the earth.
$b.$ Bacteria along with certain fungi play an important role in maintaining the fertility of the soil. Some bacteria live in the root nodules of plants, such as pea, gram and beans. These bacteria absorb the nitrogen of the atmosphere and convert it into nitrates which are used by the plants.
$c.$ The digestive tract of animals like cows, sheep and camel consists of bacteria that break down cellulose of the plant into simple sugars which are readily absorbed by the animals.
$d.$ Manufacture of vinegar, curd and cheese involves the activity of bacteria. Bacteria are also used in the production of tea, coffee and cocoa. Some industrial products, such as lactic acid, citric acid, and alcohol are obtained by the action of bacteria.
$e.$ Bacteria are also involved in tanning of leather. Separation of fibres from the rest of the tissues of fibre plants, such as flax, jute is called retting of fibres. This is brought about by the action of bacteria on plant parts submerged in water.
$f.$ Certain medicines like antibiotics and vitamin $B-$ complex tablets are manufactured with the help of bacteria.
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