Question

(a) sugar
I. Multiple Choice Questions Put () mark against the correct choice :
1. Yeast helps in the production of
(b) alcohol
(c) oxygen
2. Pasteurisation of milk destroys its
(a) vitamins
(b) fat content
(c) bacteria
3. The bread or dosa dough rises because of the action of
(a) heat
(b) growth of yeast cells (c) kneading or grinding.
4. Salting the food helps to preserve it by
(a) extracting water from the cells (b) lowering its temperature (c) increasing its acidity.
5. The process of conversion of sugar into alcohol is called
(a) fermentation
(b) decomposition (c) nitrogen fixation
6. Which of the following is a chemical preservative?
(a) Streptomycin
(b) Alcohol
(c) Sodium benzoate
7. Carrier of malaria causing pathogen is
(a) housefly
(b) cockroach
(c) female Ampheles
8. The micro-organism which lives in the root nodules of leguminous plants is a
(a) bacterium
(b) virus
(c) fungus
II. Fill in the blanks :
1. Microorganisms can be seen with the help of a
2. Viruses are
in size than bacteria.
A-23​

Answer 1

1. Yeast help in the production of


${ \sf{ \red{b) \: \: alcohol}}}$


⛦ Fermentation is an anaerobic process in which microorganisms like yeast convert sugar, starch, glucose into alcohol (Ethanol), and produce carbon dioxide gas. Yeast is used for the fermentation process to produce ethanol. yeast and water are mixed together and allow to evolve carbon dioxide and ethanol.
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2. Pasteurization of milk destroys its


${ \sf{ \red{c) \: \: bacteria}}}$




⛦ Pasteurization involves heating liquids at high temperatures for short amounts of time. Pasteurization kills harmful microbes in milk without affecting the taste or nutritional value (sterilization= all bacteria are destroyed).



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3. The bread or dosa dough rises because of the action


${ \red{ \sf{b) \: yeast \: cells}}}$


⛦ The species of yeasts which is commonly used for baking is Saccharomyces cerevisiae and thus known as baker's yeasts. The yeast cells perform fermentation reactions. In these reactions, the fermentable sugars are converted to ethanol and carbon dioxide. The yeast cells are added to the dough of idli, bread and cake.


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4. Salting the food hELpS it to preserve it by


${ \red{ \sf{a) \: extracting \: water \: from \: the \: cells}}}$



⛦ Salting preserves food by drawing water out of the food, preventing bacteria growing and spoiling the food.

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5. The process of conversion of sugar into alcohol

${ \sf{ \red{a) \: \: fermentation}}}$


⛦ Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products..


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6. Which of the following is a chemical preservative?


${ \red{ \sf{c) \: \: sodium \: benzoate}}}$


⛦ Sodium benzoate is a substance which has the chemical formula C6H5COONa. It is a widely used food preservative, with an E number of E211. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.


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7. Carrier of malaria causing pathogen is


${ \red{ \sf{c) \: female \: anopheles}}}$

⛦ Malaria is caused by a one-celled parasite called a Plasmodium. Female Anopheles mosquitoes pick up the parasite from infected people when they bite to obtain blood needed to nurture their eggs.


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8. The microorganism which lives in the root nodules of leguminous plants is a


${ \red{ \sf{a) \: \: bacteria}}}$


⛦ The root nodules of leguminous plants contain nitrogen-fixing bacteria, e,g clover, peas. Farmers grow and then plough in leguminous plants into their fallow fields to enrich the soil with the nodules of fixed nitrogen, so that their crops will do better next time round.


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1 . microorganisms can be seen with the help of a microscope.



2 . Viruses are smaller in size than bacteria.