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Que. Short answer type questions.

1. Why :-

(a) Milk gets spoiled quickly in summer?

(b) Curdling of milk takes place when a little curd is added to it?

(c) Ripened fruits do not rot in deep freezer?

(d) Milk takes long time to form curd during winter?

(e) Pasteurisation prevents spoilage of milk?

(f) Dead animal body starts emitting foul smell after sometime?

(g) Fresh food should be kept covered?

(h) Vaccination is given to a healthy person? O Dough rises when yeast is added to it?

(i) Bacteria do not grow around the mycelium of Penicillum notatum?

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2. What are antibiotics?

3. Name five major groups of micro-organisms.

4. What are microorganisms?​

Answer 1

Answer:

Ans.(a) The bacteria named as Lactobacillus are present in the milk. Milk contains lactose which is easily fermented into lactic acid with the helpful bacteria and become sour. This is the reason why the milk gets easily curdled more easily in summer than in the winter when it is left outside.

Ans.(b):- A bacterium - lactobacillus, is present in the curd. when that curd, or you can say, bacteria, is added to the milk, it multiplies and converts the milk into curd.

Ans.(c) Ripened fruits do not rot in deep freezer because microorganism cannot grow or multiply in low temperature.

Ans.(d) Lactobacillus is the baceria that is responsible for setting of curd. The temperature range at which this bacteria is most active lies between 30-40oC. In winters as the temperature decreases, the activity of this bacteria also decreases. This is the reason why setting of curd takes long time in winters.

Ans.(e) Pasteurization is intended to make milk and milk products safe by destroying all the vegetative pathogenic organisms. ... The spoilage microflora of pasteurized milk is of two types: postpasteurization contaminants, which have entered the milk after heating; and heat-resistant bacteria, which have survived heating.

Ans.(f) The reason for emission of foul smell when an animal dies is due to release of gases during decomposition like hydrogen sulphide.

Ans.(g) Also keeping food covered protects your food from harmful bacteria and objects or chemicals from getting into the food. There are certain defenses that can be used for raw and ready-to-eat foods to prevent the harmful bacteria from spreading. You can package the food properly in cling foil.

Ans.(h) Yeast is used to make bread dough. ... During fermentation, carbon dioxide is produced and trapped as tiny pockets of air within the dough. This causes it to rise. During baking the carbon dioxide expands and causes the bread to rise further..

Ans.(i) Bacteria does not grow around the mycelium of penicillium because the mycelium of the penicillium kills the bacteria. It is caused by hyphae which is contained by the mycelium.

Ans.2. Antibiotics are medicines that treat infections by killing bacteria. They don't work on viruses, like the flu.

Ans.3.Microorganisms or microbes are microscopic organisms that exist as unicellular, multicellular, or cell clusters. Microorganims are widespread in nature and are beneficial to life, but some can cause serious harm. They can be divided into six major types: bacteria, archaea, fungi, protozoa, algae, and viruses.

Ans.4.An organism that can be seen only through a microscope. Microorganisms include bacteria, protozoa, algae, and fungi. Although viruses are not considered living organisms, they are sometimes classified as microorganism..

Hope it helps you..

Answer 2

Answer:

Answer 1. In summers, due to increase in temperature, the microbes easily ferment milk-sugar lactose into lactic acid.

This causes spoiling of milk in summers when left outside.

The bacteria responsible for converting lactose to lactic acid is Lactobacillus (lactic acid bacteria).

Answer 2. A bacterium - lactobacillus, is present in the curd. when that curd, or you can say, bacteria, is added to the milk, it multiplies and converts the milk into curd.

Answer 3. Microorganism can't grow in low temperature that's why ripened fruits do not rot in deep freezer.

Answrer 4. At warm condition bacteria turn the milk into curd. So in summer the temperature is high and favourable for the bacteria growth. As a result, the bacteria multiply faster which leads to change the milk into curd. That iss why it takes more time in winter for the curd to set compare to summer time.

Answer 5. Pasteurization is intended to make milk and milk products safe by destroying all the vegetative pathogenic organisms. ... The spoilage microflora of pasteurized milk is of two types: postpasteurization contaminants, which have entered the milk after heating; and heat-resistant bacteria, which have survived heating.

Answer 3. bacteria, archea, fungi, algae,viruses are the major groups of microorganisms.

Answer 4. a very small living thing that you can only see with a special piece of equipment (a microscope)..