Cooling helps in food preservation by inhibiting the growth of microbes. This is because most of the microorganisms are able to multiply only under warm conditions.

Yes, microorganisms play an important and useful role in environment by making it clean. They decompose dead organic waste of plants and animals into simpler substances. These simpler harmless substances contain nutrients and are used by plants as manures. Thus, microorganisms can be used for degradation and thereby cleaning the environment.

Microorganisms are harmful for human beings in many ways. They cause diseases in humans, plants and animals, e.g.
(i) In humans, bacteria cause diseases such as cholera, typhoid, tuberculosis, etc.
(ii) In cattle, the foot and mouth disease is caused by a virus.
(iii) Also several microbes cause diseases in plants, e.g. tikka disease, late blight of potato. Some microbes grow on food and secrete toxic substances which make the food poisonous.

Bacteria such as Rhizobium and certain blue-green algae (Anabaena, Nostoc) present in the soil can fix atmospheric nitrogen and convert it into usable nitrogenous compounds.

Anabaena and Nostoc are two blue-green algae which help in nitrogen fixation.

Vinegar and oil are common preservatives, used in kitchen.

Chickenpox and ringworm are diseases that can spread through direct contact with infected person.

Carbon dioxide given out by yeast is responsible for increase in volume of dough.

Pulse Polio Immunisation Programme was launched in India in 1995 for eradication of polio.

The groups of microorganisms which live in colonies are bacteria and fungi.

Amoeba is a protozoan in the list given.

Yes, the study of microorganisms is called Microbiology.

(a) Microorganism is bread mould (Rhizopus) and the group is fungi.
(b) Organism grows on moist and stale bread.
(c) It grows well in moist condition.
(d) No, the fungus spoils the bread by producing poisonous substances (toxins).

(a) Organisms that cannot be seen with eyes alone are called microbes.
(b) Microbes are useful to humans in many ways. They help in the production of curd, cheese, in cleaning the environment, etc.
(c) (i) Lactobacillus bacteria.
(ii) Penicillium
(d) Diseases caused by microbes are polio, malaria, etc.
(e) Jasmine is attentive, intelligent and curious.