Lakhmir singh solutions science class 8 Solutions for Chapter 2 microorganisms friends and foe

Exercises in Chapter 2 microorganisms friends and foe Grade 8

Exercise

Questions in Exercise

Name the instrument (or device) which is needed to see the micro-organisms.

What is the name of micro-organisms which reproduce only inside the living cells of other organisms?

What are the major groups of microorganisms?

Name any two human diseases caused by bacteria.

Name any two human diseases caused by viruses.

Name any two human diseases caused by protozoa.

Name any two human diseases caused by fungi.

Which micro-organism is utilized in making curd from milk?

Name the micro-organism which is used for the large scale production of alcohol.

Name any two antibiotics.

Name an antibiotic extracted from fungus (mold). Name the fungus.

Name any four diseases which can be prevented by vaccination.

Name the scientist who discovered the-vaccine for 'smallpox.

Name the scientist who discovered 'penicillin'.

State an important function performed by blue-green algae.

Name one 'biological nitrogen-fixer'.

Name two common insects that act as carriers of disease-causing micro-organisms (or disease-causing microbes).

Name any two diseases spread by houseflies.

Name the insect which is the carrier of a parasite of malaria.

Name the insect which carries the dengue virus.

Which of the two spreads dengue: mosquito or housefly?

Name two diseases spread by mosquitoes.

Name the microbe which causes malaria disease.

Name one disease which spreads through insect bites.

Name one disease which spreads through infected food or water.

Name the causative micro-organisms of the following animal diseases: (a) Foot and mouth disease (b) Anthrax.

Name two food materials that are preserved by the sun-drying method in our homes.

Name two food materials that are preserved by using common salt.

Name two food materials which can be preserved by using sugar.

Name two food materials which are usually preserved by deep freezing.

Name some of the preservatives which are used in the preservation of fruits as jams and jellies.

Name some of the preservatives which are used in the preservation of fruits and vegetables as pickles.

Name two food materials which can be preserved by using oil or vinegar.

Name any two special chemicals which are used as food preservatives.

Name the micro-organisms which can fix atmospheric nitrogen in the soil.

What type of plants can fix nitrogen gas of the air into compounds of nitrogen?

Name the microorganisms present in the soil and in the root nodules of leguminous plants which can fix atmospheric nitrogen.

Name two leguminous plants that can fix nitrogen.

Fill in the following blanks with suitable words :

(a)Alcohol is produced with the help of_.

(b)Blue-green algae fix _________directly from air to enhance fertility of soil.

(c)Micro-organisms can be seen with help of _________.

(d)Cholera is caused by_.

(e)Common salt has been used to preserve_ and _________for ages.

(f)The food material which is preserved by pasteurization is _________.

(g)As a result of the nitrogen cycle, the percentage of nitrogen in the atmosphere remains moreor less_.

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Chapters in this book

Crop Production And Management

Microorganisms: Friends and Foe

Synthetic Fibres And Plastics

Materials: Metals and Non-Metals

Coal And Petroleum

Combustion And Flame

Conservation Of Plants And Animals

Cell Structure And Its Functions

Reproduction In Animals

Reaching The Age Of Adolescence

Force and Pressure

Friction

Sound

Chemical Effect Of Electric Current

Some Natural Phenomena

Light

Stars And The Solar System

Pollution Of Air And Water