Last updated on June 28th, 2023 at 11:09 pm
NCERT Solution Class 8 Chapter 2 Microorganisms
Fill in the blanks.
(a) Microorganisms can be seen with the help of a _______[microscope]
(b) Blue green algae fix _______ directly from air and enhance fertility
of soil. [nitrogen]
(c) Alcohol is produced with the help of __________.[yeast]
(d) Cholera is caused by __________.[bacteria]
Tick the correct answer.
(a) Yeast is used in the production of
- sugar
- alcohol
- hydrochloric acid
- oxygen
alcohol
(b) The following is an antibiotic
- Sodium bicarbonate
- Streptomycin
- Alcohol
- Yeast
streptomycin
(c) Carrier of malaria-causing protozoan is
- female Anopheles mosquito
- cockroach
- housefly
- butterfly
Female anopheles mosquito
(d) The most common carrier of communicable diseases is
- ant
- housefly
- dragonfly
- spider
Housefly
(e) The bread or idli dough rises because of
- heat
- grinding
- growth of yeast cells
- kneading
Growth of yeast cells
(f) The process of conversion of sugar into alcohol is called……
- nitrogen fixation
- moulding
- fermentation
- infection
Fermentation
[Que] Can microorganisms be seen with the naked eye? If not, how can they be seen?
It is very difficult to see bacteria with the naked eye due to their very small size. Using a microscope is the only way to see them.
[Que] What are the major groups of microorganisms?
There are five major groups of microorganisms:
- Bacteria – single-celled, spiral, or rod-shaped.
- Fungi – multicellular
- Protozoa – unicellular or multicellular.
- Virus –
- Algae – multicellular
[Que] Name the microorganisms which can fix atmospheric nitrogen in the soil.
Nitrogen can be fixed in the soil by bacteria like Rhizobium and blue-green algae. Plants can easily use these nitrogenous compounds to synthesize proteins and other compounds.
[Que] Write 10 lines on the usefulness of microorganisms in our lives.
Importance of microorganisms:
- It is used in making wine and other food such as cake etc.
- yeast is also used in making bread.
- To reduce pollution, microbes are used.
- With the help of the bacterium Rhizobium and some other blue-green algae, they increase soil fertility by fixing atmospheric nitrogen.
- Medicine is also prepared using microbes.
- Microorganisms produce antibiotics as a way to kill bacteria.
- Many plant diseases can be controlled with antibiotics.
[Que] Write a short paragraph on the harmful effects of microorganisms.
Harmful effects of microorganisms:
[Que] What are antibiotics? What precautions must be taken while taking antibiotics?
Solution:
Some microorganisms produce antibiotics to kill other microorganisms that cause disease. The most common sources of antibiotics are bacteria and fungi.
- Antibiotics should be taken with the following precautions:
- It should be taken under the guidance of a skilled doctor.
- The antibiotic course should be finished in accordance with the doctor’s prescription.
- Antibiotics should be administered in the appropriate dosage and at the appropriate time.
- When an antibiotic is given at the incorrect dosage, it becomes useless.
Learn More –
Class 8 Science Chapter 2 Microorganisms Extra Question and Answers
