NCERT Solutions Class 8 Science Chapter 2 Microorganisms : Friend And Foe
NCERT Solutions Class 8 Science Chapter 2 Microorganisms : Friend And Foe: National Council of Educational Research and Training Class 8 Science Chapter 2 Solutions – Microorganisms : Friend And Foe. NCERT Solutions Class 8 Science Chapter 2 PDF Download.
NCERT Solutions Class 8 Science Chapter 2: Overview
Board |
NCERT |
Class |
8 |
Subject |
Science |
Chapter |
2 |
Chapter Name |
Microorganisms : Friend And Foe |
Topic |
Exercise Solutions |
NCERT Solutions Class 8 Science Chapter 2 – Microorganisms : Friend And Foe
CHAPTER: – 2
(MICROORGANISMS: FRIEND AND FOE)
Exercise
1) Fill in the blanks.
(a) Microorganisms can be seen with the help of a ______microscope______.
Explanation – (As with help of the lens we zoom it accordingly)
(b) Blue green algae fix __nitrogen________ directly from air and enhance fertility of soil.
Explanation – (Nitrogen reach soil productivity is more)
(c) Alcohol is produced with the help of ____yeast______. (As this yeast helps in forming the microorganisms)
(d) Cholera is caused by___bacteria___.
Explanation- (This disease is spread through the used substance of the infected person)
2) Tick the correct answer.
(a) Yeast is used in the production of
(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) Oxygen.
Ans: – Option(ii).
Explanation – This yeast stores in a place sometimes thereby by reacting alcohol produced.
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast.
Ans: – Option(ii).
Explanation –We sometimes for the disease control also takes this streptomycin as a antibiotics.
(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) yeast.
Ans: – Option(i).
Explanation – As this female Anopheles mosquito only transfer this disease.
(d) The most common carrier of communicable diseases is
(i) ant (ii) housefly (iii) dragonfly (iv) spider
Ans: – option(ii).
Explanation – As this carries the communicable disease agents throughout different organs.
(e) The bread or idli dough rises because of
(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading
Ans: – Option(iii).
Explanation – As this yeast cell after reacting with water grows in number as a result dough rises.
(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection
Ans: – Option (iii).
3)Match the organisms in Column A with their action in Column B.
Ans: –
Column A. |
Column B |
Bacteria. | Causing cholera |
Rhizobium. | Fixing nitrogen |
Lactobacillus. | Settings of curd |
Yeast. | Baking of bread |
Protozoa. | Causing malaria |
A virus. | Causing AIDS |
4) Can microorganisms be seen with the naked eye? If not, how can they be seen?
Ans: – The microorganisms would not be seen in naked eyes. These microorganisms will be seen through the microscope which have high power lens in it. And for that we use high power lenses.
5)What are the major groups of microorganisms?
Ans: – The group of microorganisms are
- Bacteria
- Fungus
- Protozoa
- Algae
6) Name the microorganisms which can fix atmospheric nitrogen in the soil.
Ans: – The microorganisms which helps in the nitrogen fixation in the soil from atmosphere is known as the nitrogen fixation bacteria which are rhizobium, blue green algae etc.
7) Write some lines on the usefulness of microorganisms in our lives.
Ans: – The microorganisms are very necessary in the crop field. These microorganisms increase the fertility of the soil. This helps in nitrogen fixation. The bacteria which help in nitrogen fixation is known as farmers friends. This produce from the decompose of plant and animal. The rhizobium is known as a nitrogen fixing bacteria.
8) Write a short paragraph on the harmful effects of microorganisms.
Ans: – These microorganisms affect the body in various ways. If we talk about the disease cholera which is caused by the microorganism’s plasmodium is a microbe. These organisms also affect the immunity power of our body as a result disease are seen. The disease typhoid also happens because of microbes.
9) What are antibiotics? What precautions must be taken while taking antibiotics?
Ans: – The antibiotics is the substance that when we took it helps in defeating the pathogens present in the body by various way. This helps us for growing the immunity of the body.
The most important precautions which will be taken while taking the antibiotics we should consult a doctor before that.