MICROORGANISMS friend and foe chapter solution

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1. Fill in the blanks :


(a) Microorganisms can be seen with the help of a_____________________________.


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


(c) Alcohol is produced with the help of _______________________ .




 (d) Cholera is caused by____________________








Ans. (a) microscope

          (b) nitrogen

          (c) yeast

           (d) bacteria









2. Tick the correct answer :


(a) Yeast is used in the production of


(i) sugar

(ii) alcohol. ✔️

(iii) Hydrochloric acid

(iv) oxygen






(b) The following is an antibiotic.


(i) Sodium bicarbonate

(ii) Streptomycin✔️

(iii) Alcohol

(iv) Yeast 







(c) Carrier of malaria-causing protozoan is 


(i) female Anopheles mosquito ✔️

(ii) cockroach

(iii) Housefly

(iv) butterfly






(d) The most common carrier of communicable diseases is 




(i) ant

(ii) Housefly✔️

(iii) Dragonfly

(iv)Spider


(e) The bread or idli dough rises because of


because of

(i) Heat

(ii) grinding

(iii) Growth of yeast cells✔️

(iv) kneading




(f) The process of conversion of sugar into alcohol is called


(i) nitrogen fixation

(ii) Moulding

(iii) fermentation✔️

(iv) infection




3. Match the organisms in Column A with their action in Column B.



Column A.                                       Column B



(i) Bacteria.                                     (a) Fixing

                                                            nitrogen




(ii) Rhizobium.                             (b) setting                   

                                                         Of curd





(iii) lactobacillus.                     (c) baking of          

                                                              Bread






(iv) Yeast                                  (d) causing       

                                                           malaria




(v) A protozoan.                      (e) causing              

                                                       cholera





(vi)A virus.                                 (f) causing  

                                                           AIDS





Solution 


(a) ➡️➡️  (e) causing cholera

(b)➡️➡️   (a) fixing nitrogen

(c)➡️➡️   (b)  setting of curd   

(d)➡️➡️   (c) baking of bread

(e)➡️➡️   (d) causing malaria

(f)➡️➡️    (f) causing AIDS























4. Can microorganisms be seen with the naked eye? If not, how can they be seen ?


 Answer. No Microorganisms can be seen with a magnifying glass or a microscope.







5. What are the major groups of microorganisms ? 


Answer. Major groups of microorganisms are: Bacteria, Fungi. Algae, Protozoa and virus.





6. Name the microorganisms which can fix atmospheric nitrogen in the soil.


Ans.• Blue-green Algae

        • Symbiotic bacteria.






7. Write 10 lines on the usefulness of microorganisms in our lives. 



Answer. •they are used in soil to make      fertile

•used in some food preparation

 • used in biology laboratories

 • used in some industries for production

• some microorganisms are also used in    the preparation of medicines they are  used in keeping the environment clean

used in research centers used in manufacturing

•they help in digestion process

•they are also help in providing immune system






8. Write a short paragraph on the harms caused by microorganisms. 


Answer.Micro-organisms such as bacteria cause diseases like typhoid, tuberculosis,cholera, etc. fungi cause the rusting of wheat and it also spoils food

algae produces toxins which are harmful to aquatic lifeprotozoa causes diseases like dysentery and malariaviruses cause cold and influenza(flu)






9.What are antibiotics? What precaution must be taken while taking antibiotics?




Ans. The chemicals produced by certain microorganisms which inhibit the growth of microorganisms are called antibiotics.


• Antibiotics should be taken only on the advise of a doctor 

• Do not take antibiotics, if not needed. In such a situation, the antibiotics may kill helpful






1. Fill in the blanks :


(a) Microorganisms can be seen with the help of a_____________________________.


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


(c) Alcohol is produced with the help of _______________________ .




 (d) Cholera is caused by____________________








Ans. (a) microscope

          (b) nitrogen

          (c) yeast

           (d) bacteria









2. Tick the correct answer :


(a) Yeast is used in the production of


(i) sugar

(ii) alcohol. ✔️

(iii) Hydrochloric acid

(iv) oxygen






(b) The following is an antibiotic.


(i) Sodium bicarbonate

(ii) Streptomycin✔️

(iii) Alcohol

(iv) Yeast 







(c) Carrier of malaria-causing protozoan is 


(i) female Anopheles mosquito ✔️

(ii) cockroach

(iii) Housefly

(iv) butterfly






(d) The most common carrier of communicable diseases is 




(i) ant

(ii) Housefly✔️

(iii) Dragonfly

(iv)Spider


(e) The bread or idli dough rises because of


because of

(i) Heat

(ii) grinding

(iii) Growth of yeast cells✔️

(iv) kneading




(f) The process of conversion of sugar into alcohol is called


(i) nitrogen fixation

(ii) Moulding

(iii) fermentation✔️

(iv) infection




3. Match the organisms in Column A with their action in Column B.



Column A.                                       Column B



(i) Bacteria.                                     (a) Fixing

                                                            nitrogen




(ii) Rhizobium.                             (b) setting                   

                                                         Of curd





(iii) lactobacillus.                     (c) baking of          

                                                              Bread






(iv) Yeast                                  (d) causing       

                                                           malaria




(v) A protozoan.                      (e) causing              

                                                       cholera





(vi)A virus.                                 (f) causing  

                                                           AIDS





Solution 


(a) ➡️➡️  (e) causing cholera

(b)➡️➡️   (a) fixing nitrogen

(c)➡️➡️   (b)  setting of curd   

(d)➡️➡️   (c) baking of bread

(e)➡️➡️   (d) causing malaria

(f)➡️➡️    (f) causing AIDS























4. Can microorganisms be seen with the naked eye? If not, how can they be seen ?


 Answer. No Microorganisms can be seen with a magnifying glass or a microscope.







5. What are the major groups of microorganisms ? 


Answer. Major groups of microorganisms are: Bacteria, Fungi. Algae, Protozoa and virus.





6. Name the microorganisms which can fix atmospheric nitrogen in the soil.


Ans.• Blue-green Algae

        • Symbiotic bacteria.






7. Write 10 lines on the usefulness of microorganisms in our lives. 



Answer. •they are used in soil to make      fertile

•used in some food preparation

 • used in biology laboratories

 • used in some industries for production

• some microorganisms are also used in    the preparation of medicines they are  used in keeping the environment clean

used in research centers used in manufacturing

•they help in digestion process

•they are also help in providing immune system






8. Write a short paragraph on the harms caused by microorganisms. 


Answer.Micro-organisms such as bacteria cause diseases like typhoid, tuberculosis,cholera, etc. fungi cause the rusting of wheat and it also spoils food

algae produces toxins which are harmful to aquatic lifeprotozoa causes diseases like dysentery and malariaviruses cause cold and influenza(flu)






9.What are antibiotics? What precaution must be taken while taking antibiotics?




Ans. The chemicals produced by certain microorganisms which inhibit the growth of microorganisms are called antibiotics.


• Antibiotics should be taken only on the advise of a doctor 

• Do not take antibiotics, if not needed. In such a situation, the antibiotics may kill helpful

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