Sunday, May 10, 2015

Microorganisms friend and Foe class 8 Solved Questions answer

Q. Viruses are considered as being on the border line between living and non-living organisms,Why?
Ans: Viruses is nonliving out side living cells but grows and multiplies inside living cell so,viruses are considered as being on the border line between living and non-living organisms.The study of viruses is called Virology.

Questions: What does Sargasso Sea woe its name to?
Ans: Sargasso Sea woe its name to Sargassum, a particular sea weeds that grow abundantly in sea. Sailor avoids this sea as their boat stuck in the tangled mass of seaweeds.

Questions: What are the difference between the cell of bacteria and the cell of other living body?
Ans: The difference between the cell of bacteria and the cell of other living body are

(i) Cell wall is not made up of cell wall

(ii) Do not have nucleus

(iii)Does not have membrane bound organelles

Questions: Do red and brown algae have chlorophyll?
Ans: Yes, red and brown algae have pigment of colour which cover the colour of chlorophyll and make them appear red brown or yellowish

Questions: Name a protozoon which can photosynthesize?
Ans: Euglena contain chlorophyll and can photosynthesise, lack of cell wall

Questions: How do bacteria reproduce?
Ans: Bacteria reproduce by binary fission

Question: What are antibiotics? What precautions must be taken while taking antibiotics?
Answer: Antibioticsare medicines produced by certain micro­organisms to kill other diseasecausing micro­organisms. These medicines are commonly obtained from bacteria and fungi. Streptomycin, tetracycline, penicillin, etc. are common antibiotics.

Precautions to be taken while using antibiotics:

(i) Antibiotics should be taken under the supervision of a well qualified doctor.
(ii) Course (intake) of antibiotics should be completed as per the prescription given by the doctor.
(iii) Antibiotics should be taken in the right amount and at the right time. A wrong dose of antibiotics makes the drug ineffective. Also, excessive consumption of drugs may kill the useful bacteria present in our body.

Question: Why do bacteria classified under plants?
Ans: The cell of bacteria is covered by protective layer called cell wall. This is the reason because which bacteria classified under plants.
Sometime bacteria passing through adverse condition, they developed additional protective wall called cyst around them. The process of the formation of cyst is called encystment.

Question: Which protozoan exhibits both characteristics of plants and animals?
Ans: Euglena

Question: what are retroviruses?
Ans: viruses lack of cellular structure like cytoplasm and organelles. they only consist of DNA and RNA encompassed by a protein layer called capsid. viruses carring RNA are called retroviruses.

Question: what are chemosynthetic bacteria
Ans: Bacteria that obtain energy required for metabolic processes from exothermic oxidation of inorganic or simple organic compounds without the aid of light.

Question: what are viruses that infect bacteria

Ans: Bacteriophage is a virus that infects and replicates within a bacterium.

Question: Why is it difficult to prepared vaccine for diseases caused by viruses?
Ans: viruses are difficult to be grown in an artificial nutrient medium . Hence, it difficult to prepared vaccine for diseases caused by viruses.

Question: Why do some bacteria and fungi considered as natural purifier?
Ans: some bacteria and fungi decompose the dead organic matter and therefore called natural purifier

Question: Why are legumes plants considered important in crop rotation?
Rhizobium bacteria present in the root nodules of legumes plants fix the atmospheric nitrogen ad maintain the fertility of soil.

Usefull links by jsuniltutorialMicroorganisms- : 

  • Objective Questions 
  • Microorganisms- : Notes 
  • Microorganisms- : MCQ 's 
  • Microorganisms : Test Paper-1 
  • Microorganisms : Test Paper -2 
  • Basic science solved Questions 

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