Are you looking for Microorganisms Friend and Foe Extra Questions and Answers, if yes? then you the right place. Here we are providing Microorganisms Friend and Foe Extra Questions and Answers Class 8 Science Chapter 2.
Microorganisms Friend and Foe Extra Questions and Answers Science Chapter 2
Que. 1) Solve the following multiple choice questions-
1) Microorganisms are classified into………………….major groups.
a.) one
b.) two
c.) three
d.) four
Ans. d. four
2) This process of conversion of sugar into alcohol is known as………………
a.) conversation
b.) fermentation
c.) solvation
d.) sublimation
Ans. b. fermentation
3) Pathogens are-
a.) harmful micro- organisms
b.) useful micro- organisms
c.) underground micro- organisms
d.) none of above
Ans. a. harmful micro- organisms
4) Tuberculosis is caused by……………..
a.) bacteria
b.) virus
c.) protozoa
d.) human
Ans. a. bacteria
Que. 2. Answer the following questions in short-
1) Define preservatives.
Ans. chemicals that are used to check the growth of microorganisms in foodstuffs are called preservatives.
2) Who discovered pasteurisation?
Ans. pasteurisation is discovered by Louis Pasteur.
3) Vaccine is discovered by whom?
Ans. Edward Jenner discovered the vaccine
4) What is used in baking industry for making breads, pastries and cakes?
Ans. Yeast is used in baking industry for making breads, pastries and cakes.
Que. 3. Answer the following questions:
1) Name the four major groups of Microorganisms?
Ans. the four major groups of Microorganisms are:
- bacteria,
- fungi,
- protozoa and
- Algae.
2) Where do micro- organisms live?
Ans. micro- organisms live in all types of environment, ranging from ice cold to hot springs; and from hot deserts to marshy lands. They are also found inside the bodies of animals including body of humans.
3) What are antibiotics? Give examples.
Ans. the medicines like penicillium which kill or stop the growth of the disease-causing microorganisms are called as antibiotics.
Streptomycin, tetracycline and erythromycin are examples of antibiotics.
4) Which bacteria is involved in the fixation of nitrogen in leguminous plants? Where does it lives?
Ans. Rhizobium is involved in the fixation of nitrogen in leguminous plants. It lives in root nodules of the leguminous plants.
5) Why nitrogen is an essential constituent?
Ans. nitrogen is part of proteins, chlorophyll, nucleic acids and vitamins. Hence, it is an essential constituent for us as it is a major constituent of biomolecules.
Que. 4. Explain the following:
1) Describe the method of food Preservation by Common Salt.
Ans. Common salt is used to preserve food products such as meat and fish. dry salt inhibits the growth of bacteria over foodstuffs. Meat and fish are covered with dry salt to check the growth of harmful bacteria preventing to food spoilage. Salting is also used to preserve foodstuffs like amla, raw mangoes, tamarind, etc.
2) Why Viruses are different from other Microorganisms? Explain.
Ans. other micro-organisms can reproduce themselves in their natural habitat whereas viruses can reproduce only inside the host organism which can be a bacterium, a plant or an animal cell. Viruses cannot reproduce in absence of the host hence Viruses are different from other Microorganisms
3) One of your friend is affected with typhoid. What preventive measures will you suggest to him?
Ans. I would suggest my friend to maintain the personal hygiene
And good sanitary habits. I will also recommend him to consume properly cooked and healthy food and boiled drinking water. I will also tell him to take medicines timely.
4) What are communicable diseases? Explain with suitable examples.
Ans. Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases. They can also get transmitted by direct contact with an infected person or carried by an animal. Cholera, common cold, chicken pox and tuberculosis are the examples of communicable diseases.
5) Why yeast is used in baking industry?
Ans. Yeast reproduces rapidly in great volume and it produces carbon dioxide during respiration. Bubbles of the carbon dioxide gas fill the dough and it increases the volume of dough. This is the basis of the use of yeast in the baking industry for making breads, pastries and cakes.
Question 2
Who discover Pasteurisation it’s is worng because louis pasteur discover fermentation