Class 8 Science Chapter 2 MCQ for 2020-21
Class: 8 | Science |
Chapter 2: | MCQ Tests of Microorganism: Friend and Foe |
Class 8 Science Chapter 2 MCQ Tests for Exams
Class 8 Science Chapter 2 MCQ Tests of Microorganism: Friend and Foe with complete explanation and answers. All the questions have four option with one option correct. After attempting you can see the answer and explanation for justification. All the important topics of NCERT Books 8th Science Chapter 2 have been added in these MCQs.
Q1
Consider the following sentences and choose the correct statements.
[A]. Edward Jenner is known for his role in identification of the causing agent of Anthrax.
[B]. Robert Koch discovered the vaccine for smallpox in 1798.
[C]. Louis Pasteur discovered fermentation in 1857 by demonstrating the microbes cause souring of milk.
[D]. All the above
Answer: Option C
Explanation:Robert coach is known for his role in identification of the causing agent of Anthrax. Edward Jenner is known as father of immunology. He discovered the vaccine for smallpox in 1798. Louis Pasteur discovered fermentation in 1857 by demonstrating the microbes cause souring of milk.
Q2
A disease in human beings caused by virus is
[A]. Typhoid
[B]. Influenza
[C]. Dysentery
[D]. Cholera
Answer: Option B
Explanation:Influenza is an infectious disease caused by the influenza virus. It is also known as flu symptoms include high fever, running nose, sore throat, headache, coughing and muscles pain etc. Typhoid, dysentery and cholera are bacterial infections.
Q3
Pathogenic microorganisms present in host cells are killed by medicines called
[A]. Pain killer
[B]. Antibodies
[C]. Antibiotics
[D]. Vaccines
Answer: Option C
Explanation:Antibiotics are substances that may inhibit or kill the growth of different microbes. Microorganisms causing infection in host bodies are killed by consumption of these antibiotics.
Q4
A disease “Tetanus” is caused by which bacteria:
[A]. Clostridium tetani
[B]. Vibrio cholerae
[C]. Salmonella typhi
[D]. Mycobacterium tuberculosis
Answer: Option A
Explanation:In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).
Q5
The two microorganisms which live in symbiotic association in lichens are
[A]. Fungus and protozoa
[B]. Algae and bacteria
[C]. Bacteria and protozoa
[D]. Algae and fungus
Answer: Option D
Explanation:Lichens is an association between fungal and an algal species. It is a mutually benefiting association where algae provide food to the fungus and in return gets shelter from it.
Q6
In which of the following human diseases are caused by viruses?
[A]. Measles
[B]. Polio
[C]. Chicken Pox
[D]. All the above
Answer: Option D
Explanation:Measles is caused by infection with the rubeola virus. The virus lives in the mucus of the nose and throat of an infected child or adult. Poliomyelitis is an acute communicable disease of humans. Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over.
Q7
In which of the following human disease is or are caused by bacteria?
[A]. Typhoid
[B]. Cholera
[C]. Tuberculosis
[D]. All the above
Answer: Option D
Explanation:Typhoid is a bacterial infection that can lead to a high fever, diarrhea, and vomiting. It can be fatal. It is caused by the bacteria Salmonella typhi. Cholera is an infectious disease that causes severe watery diarrhea, which can lead to dehydration and even death if untreated. It is caused by eating food or drinking water contaminated with a bacterium called Vibrio cholerae.
Tuberculosis (TB) develops when Mycobacterium tuberculosis bacteria are inhaled into the lungs. The infection usually stays in the lungs.
Q8
In which of the following statement is or are incorrect?
[A]. We should avoid eating covered food items.
[B]. The food should always be kept covered.
[C]. We should not leave household garbage here and there.
[D]. Some of disease can be prevented by vaccination.
Answer: Option A
Explanation:We should avoid eating uncovered food items. Rest of all are correct. Hence, your answer will be option [A].
Q9
The precaution is observed in the use of antibiotics. Choose the incorrect sentence(s):
[A]. Antibiotic may kill the useful bacteria in the body and harm us.
[B]. Wrong dose of antibiotics makes the antibiotic less effective.
[C]. Antibiotics should be taken only on the advice of perfect doctor.
[D]. None of the above
Answer: Option C
Explanation:Antibiotics should be taken only on the advice of “Qualified Doctor”. Qualified doctor means a person who is legally qualified to practice medicine; doctor of medicine. In the other words, a person who engaged in general medical practice, as distinguished from one specializing in surgery.
Q10
A disease “Tetanus” is caused by which bacteria:
[A]. Clostridium tetani
[B]. Vibrio cholerae
[C]. Salmonella typhi
[D]. Mycobacterium tuberculosis
Answer: Option A
Explanation:In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).
Types of Fungi
Yeasts: | Unicellular organisms. |
Moulds: | Multi cellular organisms. |
Mushrooms: | Multi cellular organisms. |
Maldews: | Unicellular organisms. |
The Common Characters of Viruses
- They are the smallest living organisms.
- They do not have a cellular structure.
- They have a simple structure, consisting of a small piece of Nucleic Acid (either DNA or RNA), surrounded by a protein coat.
- They are on the boundary between living and non-living.
Discovery of Viruses
In 1852, a Russian botanist D.I. Ivanovsky discovered viruses from tobacco plants. These viruses were named as TMV (Tabacco Mosaic Viruses). Viruses are the smallest living organisms, ranging in size from about 20-300 mm on average. They cannot be seen with the simple microscope. They pass through filters which retain bacteria.
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What is micro-biology?
There is a world of living organisms which cannot be seen with the naked eyes. They can be seen only through a microscope. Microorganisms are often described as single -celled or unicellular organisms, but there are certain species that are multi-cellulars. The study of micro-organisms is called micro-biology.
What are Extremophiles?
Micro-organisms are found in a variety of places, and they can survive in extremely harsh environmental
conditions. Some types of micro-organisms have adapted to the extreme conditions and sustained colonies; these organisms are known as Extremophiles.
What is Bacteriology?
Becteria are microscopic, unicellualar organisms. They are often coocus -(Spherical) or red-shaped and 0.5- 51/m in the longest dimension. The study of bacteria is known as Bacteriology.
What are Pathogens?
Some micro-organisms are useful to us in many ways, while some are definitely harmful since they cause diseases. The microorganisms which cause disease are known as Pathogens.