Science Quiz

Class 8 Science Chapter 2 MCQ

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Important Multiple choice questions from chapter 2 Microorganisms: Friend and Foe of CBSE Class 8 Science. This article covers all the questions from this chapter. These questions are important for your school exam and also for future competitive exams. Each questions have been taken from NCERT. So, try to answer all these questions.

 

Science Quiz for Class 8

Question 1
Which of the following reproduces only inside a host cell?
A
Virus
B
Bacteria
C
Fungus
D
Amoeba
Question 1 Explanation: 
Virus reproduce only inside the cells of the host organisms like bacterium, plant or animal.
Question 2
Which microorganism is used in the production of alcohol?
A
Bacteria
B
Algae
C
Protozoa
D
Yeasts
Question 2 Explanation: 
Yeasts are the main fermentor and alcohol producer in the production of wine, beer and other alcohol drinks. The main yeast species used is Saccharomyces cerevisiae. It ferments the sugars, coming from different sources, e.g., grapes for wine, barley for beer, to alcohol and carbon dioxide.
Question 3
Which type of mosquito causes malaria?
A
Female Aedas Mosquito
B
Female Anopheles Mosquito
C
yellow fever mosquito
D
Asian tiger mosquito
Question 3 Explanation: 
Malaria is transmitted to humans by female mosquitoes of the genus Anopheles. Female mosquitoes take blood meals for egg production, and these blood meals are the link between the human and the mosquito hosts in the parasite life cycle.
Question 4
Acetic acid and lactic acid are used for __________________
A
curing meats
B
preservation of color
C
preservation of pickles
D
inhibiting mold growth
Question 4 Explanation: 
Foods prepared from fermentation processes,e.g., sauerkraut, pickles, and silage for animals are preserved mainly by acetic, lactic and propionic acids produced during the microbial fermentation.
Question 5
Which chemical is used to inhibit mold growth in bread?
A
benzoic acid
B
nitrates
C
sorbic acid
D
lactic acid
Question 5 Explanation: 
Sorbic acid and propionic acid are used to inhibit mold growth in bread. They are organic in nature.
Question 6
Plant disease 'citrus canker' is caused by which microorganisms?
A
Bacteria
B
Fungi
C
Virus
D
Amoeba
Question 6 Explanation: 
Citrus canker is a serious bacterial disease of commercial varieties of citrus, and relatives, caused by the bacterium Xanthomonas citri subsp. citri. The disease affects the leaves, twigs and fruit causing the leaves to drop and fruit to fall to the ground before it ripens.
Question 7
Rhizobium, the organism found in root nodules of legumes are
A
Bacteria
B
Fungi
C
Lichen
D
Algae
Question 7 Explanation: 
Rhizobium is a genus of bacteria associated with the formation of root nodules on plants. These bacteria live in symbiosis with legumes. They take in nitrogen from the atmosphere and pass it on to the plant, allowing it to grow in soil low in nitrogen.
Question 8
Who discovered the process of fermentation?
A
Edward Jenner
B
Louis Pasteur
C
Jonas Salk
D
William Harvey
Question 8 Explanation: 
Louis Pasteur discovered that microbes were responsible for souring alcohol and came up with the process of pasteurization, where bacteria are destroyed by heating beverages and then allowing them to cool. His work in germ theory also led him and his team to create vaccinations for anthrax and rabies.
Question 9
What is shape of an amoeba?
A
Spherical
B
Elongated
C
Spiral
D
No definite shape
Question 9 Explanation: 
An amoeba has no definite shape. If it wants to move somewhere it can extend part of its body in the appropriate direction to form a temporary foot, or pseudopod.
Question 10
Which microorganism is responsible for causing rust of wheat?
A
Bacteria
B
Protozoa
C
Virus
D
Fungi
Question 10 Explanation: 
Leaf rust, also known as brown rust, is caused by the fungus Puccinia triticina. This rust disease occurs wherever wheat, barley and other cereal crops are grown.
Question 11
Yeast are used in making bread and alcohol beverages.  It is a kind of_______________
A
Bacteria
B
Fungi
C
Protist
D
Virus
Question 11 Explanation: 
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species.
Question 12
Nitrogen is absorbed by the plants in the form of__________
A
Ammonium
B
Nitrites
C
Nitrates
D
All of the above
Question 12 Explanation: 
Nitrogen assimilation in plants. Plants absorb nitrogen from the soil in the form of nitrate (NO3−) and ammonium (NH4+). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed.
Question 13
Rhizobium bacteria live in the root nodules of which plant?
A
Parasponia
B
Legumes
C
Brassicas
D
mustards
Question 13 Explanation: 
Well-known legumes include alfalfa, clover, beans, peas, chickpeas, lentils, lupins, mesquite, carob, soybeans, peanuts, and tamarind. Legumes produce a botanically unique type of fruit – a simple dry fruit that develops from a simple carpel and usually dehisces (opens along a seam) on two sides.
Question 14
The circulation of nitrogen between organisms and the atmosphere is called the________________
A
Nitrogen Fixation
B
Eutrophication
C
Nitrogen Cycle
D
Kreb's Cycle
Question 14 Explanation: 
Nitrogen (N) is an essential component of DNA, RNA, and proteins, the building blocks of life. The movement of nitrogen between the atmosphere, biosphere, and geosphere in different forms is called the nitrogen cycle (Figure 1), one of the major biogeochemical cycles.
Question 15
The bread or idli dough rises because of___________
A
heat
B
grinding
C
kneading
D
growth of yeast cells
Question 15 Explanation: 
Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume. This is the basis of the use of yeast in the baking industry for making breads, pastries and cakes.
Question 16
Dengue is caused by which mosquito?
A
Culex mosquitoes
B
Female Aedes aegypti mosquito
C
Culex pipiens
D
Culiseta annulata
Question 16 Explanation: 
The Aedes aegypti mosquito is the main vector that transmits the viruses that cause dengue. The viruses are passed on to humans through the bites of an infective female Aedes mosquito, which mainly acquires the virus while feeding on the blood of an infected person.
Question 17
Penicillin was discovered by which scientist?
A
Robert Koch
B
Edward Jenner
C
Louis Pasteur
D
Alexander Fleming
Question 17 Explanation: 
Fleming discovered the mould was effective against bacteria that caused diseases such as anthrax, meningitis and diphtheria. He published his discoveries but did not have the resources to experiment more widely with penicillin.
Question 18
'Yellow vein mosaic of bhindi (okra)' caused by which microorganism?
A
Virus
B
Fungi
C
Bacteria
D
Protist
Question 18 Explanation: 
Yellow vein mosaic disease is the major limitation in the production of bhendi or okra, an important vegetable crop of India.
Question 19
A Disease “Tetanus” Is Caused By Which Bacteria:
A
Vibrio cholerae
B
Mycobacterium tuberculosis
C
Salmonella typhi
D
Clostridium tetani
Question 19 Explanation: 
Tetanus is an infection caused by a bacterium called Clostridium tetani. Spores of tetanus bacteria are everywhere in the environment, including soil, dust, and manure.
Question 20
A disease called "measles" caused by which virus:
A
Hepatitis B virus
B
Influenza B virus
C
Rubeola virus
D
Norwalk virus
Question 20 Explanation: 
Measles is caused by Rubeola virus, which belongs to the Paramyxovirus family. Measles is an acute systemic viral infection with fever, respiratory involvement and symptoms, and a rash. Measles can cause serious complications and even fatalities. Infection confers lifelong immunity.
There are 20 questions to complete.

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