Question

Class 8 Science MCQ Questions of Microorganisms: Friend and Foe with Answers?

Answer 1

Students can allude to these Class 8 Science MCQ Questions of Microorganisms: Friend and Foe with Answers and evaluate their preparation level. Modify every one of the ideas effectively by taking assistance from the MCQ Questions for Class 8 Science with Answers are arranged to depend on the most recent exam pattern. 

This includes just the Multiple Choice Questions taken from different significant topics in the section with answers gave. The CBSE Class 8 Science Objective Questions are additionally organized according to the syllabus proposed by CBSE. 

Students can practice the Class 8 Science MCQ Questions of Microorganisms Friend and Foe with Answers will allow them an opportunity to exam their insight and furthermore plan for the test in the most ideal manner.

Practice Class 8 Science MCQ Question chapterwise

1. Alcohol is produced with the help of

(a) sodium chloride
(b) yeast
(c) nitrogen
(d) carbon dioxide

2. Which of the following drug is an antipyretic?

(a) Insulin
(b) Alcohol
(c) Streptomycin
(d) Paracetamol

3. What helps in the rise of bread or dosa dough?

(a) Heat
(b) Grinding
(c) Growth of yeast cells
(d) Low pressure

4. The order of organism is an aquatic food chain is

(a) Bacteria → Seal → Diatom → Fish → Crustacea
(b) Crustacea → Seal → Fish → Polar bear → Diatom
(c) Polar bear → Diatom → Seal → Crustacea
(d) Diatom → Crustacea → Fish → Seal → Bacteria

5. The rod-shaped bacteria are called

(a) Bacillus
(b) Coccus
(c) Vibrio
(d) Spirillum

6. Bacteria present in root nodules of pea

(a) Coli
(b) Plasmodium
(c) Rhizobium
(d) Penicillin

7. Which of the following does not contain chlorophyll?

(a) Fungi
(b) Algae
(c) Bryophyta
(d) Pteridophyta

8. The disease caused by protozoa is

(a) tuberculosis
(b) polio
(c) typhoid
(d) malaria

9. Which of the following does not fix atmospheric nitrogen?

(a) Nostoc
(b) Anabaena
(c) Spirogyra
(d) Azotobacter.

10. The disease caused by fungi is

(a) measles
(b) chickenpox
(c) polio
(d) ringworm

11. Which microorganism causes AIDS?

(a) A protozoa
(b) A bacteria
(c) A virus
(d) An algae

12. Which of the following disease is spread due to bacteria?

(a) Tuberculosis
(b) Measles
(c) Chicken pox
(d) Polio

13. Which of the following is not used as food preservatives?

(a) Salt
(b) Sugar
(c) Vinegar
(d) Methane

14. Concentration of nitrogen remains constant by 

(a) Nitrogen cycle
(b) Thundering and light
(c) Proteins
(d) Both A and B

15. Tiny organisms which cannot be seen with the naked eyes are called

(a) microorganisms
(b) animals
(c) fungi
(d) bacteria

16. Microorganisms that cause disease are also known as

(a) pathogens
(b) fungi
(c) antigen
(d) microbes

17. Bacteria are ______ organisms.

(a) multicellular
(b) unicellular
(c) bicellular
(d) tricellular

18. Medicine that kills or stops the growth of harmful disease-causing microbes is known as

(a) antibiotic
(b) antibody
(c) antigen
(d) vaccine

19. The process in which sugar in the food is transformed into alcohol and carbon dioxide by using microorganisms is known as

(a) transformation
(b) beverage
(c) fermentation
(d) respiration

20. Giardia is 

(a) Ectoparasite
(b) Intracellular parasite
(c) Tissue parasite
(d) Coelozoic parasite

21. The host for malaria-causing protozoan is:

(a) anapheles mosquito
(b) the cow
(c) the earthworm
(d) the tapeworm

22. In Pasteurisation the milk is heated to about:

(a) 100°C
(b) 50°C
(c) 70°C
(d) 110°C

23. Leprosy is caused by:

(a) bacteria
(c) virus
(b) protozoa
(d) fungi

24.  A common preservative used in jam and pickles is

(a) Sodium benzoate
(c) Nitric acid
(b) Sodium Chloride
(d) Copper Sulphate

25. Scientist who discovered fermentation is

(a) Louis pasteur
(b) Alexander fleming
(c) John mendal
(d) Edward jenner

Answer 2

1. Answer: (b) yeast

Explanation: Alcohol is formed when yeast ferments (breaks down without oxygen) the sugars in different food. For example, wine is made from the sugar in grapes, beer from the sugar in malted barley (a type of grain), cider from the sugar in apples, vodka from the sugar in potatoes, beets or other plants.

2. Answer: (d) Paracetamol

Explanation:  Paracetamol (acetaminophen) is N-acetyl-p-aminophenol, which is widely used as an analgesic (pain reliever) and antipyretic (fever reducer).

3. Answer: (c) Growth of yeast cells

Explanation:  Yeast is used as a leavening agent in bread and idli making. A leavening agent or yeast converts sugars present in dough to carbon dioxide and derive energy from this reaction. Due to this, yeast cells grow and dough also expands. When such dough is baked then air pockets formed due to carbon dioxide will give soft and spongy texture to bread and idli. 

4. Answer: (d) Diatom → Crustacea → Fish → Seal → Bacteria

Explanation: The food-chain includes the producer, primary consumer, secondary consumer and decomposers. Diatoms are a major group of algae, and are among the most common types of phytoplankton so are the producers, crustacean belongs to primary consumer, fish is secondary consumer, seal is tertiary and bacteria are decomposers.

5. Answer: (a) Bacillus

Explanation: Spherical bacteria are known as cocci, rod-shaped bacteria are bacilli, and spiral-shaped bacteria are spirilla.

6. Answer: (c) Rhizobium

Explanation: Rhizobium bacteria are found in the root nodules of leguminous plants, such as pulses and pea.

7. Answer: (a) Fungi

Explanation: Fungi do not have chlorophyll in their cells. Therefore they cannot produce food and must depend upon other living or dead things for food. They are heterotrophic and can be classified as saprophytes, parasites, symbionts.They live as saprophytes getting their nourishment from the surroundings and play key role in nature by decomposing dead organisms and releasing their nutrients for reuse by the living. Some live in a mutually beneficial symbiotic relationship with another organism, often a plant. The association of fungus and plant root is called a mycorrhiza.Some fungi are parasitic, causing serious damage to their host.

8. Answer: (d) malaria

Explanation: Malaria is caused by the Plasmodium which is protozoa. So, It is a protozoan disease. Typhoid is caused by bacteria named Salmonella Typhi.

9. Answer: (c) Spirogyra

Explanation: Blue green algae like Nostoc and Anabaena have some thick walled cells, called as heterocysts, which are specialized for nitrogen fixation. Azotobacter  is aerobic, free-living soil microbe, which plays an important role in the nitrogen cycle in nature, fixing atmospheric nitrogen, into ammonium ions. Spirogyra is a free living filamentous green alga.

10. Answer: (d) ringworm

Explanation: Ringworm is an infection of the skin caused by a fungal infection. Ringworm is characterized by the ring-shaped rashes on the skin, itching, yellowing or decolouration of the affected area. It may also result in hair loss, if it infects the areas covered by hair. It is spread through skin contact with infected person.

11. Answer: (c) A virus

Explanation: HIV (human immunodeficiency virus) is a virus that attacks the body's immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome).

12. Answer: (a) Tuberculosis

Explanation: The disease which is caused by bacteria is tuberculosis. Tuberculosis i.e TB is caused by Mycobacterium tuberculosis that most often affects our lungs. it's a curable and preventable disease.

13. Answer: (d) Methane

Explanation: Food preservative spilage of food due to microbial growth. The most commonly used preservatives include table salt, sugar, vegetable oils and sodium benzoate. Sodium hydrogen carbonate and cane sugar are not used as food preservatives.

14. Answer: (d) Both A and B

Explanation: The nitrogen cycle is the process by which the atmospheric nitrogen is fixed into several usable form. Atmospheric nitrogen must be processed, or fixed, to be used by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria known as diazotrophs. The enormous energy of lightning breaks nitrogen molecules and enables their atoms to combine with oxygen in the air forming nitrogen oxides. These dissolve in rain, forming nitrates, that are carried to the earth. 
Thus, Due to constant presence of nitrogen cycle and thundering, concentration of nitrogen remains constant in the atmosphere.

15. Answer: (a) microorganisms

Explanation: Microorganisms are defined as the microscopic bodies which cannot be seen directly with the naked eye. These organisms are of the size in microns. The study that deals with microbes is known as microbiology. There are different types of microbes like bacteria, viruses, fungi, etc.

16. Answer: (a) pathogens

Explanation: Microorganisms that cause disease are collectively called pathogens.

Answer 3

17. Answer: (b) unicellular

Explanation: Bacteria are tiny, single-celled organisms that get nutrients from their environments. Some bacteria are good for our bodies — they help keep the digestive system in working order and keep harmful bacteria from moving in. Some bacteria are used to make medicines and vaccines.

18. Answer: (a) antibiotic

Explanation: Antibiotics, also known as antibacterials, are medications that destroy or slow down the growth of bacteria. They include a range of powerful drugs and are used to treat diseases caused by bacteria.

19. Answer: (c) fermentation

Explanation: Alcoholic fermentation is a biotechnological process accomplished by yeast, some kinds of bacteria, or a few other microorganisms to convert sugars into ethyl alcohol and carbon dioxide.

20. Answer:(a) Ectoparasite

Explanation: Giardia duodenalis is a flagellated parasitic microorganism, that colonizes and reproduce in the small intestine, causing a diarrheal condition known as giardiasis. The parasite attaches to the epithelium by a ventral adhesive disc or sucker and then reproduces by a binary fission.

21. Answer: (a) anapheles mosquito

Explanation: Malaria is a protozoan infection of the red blood cells, transmitted by the bite of a female anopheles mosquito. Malaria is caused by the protozoa of the genus Plasmodium.

22. Answer: (c) 70°C

Explanation: In pasteurisation the milk is heated to about 70°C for 15 to 30 seconds and then suddenly chilled and stored.

23. Answer: (a) bacteria

Explanation: Leprosy (Hansen's Disease) is a chronic infectious disease that primarily affects the peripheral nerves, skin, upper respiratory tract, eyes, and nasal mucosa (lining of the nose). The disease is caused by a bacillus (rod-shaped) bacterium known as Mycobacterium leprae.

24. Answer: (a) Sodium benzoate

Explanation: Sodium benzoate is a common preservative in acid or acidified foods such as fruit juices, syrups, jams and jellies, sauerkraut, pickles, preserves, fruit cocktails, etc.

25. Answer: (a) Louis pasteur

Explanation: Louis Pasteur discovered fermentation in the year 1857. In 1857, Pasteur demonstrated that lactic corrosive aging is caused by living beings. In 1860, he showed that microscopic organisms cause souring in drain, a procedure in the past idea to be just a substance change, and his work in recognizing the job of microorganisms in nourishment decay prompted the procedure of pasteurization.

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