MICROBES IN HUMAN WELFARE MCQs for NEET UG BIOLOGY — Easy

1 Easy

1 of 35

Understanding +4 | -1

Assertion (A): Streptokinase acts as a clot-buster.

Reason (R): Streptokinase is given to patients who have undergone myocardial infarction.

View answer and explanation

Correct option: B

Both (A) and (R) are true and (R) is not correct explanation of (A)

Option B is correct because both the assertion and the reason are true, but the reason is not the correct explanation of the assertion. Streptokinase is a clot-buster and is used in myocardial infarction, but the reason doesn't fully explain the mechanism.

Solution approach

Correct Answer + Core Reason: Both (A) and (R) are true and (R) is not correct explanation of (A). Streptokinase is a clot-buster used in myocardial infarction, but the reason doesn't fully explain the mechanism.

Step-by-Step Solution:

Step 1: Analyze the assertion: Streptokinase acts as a clot-buster. This is true.

Step 2: Analyze the reason: Streptokinase is given to patients who have undergone myocardial infarction. This is also true.

Step 3: Determine if the reason correctly explains the assertion. While streptokinase is used in myocardial infarction because it's a clot-buster, the reason doesn't fully explain *how* it acts as a clot-buster (by activating plasminogen).

Step 4: Conclude that both A and R are true, but R is not the correct explanation of A.

Why other options are wrong:
- Option A: The reason is not a complete explanation.
- Option C: The reason is true, not incorrect.
- Option D: The assertion is true, not incorrect.

Key Concepts:
- Streptokinase
- Myocardial infarction
- Thrombolytic agents

Memory Aids:
- Streptokinase = Clot-buster

Quick Tips:
- Carefully evaluate the relationship between assertion and reason.

2 Easy

2 of 35

Remembering +4 | -1

During the primary treatment of sewage, solid particles that settle down are called

View answer and explanation

Correct option: C

Primary sludge

Option C (Primary sludge) is correct because the solid particles that settle down during the primary treatment of sewage are called primary sludge.

Solution approach

Correct Answer + Core Reason: Primary sludge. The solid particles settling during primary treatment are termed primary sludge.

Step-by-Step Solution:

Step 1: Define the term \"sludge\" in the context of sewage treatment.

Step 2: Understand that primary sludge is the solid material that settles out during the primary treatment phase.

Step 3: Differentiate primary sludge from other types of sludge formed in subsequent treatment stages.

Why other options are wrong:
- Option A: Activated sludge is formed during secondary treatment.
- Option B: Secondary sludge is a general term for sludge from secondary treatment, but the initial sludge is \"primary.\"
- Option D: Anaerobic sludge is sludge that has undergone anaerobic digestion.

Key Concepts:
- Sewage treatment
- Primary treatment
- Primary sludge
- Sedimentation

Memory Aids:
- Associate \"primary\" with the first stage and \"primary sludge\" with the solids from that stage.

Quick Tips:
- Keep track of the different types of sludge formed during each stage of sewage treatment.

3 Easy

3 of 35

Remembering +4 | -1

The most common indicator organism that represents polluted water is

View answer and explanation

Correct option: A

E.coli

Option A (E.coli) is correct because E. coli is a common indicator organism used to represent polluted water, indicating fecal contamination.

Solution approach

Correct Answer + Core Reason: E.coli. E. coli is a widely used indicator organism for water pollution, specifically fecal contamination.

Step-by-Step Solution:

Step 1: Define the concept of an indicator organism in water quality assessment.

Step 2: Understand that E. coli is a bacterium commonly found in the intestines of humans and animals.

Step 3: Recognize that the presence of E. coli in water indicates fecal contamination, which may carry other pathogens.

Why other options are wrong:
- Option B: P.typhi causes typhoid fever but is not a general indicator of pollution.
- Option C: C.vibrio includes species that cause cholera, but it's not a general indicator.
- Option D: Entamoeba causes amoebic dysentery but is not a general indicator of pollution.

Key Concepts:
- Water pollution
- Indicator organism
- Fecal contamination
- E. coli

Memory Aids:
- Remember E. coli as a common indicator of fecal contamination in water.

Quick Tips:
- Learn the common indicator organisms used in environmental monitoring.

4 Easy

4 of 35

Understanding +4 | -1

Pollution from animal excreta and organic waste from kitchen can be most profitably minimised by

View answer and explanation

Correct option: B

Using them for producing biogas

The correct answer is B (Using them for producing biogas) because biogas production is an efficient way to convert organic waste into a valuable energy source while minimizing pollution.

Solution approach

Correct Answer + Core Reason: Using them for producing biogas. This converts waste into a valuable energy source and reduces pollution.

Step-by-Step Solution:

Step 1: Animal excreta and kitchen waste are rich in organic matter.

Step 2: Biogas production involves the anaerobic digestion of organic matter by methanogens, producing methane-rich biogas.

Step 3: This process reduces the volume of waste, minimizes pollution, and generates a renewable energy source.

Why other options are wrong:
- Option A: Storing waste in underground tanks only contains the pollution but does not eliminate it or provide any benefit.
- Option C: Vermiculture (using earthworms) is useful for composting but less efficient for large-scale waste management and energy production compared to biogas.
- Option D: Using them directly as biofertilizers can be beneficial, but it doesn't address the pollution potential and may not be suitable for all types of waste.

Key Concepts:
- Biogas production
- Anaerobic digestion
- Waste management

Memory Aids:
- Biogas \"digests\" waste and produces gas for energy.

Quick Tips:
- Consider the environmental and economic benefits of different waste management strategies.

5 Easy

5 of 35

Remembering +4 | -1

Toddy is formed by the fermentation of

View answer and explanation

Correct option: A

Sap from palms

Option A (Sap from palms) is correct because Toddy is a traditional alcoholic beverage made by fermenting the sap of palm trees.

Solution approach

Correct Answer + Core Reason: Sap from palms. Toddy is made by fermenting sap from palm trees.

Step-by-Step Solution:

Step 1: Toddy is an alcoholic beverage.

Step 2: It is made by fermenting the sap of various palm trees.

Why other options are wrong:
- Option B: Soyabean is used to make soy sauce and other products, not toddy.
- Option C: Fishes are not used to make toddy.
- Option D: Bamboo shoots are used in cooking, not to make toddy.

Key Concepts:
- Fermentation
- Alcoholic beverages
- Toddy production

Memory Aids:
- Toddy = Palm sap

Quick Tips:
- Know the raw materials used for different fermented beverages.

6 Easy

6 of 35

Remembering +4 | -1

Saccharomyces cerevisiae is used for commercial production of

View answer and explanation

Correct option: B

Ethanol

Option B (Ethanol) is correct because *Saccharomyces cerevisiae* is widely used in the commercial production of ethanol through fermentation.

Solution approach

Correct Answer + Core Reason: Ethanol. Saccharomyces cerevisiae is used for the commercial production of ethanol.

Step-by-Step Solution:
Step 1: Recall the uses of Saccharomyces cerevisiae.
Step 2: Relate Saccharomyces cerevisiae to ethanol production. Saccharomyces cerevisiae, also known as baker's yeast or brewer's yeast, is used in the fermentation process to produce ethanol from sugars.

Why other options are wrong:
- Option A: Butanol is produced by other bacteria, not primarily Saccharomyces cerevisiae.
- Option C: Methanol is not produced by Saccharomyces cerevisiae.
- Option D: Acetic acid can be produced by bacteria, but Saccharomyces cerevisiae is not the primary organism used for its commercial production.

Key Concepts:
- Saccharomyces cerevisiae
- Fermentation
- Ethanol production

Memory Aids:
- Saccharomyces cerevisiae: Ethanol (alcohol)

Quick Tips:
- Remember the role of Saccharomyces cerevisiae in ethanol production.

7 Easy

7 of 35

Understanding +4 | -1

Methanogenic bacteria are not found in;

View answer and explanation

Correct option: D

flocs.

Option D (flocs) is correct because methanogenic bacteria are anaerobic and are not found in flocs, which are aerobic microbial masses in activated sludge.

Solution approach

Correct Answer + Core Reason: flocs. Methanogens are anaerobic and not found in aerobic flocs.

Step-by-Step Solution:
Step 1: Recall the characteristics of methanogenic bacteria.
Step 2: Remember that methanogens are anaerobic.
Step 3: Consider the environments listed in the options.
Step 4: Recognize that flocs are aerobic microbial masses.
Step 5: Conclude that methanogens are not found in flocs.

Why other options are wrong:
- Option A: rumen of cattle: The rumen is an anaerobic environment where methanogens are found.
- Option B: gobar gas plant: Gobar gas plants utilize methanogens to produce biogas.
- Option C: anaerobic sludge digester: Anaerobic sludge digesters are designed for methanogenesis.

Key Concepts:
- Methanogenesis
- Methanogenic bacteria
- Anaerobic conditions
- Flocs

Memory Aids:
- \"Methano\" means methane, and methane production happens without air (anaerobically).

Quick Tips:
- Remember that methanogens are strictly anaerobic.

8 Easy

8 of 35

Remembering +4 | -1

Yeast is an important source of

View answer and explanation

Correct option: A

Riboflavin

Option A (Riboflavin) is correct because yeast is a rich source of B vitamins, including riboflavin (vitamin B2).

Solution approach

Correct Answer + Core Reason: Riboflavin. Yeast is a good source of riboflavin (Vitamin B2).

Step-by-Step Solution:

Step 1: Yeast is a single-celled fungus used in various food and industrial processes.

Step 2: Yeast is a rich source of B vitamins, especially riboflavin.

Why other options are wrong:
- Option B: Yeast is not a primary source of ascorbic acid (Vitamin C).
- Option C: While yeast contains carbohydrates, it is not its primary nutritional benefit.
- Option D: Yeast contains proteins, but it is better known for its vitamin content.

Key Concepts:
- Nutritional value of yeast
- Vitamins
- Riboflavin

Memory Aids:
- Yeast = B vitamins

Quick Tips:
- Know the nutritional benefits of common microorganisms.

9 Easy

9 of 35

Remembering +4 | -1

Primary treatment is the

View answer and explanation

Correct option: A

Physical removal of large and small particles from sewage

Option A (Physical removal of large and small particles from sewage) is correct because primary treatment involves physical processes like sedimentation and filtration to remove solids.

Solution approach

Correct Answer + Core Reason: Physical removal of large and small particles from sewage. Primary treatment focuses on the physical separation of solids from sewage.

Step-by-Step Solution:

Step 1: Define primary treatment in sewage treatment.

Step 2: Understand that primary treatment involves physical processes like screening, grit removal, and sedimentation.

Step 3: Recognize that these processes aim to remove large and small solid particles from the sewage.

Why other options are wrong:
- Option B: Biological removal occurs in secondary treatment, not primary.
- Option C: Primary treatment is only physical, not biological.
- Option D: Chemical removal is not the primary focus of primary treatment, although chemicals may be used in later stages.

Key Concepts:
- Sewage treatment
- Primary treatment
- Physical separation
- Sedimentation
- Filtration

Memory Aids:
- Think of \"primary\" as the first step, which involves physical removal.

Quick Tips:
- Remember the order of sewage treatment stages: primary, secondary, and tertiary.

10 Easy

10 of 35

Remembering +4 | -1

Cheese and yoghurt are products of

View answer and explanation

Correct option: B

Fermentation

Option B (Fermentation) is correct because cheese and yogurt production relies on the fermentation of milk by specific bacteria.

Solution approach

Correct Answer + Core Reason: Fermentation. Cheese and yogurt are produced through fermentation.

Step-by-Step Solution:

Step 1: Understand the process of cheese and yogurt production. Both involve the use of microorganisms to convert milk sugars into lactic acid.

Step 2: Define fermentation. Fermentation is the process of using microorganisms to convert a substance into another substance.

Step 3: Relate fermentation to cheese and yogurt. Bacteria ferment lactose (milk sugar) into lactic acid, which causes milk to coagulate and form cheese or yogurt.

Step 4: Conclusion: Cheese and yogurt are products of fermentation.

Why other options are wrong:
- Option A: Pasteurization is a heat treatment to kill harmful bacteria, but it doesn't produce cheese or yogurt.
- Option C: Dehydration is the removal of water, not the primary process in cheese or yogurt production.
- Option D: Distillation is a process of separating liquids based on boiling points, not used in cheese or yogurt production.

Key Concepts:
- Fermentation
- Cheese production
- Yogurt production
- Lactic acid bacteria

Memory Aids:
- Milk + Bacteria = Fermentation = Cheese/Yogurt

Quick Tips:
- Fermentation is key to many food production processes.

11 Easy

11 of 35

Remembering +4 | -1

The residue left after methane production from cattle dung is

View answer and explanation

Correct option: C

Used as manure

Option C (Used as manure) is correct because the residue from biogas production is rich in nutrients and can be used as a fertilizer.

Solution approach

Correct Answer + Core Reason: Used as manure. The residue is nutrient-rich and good for soil.

Step-by-Step Solution:

Step 1: Understand the process. Methane production from cattle dung involves anaerobic digestion.

Step 2: Identify the residue. The residue left after methane production contains undigested organic matter and nutrients.

Step 3: Determine the use of the residue. This residue is rich in nutrients like nitrogen, phosphorus, and potassium, making it suitable as manure.

Step 4: Conclusion: The residue is used as manure.

Why other options are wrong:
- Option A: Burning the residue would release pollutants and waste the nutrients.
- Option B: Burying in landfills is not a sustainable solution and wastes the nutrients.
- Option D: The residue is not suitable for civil construction.

Key Concepts:
- Biogas production
- Anaerobic digestion
- Manure
- Nutrient recycling

Memory Aids:
- Dung -> Biogas -> Manure

Quick Tips:
- Biogas production provides both energy and fertilizer.

12 Easy

12 of 35

Understanding +4 | -1

Which of the following is a wrong matching of a microbe and its industrial product?

View answer and explanation

Correct option: C

Clostridium acedobutylicum – Lactic acid

Option C is the wrong matching because Clostridium acetobutylicum is primarily known for producing butanol and acetone, not lactic acid.

Solution approach

Correct Answer + Core Reason: Clostridium acedobutylicum – Lactic acid. Clostridium acedobutylicum produces butanol and acetone, not lactic acid.

Step-by-Step Solution:

Step 1: Review the industrial products of different microbes.

Step 2: Identify the products of Acetobacter aceti, Aspergillus niger, Yeast, and Clostridium acedobutylicum.

Step 3: Determine that Clostridium acedobutylicum primarily produces butanol and acetone.

Step 4: Conclude that the matching of Clostridium acedobutylicum with lactic acid is incorrect.

Why other options are wrong:
- Option A: Yeast produces statins (e.g., Monascus purpureus).
- Option B: Acetobacter aceti produces acetic acid (vinegar).
- Option D: Aspergillus niger produces citric acid.

Key Concepts:
- Industrial microbiology
- Microbial products

Memory Aids:
- Acetobacter = Acetic acid
- Aspergillus = Citric acid

Quick Tips:
- Memorize the common industrial products of important microbes.

13 Easy

13 of 35

Remembering +4 | -1

Which of the given household product is obtained by using only bacteria?

View answer and explanation

Correct option: C

Dosa

Option C (Dosa) is correct because the batter used to make dosa is fermented by bacteria.

Solution approach

Correct Answer + Core Reason: Dosa. Dosa batter fermentation relies on bacteria.

Step-by-Step Solution:
Step 1: Consider Bread. Bread uses yeast for fermentation.
Step 2: Consider Toddy. Toddy uses yeast for fermentation.
Step 3: Consider Dosa. Dosa uses bacteria for fermentation.
Step 4: Consider Roquefort cheese. Roquefort cheese uses fungi (Penicillium) for ripening.

Why other options are wrong:
- Option A: Bread uses yeast, not only bacteria.
- Option B: Toddy uses yeast, not only bacteria.
- Option D: Roquefort cheese uses fungi, not bacteria.

Key Concepts:
- Fermentation
- Role of bacteria and yeast in food production

Memory Aids:
- Dosa: Bacteria
- Bread & Toddy: Yeast
- Cheese: Fungi

Quick Tips:
- Remember common examples of fermentation by bacteria and yeast.

14 Easy

14 of 35

Understanding +4 | -1

Identify the mismatched pair.

View answer and explanation

Correct option: C

Streptokinase - Blood-cholesterol lowering agent.

Option C is the mismatched pair because Streptokinase is a clot-buster (thrombolytic agent), not a blood-cholesterol lowering agent.

Solution approach

Correct Answer + Core Reason: Streptokinase - Blood-cholesterol lowering agent. Streptokinase is a clot-buster, not a cholesterol-lowering agent.

Step-by-Step Solution:

Step 1: Review the functions of the given substances.

Step 2: Identify the role of Streptokinase in dissolving blood clots.

Step 3: Recognize that Streptokinase is not involved in lowering blood cholesterol levels.

Step 4: Conclude that the pair Streptokinase - Blood-cholesterol lowering agent is mismatched.

Why other options are wrong:
- Option A: Saccharomyces cerevisiae is used in the production of ethanol.
- Option B: Lipases are used to remove oily stains.
- Option D: Cyclosporin A is an immunosuppressive agent.

Key Concepts:
- Microbial products
- Enzymes and their applications
- Immunosuppressants

Memory Aids:
- Streptokinase = Kills clots

Quick Tips:
- Remember the specific functions of important microbial products.

15 Easy

15 of 35

Remembering +4 | -1

The chemical substances produced by some microbes, which can kill or retard the growth of other microbes are called

View answer and explanation

Correct option: C

Antibiotics

Option C (Antibiotics) is correct because antibiotics are chemical substances produced by microbes that inhibit or kill other microbes.

Solution approach

Correct Answer + Core Reason: Antibiotics. Antibiotics are defined as substances produced by microbes that inhibit or kill other microbes.

Step-by-Step Solution:
Step 1: Define antibiotics. Antibiotics are antimicrobial substances produced by microorganisms.
Step 2: Relate antibiotics to microbial growth. Antibiotics inhibit or kill other microbes.

Why other options are wrong:
- Option A: Ethanol is an alcohol produced by microbes, but not specifically for killing other microbes.
- Option B: Citric acid is an organic acid produced by microbes, but not specifically for killing other microbes.
- Option D: Opiates are drugs derived from plants, not microbes.

Key Concepts:
- Antibiotics
- Antimicrobial substances
- Microbial interactions

Memory Aids:
- Antibiotics: Anti (against) + biotic (life) - against microbial life

Quick Tips:
- Remember the definition of antibiotics.

16 Easy

16 of 35

Remembering +4 | -1

Bacillus thuringiensis is used as

View answer and explanation

Correct option: B

Biopesticide

Option B (Biopesticide) is correct because Bacillus thuringiensis (Bt) produces toxins that are harmful to certain insects, making it an effective biopesticide.

Solution approach

Correct Answer + Core Reason: Biopesticide. Bacillus thuringiensis produces toxins that kill insects, making it a biopesticide.

Step-by-Step Solution:

Step 1: Recall the function of Bacillus thuringiensis.

Step 2: Identify its insecticidal properties.

Step 3: Classify it as a biopesticide.

Step 4: Eliminate other options that do not accurately describe its function.

Why other options are wrong:
- Option A: Biofungicide controls fungi, not insects.
- Option C: Biocontroller is a broader term, but biopesticide is more specific to Bt's function.
- Option D: Bioweapon is not an accurate description of Bt's use.

Key Concepts:
- Biopesticides
- Bacillus thuringiensis (Bt)
- Insecticidal toxins

Memory Aids:
- Remember that \"Bt\" kills \"bugs.\"

Quick Tips:
- Focus on the specific action of Bt on insects.

17 Easy

17 of 35

Analyzing +4 | -1

Assertion (A) Baculoviruses are broad spectrum insecticides.

Reason (R) These viruses are excellent choices for biocontrol in an ecologically sensitive area for integrated pest management

View answer and explanation

Correct option: D

If A is false, but R is true

Option D (If A is false, but R is true) is correct because Baculoviruses are narrow-spectrum insecticides, making them suitable for integrated pest management in ecologically sensitive areas.

Solution approach

Correct Answer + Core Reason: If A is false, but R is true. Baculoviruses are narrow-spectrum, not broad-spectrum, making them suitable for IPM.

Step-by-Step Solution:
Step 1: Analyze Assertion (A). Baculoviruses are described as broad-spectrum insecticides. This is false. Baculoviruses are known for their narrow host range, affecting specific insect pests.
Step 2: Analyze Reason (R). These viruses are excellent choices for biocontrol in an ecologically sensitive area for integrated pest management. This is true because their narrow spectrum minimizes harm to non-target organisms.
Step 3: Determine the relationship. Since A is false and R is true, the correct option is D.

Why other options are wrong:
- Option A: Incorrect because assertion A is false.
- Option B: Incorrect because assertion A is false.
- Option C: Incorrect because reason R is true.

Key Concepts:
- Baculoviruses
- Insecticides (broad vs. narrow spectrum)
- Biocontrol
- Integrated Pest Management (IPM)

Memory Aids:
- Baculoviruses: Narrow spectrum = Safe for environment

Quick Tips:
- Remember that narrow-spectrum insecticides are preferred for IPM to minimize ecological damage.

18 Easy

18 of 35

Understanding +4 | -1

Assertion (A) An organ transplant patient is administered regular dose of cyclosporin-A.

Reason (R) Cyclosporin-A is an immunosuppressant agent.

View answer and explanation

Correct option: A

If both A and R are true and R is the correct explanation of A.

Option A (If both A and R are true and R is the correct explanation of A) is correct because Cyclosporin-A is indeed an immunosuppressant agent, and this is why it's administered to organ transplant patients.

Solution approach

Correct Answer + Core Reason: If both A and R are true and R is the correct explanation of A. Cyclosporin-A is an immunosuppressant used in organ transplant patients.

Step-by-Step Solution:

Step 1: Analyze the assertion (A) and the reason (R) separately.

Step 2: Determine if both the assertion and the reason are true statements.

Step 3: Evaluate if the reason correctly explains the assertion.

Step 4: Recognize that Cyclosporin-A is an immunosuppressant, and this is why it's given to organ transplant patients to prevent rejection.

Why other options are wrong:
- Option B: The reason is the correct explanation for the assertion.
- Option C: The reason is true, not false.
- Option D: The assertion is true, not false.

Key Concepts:
- Immunosuppressant
- Cyclosporin-A
- Organ transplant
- Assertion and Reason

Memory Aids:
- Remember that immunosuppressants are used to prevent organ rejection.

Quick Tips:
- Carefully analyze the relationship between the assertion and the reason.

19 Easy

19 of 35

Remembering +4 | -1

The most common fungal partner of mycorrhiza belongs to genus

View answer and explanation

Correct option: B

Glomus

Option B (Glomus) is correct because Glomus is a genus of fungi that commonly forms mycorrhizal associations with plant roots, aiding in nutrient absorption.

Solution approach

Correct Answer + Core Reason: Glomus. Glomus is a genus of fungi that forms mycorrhizal associations with plant roots, enhancing nutrient uptake.

Step-by-Step Solution:

Step 1: Define mycorrhiza and its function.

Step 2: Recall the common fungal partners in mycorrhizal associations.

Step 3: Identify Glomus as the most common fungal partner.

Step 4: Eliminate other options that are not typically associated with mycorrhiza.

Why other options are wrong:
- Option A: Azotobacter is a nitrogen-fixing bacteria, not a mycorrhizal fungus.
- Option C: Azolla is a water fern that forms a symbiotic relationship with Anabaena, a cyanobacterium.
- Option D: Frankia is a nitrogen-fixing bacteria associated with non-leguminous plants.

Key Concepts:
- Mycorrhiza
- Fungal symbiosis
- Nutrient uptake

Memory Aids:
- Think of \"Glomus\" as \"gluing\" to the roots for nutrient absorption.

Quick Tips:
- Focus on the role of fungi in mycorrhizal associations.

20 Easy

20 of 35

Remembering +4 | -1

Which gas is released during the process of fermentation that gives the puffy appearance to dough for making bread

View answer and explanation

Correct option: A

C{O_2}

Option A (

C{O_2}

) is correct because carbon dioxide is released during fermentation, causing the dough to rise.

Solution approach

Correct Answer + Core Reason: $C{O_2}$ . Carbon dioxide is produced during fermentation, causing the dough to rise.

Step-by-Step Solution:
Step 1: Describe the fermentation process in bread making. Yeast ferments sugars in the dough.
Step 2: Identify the gas produced during fermentation. The main gas produced is carbon dioxide ( $C{O_2}$ ).
Step 3: Explain the effect of the gas on the dough. The carbon dioxide gets trapped in the dough, causing it to rise and become puffy.

Why other options are wrong:
- Option B: CO is carbon monoxide, not produced in bread fermentation.
- Option C: ${O_2}$ is oxygen, not produced in bread fermentation; it's consumed.
- Option D: ${H_2}$ is hydrogen, not produced in bread fermentation.

Key Concepts:
- Fermentation
- Bread making
- Carbon dioxide production

Memory Aids:
- Yeast + Sugar = $C{O_2}$ + Alcohol

Quick Tips:
- Remember that carbon dioxide is the gas responsible for the rise in bread dough.

21 Easy

21 of 35

Understanding +4 | -1

BOD of waste water is reduced by

View answer and explanation

Correct option: B

Aerobic bacteria

Option B is correct because aerobic bacteria consume organic matter in wastewater, reducing the BOD (Biochemical Oxygen Demand).

Solution approach

Correct Answer + Core Reason: Aerobic bacteria. Aerobic bacteria consume organic matter, reducing BOD.

Step-by-Step Solution:

Step 1: Define BOD (Biochemical Oxygen Demand).

Step 2: Understand that BOD is a measure of the amount of oxygen required by microorganisms to decompose organic matter in water.

Step 3: Recognize that aerobic bacteria utilize oxygen to break down organic pollutants.

Step 4: Conclude that aerobic bacteria reduce BOD.

Why other options are wrong:
- Option A: Methanogens produce methane, not directly reducing BOD.
- Option C: Anaerobic bacteria may contribute to the breakdown of some organic matter, but aerobic bacteria are more efficient in reducing BOD.
- Option D: Green sulfur bacteria are photosynthetic and do not primarily reduce BOD.

Key Concepts:
- Biochemical Oxygen Demand (BOD)
- Wastewater treatment
- Aerobic and anaerobic bacteria

Memory Aids:
- Aerobic = Oxygen using = Reduces BOD

Quick Tips:
- Remember that aerobic bacteria are key in reducing BOD in wastewater treatment.

22 Easy

22 of 35

Remembering +4 | -1

Which of the following microbe convert milk into curd?

View answer and explanation

Correct option: A

Bacteria

Option A (Bacteria) is correct because bacteria, particularly *Lactobacillus*, convert milk into curd.

Solution approach

Correct Answer + Core Reason: Bacteria. Bacteria, especially Lactobacillus, are responsible for converting milk into curd.

Step-by-Step Solution:
Step 1: Recall the process of curd formation. Milk is inoculated with a starter culture containing bacteria.
Step 2: Identify the type of microbe involved. The microbes are bacteria, specifically Lactobacillus species.
Step 3: Explain the role of bacteria. Lactobacillus converts lactose (milk sugar) into lactic acid, which coagulates the milk proteins and forms curd.

Why other options are wrong:
- Option B: Viruses do not convert milk into curd.
- Option C: Fungi are not primarily responsible for converting milk into curd, though they are used in some cheese production.
- Option D: Protozoa are not involved in converting milk into curd.

Key Concepts:
- Curd formation
- Lactobacillus
- Fermentation

Memory Aids:
- Lactobacillus: Lacto (milk) + bacillus (bacteria)

Quick Tips:
- Remember that Lactobacillus is the key bacteria in curd formation.

23 Easy

23 of 35

Remembering +4 | -1

What is IARI’s full name?

View answer and explanation

Correct option: D

Indian Agricultural Research Institute

Option D (Indian Agricultural Research Institute) is correct because IARI stands for the Indian Agricultural Research Institute.

Solution approach

Correct Answer + Core Reason: Indian Agricultural Research Institute. IARI is the abbreviation for Indian Agricultural Research Institute.

Step-by-Step Solution:

Step 1: Recall the full form of the acronym IARI.

Step 2: Recognize that IARI is a prominent agricultural research institute in India.

Why other options are wrong:
- Option A: Indian Ayurveda Research Institute is not the correct full form.
- Option B: Indian Aeronautical Research Institute is not the correct full form.
- Option C: Indian Aerospace Research Institute is not the correct full form.

Key Concepts:
- Acronyms
- Agricultural research
- Indian Agricultural Research Institute (IARI)

Memory Aids:
- Associate IARI with agriculture and research in India.

Quick Tips:
- Familiarize yourself with common acronyms related to research institutions.

24 Easy

24 of 35

Understanding +4 | -1

Assertion: Antibiotics are chemical substance produces by some microbes and can kill or retard the growth of other microbes.

Reason: Meaning of antibiotic is against life for human.

View answer and explanation

Correct option: C

If the assertion is true but the reason is false.

Option C is correct because the assertion is true about antibiotics, but the reason is false as \"antibiotic\" means \"against life\" for microbes, not humans.

Solution approach

Correct Answer + Core Reason: If the assertion is true but the reason is false. The assertion accurately describes antibiotics, while the reason misinterprets the meaning of \"antibiotic.\"

Step-by-Step Solution:

Step 1: Analyze the assertion: Antibiotics are indeed chemical substances produced by microbes that inhibit or kill other microbes. This is a fundamental concept in microbiology.

Step 2: Analyze the reason: The term \"antibiotic\" does mean \"against life,\" but specifically against the life of microbes, not humans. The prefix \"anti-\" means \"against,\" and \"biotic\" refers to life.

Step 3: Determine the relationship: The assertion is true, but the reason provides an incorrect interpretation of the word \"antibiotic.\" Therefore, the reason is false.

Step 4: Conclusion: The assertion is true, and the reason is false.

Why other options are wrong:
- Option A: This is incorrect because the reason is false.
- Option B: This is incorrect because the reason is false.
- Option D: This is incorrect because the assertion is true.

Key Concepts:
- Antibiotics and their function
- Etymology of \"antibiotic\"
- Microbiology

Memory Aids:
- \"Anti-\" means \"against.\"
- \"Bio-\" means \"life.\"

Quick Tips:
- Carefully analyze the definitions and meanings of scientific terms.

25 Easy

25 of 35

Remembering +4 | -1

An organism used as biofertiliser for raising any legume crop is

View answer and explanation

Correct option: D

Rhizobium

Option D (Rhizobium) is correct because Rhizobium is a nitrogen-fixing bacteria that forms a symbiotic relationship with legume plants, acting as a biofertilizer.

Solution approach

Correct Answer + Core Reason: Rhizobium. Rhizobium bacteria fix atmospheric nitrogen in the root nodules of legume plants.

Step-by-Step Solution:

Step 1: Recall the role of biofertilizers.

Step 2: Consider the nitrogen fixation process in legume crops.

Step 3: Identify Rhizobium as the key nitrogen-fixing bacteria.

Step 4: Eliminate other options that are not primarily associated with legume crops.

Why other options are wrong:
- Option A: Nostoc is a cyanobacterium, but not primarily used for legume crops.
- Option B: Anabaena is a cyanobacterium, but not primarily used for legume crops.
- Option C: Clostridium is a nitrogen-fixing bacteria, but not typically associated with legume crops.

Key Concepts:
- Biofertilizers
- Nitrogen fixation
- Rhizobium-legume symbiosis

Memory Aids:
- Remember \"Rhizobium\" is related to \"roots\" and legumes.

Quick Tips:
- Focus on the symbiotic relationship between Rhizobium and legume plants.

26 Easy

26 of 35

Understanding +4 | -1

During sewage treatment, methane is formed

View answer and explanation

Correct option: A

In anaerobic sludge digester

Option A (In anaerobic sludge digester) is correct because methane is produced by methanogenic bacteria under anaerobic conditions in the sludge digester during sewage treatment.

Solution approach

Correct Answer + Core Reason: In anaerobic sludge digester. Methane is produced by anaerobic bacteria in the sludge digester.

Step-by-Step Solution:
Step 1: Recall the process of sewage treatment.
Step 2: Identify the stages where methane production occurs.
Step 3: Remember that methane is produced by methanogens under anaerobic conditions.
Step 4: Recognize that anaerobic sludge digesters provide the necessary conditions for methane production.

Why other options are wrong:
- Option B: In tertiary treatment step: Tertiary treatment primarily focuses on removing specific pollutants, not methane production.
- Option C: In primary settling tank: Primary settling tanks remove solids, but methane production is minimal at this stage.
- Option D: By aerobic bacteria: Methane production is an anaerobic process, not aerobic.

Key Concepts:
- Sewage treatment
- Anaerobic digestion
- Methanogenesis
- Methanogenic bacteria

Memory Aids:
- Think of \"Anaerobic\" as \"Absolutely No Air,\" which is needed for methane production in sludge digesters.

Quick Tips:
- Remember that methane production is an anaerobic process in sewage treatment.

27 Easy

27 of 35

Understanding +4 | -1

Assertion: Azospirillum and Azotobacter enriching the nitrogen content of soil.

Reason: They are free living nitrogen fixer in soil.

View answer and explanation

Correct option: A

If both the assertion and the reason are true and the reason is a correct explanation of the assertion.

Option A (If both the assertion and the reason are true and the reason is a correct explanation of the assertion) is correct because Azospirillum and Azotobacter enrich the soil with nitrogen, and this is because they are free-living nitrogen fixers.

Solution approach

Correct Answer + Core Reason: If both the assertion and the reason are true and the reason is a correct explanation of the assertion. Azospirillum and Azotobacter enrich soil nitrogen because they are free-living nitrogen fixers.

Step-by-Step Solution:
Step 1: Evaluate the assertion.
Step 2: Evaluate the reason.
Step 3: Determine if the reason explains the assertion.
Step 4: Recognize that Azospirillum and Azotobacter are indeed nitrogen-fixing bacteria.
Step 5: Understand that their nitrogen-fixing ability is why they enrich the soil.

Why other options are wrong:
- Option B: If both the assertion and reason are true but the reason is not a correct explanation of the assertion: The reason *is* the correct explanation.
- Option C: If the assertion is true but the reason is false: Both are true.
- Option D: If both the assertion and reason are false: Both are true.

Key Concepts:
- Nitrogen fixation
- Azospirillum
- Azotobacter
- Free-living bacteria

Memory Aids:
- Remember \"Azoto\" and \"Azospi\" as being related to nitrogen in the soil.

Quick Tips:
- When evaluating assertion-reason questions, first check if both are true, then see if the reason explains the assertion.

28 Easy

28 of 35

Understanding +4 | -1

In sewage treatment plants, the soil and small pebbles are removed by

View answer and explanation

Correct option: B

Sedimentation during primary treatment

Option B (Sedimentation during primary treatment) is correct because soil and small pebbles are removed by sedimentation during the primary treatment of sewage.

Solution approach

Correct Answer + Core Reason: Sedimentation during primary treatment. Soil and small pebbles are removed by sedimentation during primary treatment.

Step-by-Step Solution:

Step 1: Identify the processes involved in primary treatment of sewage.

Step 2: Understand that sedimentation is a key process for removing heavy particles like soil and pebbles.

Step 3: Recognize that this occurs during the primary treatment stage.

Why other options are wrong:
- Option A: Sequential filtration is part of primary treatment, but sedimentation is the primary method for removing soil and pebbles.
- Option C: Sedimentation in the aeration tank is not the primary method for removing soil and pebbles.
- Option D: Aerobic microbes are involved in secondary treatment, not the removal of soil and pebbles.

Key Concepts:
- Sewage treatment
- Primary treatment
- Sedimentation

Memory Aids:
- Remember that sedimentation is used to remove heavy particles during primary treatment.

Quick Tips:
- Focus on the specific processes involved in each stage of sewage treatment.

29 Easy

29 of 35

Understanding +4 | -1

Assertion: We give cyclosporin A to organ transplanted patients.

Reason: It is an immunosuppressive agent.

View answer and explanation

Correct option: A

If both the assertion and the reason are true and the reason is a correct explanation of the assertion.

The correct answer is A (If both the assertion and the reason are true and the reason is a correct explanation of the assertion) because Cyclosporin A is indeed given to organ transplant patients because it suppresses the immune system, preventing rejection.

Solution approach

Correct Answer + Core Reason: If both the assertion and the reason are true and the reason is a correct explanation of the assertion. Cyclosporin A is an immunosuppressant used to prevent organ rejection.

Step-by-Step Solution:

Step 1: Assertion: Cyclosporin A is given to organ transplant patients.

Step 2: Reason: It is an immunosuppressive agent.

Step 3: Cyclosporin A is a calcineurin inhibitor that suppresses the immune system, preventing the rejection of transplanted organs.

Step 4: Therefore, the reason correctly explains the assertion.

Why other options are wrong:
- Option B: The reason *is* a correct explanation of the assertion.
- Option C: Both the assertion and the reason are true.
- Option D: Both the assertion and the reason are true.

Key Concepts:
- Immunosuppression
- Organ transplantation
- Cyclosporin A

Memory Aids:
- Cyclosporin \"suppresses\" the immune system to prevent organ rejection.

Quick Tips:
- Understand the role of immunosuppressants in organ transplantation.

30 Easy

30 of 35

Understanding +4 | -1

Find the wrong matched pair

View answer and explanation

Correct option: B

Swiss cheese – Has large holes that are produced by a fungus

Option B is the wrong matched pair because the large holes in Swiss cheese are produced by carbon dioxide (

CO_2

) produced by bacteria, not a fungus.

Solution approach

Correct Answer + Core Reason: Swiss cheese – Has large holes that are produced by a fungus. The holes are produced by bacteria, not a fungus.

Step-by-Step Solution:

Step 1: Review the production methods of different types of cheese.

Step 2: Identify the role of bacteria in Swiss cheese production.

Step 3: Recognize that the large holes in Swiss cheese are due to $CO_2$ produced by bacteria (Propionibacterium).

Step 4: Conclude that the matching of Swiss cheese with fungus is incorrect.

Why other options are wrong:
- Option A: Roquefort cheese is ripened by a fungus (Penicillium roqueforti).
- Option C: Penicillin is obtained from a mould (Penicillium notatum).
- Option D: Ethanol is produced by yeast (Saccharomyces cerevisiae).

Key Concepts:
- Food microbiology
- Cheese production

Memory Aids:
- Swiss cheese = Bacteria = Holes

Quick Tips:
- Remember the specific microbes involved in different food production processes.

Your Progress

Microbes in human welfare practice · Easy

Explore Other Chapters in BIOLOGY

Key Takeaways

Continue Your Practice

Your practice