CUET UG Categorised PYQ Biology Unit 8 -

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CUET UG Categorised PYQ Biology Unit 8

BIOLOGY

⏱️ 30 Minutes

❓ 19 Questions

📅 2022, 2023, 2024 & 2025

✍️ Long Answers

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Categorised PYQ Biology Unit 8

1 / 19

QUESTION 1 OF 19

Match List – I with List – II (PYQ 2022 Shift 1)

List – I	List – II
(A) Streptokinase	(I) Blood-Cholesterol lowering agents
(B) Cyclosporin A	(II) Clot Buster
(C) Statins	(III) Propionibacterium sharmanii
(D) Swiss Cheese	(IV) Immuno suppressive agent

Answer Review

1 Match List – I with List – II (PYQ 2022 Shift 1)

List – I	List – II
(A) Streptokinase	(I) Blood-Cholesterol lowering agents
(B) Cyclosporin A	(II) Clot Buster
(C) Statins	(III) Propionibacterium sharmanii
(D) Swiss Cheese	(IV) Immuno suppressive agent

A (A) - (II), (B) - (IV), (C) - (III), (D) - (I)

B (A) - (II), (B) - (IV), (C) - (I), (D) - (III)

C (A) - (IV), (B) - (I), (C) - (II), (D) - (III)

D (A) - (IV), (B) - (I), (C) - (III), (D) - (I)

💡 Short Explanation

Streptokinase → Clot buster. Cyclosporin A → Immunosuppressant. Statins → Lower cholesterol. Swiss cheese → Propionibacterium.

✅ Correct Answer Explanation

The correct matching is: • Streptokinase → Clot buster • Cyclosporin A → Immunosuppressive agent • Statins → Blood cholesterol lowering agents • Swiss cheese → Propionibacterium sharmanii

❓ Why Other Options Are Incorrect

Option A) Statins incorrectly matched.
Option C) Multiple mismatches.
Option D) Multiple mismatches.

🎯 Strategy

Used: Option Grouping

Option A → Incorrect.
Option B → Correct.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option B.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Microbes in Industrial Products

2 Given below are two statements: (PYQ 2022 Shift 1)
Statement I: Ladybird and Dragonflies are useful to get rid of aphids and mosquitoes. Trichoderma fungus are effective bio control agents of several plant pathogens.
Statement II: The biological control of plant diseases and pest can control increasing use of insecticides and pesticides, thus saving our environment from being polluted.

A Both Statement I and Statement II are correct

B Both Statement I and Statement II are incorrect

C Statement I is correct but Statement II is incorrect

D Statement I is incorrect but Statement II is correct

💡 Short Explanation

Ladybirds control aphids. Dragonflies control mosquitoes. Trichoderma is a biocontrol agent.

✅ Correct Answer Explanation

Statement I is correct because ladybird beetles prey on aphids, dragonflies help control mosquitoes and Trichoderma species act as biological control agents against plant pathogens. Statement II is also correct because biological control reduces dependence on chemical pesticides, thereby reducing environmental pollution.

❓ Why Other Options Are Incorrect

Option B) Both statements are actually correct.
Option C) Statement II is also correct.
Option D) Statement I is correct.

🎯 Strategy

Used: NCERT Recall

Option A → Correct.
Option B → Incorrect.
Option C → Statement II correct.
Option D → Statement I correct.

Final Answer → Option A.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Biocontrol Agents

3 Propionibacterium sharmanii is used in making which of the following food item? (PYQ 2023 Shift 1)

A Swiss cheese

B Roquefort cheese

C Bread

D Toddy

💡 Short Explanation

Produces CO₂. Creates characteristic holes. Used in Swiss cheese production.

✅ Correct Answer Explanation

Propionibacterium sharmanii is used during Swiss cheese manufacture. It releases carbon dioxide, forming the characteristic large holes and imparting a distinct flavour.

❓ Why Other Options Are Incorrect

Option B) Roquefort cheese uses Penicillium roqueforti.
Option C) Bread uses Saccharomyces cerevisiae.
Option D) Toddy is produced by natural fermentation of palm sap.

🎯 Strategy

Used: NCERT Recall

Option A → Correct organism-product pair.
Option B → Different microbe.
Option C → Yeast-based product.
Option D → Fermented beverage.

Final Answer → Swiss cheese.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Microbes in Household Products

4 Which of the following is used as 'clot buster'? (PYQ 2023 Shift 1)

A Streptokinase

B Cyclosporin-A

C Statins

D Penicillin

💡 Short Explanation

Dissolves blood clots. Produced by Streptococcus. Used during myocardial infarction.

✅ Correct Answer Explanation

Streptokinase is a thrombolytic enzyme used to dissolve blood clots in blood vessels. It is often administered in cases of heart attack and other thrombotic disorders.

❓ Why Other Options Are Incorrect

Option B) Immunosuppressant drug.
Option C) Cholesterol-lowering drug.
Option D) Antibiotic.

🎯 Strategy

Used: Elimination

Option A → Clot dissolver.
Option B → Organ transplant drug.
Option C → Lipid lowering.
Option D → Antibacterial drug.

Final Answer → Streptokinase.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Microbes as Biocontrol and Therapeutic Agents

5 Match the following: (PYQ 2023 Shift 1)

List I	List II
A. Aspergillus niger	I. Butyric acid
B. Clostridium butylicum	II. Acetic acid
C. Saccharomyces cerevisiae	III. Citric acid
D. Acetobacter aceti	IV. Ethanol

A (A)-(II), (B)-(IV), (C)-(I), (D)-(III)

B (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

C (A)-(I), (B)-(III), (C)-(II), (D)-(IV)

D (A)-(IV), (B)-(II), (C)-(III), (D)-(I)

💡 Short Explanation

Aspergillus niger → Citric acid. Clostridium butylicum → Butyric acid. Yeast → Ethanol. Acetobacter → Acetic acid.

✅ Correct Answer Explanation

Industrial microbiology utilizes Aspergillus niger for citric acid production, Clostridium butylicum for butyric acid, Saccharomyces cerevisiae for ethanol and Acetobacter aceti for acetic acid production.

❓ Why Other Options Are Incorrect

Option A) Product-organism mismatches.
Option C) Incorrect assignments.
Option D) Multiple wrong matches.

🎯 Strategy

Used: Option Grouping

Option A → Incorrect.
Option B → All correct matches.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option B.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Industrial Products

6 Match the following: (PYQ 2023 Shift 2)

List I	List II
A. Aspergillus niger	I. Cyclosporin-A
B. Trichoderma polysporum	II. Ethanol
C. Lactobacillus	III. Citric acid
D. Saccharomyces cerevisiae	IV. Lactic acid

A (A)-(III), (B)-(II), (C)-(I), (D)-(IV)

B (A)-(I), (B)-(II), (C)-(IV), (D)-(III)

C (A)-(I), (B)-(IV), (C)-(II), (D)-(III)

D (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

💡 Short Explanation

Aspergillus niger → Citric acid. Trichoderma polysporum → Cyclosporin-A. Lactobacillus → Lactic acid. Yeast → Ethanol.

✅ Correct Answer Explanation

Aspergillus niger produces citric acid, Trichoderma polysporum produces Cyclosporin-A, Lactobacillus produces lactic acid and Saccharomyces cerevisiae produces ethanol.

❓ Why Other Options Are Incorrect

Option B) Product assignments incorrect.
Option C) Lactobacillus mismatched.
Option D) Multiple incorrect associations.

🎯 Strategy

Used: Option Grouping

Option A → Correct.
Option B → Incorrect.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option A.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Industrial Products

7 Which of the following acts as biofertilizer in paddy field? (PYQ 2023 Shift 2)

A Nostoc

B Rhizobium

C Azospirillum

D Azotobacter

💡 Short Explanation

Cyanobacteria used in paddy fields. Fixes atmospheric nitrogen. Improves soil fertility.

✅ Correct Answer Explanation

Nostoc is a nitrogen-fixing cyanobacterium widely used as a biofertilizer in paddy fields. It enriches soil nitrogen and improves crop productivity.

❓ Why Other Options Are Incorrect

Option B) Associated mainly with legumes.
Option C) Used in cereals but not the NCERT paddy-field example.
Option D) Free-living nitrogen fixer.

🎯 Strategy

Used: NCERT Recall

Option A → Correct.
Option B → Legumes.
Option C → Non-specific.
Option D → Different application.

Final Answer → Nostoc.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Biofertilizers

8 The puffed-up appearance of dough is due to the production of : (PYQ 2023 Shift 2)

A Carbon dioxide gas

B Alcohol

C Acetic acid

D Oxygen gas

💡 Short Explanation

Yeast ferments sugars. CO₂ gets trapped in dough. Dough expands.

✅ Correct Answer Explanation

During fermentation, yeast converts sugars into alcohol and carbon dioxide. The trapped carbon dioxide gas causes the dough to rise and become puffed up.

❓ Why Other Options Are Incorrect

Option B) Produced, but does not cause puffing.
Option C) Not responsible.
Option D) Not produced by fermentation.

🎯 Strategy

Used: NCERT Recall

Option A → Correct.
Option B → Secondary product.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Carbon dioxide.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Baker's Yeast

9 Which of the following microbe is used for making bread? (PYQ 2023 Shift 3)

A Propionibacterium sharmanii

B Saccharomyces cerevisiae

C Aspergillus niger

D Trichoderma polysporum

💡 Short Explanation

Commonly called baker's yeast. Produces carbon dioxide. Causes dough to rise.

✅ Correct Answer Explanation

Saccharomyces cerevisiae (baker's yeast) ferments sugars present in dough and releases carbon dioxide. The trapped gas makes the dough rise and gives bread its soft texture.

❓ Why Other Options Are Incorrect

Option A) Used in Swiss cheese production.
Option C) Produces citric acid.
Option D) Produces Cyclosporin-A.

🎯 Strategy

Used: NCERT Recall

Option A → Cheese industry.
Option B → Bread making.
Option C → Citric acid.
Option D → Immunosuppressant production.

Final Answer → Saccharomyces cerevisiae.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Household Food Processing

10 Baculoviruses attack on: (PYQ 2023 Shift 3)

A Birds

B Arthropods

C Mammals

D Fishes

💡 Short Explanation

Used as biological control agents. Infect insects and arthropods. Safe for vertebrates.

✅ Correct Answer Explanation

Baculoviruses are pathogens that specifically infect arthropods, especially insects. They are widely used in biological pest control because they do not harm plants, mammals, birds or fishes.

❓ Why Other Options Are Incorrect

Option A) Birds are not hosts.
Option C) Mammals are not affected.
Option D) Fishes are not hosts.

🎯 Strategy

Used: NCERT Recall

Option A → Incorrect.
Option B → Correct.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Arthropods.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Biocontrol Agents

11 Match List I with List II (PYQ 2023 Shift 3)

List I	List II
A. Methanobacterium	I. Butyric acid
B. Monascus purpureus	II. Breakdown of cellulose
C. Clostridium butylicum	III. Clot buster
D. Streptococcus	IV. Blood-cholesterol lowering agent

A A–I, B–II, C–III, D–IV

B A–II, B–I, C–III, D–IV

C A–II, B–IV, C–I, D–III

D A–I, B–III, C–II, D–IV

💡 Short Explanation

Methanobacterium → Cellulose breakdown. Monascus → Statins. Clostridium → Butyric acid. Streptococcus → Clot buster.

✅ Correct Answer Explanation

Methanobacterium helps in cellulose digestion. Monascus purpureus produces statins that lower blood cholesterol. Clostridium butylicum produces butyric acid. Streptococcus produces streptokinase, a clot buster.

❓ Why Other Options Are Incorrect

Option A) Multiple mismatches.
Option B) Monascus incorrectly matched.
Option D) Incorrect assignments.

🎯 Strategy

Used: Option Grouping

Option A → Incorrect.
Option B → Incorrect.
Option C → Correct.
Option D → Incorrect.

Final Answer → Option C.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Industrial Products

12 Which of the following is not used as Single Cell Protein (SCP)? (PYQ 2023 Shift 3)

A Methylophilus methylotrophus

B Chlorella

C Spirulina

D Gracilaria

💡 Short Explanation

SCP includes microbes and microalgae. Chlorella and Spirulina are SCP sources. Gracilaria is mainly used for agar production.

✅ Correct Answer Explanation

Methylophilus methylotrophus, Chlorella and Spirulina are well-known sources of Single Cell Protein. Gracilaria is a red alga primarily used for agar extraction and is not commonly used as SCP.

❓ Why Other Options Are Incorrect

Option A) SCP source.
Option B) SCP source.
Option C) SCP source.

🎯 Strategy

Used: Odd One Out

Option A → SCP.
Option B → SCP.
Option C → SCP.
Option D → Agar-producing alga.

Final Answer → Gracilaria.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Single Cell Protein (SCP)

13 Streptokinase enzyme is used for: (PYQ 2024 Shift 1, 2024 Shift 2)

A Removing clot from blood vessels

B Clarifying fruit juices

C Synthesis of cholesterol

D Removing oily stains

💡 Short Explanation

Clot-buster enzyme. Produced by Streptococcus. Used in heart attack treatment.

✅ Correct Answer Explanation

Streptokinase acts as a thrombolytic agent. It dissolves blood clots by activating plasminogen into plasmin and is used in patients suffering from myocardial infarction.

❓ Why Other Options Are Incorrect

Option B) Pectinase is used for fruit juice clarification.
Option C) Not related to cholesterol synthesis.
Option D) Lipases are used for oily stain removal.

🎯 Strategy

Used: Elimination

Option A → Medical clot removal.
Option B → Different enzyme.
Option C → Incorrect function.
Option D → Different enzyme.

Final Answer → Option A.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Therapeutic Products

14 Which of the following plays a significant role in our stomach in checking disease causing microbes? (PYQ 2024 Shift 1, 2024 Shift 2)

A Penicillium notatum

B Monascus purpureus

C Trichoderma polysporum

D Lactobacillus

💡 Short Explanation

Beneficial bacterium. Produces acids. Suppresses harmful microbes.

✅ Correct Answer Explanation

Lactobacillus is a probiotic bacterium that helps maintain microbial balance in the digestive tract and inhibits disease-causing microorganisms.

❓ Why Other Options Are Incorrect

Option A) Produces penicillin.
Option B) Produces statins.
Option C) Produces cyclosporin A.

🎯 Strategy

Used: Odd One Out

Option A → Antibiotic producer.
Option B → Statin producer.
Option C → Immunosuppressant producer.
Option D → Gut microflora.

Final Answer → Lactobacillus.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Microbes in Household Products

15 Given below are two statements: (PYQ 2024 Shift 1, 2024 Shift 2)
Statement I: Whisky, brandy and rum are produced without distillation of the fermented broth.
Statement II: Saccharomyces cerevisiae is called doctor's yeast.

A Both true

B Both false

C I true, II false

D I false, II true

💡 Short Explanation

Alcoholic beverages require distillation. Saccharomyces cerevisiae is brewer's yeast. Both statements are incorrect.

✅ Correct Answer Explanation

Whisky, rum and brandy are produced by distillation of fermented broth. Saccharomyces cerevisiae is known as brewer's yeast, not doctor's yeast. Therefore both statements are false.

❓ Why Other Options Are Incorrect

Option A) Both statements are not true.
Option C) Statement I is false.
Option D) Statement II is false.

🎯 Strategy

Used: Elimination

Option A → Incorrect.
Option B → Both false.
Option C → First statement false.
Option D → Second statement false.

Final Answer → Option B.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Industrial Products

16 Match the following: (PYQ 2025 Shift 1)

List I	List II
A. Clostridium butylicum	I. Lactic acid
B. Aspergillus niger	II. Butyric acid
C. Acetobacter aceti	III. Citric acid
D. Lactobacillus	IV. Acetic acid

A (A)-(I), (B)-(II), (C)-(III), (D)-(IV)

B (A)-(II), (B)-(III), (C)-(IV), (D)-(I)

C (A)-(III), (B)-(II), (C)-(IV), (D)-(I)

D (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

💡 Short Explanation

Clostridium → Butyric acid. Aspergillus → Citric acid. Acetobacter → Acetic acid. Lactobacillus → Lactic acid.

✅ Correct Answer Explanation

Industrial microbiology uses specific microbes for commercial products. Clostridium butylicum produces butyric acid, Aspergillus niger produces citric acid, Acetobacter aceti produces acetic acid, and Lactobacillus produces lactic acid during fermentation. These are standard NCERT examples.

❓ Why Other Options Are Incorrect

Option A) Most producer-product combinations are incorrect.
Option C) Clostridium and Aspergillus are mismatched.
Option D) Nearly all pairings are wrong.

🎯 Strategy

Used: NCERT Recall

Option A → Incorrect pairing.
Option B → Complete correct matching.
Option C → Wrong acids assigned.

Final Answer → Based on NCERT recall.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Industrial Products

17 Match the following: (PYQ 2025 Shift 1)

Column A (Product)	Column B (Producer)
A. Citric Acid	I. Trichoderma polysporum
B. Ethanol	II. Monascus purpureus
C. Statins	III. Saccharomyces cerevisiae
D. Cyclosporin A	IV. Aspergillus niger

A (A)-(IV), (B)-(III), (C)-(II), (D)-(I)

B (A)-(I), (B)-(III), (C)-(II), (D)-(IV)

C (A)-(I), (B)-(II), (C)-(IV), (D)-(III)

D (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

💡 Short Explanation

Aspergillus → Citric acid. Yeast → Ethanol. Monascus → Statins. Trichoderma → Cyclosporin A.

✅ Correct Answer Explanation

Aspergillus niger is used commercially for citric acid production. Saccharomyces cerevisiae (yeast) produces ethanol through fermentation. Monascus purpureus produces statins, which help lower blood cholesterol levels. Trichoderma polysporum produces cyclosporin A, an immunosuppressive agent used during organ transplantation.

❓ Why Other Options Are Incorrect

Option B) Citric acid and cyclosporin A producers are incorrectly matched.
Option C) Several microbial products are wrongly assigned.
Option D) Most producer-product combinations are incorrect.

🎯 Strategy

Used: NCERT Recall

Option A → Exact NCERT matching.
Option B → Citric acid mismatch.
Option C → Multiple mismatches.

Final Answer → Based on NCERT recall.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Microbes in Industrial Products

18 Baculoviruses are pathogens that attack: (PYQ 2025 Shift 1)

A Insects

B Roundworms

C Molluscs

D Birds

💡 Short Explanation

Baculoviruses infect insects. Used as biological control agents. Environment-friendly pest control.

✅ Correct Answer Explanation

Baculoviruses are insect-specific pathogens widely used in biological pest control programs. The most commonly used species belong to the genus Nucleopolyhedrovirus (NPV). They are highly specific to insects and do not harm beneficial organisms, humans, or other vertebrates.

❓ Why Other Options Are Incorrect

Option B) Baculoviruses do not infect nematodes.
Option C) Not the target hosts of baculoviruses.
Option D) Birds are not infected by baculoviruses.

🎯 Strategy

Used: NCERT Recall

Option A → Correct host group.
Option B → Incorrect organism group.
Option C → Not targeted.

Final Answer → Based on NCERT recall.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Biocontrol Agents

19 Arrange the given products formed during sewage treatment in correct sequence: (PYQ 2025 Shift 1)
(A) Biogas
(B) Activated sludge
(C) Flocs
(D) Primary sludge

A (A), (B), (C), (D)

B (D), (C), (B), (A)

C (C), (D), (B), (A)

D (B), (A), (D), (C)

💡 Short Explanation

Primary treatment forms primary sludge. Secondary treatment forms flocs. Activated sludge is produced. Anaerobic digestion generates biogas.

✅ Correct Answer Explanation

During primary treatment, suspended solids settle and form primary sludge. In secondary treatment, microbial masses called flocs develop and degrade organic matter. Part of the flocs settle to form activated sludge. Activated sludge is then transferred to anaerobic digesters where methanogenic bacteria produce biogas. Thus, the correct sequence is D → C → B → A.

❓ Why Other Options Are Incorrect

Option A) Reverses the actual treatment sequence.
Option C) Flocs cannot form before primary sludge.
Option D) Places activated sludge and biogas before treatment begins.

🎯 Strategy

Used: Sequential Biology Process

Option A → Reverse order.
Option B → Matches sewage treatment sequence.
Option C → Incorrect starting step.

Final Answer → Based on process order.

🧠 Memory Trick

📚 Class XII → Biology → Chapter: Microbes in Human Welfare → Section/Theme: Sewage Treatment

CUET UG Categorised PYQ Biology Unit 8

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