CUET UG Booster Biology Unit 8Test (M2) -

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CUET UG Booster Biology Unit 8Test (M2)

⏱️ 30 Minutes

❓ 20 Questions

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

CUET UG Booster Biology Unit 8Test (M2)

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QUESTION 1 OF 20

Why are very large vessels called fermentors strictly required for industrial applications?

Answer Review

1 Why are very large vessels called fermentors strictly required for industrial applications?

A To safely isolate disease-causing microbes from the environment.

B Because production on an industrial scale requires growing microbes in massive quantities.

C To allow enough space for yeast to undergo distillation.

D To separate primary sludge from the effluent.

💡 Short Explanation

Industrial production requires massive yields of products to fulfill human demand. Achieving high yields is impossible using standard laboratory-scale culture flasks. Large-scale vessels optimize growth kinetics for huge volumes of microbial biomass.

✅ Correct Answer Explanation

Production of high-value human welfare commodities (like beverages, organic acids, and life-saving antibiotics) on a commercial or industrial scale requires immense yields. To optimize metabolic productivity and accommodate these massive cultivation parameters, microbes must be grown in high volumes. Fermentors or bioreactors provide thousands of liters of nutrient media along with automated control systems for temperature, pH, and dissolved oxygen, maximizing the biomass output.

❓ Why Other Options Are Incorrect

Option A → While bio-containment is important in pathogenic laboratories, it is not the primary commercial reason for building giant industrial fermentation vessels.
Option B → (Note: This is the correct statement itself).
Option C → Yeast undergoes biological fermentation, not distillation; distillation is a distinct thermodynamic heat-separation process performed in metal stills.
Option D → Separating primary sludge from effluent is an environmental engineering step performed in primary settling tanks during sewage treatment, not in industrial fermentors.

🎯 Strategy

Application: Align the scale criteria mentioned in the question ("industrial applications") with the corresponding rationale. Industrial scale corresponds directly with "massive quantities."

Final Logic: Option B matches the economic and physical requirements of industrial production layouts.

🧠 Memory Trick

Massive Industrial Needs: Industrial scale demands Massive quantities in large vessels.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Microbes in Industrial Products

2 Which of the following is NOT an example of a product synthesized using microbes on a large industrial scale as discussed in the provided text?

A Beverages like beer and wine

B Antibiotics like penicillin

C Biogas from concrete tanks

D Enzymes like lipases and pectinases

💡 Short Explanation

Industrial fermentors cultivate specific, pure strains for high-value biological products. Biogas is produced via wild, mixed anaerobic consortia processing bulk animal manure. The textbook separates the industrial fermentor section from rural biogas production.

✅ Correct Answer Explanation

This negative question asks for an item not classified under standard industrial fermentation synthesis. Fermented beverages (beer/wine), antibiotics (penicillin), and industrial enzymes (lipases/pectinases) are pure-culture products grown in automated fermentor vessels. Biogas production occurs in rural, low-tech brick or concrete digesters using mixed methanogenic strains and dung, separating it from high-purity industrial fermentor lines.

❓ Why Other Options Are Incorrect

Option A → Beverages like beer and wine are primary examples covered in the industrial products section.
Option B → Antibiotics like penicillin are prominent industrial products highlighted in the history of medicine.
Option D → Chemical enzymes like lipases and pectinases are produced on a large scale using specialized industrial fermentors.

🎯 Strategy

Application: Eliminate the options that are explicitly managed inside high-purity industrial fermentors (beverages, antibiotics, and enzymes), leaving the odd choice out.

Final Logic: Biogas is processed in decentralized wastewater/manure concrete tanks, making Option C the correct choice for this negative question.

🧠 Memory Trick

High Tech vs. Low Tech: Fermentors make high-tech pure chemicals; concrete tanks handle rural Biogas.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Microbes in Industrial Products

3 Match the industrial product with its associated microbial genus/species:

Column 1	Column 2
1. Brewer's yeast	a. Aspergillus
2. Fungal source of Citric acid	b. Monascus
3. Fungal source of Cyclosporin A	c. Trichoderma
4. Yeast source of Statins	d. Saccharomyces

A 1-d, 2-b, 3-a, 4-c

B 1-d, 2-a, 3-c, 4-b

C 1-a, 2-d, 3-c, 4-b

D 1-d, 2-a, 3-b, 4-c

💡 Short Explanation

Brewer's yeast is classified as Saccharomyces cerevisiae. Citric acid and Cyclosporin A are produced by Aspergillus and Trichoderma, respectively. Statins are cardiovascular molecules harvested from the yeast Monascus purpureus.

✅ Correct Answer Explanation

Matching each commercial compound to its correct taxonomic genus: 1 matches with d: Brewer's yeast is the common name for Saccharomyces cerevisiae. 2 matches with a: Citric acid is an organic acid synthesized industrially by the fungus Aspergillus niger. 3 matches with c: Cyclosporin A is an immunosuppressive drug harvested from the fungus Trichoderma polysporum. 4 matches with b: Statins are blood-cholesterol lowering molecules made by the yeast Monascus purpureus. This generates the matching string 1-d, 2-a, 3-c, 4-b, which corresponds to Option B.

❓ Why Other Options Are Incorrect

Option A → Incorrect because it matches the yeast source of statins (4) with Aspergillus (a), which actually produces citric acid.
Option C → Incorrect because it links Brewer's yeast (1) with Aspergillus (a) instead of Saccharomyces (d).
Option D → Incorrect because it switches the source organisms for Cyclosporin A and statins.

🎯 Strategy

Application: Use an absolute anchor connection. Brewer's yeast (1) must pair with Saccharomyces (d). This requirement immediately eliminates Option C. Next, match Statins (4) with Monascus (b), which isolates Option B.

Final Logic: Verifying the unique pairs leaves Option B as the only layout that matches all four organisms correctly.

🧠 Memory Trick

Biotech Matching: Saccharomyces = Spirit/Bread; Aspergillus = Acid (Citric); Trichoderma = Transplant drug; Monascus = Manage cholesterol.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

4 Consider the following statements regarding the biological production of ethanol:
I. It relies on the fermentation of malted cereals and fruit juices by yeast.
II. Saccharomyces cerevisiae is used for its commercial production.
III. Ethanol is only produced through a distillation process. Which of these statements are accurate?

A I and III

B II and III

C I and II

D I, II, and III

💡 Short Explanation

Yeast produces ethanol via natural metabolic fermentation. Saccharomyces cerevisiae is the primary industrial organism used for this process. Distillation is an optional downstream concentration step, not a production requirement.

✅ Correct Answer Explanation

Statements I and II are correct; industrial ethanol production relies on brewing yeast (Saccharomyces cerevisiae) fermenting sugar substrates found in malted grains or fruit extracts. Statement III is incorrect because fermentation itself produces ethanol naturally at lower concentrations (as seen in wine and beer). Distillation is simply a downstream step used to concentrate alcohol levels for spirits like whisky or rum; it is not the process that creates the ethanol molecule itself.

❓ Why Other Options Are Incorrect

Option A → Incorrect because it includes the false Statement III while leaving out the core role of yeast detailed in Statement I.
Option B → Incorrect because it includes Statement III, which misinterprets distillation as the chemical synthesis step for ethanol.
Option D → Incorrect because it includes all options, failing to identify that Statement III is factually incorrect.

🎯 Strategy

Application: Statement III contains the extreme word "only" ("Ethanol is only produced through a distillation process"). In biology, absolute terms like "only" often flag a statement as false, since fermentation creates ethanol before any distillation occurs.

Final Logic: Eliminating Statement III leaves Option C as the only logical combination.

🧠 Memory Trick

Yeast Makes, Still Concentrates: Yeast makes the alcohol (Statements I & II); distillation just concentrates it.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Fermented Beverages

5 Arrange the logical sequence of steps required to produce a distilled spirit like rum:
I. Distillation of the fermented broth.
II. Fermentation of raw material using Saccharomyces cerevisiae.
III. Sourcing of raw material (malted cereals/fruit juices).

A III-I-II

B I-II-III

C II-III-I

D III-II-I

💡 Short Explanation

Production must begin by gathering raw carbohydrate agricultural inputs. Yeast then ferments these raw sugars into a low-alcohol broth. Post-fermentation distillation concentrates this broth into a high-proof spirit.

✅ Correct Answer Explanation

The production timeline for a distilled alcoholic beverage must follow a logical sequence from field to final product: 1. Step III: Sourcing the raw materials (such as molasses, fruit juices, or malted cereals) that provide the sugars needed for the process. 2. Step II: Inoculating the sugar mash with Saccharomyces cerevisiae to ferment those sugars into ethanol and CO2. 3. Step I: Distilling the low-alcohol fermented wash to boil off and concentrate the ethanol into a high-proof spirit like rum. This yields the correct chronological sequence: III →II →I.

❓ Why Other Options Are Incorrect

Option A → Incorrect because it places distillation (I) before fermentation (II) has even occurred to create the alcohol.
Option B → This option reverses the entire timeline, placing the final distillation step (I) before sourcing the raw materials (III).
Option C → Incorrect because microbial fermentation (II) cannot take place before the raw sugar materials (III) have been sourced and prepared.

🎯 Strategy

Application: A logical manufacturing timeline must start with harvesting raw ingredients (Step III). This requirement immediately eliminates choices A and B. Next, place the final concentration step (distillation/Step I) at the very end of the sequence.

Final Logic: Following the steps from sourcing to fermenting and distilling points directly to Option D.

🧠 Memory Trick

Source, Ferment, Still: Buy the fruit (III), brew the mash (II), and heat the still (I).

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Fermented Beverages

6 Based on the text, what differentiates the production process of wine from that of brandy?

A Wine requires bacterial fermentation, whereas brandy requires yeast.

B Wine is produced without distillation, whereas brandy is produced by distillation of the fermented broth.

C Brandy is produced from fruit juices, but wine is not.

D Wine uses enzymes for clarification, whereas brandy uses antibiotics.

💡 Short Explanation

Wine is an undistilled beverage bottled directly after fermentation. Brandy is a spirit produced by distilling wine or fermented fruit juices. Distillation is the key manufacturing difference between these two beverages.

✅ Correct Answer Explanation

The textbook classifies alcoholic beverages based on whether they undergo post-fermentation distillation. Wine and beer are classic undistilled drinks with lower alcohol concentrations because they are clarified and bottled directly after fermentation. In contrast, brandy, whisky, and rum are distilled spirits. Brandy is produced by distilling fermented fruit juices or wine, using heat to concentrate the alcohol content.

❓ Why Other Options Are Incorrect

Option A → Incorrect because both wine and brandy require yeast (Saccharomyces cerevisiae) to carry out alcoholic fermentation.
Option C → Incorrect because both wine and brandy are typically derived from fermented grape or fruit juices.
Option D → Incorrect because neither beverage utilizes therapeutic antibiotics during its industrial processing phases.

🎯 Strategy

Application: Sort both drinks into their textbook categories: Wine = Undistilled, Brandy = Distilled. Look for the option that highlights this processing difference.

Final Logic: Option B correctly identifies distillation as the primary technical difference between wine and brandy production.

🧠 Memory Trick

Wine is Raw, Brandy is Cooked: Wine goes straight to the bottle; brandy passes through a hot distillation still.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Fermented Beverages

7 Which of the following statements is NOT a correct reflection of Alexander Fleming's discovery of penicillin?

A It was the first antibiotic to be discovered.

B It was a completely planned and heavily engineered discovery.

C It involved an unwashed culture plate containing Staphylococci.

D It involved the observation of a mould called Penicillium notatum.

💡 Short Explanation

Penicillin was discovered entirely by accident in a London laboratory. Fleming did not plan to study molds or find an antibiotic agent. This makes the discovery a classic example of scientific serendipity rather than a planned project.

✅ Correct Answer Explanation

The question looks for the statement that is NOT a correct reflection of history. Penicillin's discovery was completely unplanned, happening by chance when an airborne mold spore contaminated an unwashed petri dish while Fleming was on vacation. It was an accidental observation of natural competition between a fungus and bacteria, rather than a planned, engineered research project. This makes Option B factually false and the correct choice for this negative question.

❓ Why Other Options Are Incorrect

Option A → This is a true statement; penicillin was the first authentic clinical antibiotic discovered in medical history.
Option C → This is a true statement; the discovery happened because Fleming left his Staphylococci culture plates unwashed on his workbench.
Option D → This is a true statement; the contaminant was identified as the mold species Penicillium notatum.

🎯 Strategy

Application: Identify the word that contradicts the historical narrative. The textbook emphasizes that penicillin was a "chance discovery" (serendipity), directly contradicting the terms "planned" and "heavily engineered" in Option B.

Final Logic: Option B makes an incorrect claim about how the drug was discovered, making it the right choice for this negative question.

🧠 Memory Trick

Pure Luck: Penicillin was an accidental surprise, not a planned enterprise.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

8 Fleming deduced that Staphylococci could not grow around the mould because:
I. The mould mechanically trapped the bacteria.
II. A chemical was produced by the mould.
III. The chemical was named Penicillin. Which points accurately describe his findings?

A I and II

B I and III

C II and III

D I, II, and III

💡 Short Explanation

Fleming observed a clear zone of inhibition around the invading mold colony. He concluded the mold was secreting a soluble antibacterial chemical compound. He named this defensive chemical Penicillin, after the mold genus.

✅ Correct Answer Explanation

When Alexander Fleming examined the contaminated culture plate, he noticed a clear zone where Staphylococci colonies could not grow around the mold. He deduced this inhibition was caused by a chemical substance secreted by the mold that killed or dissolved the bacteria (Statement II). He extracted this chemical substance and named it Penicillin after the parent mold Penicillium notatum (Statement III). Statement I is incorrect because the mold uses chemical warfare to inhibit bacteria, not physical or mechanical trapping.

❓ Why Other Options Are Incorrect

Option A → Incorrect because it includes Statement I, which misinterprets the chemical inhibition zone as a mechanical trap.
Option B → Incorrect because it includes Statement I while omitting the core chemical synthesis concept explained in Statement II.
Option D → Incorrect because it includes all statements, failing to filter out the false claim in Statement I.

🎯 Strategy

Application: Evaluate the physical nature of antibiotics. Antibiotics are chemical molecules, not mechanical or physical barriers. This distinction flags Statement I as false and eliminates options A, B, and D.

Final Logic: Eliminating the mechanical trapping statement leaves Option C (II and III) as the correct choice.

🧠 Memory Trick

Chemical Warfare, Not Netting: Molds use chemical weapons (Penicillin) to clear out bacteria; they don't catch them in physical nets.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

9 Why were Ernest Chain and Howard Florey crucial to the history of antibiotics?

A They discovered the Penicillium notatum mould independently.

B They established the full potential of Penicillin as an effective antibiotic.

C They were the first to identify Staphylococci bacteria.

D They genetically engineered Penicillin to treat viral diseases.

💡 Short Explanation

Fleming discovered penicillin but could not fully purify or concentrate it for clinical use. Chain and Florey took over the research to develop it into a stable medicine. Their development work unlocked the drug's full therapeutic potential.

✅ Correct Answer Explanation

Although Alexander Fleming discovered penicillin, his crude extracts were unstable and difficult to use clinically. Years later, researchers Ernest Chain and Howard Florey undertook the complex biochemical work needed to purify and concentrate the molecule. Their research established penicillin's full potential as a reliable, highly effective systemic antibiotic, transforming it into a life-saving medicine used worldwide.

❓ Why Other Options Are Incorrect

Option A → They did not discover the mold; they built upon the original specimen and findings published by Fleming.
Option C → Staphylococci bacteria were well-known clinical pathogens long before Chain and Florey began their research.
Option D → Antibiotics only target bacterial cellular structures; they are completely ineffective against viral diseases.

🎯 Strategy

Application: Connect the names "Chain and Florey" directly with their specific historical achievement as detailed in the textbook: establishing the full potential of penicillin.

Final Logic: Option B uses the exact phrasing from the textbook to describe Chain and Florey's role in antibiotic history.

🧠 Memory Trick

Fleming Found, Chain Chained: Fleming found the mold, but Chain and Florey bound its medical potential into a real drug.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

10 The massive scale of Penicillin utilization during World War II proved its effectiveness primarily as a:

A 'Clot buster' for vascular injuries.

B Agent to kill or retard disease-causing microbes in wounded soldiers.

C Competitive inhibitor of blood cholesterol in soldiers.

D Tool for clarifying bottled juices in military rations.

💡 Short Explanation

Battlefield wounds frequently lead to severe secondary bacterial infections. Penicillin was deployed to treat infected soldiers and prevent sepsis. The drug works by killing or halting the growth of these bacterial pathogens.

✅ Correct Answer Explanation

During World War II, battlefield injuries often became infected with pathogenic bacteria, leading to gangrene or fatal sepsis. Mass-producing penicillin allowed doctors to treat wounded Allied soldiers on a huge scale. The antibiotic worked by disrupting bacterial cell wall synthesis, killing or halting the pathogens to save thousands of lives and demonstrating the clinical power of antibiotic therapy.

❓ Why Other Options Are Incorrect

Option A → Dissolving blood clots is the specific function of the enzyme streptokinase, not an antibacterial drug like penicillin.
Option C → Lowering blood cholesterol via competitive inhibition is the role of statins, which are unrelated to treating battlefield infections.
Option D → Clarifying bottled fruit juices relies on plant-digesting enzymes like pectinases and proteases, not clinical antibiotics.

🎯 Strategy

Application: Match the clinical function of an antibiotic to the wartime scenario. Wounded soldiers need protection from infected injuries, which requires an agent that kills or retards disease-causing microbes.

Final Logic: Option B correctly pairs the biological function of penicillin with its historic wartime medical application.

🧠 Memory Trick

Wound Protection: Penicillin protects Wounded soldiers by killing the Wicked microbes trying to infect them.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

11 Which of the following traditionally deadly diseases is NOT explicitly stated in the text as being treated with antibiotics?

A Plague

B Whooping cough (kali khansi)

C Diphtheria (gal ghotu)

D Cholera

💡 Short Explanation

NCERT explicitly names a specific set of human plagues curbed by antibiotics. Plague, whooping cough, diphtheria, and leprosy are listed together in the paragraph. Cholera is a major bacterial disease but is completely omitted from this specific historical list.

✅ Correct Answer Explanation

While discussing the revolutionary impact of antibiotics on human history, the NCERT textbook emphasizes how these compounds have saved millions of lives from devastating infectious diseases. The text specifically highlights four historic killers that were brought under control: plague, whooping cough (kali khansi), diphtheria (gal ghotu), and leprosy (kusht rog). Although cholera is a notorious waterborne bacterial disease treated with antibiotics in modern clinical practice, it is not explicitly mentioned in this specific list in the core textbook chapter.

❓ Why Other Options Are Incorrect

Option A → Plague is explicitly mentioned as one of the major deadly diseases tamed by antibiotics.
Option B → Whooping cough (kali khansi) is explicitly listed in the textbook passage alongside its vernacular name.
Option C → Diphtheria (gal ghotu) is explicitly cited in the paragraph as a disease manageable with antibiotic treatments.

🎯 Strategy

Application: Cross-reference each option directly with the specific list provided in the textbook passage. Eliminate the three options that appear explicitly in the text (Plague, Whooping cough, Diphtheria).

Final Logic: The remaining option, Cholera, is not in the textbook's list of diseases treated by antibiotics, making it the correct choice for this negative question.

🧠 Memory Trick

The NCERT Four: Antibiotics saved us from Plague, Whooping cough, Diphtheria, and Leprosy (People Win Disease Leagues). Cholera is left out.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

12 Arrange the conceptual steps of how antibiotics manage disease control:
I. An antibiotic chemical is produced by a specific microbe.
II. The antibiotic is administered and encounters disease-causing microbes.
III. The growth of the disease-causing microbes is killed or retarded.

A II-III-I

B I-II-III

C I-III-II

D III-II-I

💡 Short Explanation

An antibiotic must first be biosynthesized by a source microbial strain. The molecule must then be harvested, formulated, and introduced to a pathogen. Once the antibiotic encounters the pathogen, it acts biochemically to kill or inhibit it.

✅ Correct Answer Explanation

The process of using antibiotics to manage disease follows a logical biological and clinical sequence: 1. Step I (Biosynthesis): An antibiotic compound is naturally produced as a secondary metabolite by a specific regulatory microbe (e.g., Penicillium or Streptomyces). 2. Step II (Administration): The purified chemical is administered to a human patient, where it travels through the body to reach the site of infection and encounter the target pathogens. 3. Step III (Action): The antibiotic binds to its specific cellular targets in the pathogens, killing them or halting their growth to cure the infection. This yields the correct chronological sequence: I →II →III.

❓ Why Other Options Are Incorrect

Option A → Incorrect because administration (II) and pathogen inhibition (III) cannot happen before the antibiotic molecule has actually been produced (I).
Option C → Incorrect because the drug must be administered to the host (II) before it can physically interact with and inhibit the target pathogens (III).
Option D → This option completely reverses the logical sequence, placing the final therapeutic outcome (III) at the very beginning of the timeline.

🎯 Strategy

Application: A logical biological timeline must start with the initial synthesis of the compound (Step I). This requirement immediately eliminates choices A and D. Next, place the final clinical outcome (killing/halting the pathogens or Step III) at the very end of the sequence.

Final Logic: Tracing the steps from initial production to administration and therapeutic action confirms that Option B is the correct sequence.

🧠 Memory Trick

Make, Medicate, Manage: Make the drug (I) →Medicate the patient (II) →Manage and kill the infection (III).

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Antibiotics

13 If an industrial fermentor is utilizing a fungus rather than a bacterium to produce an organic acid, which acid is most likely being produced according to the text?

A Acetic acid

B Butyric acid

C Lactic acid

D Citric acid

💡 Short Explanation

Industrial organic acids are produced by either bacterial or fungal cultures. Acetic, butyric, and lactic acids are all produced by bacterial strains. Citric acid is produced using Aspergillus niger, which is a filamentous fungus.

✅ Correct Answer Explanation

The textbook divides industrial organic acid producers into bacteria and fungi. Acetic acid is produced by the bacterium Acetobacter aceti, butyric acid by the bacterium Clostridium butylicum, and lactic acid by the bacterium Lactobacillus. Citric acid, however, is synthesized commercially by fermenting sugary substrates with Aspergillus niger, which is a filamentous fungus belonging to the kingdom Fungi. This makes citric acid the correct choice for a fungal-driven process.

❓ Why Other Options Are Incorrect

Option A → Acetic acid is incorrect because its production organism, Acetobacter aceti, is a true bacterium.
Option B → Butyric acid is incorrect because its production organism, Clostridium butylicum, is an anaerobic bacterium.
Option C → Lactic acid is incorrect because it is produced by Lactobacillus, a well-known genus of bacteria.

🎯 Strategy

Application: Classify each organic acid based on whether its source organism is a bacterium or a fungus. Since options A, B, and C are all produced by bacteria, the fungal product stands out.

Final Logic: Citric acid is the only organic acid listed that is produced by a fungus (Aspergillus niger), making it the correct choice.

🧠 Memory Trick

Fungal Citric: Aspergillus is a fungus, and it makes citric acid. All the other organic acids are produced by bacteria.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

14 Match the specific bacterium with its corresponding organic acid product:

Column 1	Column 2
1. Acetobacter aceti	a. Lactic acid
2. Clostridium butylicum	b. Acetic acid
3. Lactobacillus	c. Butyric acid

A 1-b, 2-a, 3-c

B 1-c, 2-b, 3-a

C 1-b, 2-c, 3-a

D 1-a, 2-c, 3-b

💡 Short Explanation

Acetobacter aceti oxidizes ethanol into acetic acid. Clostridium butylicum ferments carbohydrates into butyric acid. Lactobacillus cultures convert lactose and simple sugars into lactic acid.

✅ Correct Answer Explanation

Matching each industrial bacterium with its specific metabolic organic acid product: 1 matches with b: Acetobacter aceti is the bacterial species used to manufacture acetic acid (vinegar). 2 matches with c: Clostridium butylicum is an anaerobic bacterium used to produce butyric acid. 3 matches with a: Lactobacillus is the genus of lactic acid bacteria (LAB) that produces lactic acid. This produces the matching combination 1-b, 2-c, 3-a, which corresponds exactly to Option C.

❓ Why Other Options Are Incorrect

Option A → Incorrect because it pairs Clostridium butylicum (2) with lactic acid (a) and Lactobacillus (3) with butyric acid (c).
Option B → Incorrect because it matches Acetobacter aceti (1) with butyric acid (c) and Clostridium butylicum (2) with acetic acid (b).
Option D → Incorrect because it pairs Acetobacter aceti (1) with lactic acid (a) and Lactobacillus (3) with acetic acid (b).

🎯 Strategy

Application: Look for the most obvious linguistic connections in the names. Acetobacter aceti corresponds to acetic acid (1-b), and Clostridium butylicum corresponds to butyric acid (2-c). This quickly narrows the choices down.

Final Logic: Checking the remaining pair (Lactobacillus to lactic acid) confirms that Option C is the only combination that matches all items correctly.

🧠 Memory Trick

Names Give It Away: Aceti = Acetic acid; Butylicum = Butyric acid; Lacto = Lactic acid.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

15 Which of the following is NOT an application or trait associated with lipases in the text?

A They are used in detergent formulations.

B They are helpful in removing oily stains from laundry.

C They are produced by microbes.

D They are used as 'clot busters' for myocardial infarction patients.

💡 Short Explanation

Lipases break down fats and oils, making them useful in laundry detergents. These commercial enzymes are produced using microbial fermentation. Dissolving dangerous blood clots in patients is the medical function of streptokinase, not lipases.

✅ Correct Answer Explanation

This negative question asks for an application that is NOT associated with lipases. Lipases are lipid-digesting enzymes produced through microbial fermentation (C) and added to commercial detergent formulations (A) to break down oily stains on clothing (B). Using an enzyme as a "clot buster" to dissolve blood clots in myocardial infarction patients is a specialized medical application that belongs to streptokinase, making Option D the false statement and the correct answer.

❓ Why Other Options Are Incorrect

Option A → This is a correct statement; lipases are standard ingredients added to modern commercial detergent formulations.
Option B → This is a correct statement; because they digest lipids, lipases are highly effective at breaking down oily laundry stains.
Option C → This is a correct statement; industrial lipases are grown and harvested from specific microbial cultures.

🎯 Strategy

Application: Separate industrial cleaning functions from specialized medical treatments. Dissolving blood clots to treat heart attacks is a medical emergency role that points directly to streptokinase, not a laundry enzyme.

Final Logic: Because Option D misassigns the medical function of streptokinase to lipases, it is factually false and is the correct answer.

🧠 Memory Trick

Clot Busters vs. Stain Busters: Lipase busts fat stains in the laundry; Streptokinase busts clots in the bloodstream.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

16 The process of clarifying bottled fruit juices to make them clearer than homemade juices fundamentally relies on:

A Distillation of the juices.

B The enzymatic action of pectinases and proteases.

C The fermentation of fruit sugars into ethanol.

D The addition of statins.

💡 Short Explanation

Homemade fruit juices look cloudy because they contain suspended fibers and proteins. Industrial processing uses specific enzymes to break down these cloudiness-causing molecules. Pectinases and proteases clear the liquid by digesting these plant fibers and proteins.

✅ Correct Answer Explanation

Freshly squeezed homemade fruit juices look cloudy because they contain large amounts of suspended plant proteins and structural pectin fibers from cell walls. To produce clear, store-bought bottled juices, manufacturers add industrial pectinases and proteases. These enzymes hydrolyze the structural pectin and proteins, breaking them down into soluble molecules and clarifying the juice.

❓ Why Other Options Are Incorrect

Option A → Distillation uses heat to separate liquids by boiling point, which would ruin the flavor of a fruit juice and turn it into a distilled spirit.
Option C → Fermenting fruit sugars into ethanol converts the juice into an alcoholic wine, rather than keeping it a fresh fruit beverage.
Option D → Statins are specialized medical molecules used to lower blood cholesterol in humans; they have no function in food manufacturing or juice clarification.

🎯 Strategy

Application: Directly connect the food manufacturing goal (clarifying fruit juice) with its specific biochemical solution: adding pectinase and protease enzymes.

Final Logic: Option B correctly names the pair of enzymes specified in the textbook for industrial juice clarification.

🧠 Memory Trick

P&P Clears the Juice: Pectinase and Protease make bottled juice Perfectly Pure and clear.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

17 A patient suffering from a heart attack due to a myocardial infarction requires a 'clot buster'. The bioactive molecule administered is derived from which microbe?

A Streptococcus

B Trichoderma polysporum

C Monascus purpureus

D Aspergillus niger

💡 Short Explanation

Heart attacks can be triggered by blood clots blocking key coronary arteries. Doctors use a "clot buster" enzyme called streptokinase to dissolve these blockages. This medical enzyme is harvested from cultures of the bacterium Streptococcus.

✅ Correct Answer Explanation

During a myocardial infarction (heart attack), blood clots block blood flow through the coronary arteries, starving the heart muscle of oxygen. To dissolve these blockages quickly, doctors administer streptokinase, an enzyme that acts as a "clot buster" to dissolve the blood clots and restore normal circulation. This life-saving medical enzyme is produced industrially using cultures of the bacterium Streptococcus.

❓ Why Other Options Are Incorrect

Option B → Trichoderma polysporum is a fungus used to produce Cyclosporin A, an immunosuppressive drug given to organ transplant patients.
Option C → Monascus purpureus is a yeast used to manufacture statins, which help lower blood cholesterol levels.
Option D → Aspergillus niger is a filamentous fungus used exclusively to manufacture industrial citric acid.

🎯 Strategy

Application: Use the name of the drug to identify its parent microbe. The drug streptokinase shares its name prefix with its source bacterium, Streptococcus.

Final Logic: Option A correctly pairs the clinical clot-busting enzyme with its biological source organism.

🧠 Memory Trick

Name Clue: Streptokinase comes directly from the bacterium Streptococcus.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

18 Why is the administration of Cyclosporin A critical for a patient undergoing an organ transplant?

A It competitively inhibits cholesterol synthesis during surgery.

B It clears clots from the newly connected blood vessels.

C It acts as an immunosuppressive agent.

D It clarifies the blood plasma.

💡 Short Explanation

The human immune system naturally attacks foreign tissues, including transplanted organs. Preventing this attack requires lowering the patient's immune response. Cyclosporin A serves as an effective immunosuppressive drug to prevent organ rejection.

✅ Correct Answer Explanation

After an organ transplant surgery, the recipient's immune system recognizes the new organ's surface antigens as foreign and activates cytotoxic T-cells to attack and destroy the graft tissue. To prevent this rejection, patients are treated with Cyclosporin A. This bioactive peptide acts as an immunosuppressive agent, dampening T-cell activity so the patient's body can accept the new, life-saving organ.

❓ Why Other Options Are Incorrect

Option A → Inhibiting cholesterol synthesis is the specific clinical function of statin drugs, which are unrelated to managing immune system responses.
Option B → Dissolving dangerous blood clots inside blood vessels is the function of the enzyme streptokinase.
Option D → Clarifying liquids using enzymes applies to fruit juice manufacturing (using pectinases), not to treating blood plasma inside a human patient.

🎯 Strategy

Application: Connect the specific drug (Cyclosporin A) directly to its vital medical role in organ transplant surgeries: serving as an immunosuppressant.

Final Logic: Option C accurately describes the core medical purpose of Cyclosporin A as detailed in the textbook.

🧠 Memory Trick

Safe Transplants: Cyclosporin A secures the Acceptance of new organs by suppressing the immune system.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

📄 Passage

"Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents. It acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol."

According to the passage, the biological source of commercialized statins is a:

A Bacterium

B Fungus (specifically a mould)

C Yeast

D Virus

💡 Short Explanation

Statins are harvested from the microbe Monascus purpureus. Biologically, Monascus purpureus is classified as a single-celled yeast strain. The provided passage explicitly defines this organism as a yeast.

✅ Correct Answer Explanation

The question looks for the correct biological classification of the statin-producing microbe based on the text. The provided passage explicitly states: "Statins produced by the yeast Monascus purpureus have been commercialised..." This direct statement identifies the organism as a single-celled fungus classified as a yeast, making Option C the factually correct choice.

❓ Why Other Options Are Incorrect

Option A → A bacterium is a prokaryotic organism; Monascus is a eukaryotic fungus, making this classification incorrect.
Option B → While yeasts belong to the kingdom Fungi, the text explicitly specifies that this organism is a single-celled yeast rather than a multicellular, filamentous mold.
Option D → A virus is a non-cellular pathogen; it cannot carry out the complex metabolic pathways needed to produce statins.

🎯 Strategy

Application: Extract the classification directly from the text passage, which explicitly pairs the drug's source with the word "yeast".

Final Logic: The text states "produced by the yeast Monascus purpureus," making yeast the clear choice.

🧠 Memory Trick

Read the Text: The passage explicitly uses the word "yeast" right before the organism's name, confirming its classification.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

📄 Passage

According to the passage, how do statins from Monascus purpureus lower blood cholesterol?

A By digesting existing cholesterol molecules in the blood.

B By genetically modifying the liver cells.

C By competitively inhibiting the enzyme responsible for synthesizing cholesterol.

D By acting as an immunosuppressive agent against cholesterol-producing cells.

💡 Short Explanation

Statins lower cholesterol levels by blocking its production at the source. They work through competitive inhibition, blocking the active site of a key liver enzyme. The provided text passage explicitly outlines this enzyme-blocking mechanism.

✅ Correct Answer Explanation

The question asks for the mechanism of action explicitly detailed in the provided text. The passage states: "It acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol." Statins match the chemical shape of the enzyme's natural substrate, allowing them to bind to and block the active site of HMG-CoA reductase, halting cholesterol production in the liver and lowering blood cholesterol levels.

❓ Why Other Options Are Incorrect

Option A → Statins do not break down or digest cholesterol molecules that are already floating in the blood; they work by stopping new cholesterol from being produced.
Option B → Statins are transient chemical inhibitors; they do not alter or genetically modify the patient's liver cell DNA.
Option D → Suppressing immune cell activity is the specific function of Cyclosporin A, which is unrelated to managing blood cholesterol.

🎯 Strategy

Application: Pull the exact mechanism directly from the provided text passage, which states that statins work by "competitively inhibiting the enzyme."

Final Logic: Option C uses the exact wording from the text passage to explain how statins function in the body.

🧠 Memory Trick

Block the Maker: Statins don't clear out old cholesterol; they competitively inhibit the enzyme that makes it.

📚 Class XII – Biology – Chapter: Microbes in Human Welfare – Topic: Chemicals, Enzymes and other Bioactive Molecules

CUET UG Booster Biology Unit 8Test (M2)

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