CUET UG Biology Booster Test 3-Medical Applications -

🚀

CUET UG Biology Booster Test 3-Medical Applications

⏱️ 30 Minutes

❓ 20 Questions

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

CUET UG Biology Booster Test 3-Medical Applications

1 / 20

QUESTION 1 OF 20

📄 Passage

"Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges. In mammals, including humans, insulin is synthesised as a pro-hormone (like a pro-enzyme, the pro-hormone also needs to be processed before it becomes a fully mature and functional hormone) which contains an extra stretch called the C peptide.",

Analytically speaking, based on the passage, the primary role of the retroviral vector in this ex vivo gene therapy process is to act as a:

Answer Review

📄 Passage

Analytically speaking, based on the passage, the primary role of the retroviral vector in this ex vivo gene therapy process is to act as a:

A Pathogenic agent to destroy defective lymphocytes

B Delivery vehicle to introduce functional ADA cDNA into cultured cells

C Culture medium to support the growth of lymphocytes outside the body

D Chemical catalyst to create disulfide bonds in ADA enzymes

💡 Short Explanation

Vectors in gene therapy serve as carriers for genetic material. Retroviruses are used specifically to transport functional cDNA into the host cell's genome. They do not act as culture media or catalysts.

✅ Correct Answer Explanation

In ex vivo gene therapy, the retroviral vector is engineered to carry the therapeutic (functional) ADA cDNA. It infects the patient's lymphocytes, integrating the healthy gene into the cell's genome, thereby correcting the genetic defect at the molecular level. This makes "delivery vehicle" the precise biological description.

❓ Why Other Options Are Incorrect

Option A → Vectors in this context are therapeutic, not pathogenic; they don't destroy cells.
Option C → Culture media consists of nutrients (amino acids, sugars), not viruses.
Option D → Catalysts are enzymes/chemicals, not viral vectors.

🎯 Strategy

Used: Substitution

Application: Substituting the technical definition of a "vector" into the sentence to verify accuracy.

Final Logic: Vector = Delivery vehicle for gene.

🧠 Memory Trick

"Vector = Delivery Truck."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

📄 Passage

The necessity of "periodic infusion" in the passage highlights a fundamental biological limitation of the treated lymphocytes. What is this limitation?

A The cells lack the ability to undergo cellular respiration.

B The cells are prone to spontaneous cancerous mutations.

C The cells have a finite lifespan and are not immortal.

D The cells immediately lose the ADA cDNA upon re-entering the bloodstream.

💡 Short Explanation

Lymphocytes are somatic cells with a limited lifespan. They undergo apoptosis naturally after a period. Because they die, the therapeutic effect ends, necessitating re-infusion.

✅ Correct Answer Explanation

The passage specifically notes that the cells are "not immortal." In biological terms, this means they have a finite lifespan. Once these treated cells die, the patient no longer produces the ADA enzyme, which is the direct cause for needing repeated (periodic) infusions to maintain therapeutic levels.

❓ Why Other Options Are Incorrect

Option A → Lymphocytes are alive and respiring; this is not the reason for infusion.
Option B → Cancerous mutation is a safety risk, not the reason for periodic infusion.
Option D → Integrated cDNA is stable in the cell's genome; it is not lost upon re-entry.

🎯 Strategy

Used: Contextual/Tonal Matching

Application: Matching the limitation directly to the phrase "not immortal" provided in the passage.

Final Logic: Finite lifespan = Needs replacement.

🧠 Memory Trick

"Not immortal = Cells die = Need more."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

3 Which of the following is NOT a logistical or clinical advantage of mass-producing recombinant therapeutics as described in the text?

A It circumvents the limited availability of hormones from non-human slaughtered animals.

B It allows for the extraction of human genes directly from animal byproducts.

C It enables the creation of safer drugs on an industrial scale.

D It prevents the immunological responses common with non-human sources.

💡 Short Explanation

Recombinant technology uses engineered microorganisms (like E. coli), not animal byproducts. The human gene is cloned, not "extracted from animal byproducts." A, C, and D are valid clinical advantages.

✅ Correct Answer Explanation

Recombinant technology creates drugs by inserting human DNA into microbes (bacteria/yeast). It does not use animal byproducts to obtain human genes. Therefore, Option B is factually incorrect regarding the methodology and purpose of recombinant production.

❓ Why Other Options Are Incorrect

Option A → Correct advantage; mass production solves supply chain limits of animal slaughter.
Option C → Correct advantage; industrial scale is the hallmark of RDT.
Option D → Correct advantage; avoiding foreign animal proteins prevents allergies.

🎯 Strategy

Used: Elimination

Application: Eliminating the statement that describes an incorrect (and biologically impossible) method.

Final Logic: RDT = Engineered microbes, not animal byproduct extraction.

🧠 Memory Trick

"RDT = Microbes, not Animal parts."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Recombinant Therapeutics –

4 Analyze the following statements regarding the immunological safety of therapeutics:
I. Animal-source insulin can elicit an immune response because the human body recognizes it as a foreign protein.
II. Recombinant human insulin prevents allergies because its sequence is identical to naturally produced human insulin.
III. Recombinant therapeutics contain modified animal proteins that suppress the human immune system. Which of the statements are analytically correct?

A I and II only

B II and III only

C I and III only

D I, II, and III

💡 Short Explanation

I is correct: Foreign proteins trigger immune responses. II is correct: Identity with human sequence prevents recognition as foreign. III is incorrect: Recombinant therapeutics are human-identical, not modified animal proteins.

✅ Correct Answer Explanation

Statement I accurately describes the cause of allergy (recognition of non-human protein). Statement II explains why recombinant human insulin is safe (sequence identity to "self"). Statement III is false because recombinant drugs are human-identical proteins, not immunosuppressive animal proteins.

❓ Why Other Options Are Incorrect

Options B, C, D → All include the incorrect statement III.

🎯 Strategy

Used: Substitution

Application: Identifying that RDT drugs are "human-identical" and not "modified animal suppressors."

Final Logic: RDT = Human identical; I & II are true.

🧠 Memory Trick

"RDT = Human Sequence."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Recombinant Therapeutics –

5 If a novel recombinant therapeutic is added to the 30 currently approved for human use globally, what primary characteristic must it possess compared to non-recombinant alternatives derived from animals?

A It must induce a mild, controllable immune response.

B It must be extracted from a non-human mammalian source.

C It must avoid inducing unwanted immunological responses while being effective.

D It must be administered via bone marrow transplantation.

💡 Short Explanation

The fundamental advantage of recombinant drugs over animal ones is safety. "Safety" in this context is the lack of immune reaction. Other options describe either the negative traits of old drugs or unrelated medical procedures.

✅ Correct Answer Explanation

Recombinant therapeutics were developed specifically to overcome the safety flaws of traditional animal-derived medicines. The goal is to provide a highly effective drug that is indistinguishable from human protein, thus avoiding "unwanted immunological responses" (allergies/rejection).

❓ Why Other Options Are Incorrect

Option A → We do not want any immune response.
Option B → This describes the old, flawed method.
Option D → Not all recombinant drugs require bone marrow transplants.

🎯 Strategy

Used: Substitution

Application: Defining the success criteria for recombinant drugs.

Final Logic: Recombinant = No immune response + Effective.

🧠 Memory Trick

"Recombinant = Safe & Effective."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Recombinant Therapeutics –

6 Given that 12 recombinant therapeutics are currently marketed in India, what defines their core manufacturing difference compared to traditional non-recombinant biological medicines?

A They are synthesized purely through organic chemistry without biological agents.

B They are mass-produced using genetically engineered organisms.

C They are isolated exclusively from human cadavers.

D They rely on plant tissue culture rather than microbial expression.

💡 Short Explanation

Recombinant technology uses genetically engineered hosts (like E. coli). They are "biological" (living cells), not pure organic chemistry. They are not from cadavers or plant culture (mostly).

✅ Correct Answer Explanation

The "recombinant" nature of these drugs relies on introducing human DNA into microorganisms. These engineered organisms then act as factories, mass-producing the desired human protein (like insulin or ADA).

❓ Why Other Options Are Incorrect

Option A → They are produced by biological systems, not just chemical synthesis.
Option C → They are produced in labs, not from cadavers.
Option D → Most recombinant therapeutics use microbial systems (bacteria/yeast), not plant tissue culture.

🎯 Strategy

Used: Substitution

Application: Identifying the definition of "Recombinant DNA Technology" (DNA insertion + microbial expression).

Final Logic: Engineered organisms = Factory.

🧠 Memory Trick

"RDT = Genetic Engineering + Microbes."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Recombinant Therapeutics –

7 Arrange the structural components of insulin logically to represent the transition from its immature synthesized form to its final structural composition in humans:
I. Mature hormone with Chain A and Chain B
II. Pro-hormone
III. Structure containing an extra stretch of C peptide
IV. Linked by disulphide bridges

A II → III → I → IV

B III → II → IV → I

C II → I → III → IV

D IV → III → II → I

💡 Short Explanation

II/III: Insulin is synthesized as a pro-hormone containing the C-peptide. I: Processing removes C, resulting in A+B. IV: They are held together by disulphide bridges.

✅ Correct Answer Explanation

Insulin starts as a pro-hormone (II) which contains the C-peptide (III). During maturation, the C-peptide is removed (leading to I), and the remaining chains are stabilized by disulphide bridges (IV). Note: While IV describes the final state, the sequence of development is II > III > I (and the final structure I is characterized by IV).

❓ Why Other Options Are Incorrect

Options B, C, D → Incorrect developmental sequence.

🎯 Strategy

Used: Substitution

Application: Ordering the physiological process of insulin maturation.

Final Logic: Pro-hormone > C-peptide removal > Mature Chains linked by Disulphide.

🧠 Memory Trick

"Pro > Remove C > Mature A+B."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

8 What would be the most likely structural and functional consequence if the downstream processing technology failed to establish disulphide bridges during artificial insulin production?

A Chains A and B would remain permanently attached to the C-peptide.

B The individual chains A and B would fail to assemble into a functional mature insulin molecule.

C The resulting insulin would be highly functional but trigger severe allergies.

D The E. coli host would immediately degrade the individual chains.

💡 Short Explanation

Disulphide bridges are required to join chain A and chain B together. Without these bridges, the two chains will not form the functional, complex 3D shape needed for hormone activity. This results in a loss of function.

✅ Correct Answer Explanation

Insulin's biological activity depends on its specific 3D conformation, which is maintained by the disulphide bridges connecting chain A and chain B. If these bridges fail to form, the chains cannot assemble into the correct, functional structure.

❓ Why Other Options Are Incorrect

Option A → Disulphide bridges don't affect C-peptide retention; the C-peptide is removed during prior processing.
Option C → A non-assembled insulin molecule is not functional; function cannot be maintained.
Option D → While degradation is possible, the most direct consequence of failing to assemble is loss of function.

🎯 Strategy

Used: Substitution

Application: Understanding the functional requirement of the disulfide cross-linking in the final product.

Final Logic: No bridges = No assembly = No function.

🧠 Memory Trick

"No bridges = No Insulin."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

9 Match the physiological states/components to their corresponding stages in insulin maturation:

Column I	Column II
1. Synthesized pro-hormone	i. A, B and C-peptide
2. Maturation process	ii. Removal of C-peptide
3. Mature functional insulin	iii. A and B linked by disulphide bonds
4. Analogous example	iv. Pro-enzyme processing

A 1-i, 2-ii, 3-iii, 4-iv

B 1-ii, 2-i, 3-iv, 4-iii

C 1-iv, 2-iii, 3-i, 4-ii

D 1-iii, 2-iv, 3-ii, 4-i

💡 Short Explanation

1. Synthesized pro-hormone = A, B, and C-peptide (i). 1. Maturation process = Removal of C-peptide (ii). 1. Mature functional insulin = A and B linked by disulphide (iii). 1. Analogous example = Pro-enzyme processing (iv).

✅ Correct Answer Explanation

All stages match their textbook descriptions: Pro-hormones contain the C-peptide; Maturation removes it; Mature insulin uses disulphide bridges; The process is analogous to activating enzymes (like pepsinogen).

❓ Why Other Options Are Incorrect

Options B, C, D → Incorrect mapping of components.

🎯 Strategy

Used: Option Grouping

Application: Matching physiological components of insulin maturation correctly.

Final Logic: Correct mapping of stages and definitions.

🧠 Memory Trick

"Pro=ABC, Maturity=C-out, Mature=A+B-S-S."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

10 Analytically, why did the presence of the C-peptide pose the main challenge for the commercial production of recombinant human insulin?

A Because bacteria lack the natural enzymes to accurately cleave the C-peptide and assemble the mature form.

B Because the C-peptide is highly toxic to E. coli cells.

C Because the C-peptide prevents the transcription of insulin DNA.

D Because Eli Lilly failed to synthesize the DNA sequence for the C-peptide.

💡 Short Explanation

Bacteria (prokaryotes) do not perform the same post-translational modification as human cells (eukaryotes). Human cells use specific proteases to remove the C-peptide. Bacteria cannot do this efficiently, forcing the "separate chain" approach.

✅ Correct Answer Explanation

Eukaryotic (human) cells possess specific enzymes that cleave the C-peptide during insulin maturation. Prokaryotes (bacteria like E. coli) do not have these specific enzymes. Therefore, producing full pro-insulin in bacteria would result in the C-peptide remaining attached, yielding non-functional insulin. Eli Lilly overcame this by creating chains A and B separately.

❓ Why Other Options Are Incorrect

Option B → Toxicity is not the issue; functionality is.
Option C → C-peptide presence does not block transcription.
Option D → Eli Lilly could have synthesized it, but it wouldn't have been useful to do so in bacteria.

🎯 Strategy

Used: Substitution

Application: Identifying the biological limitation of prokaryotes compared to eukaryotes regarding post-translational processing.

Final Logic: Bacteria lack cleavage enzymes = Need separate chains.

🧠 Memory Trick

"Bacteria lack human enzymes."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

11 Which of the following does NOT represent the analytical ingenuity of Eli Lilly's 1983 approach to insulin production?

A Bypassing the need to process a pro-hormone inside the bacteria.

B Preparing separate DNA sequences for Chains A and B.

C Successfully utilizing E. coli plasmids as vectors.

D Creating a single recombinant plasmid that produced a fully formed pro-insulin molecule containing the C-peptide.

💡 Short Explanation

Eli Lilly's ingenuity was in avoiding the pro-insulin approach. They used two separate sequences, not a single one for pro-insulin. D is the opposite of what they actually did.

✅ Correct Answer Explanation

Eli Lilly's success was due to preparing two distinct DNA sequences for chains A and B, producing them separately, and joining them via disulphide bridges. They did not attempt to produce pro-insulin containing the C-peptide in bacteria because bacteria cannot process it correctly.

❓ Why Other Options Are Incorrect

Option A, B, C → All accurately describe the ingenious methods used by Eli Lilly.

🎯 Strategy

Used: Substitution

Application: Identifying the statement that contradicts the actual "separate chain" used.

Final Logic: D is false; they did not use the pro-insulin method.

🧠 Memory Trick

"Separate, not Pro."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

12 In the artificial production of insulin, why were Chains A and B produced separately in E. coli rather than as a complete pro-hormone?

A Because E. coli cannot transcribe mammalian DNA.

B Because getting insulin properly assembled into a mature form (removing C-peptide) via rDNA techniques was technically challenging.

C Because plasmids can only carry one gene at a time.

D Because disulphide bridges form spontaneously inside E. coli cytoplasm.

💡 Short Explanation

Bacteria lack human enzymes for C-peptide cleavage. Without cleavage, insulin is non-functional. Producing separately allows manual/in-vitro assembly, ensuring functionality.

✅ Correct Answer Explanation

The main challenge was the post-translational modification (removing the C-peptide) which bacteria cannot perform accurately. By producing the chains separately and combining them artificially, the scientists bypassed the need for bacterial maturation mechanisms, ensuring the production of functional human insulin.

❓ Why Other Options Are Incorrect

Option A → Bacteria can transcribe mammalian DNA; that is the basis of RDT.
Option C → Plasmids can carry multiple genes.
Option D → Bridges do not form correctly in the bacterial environment in a way that generates functional insulin.

🎯 Strategy

Used: Substitution

Application: Identifying the core technical limitation of prokaryotic host systems.

Final Logic: Prokaryote $\neq$ Cleavage enzyme.

🧠 Memory Trick

"No cleavage = No pro-insulin = Separate chains."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Human Insulin –

13 Evaluate the following statements regarding the theoretical foundations of gene therapy:
I. It is exclusively used for infectious diseases like HIV.
II. It allows for the correction of genetic defects diagnosed in embryos.
III. It fundamentally operates by delivering a normal gene to take over the function of a non-functional one. Which of the statements are analytically correct?

A I and II only

B II and III only

C I and III only

D I, II, and III

💡 Short Explanation

I is false: Gene therapy is for genetic/hereditary defects, not infectious diseases (like HIV, which is viral). II is true: Embryonic correction is a goal. III is true: It is the functional definition of gene therapy.

✅ Correct Answer Explanation

Gene therapy is designed to correct hereditary genetic disorders, not infectious diseases (I is false). Statements II and III accurately reflect its scope (embryos) and mechanism (delivering a normal gene to restore/compensate for function).

❓ Why Other Options Are Incorrect

Options A, C, D → All include the incorrect statement I.

🎯 Strategy

Used: Elimination

Application: Identifying that gene therapy is for genetic diseases, not infectious ones.

Final Logic: Genetic $\neq$ Infectious.

🧠 Memory Trick

"Gene Therapy = Hereditary, not Infectious."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

14 At the molecular level, how does the delivery of a normal gene "compensate" for a non-functional gene in an individual?

A By excising the defective DNA sequence and replacing it directly.

B By producing the required functional product that the mutated gene failed to produce.

C By binding to the non-functional mRNA to initiate RNA interference.

D By stimulating the immune system to destroy cells containing the defective gene.

💡 Short Explanation

"Compensation" means providing what is missing. If a gene is missing/defective, the protein it codes for is absent. Adding a functional gene provides the protein, thus compensating for the defect.

✅ Correct Answer Explanation

Gene therapy introduces a functional gene that serves as a template. The cell then uses this template to produce the protein product that was previously missing or defective. This product "compensates" for the mutation, restoring normal cellular function.

❓ Why Other Options Are Incorrect

Option A → Gene therapy (typically) does not remove/excise the defective gene; it adds a new one.
Option C → This is not the mechanism of standard gene therapy compensation.
Option D → Destroying cells is not the goal; saving the cell function is.

🎯 Strategy

Used: Substitution

Application: Defining the term "compensation" in the context of protein expression.

Final Logic: Functional Gene = Functional Product = Compensation.

🧠 Memory Trick

"Compensate = Provide what's missing."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

15 Which of the following physiological outcomes is NOT a direct analytical result of lacking the ADA enzyme?

A Inability to produce insulin in the pancreas

B A compromised immune system

C Vulnerability to infections

D The necessity for therapies like bone marrow transplants or engineered lymphocytes

💡 Short Explanation

ADA deficiency impacts the immune system. Insulin production is a separate function of the pancreas. ADA deficiency does not cause diabetes.

✅ Correct Answer Explanation

ADA is an immune-critical enzyme. Its absence leads to immune failure (SCID) and high infection risk (B, C), and requires specialized therapies (D). It is entirely unrelated to insulin production, which is managed by the pancreatic beta cells.

❓ Why Other Options Are Incorrect

Option B, C, D → All are correct analytical results/needs of ADA deficiency.

🎯 Strategy

Used: Elimination

Application: Distinguishing the function of ADA (immune) from other metabolic/hormonal functions (insulin).

Final Logic: ADA = Immune System $\neq$ Insulin.

🧠 Memory Trick

"ADA = Immune, not Insulin."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

16 Match the genetic defect concept with its corresponding clinical presentation based on ADA deficiency:

Column I	Column II
1. Deletion of gene	i. Missing instructions
2. Hereditary	ii. Born with it
3. Lack of enzyme	iii. Immune failure
4. Molecular diagnosis	iv. Early detection

A 1-i, 2-ii, 3-iii, 4-iv

B 1-ii, 2-i, 3-iv, 4-iii

C 1-iii, 2-iv, 3-i, 4-ii

D 1-iv, 2-iii, 3-ii, 4-i

💡 Short Explanation

1. Deletion of gene = Missing instructions (i). 1. Hereditary = Born with it (ii). 1. Lack of enzyme = Immune failure (iii). 1. Molecular diagnosis = Early detection (iv).

✅ Correct Answer Explanation

The concepts align perfectly: Gene deletion means missing protein instructions; Hereditary status means being born with the condition; The lack of ADA leads directly to immune failure; Molecular diagnosis is the clinical tool used to identify these genetic defects early.

❓ Why Other Options Are Incorrect

Options B, C, D → Incorrect mapping of concepts.

🎯 Strategy

Used: Option Grouping

Application: Matching molecular concepts to their clinical reality.

Final Logic: Accurate data pairing.

🧠 Memory Trick

"Deletion=Instruction, Hereditary=Birth, Lack=Immune, Diagnosis=Target."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

17 From a long-term clinical perspective, why is enzyme replacement therapy considered a maintenance approach rather than a definitive cure?

A It alters the patient's DNA temporarily.

B It requires continuous injections because the functional ADA enzyme is gradually degraded and not naturally produced by the patient's cells.

C It eventually triggers a fatal autoimmune response.

D It relies on periodic infusion of genetically engineered lymphocytes.

💡 Short Explanation

Maintenance = Regular input of what the body lacks. Cure = Fixing the body to produce it naturally. Enzyme therapy is just injecting protein; the body is still genetically deficient.

✅ Correct Answer Explanation

Enzyme replacement therapy (ERT) acts as a bridge. The patient lacks the gene to produce ADA, so the enzyme must be introduced artificially. Because proteins have a half-life and are degraded, and the body never regains the ability to make its own ADA, ERT must be administered for the lifetime of the patient.

❓ Why Other Options Are Incorrect

Option A → ERT does not alter DNA at all.
Option C → It does not necessarily trigger fatal autoimmunity.
Option D → This describes gene therapy, not enzyme replacement.

🎯 Strategy

Used: Substitution

Application: Differentiating between therapeutic "maintenance" and "genetic correction."

Final Logic: Injection > Degrades > Need more = Maintenance.

🧠 Memory Trick

"Maintenance = Keep replacing = Never ends."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

18 Which of the following is NOT an analytical reason why bone marrow transplantation is considered "not completely curative" for all ADA deficiency patients?

A It relies on injecting functional ADA directly rather than establishing a cellular source.

B Finding an exact immunological match for transplantation is inherently difficult.

C Even if successful, it may not restore 100% of immune function in all children.

D It involves inherent cellular rejection risks unlike the patient's own genetically corrected lymphocytes.

💡 Short Explanation

Bone marrow transplantation is a cellular source. Option A is factually wrong because it describes Enzyme Replacement Therapy (ERT). Options B, C, and D are valid reasons why transplantation is a difficult or limited cure.

✅ Correct Answer Explanation

The premise of bone marrow transplantation is the replacement of the defective stem cell population with healthy ones. Option A is the correct answer to the "NOT" question because it erroneously defines bone marrow transplantation as "injecting functional ADA," which is the definition of enzyme replacement.

❓ Why Other Options Are Incorrect

Option B, C, D → All are true challenges associated with transplantation.

🎯 Strategy

Used: Substitution

Application: Identifying the incorrect definition of a clinical procedure.

Final Logic: A defines ERT, not BMT.

🧠 Memory Trick

"A is wrong; BMT = cells, not injections."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

19 Arrange the conceptual stages required to transition from a temporary gene therapy fix to a permanent cure for ADA deficiency:
I. Isolate the functional gene.
II. Identify the gene deletion.
III. Introduce the gene into the early embryo.
IV. Lifelong production.

A II → I → III → IV

B I → II → IV → III

C II → III → I → IV

D III → I → II → IV

💡 Short Explanation

II: Identify the gene deletion. I: Isolate the functional gene. III: Introduce gene into early embryo. IV: Lifelong production.

✅ Correct Answer Explanation

To move from temporary (lymphocytes) to permanent, the process is: (II) Identify the defect > (I) Isolate the gene that should be there > (III) Integrate it into the early embryonic stage > (IV) This results in continuous lifelong production of the enzyme by the host cells.

❓ Why Other Options Are Incorrect

Options B, C, D → Incorrect logical ordering.

🎯 Strategy

Used: Substitution

Application: Sequencing the steps for permanent genetic correction.

Final Logic: Diagnose > Isolate > Introduce > Function.

🧠 Memory Trick

"Diagnose > Isolate > Embryo > Lifelong."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

20 Analytically, why does the introduction of the ADA gene into early embryonic stages offer a permanent cure, unlike introducing it into adult lymphocytes?

A Embryonic cells naturally replicate retroviral vectors indefinitely.

B Embryonic insertion ensures the functional gene is copied into all somatic and immune cells as the embryo develops, establishing a permanent endogenous source.

C Lymphocytes in embryos do not require the ADA enzyme to function.

D Early embryos do not possess an immune system to reject the foreign gene.

💡 Short Explanation

Embryonic cells are progenitors for all tissues. Integration at this stage means all cells inherit the functional gene. This creates a permanent, internal source of ADA.

✅ Correct Answer Explanation

Introducing the gene into adult lymphocytes only affects a transient cell population (temporary cure). Introducing it into an early embryo means the gene is present in the precursor cells for the entire body. As the embryo divides and differentiates, every new cell contains the corrected DNA, creating a lifelong "endogenous" (internal) factory for ADA.

❓ Why Other Options Are Incorrect

Option A → Embryonic cells don't "naturally replicate vectors" in this way.
Option C → Lymphocytes in embryos absolutely require ADA.
Option D → While immune rejection is different in embryos, this is not the analytical reason for the permanency of the cure.

🎯 Strategy

Used: Substitution

Application: Identifying the biological rationale for permanent genetic correction.

Final Logic: Embryo = All cells = Endogenous Source.

🧠 Memory Trick

"Embryo = All cells = Permanent."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Gene Therapy –

CUET UG Biology Booster Test 3-Medical Applications

Test Complete!

Answer Review