28 public questions tagged with this topic.
Cyclosporin A is an immunosuppressive drug used to prevent organ transplant rejection. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Clomiphene citrate is widely used to induce ovulation in women with anovulatory infertility, particularly in PCOS. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Histamine does not reduce inflammation; instead, it promotes inflammation by causing blood vessels to dilate. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.
Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, physiology, human health and related concepts as per latest syllabus.
Histamine is released by mast lls during allergic reactions and causes inflammation. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Histamine does not inhibit inflammation; instead, it promotes inflammation and allergic responses. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Saheli is a non-steroidal oral contraceptive pill developed by CDRI, Lucknow, India. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.
Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, physiology, human health and related concepts as per latest syllabus.
Carbon dioxide is 20-25 times more soluble in blood than oxygen, making it easier to transport. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.
Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, physiology, human health and related concepts as per latest syllabus.
Oral contraceptive pills prevent pregnancy primarily by suppressing ovulation through hormonal regulation. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function, Topic: Structural organization and physiology.
MDR1 officially ABCB1, also called P-glycoprotein P-gp, is a 1280 amino acid 170 kDa glycosylated plasma membrane exporter noted for conferring resistance to colchicine and doxorubicin in selection experiments. Tissue distribution includes apical brush border of small intestinal enterocytes limiting drug absorption, canalicular membrane of hepatocytes promoting biliary excretion, luminal membrane of proximal renal tubule mediating urinary elimination, endothelial cells of blood-brain barrier restricting central entry, and placental syncytiotrophoblast protecting fetus. Substrates are typically neutral or cationic amphipathic molecules of 300 to 2000 Da that partition into lipid bilayer such as paclitaxel, vincristine, etoposide, imatinib and cyclosporine. Transport cycle involves two ATP hydrolysis events: ATP binding closes NBD dimer, induces outward-facing TMD conformation collapsing high-affinity pocket and expelling substrate, then hydrolysis resets system. Genomic amplification and pregnane X receptor mediated induction after chemotherapy increase efflux, lowering cytosolic concentration and causing therapy failure requiring dose escalation and combination strategies. Such detailed mechanistic insight is frequently examined in competitive tests including NEET, CUET, CSIR-NET and GATE where transporter classification, energetics and disease linkage are integrated into problem-solving questions.
Ref: Sharom, Pharmacogenomics 2008, P-glycoprotein; Alberts, 7th ed., Chapter 11 MDR transporters.
Aminoglycosides such as gentamicin, streptomycin and amikacin are polycationic molecules whose uptake depends on proton-motive force and electron transport, explaining reduced activity against anaerobes and biofilms. Once concentrated inside bacterial cytoplasm, they lodge with exceptionally high affinity in the decoding center formed by helix 44 of 16S rRNA within the 30S small ribosomal subunit at the A-site where aminoacyl-tRNA selection and proofreading occur during translation. The drug forces an abnormal closed conformation of rRNA, impairing proofreading and inducing misreading of mRNA codons, premature termination, frameshifting and accumulation of aberrant, misfolded membrane proteins. These defective proteins insert into inner membrane, increasing permeability, dissipating membrane potential and promoting further drug uptake, a positive feedback loop that contributes to concentration-dependent bactericidal action and post-antibiotic effect. Aminoglycosides also block formation of the 70S initiation complex comprising mRNA, formyl-methionyl-tRNA and subunits and inhibit translocation of peptidyl-tRNA from A to P site. Synergy with cell-wall agents that enhance entry underlies combination therapy for Gram-negative sepsis.
Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 5: Aminoglycosides and 30S Ribosomal Subunit Inhibition.
Glycopeptide antibiotics exhibit true bactericidal killing activity rather than simple growth arrest, a distinction critical for treating severe Gram-positive infections. Vancomycin functions by recognizing and binding with high affinity to the D-alanyl-D-alanine dipeptide terminus of the peptidoglycan precursor lipid II that is exposed on the outer face of the cytoplasmic membrane after flipping from the cytoplasm. This binding creates a large steric cap that prevents transglycosylases from polymerizing the alternating N-acetylglucosamine and N-acetylmuramic acid glycan chain and simultaneously blocks transpeptidases, the penicillin-binding proteins, from forming peptide cross-links between stems. Without cross-linking, the nascent peptidoglycan mesh in Gram-positive organisms with 20-80 nm thick wall remains mechanically weak and cannot withstand internal turgor pressures of 20 atmospheres, leading to activation of autolysins and osmotic lysis. Tetracycline, erythromycin and clindamycin bind reversibly to bacterial ribosomes, pausing translation temporarily and causing bacteriostatic arrest where cells resume growth after drug removal, explaining clinical preference for vancomycin in MRSA bacteremia and endocarditis where rapid killing is desired.
Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 5: Glycopeptide Antibiotics and Cell Wall Inhibition.
Trichoderma polysporum produces cyclosporin A, which is used to suppress immune responses in organ transplant patients.
Ref: NCERT Class 12 Biology Chapter 8: Microbes in Human Welfare Microbes as Biocontrol Agents - Bt Baculovirus Trichoderma
