Ecology, Population Biology & Environmental Science

Ecology, Population Biology & Environmental Science

Given below are two statements regarding the generation of a vast array of B-cell receptors. Statement I : Multiple gene

Immunoglobulin light chains arise from V and J segment recombination, while heavy chains include D segments, and somatic V(D)J recombination in developing lymphocytes generates vast B-cell receptor diversity essential for adaptive immunity.

Ref: Kuby, Owen and Punt, Immunology, 7th Edition, Chapter 7 Organization and Expression of Immunoglobulin Genes, describes multiple V, D, J gene segments encoding light and heavy chains and somatic recombination in B cells, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

Given below are two statements regarding vaccines : Statement I : Vaccines are effective because of adaptive immunity an

Vaccines exploit adaptive immunity by generating long-lived plasma cells secreting protective antibodies and memory B cells capable of rapid secondary responses, providing pre-existing humoral protection and recall capacity upon pathogen re-exposure.

Ref: Kuby, Owen and Punt, Immunology, 7th Edition, Chapter 14 Vaccines and Adaptive Immune Memory, explains vaccines rely on adaptive immunity memory with pre-existing antibody and memory B-cell compartments, published by W. H. Freeman and Company.

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Ecology, Population Biology & Environmental Science

The following steps are involved in the generation of antibodies specific for the T-cell receptor. (A) Induce fusion of

Generating anti-TCR antibodies requires priming mice with antigen, expanding antigen-specific T cells, fusing with immortal T-cell line to create hybridomas, screening IL-2 secreting clones, then immunizing for anti-TCR antibodies blocking recognition.

Ref: Kuby, Owen and Punt, Immunology, 7th Edition, Chapter 9 T-cell Receptor and Experimental Generation of Anti-TCR antibodies, describes immunization, T-cell fusion to hybridoma, IL-2 screening and anti-TCR monoclonal antibody production, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

The following steps are involved in characterization of antigens by Western Blotting : (A) Electrophoretic transfer of p

Western blotting first denatures proteins with SDS, separates by size through polyacrylamide electrophoresis, transfers onto nitrocellulose membrane, probes with specific primary antibody, then detects via enzyme-conjugated secondary antibody substrate reaction.

Ref: Kuby, Owen and Punt, Immunology, 7th Edition, Chapter 5 Antigen-Antibody Interactions Techniques, details Western blotting sequence from SDS denaturation, SDS-PAGE, membrane transfer, antibody labeling and substrate detection, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A):

Molecular mimicry occurs when pathogen epitopes share structural similarity with host self-antigens, leading cross-reactive lymphocyte activation to mistakenly target host tissues, thereby linking infections to autoimmunity onset like rheumatic fever.

Ref: Kuby, Owen and Punt, Immunology, 7th Edition, Chapter 16 Autoimmunity and Molecular Mimicry, explains how infections promote autoimmune diseases via cross-reactive microbial antigens and mimicry, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

The difference between inside and outside hydrostatic pressure across the plasma membrane and cell wall is known as

Turgor pressure develops when water influx generates internal hydrostatic pressure exceeding external pressure, pushing plasma membrane against cell wall, maintaining rigidity, growth, and stomatal mechanics in plant cells essential for survival.

Ref: Taiz and Zeiger, Plant Physiology and Development, 6th Edition, Chapter 3 Water and Plant Cells, discusses water potential components including turgor pressure as hydrostatic pressure difference across membrane and wall, published by Sinauer Associates.

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Ecology, Population Biology & Environmental Science

Free energy is

Gibbs free energy defines thermodynamically available work under constant temperature and pressure, predicting spontaneity. Negative ΔG indicates exergonic reaction capable of performing useful chemical work in living biological systems precisely.

Ref: Lehninger, Nelson and Cox, Principles of Biochemistry, 8th Edition, Chapter 13 Bioenergetics and Thermodynamics, defines Gibbs free energy as energy isothermally available to do work and explains ΔG and spontaneity, published by W. H. Freeman and Company.

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Ecology, Population Biology & Environmental Science

The active site of an enzyme is flexible as per the

Koshland's induced fit model proposes enzyme active site is not rigid but flexible, undergoing conformational rearrangement upon substrate binding to achieve optimal complementarity, enhancing catalytic specificity and transition state stabilization.

Ref: Lehninger, Nelson and Cox, Principles of Biochemistry, 8th Edition, Chapter 6 Enzymes Mechanism, compares lock and key model with Koshland induced fit model where active site flexibility occurs upon substrate binding, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

In allosteric regulation

Allosteric effectors bind reversibly via non-covalent interactions to regulatory sites distinct from catalytic center, inducing conformational changes that alter enzyme activity, enabling feedback inhibition and metabolic pathway coordination in cells efficiently.

Ref: Lehninger, Nelson and Cox, Principles of Biochemistry, 8th Edition, Chapter 6 Enzymes Regulation, describes allosteric regulation by non-covalent binding at sites other than active site causing conformational change, published by W. H. Freeman.

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Ecology, Population Biology & Environmental Science

The entire process of electrons being displaced from PSI due to excitation by light, getting replaced from photosystem I

Non-cyclic electron flow describes linear transfer where water is split at PSII, electrons pass via plastoquinone, cytochrome b6f, plastocyanin to PSI, then to ferredoxin and NADP+, producing ATP and NADPH needed.

Ref: Taiz and Zeiger, Plant Physiology and Development, 6th Edition, Chapter 7 Photosynthesis: Light Reactions, discusses non-cyclic versus cyclic electron flow and Z-scheme from water to NADP+, published by Sinauer Associates Oxford University Press.

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Ecology, Population Biology & Environmental Science

Rubisco gets activated by light due to (A) increase in pH of lumen (B) decrease in pH of lumen (C) decrease in pH of str

Light-driven proton pumping acidifies thylakoid lumen decreasing pH and alkalinizes stroma increasing pH, activating Rubisco via carbamylation dependent on stromal Mg2+ concentration rise, optimizing Calvin cycle activity in illuminated chloroplasts.

Ref: Taiz and Zeiger, Plant Physiology and Development, 6th Edition, Chapter 8 Photosynthesis: The Carbon Reactions, explains light-induced stromal alkalinization, lumen acidification and Rubisco activation via carbamylation and Mg2+, published by Sinauer Associates.

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Ecology, Population Biology & Environmental Science

Prions, the small proteinaceous infectious particles were named by

Stanley Prusiner coined the term prion in 1982 to describe small proteinaceous infectious particles causing scrapie and Creutzfeldt-Jakob disease, lacking nucleic acid, challenging central dogma and later earning Nobel Prize.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 5 discussion on prions and infectious proteins, credits Stanley Prusiner for naming prions in 1982 as proteinaceous infectious particles, published by Garland Science.

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