8 public questions tagged with this topic.
In NH₃ , hydrogen bonding occurs between the hydrogen of one molecule and the nitrogen lone pair of another, stronger than van der Waals forces in others.
Ref: NCERT Class 11 Chemistry > Chapter 4: Chemical Bonding and Molecular Structure > Topic: Hydrogen Bonding and Resonance and Dipole Moment
Nucleic acid hybridization is stabilized by specific non-covalent interactions. Hydrogen bonding between complementary bases confers specificity and contributes enthalpy. Base stacking interactions arising from hydrophobic effects and pi-pi overlap of aromatic rings greatly stabilize the double helix. Ionic interactions mediated by monovalent cations like Na+ shield negative charges of phosphate backbones, reducing electrostatic repulsion and increasing duplex stability. Van der Waals forces, while present in any molecular association, are not considered a major distinct stabilizing force for hybrids in classical molecular biology curricula.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
Complete Surface Plasmon Resonance interaction cycle comprises ligand immobilization, baseline stabilization, analyte association, dissociation with buffer wash, and final regeneration to strip residual bound analyte while preserving ligand functionality. Regeneration restores baseline resonance units using mild regeneration buffers, enabling reuse of same chip for multiple concentration injections and kinetic replication. Analysis, dissociation, and calibration are intermediate steps, but regeneration represents definitive concluding stage preparing surface for next cycle. Optimization prevents ligand denaturation and ensures consistent binding capacity across experiments, critical for high-quality kinetic and affinity measurements.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
AFM tapping mode minimizes damage by oscillating cantilever so tip intermittently contacts surface at bottom of swing. Intermittent contact drastically reduces lateral shear forces compared to constant contact mode dragging, preventing displacement or deformation of weakly adsorbed biomolecules, lipid bilayers, and live cells. Feedback maintains amplitude, mapping soft samples gentlly while still sensing van der Waals interactions. TEM and contact mode AFM impose harsh fixation or high friction, risking artifacts. Tapping enables high-resolution imaging of DNA-protein interactions, membrane dynamics, and molecular assembly under physiological buffer without compromising native structure and function.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
Van der Waals interactions accurately identifies the binding site, binding partner, or molecular interaction described in this question. In Chemical Bonding, molecular recognition and binding specificity are governed by complementary shape, charge, and hydrophobic interactions between molecules. Van der Waals interactions binds at the specified location due to its structural complementarity and specific non-covalent or covalent interactions. The other options (Ionic bond, Covalent bond, and Hydrogen bond) describe binding to different sites, involve different types of molecular interactions, or represent incorrect binding partners.
Ref: Campbell Biology, Urry et al., 12th Ed.
O-H---O is the scientifically accurate answer to this question. Within the study of Chemical Bonding, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of O-H---O directly address what is being asked. Among the other options, O-H---N, N-H---O, and N-H---N do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.
Ref: Campbell Biology, Urry et al., 12th Ed.
Peptide bonds is the correct choice because it does not accurately describe or belong to the category addressed in this question. In the context of Protein Structure, the other options (Hydrophobic interactions, Hydrogen bonds, and Ionic interactions) are all valid and well-established concepts. Peptide bonds is either unrelated to the topic, describes a different biological process, or represents a common misconception. Questions framed as 'which is NOT' require students to identify the exception among otherwise correct statements, demanding comprehensive knowledge of the topic rather than recognition of a single fact.
Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 4
Stacking interactions is the accurate answer because it correctly identifies the biological function or role described in this question. In DNA, understanding the specific functions of molecules, enzymes, or structures is fundamental. Stacking interactions fulfills this particular biological role through its specific structural properties, biochemical activity, or physiological mechanism. The other options (Hydrogen bonding, Hydrophobic interactions, and Ionic interactions) serve different biological functions or are associated with other processes, pathways, or structural roles within the cell or organism.
Ref: Molecular Biology of the Gene, Watson et al., 7th Ed.
