NCERT-Based Explanation
According to NCERT, dendrites transmit impulses towards the cell body, whereas the axon transmits nerve impulses away from the cell body to a synapse or neuromuscular junction. This directional structural orientation ensures a strict unidirectional impulse transmission path across the neuron from dendrites to axon terminals via the cell body.
Pedagogical Value
This question directly tests precise NCERT descriptions regarding the directional polarity of impulse transmission across neuronal anatomy (dendrite → cell body → axon).

NCERT-Based Explanation
Neurons are not the only excitable cells in the human body; muscle cells (skeletal, cardiac, and smooth) are also excitable tissues capable of generating action potentials.
Pedagogical Value
Question tests whether students remember that excitable tissues in animal physiology include both neural and muscular tissues, catching those who hold an overly narrow definition of cellular excitability.

NCERT-Based Explanation
Assertion is True: A myelinated axon features multiple uninsulated gaps along its length known as nodes of Ranvier.
Reason is True: According to NCERT, in the peripheral nervous system, the myelin sheath is not a continuous single tube; it is formed by multiple individual Schwann cells wrapping sequentially around the axon. The gaps between adjacent Schwann cells form the nodes of Ranvier, directly explaining why a single myelinated neuron possesses multiple nodes.
Pedagogical Value
Microscopic Anatomy Connection: Connects cellular structure (multiple individual Schwann cells wrapping an axon) to anatomical landmarks (multiple gaps forming nodes of Ranvier).

NCERT-Based Explanation
According to NCERT, ionic gradients across the resting membrane are maintained by active transport via the sodium-potassium pump, which moves 3 Na⁺ outwards for 2 K⁺ into the cell. Thus, both statements are true. However, the presence of opposite concentration gradients across the membrane is the functional outcome of asymmetrical ion pumping, rather than the reason why the pump operates in a dissimilar manner.
Pedagogical Value
Concept Reinforcement: Forces students to distinguish between the active transport mechanism (pumping unequal ion numbers in opposite directions) and the resultant spatial gradient configuration.

NCERT-Based Explanation
Inhibitory neurotransmitters bind to specific receptor-gated ion channels on the post-synaptic membrane, opening channels for anions (such as Cl⁻). The resulting influx of negative charges increases internal negativity (hyperpolarisation), moving the membrane potential further away from the threshold required to fire an action potential.
Pedagogical Value
This question connects the molecular action of inhibitory neurotransmitter receptor binding (opening anion channels) with the physiological event of post-synaptic hyperpolarisation.

NCERT-Based Explanation
Assertion is True: Binding of an excitatory neurotransmitter causes membrane depolarisation by facilitating the movement of positively charged ions (cations) into the post-synaptic cell.
Reason is True: According to NCERT, excitatory neurotransmitters open specific ion channels, primarily ligand-gated sodium (Na+) channels. Because sodium ions are cations, their inward movement directly accounts for the increase in cation influx described in the Assertion.
Pedagogical Value
Mechanistic Linking: Connects the broader physiological outcome (cation influx / depolarisation) directly to its underlying specific ion channel mechanism (Na+
 channel opening).

NCERT-Based Explanation
According to NCERT, impulse conduction involves sequential changes in membrane permeability: an initial rapid influx of Na+ (depolarisation) followed by an efflux of K+
 (repolarisation). Because Na+ entry precedes K+ exit in time, these two fluxes do not occur simultaneously across the same segment of the axolemma during an action potential phase.
Pedagogical Value
This question ensures students recognise the temporally ordered sequence of ionic events (depolarisation before repolarisation) rather than viewing ion fluxes as overlapping or concurrent processes.

NCERT-Based Explanation
According to NCERT, when a neuron is resting (not conducting any impulse), the axonal membrane is already selectively permeable—being comparatively more permeable to potassium ions (K+) and nearly impermeable to sodium ions (Na+). Therefore, selective permeability is an intrinsic property of the membrane at rest as well, making the Assertion statement false. The Reason statement is true because maintaining and restoring the ionic gradients required for impulse transmission depends on active transport via the Na+/K+ pump.

Pedagogical Value

Consciousness Check: Traps students who misinterpret “resting state” as a state of uniform non-selectivity, testing their recognition that selective permeability exists both at rest and during active impulse transmission.

NCERT-Based Explanation
According to NCERT, ionic permeability and flux direction change dynamically during nerve impulse transmission. During depolarisation, the membrane becomes briefly permeable to Na+ (influx), followed rapidly by repolarisation, where permeability shifts to K+ (efflux). Because these ion movements occur sequentially in discrete, short-lived phases rather than constantly or simultaneously, the overall rate of permeability and direction of ion transport across the membrane are non-uniform over time.
Pedagogical Value
This question tests whether students understand how time-dependent, sequential changes in ion-channel permeability (Na+ influx followed by K+efflux) dictate the dynamic nature of membrane potential changes.

NCERT-Based Explanation
Potassium efflux (K+ moving out) repolarises the membrane, restoring the negative electrical resting membrane potential across the axolemma. However, immediately following this repolarisation, Na+ ions remain elevated inside and K+
 ions outside; thus, original ionic concentration gradients are not yet fully restored until driven by the electrogenic Na+/K+ pump. While both statements are scientifically correct, the delayed restoration of concentration gradients by active pumps is a consequence of ionic movement rather than the direct cause of electrical repolarisation.
Pedagogical Value
Structure–Function Trap: Forces students to distinguish between electrical repolarisation (driven rapidly by passive K+ efflux) and chemical gradient restoration (driven subsequently by active Na+/K+ pumping).

NCERT-Based Explanation
According to NCERT, the electrical potential difference generated across the plasma membrane at the site of excitation is called the action potential, which is in fact termed a nerve impulse.
However, nerve impulses are generated and conducted along the axolemma (the plasma membrane of the axon) via voltage-gated ion channels and rapid ion fluxes, rather than within the axoplasm (the axonal cytoplasm). Therefore, the Assertion statement is scientifically false, while the Reason statement is true.
Pedagogical Value
Terminology Trap: Tests fine-grained structural knowledge by catching students who confuse the axonal membrane (axolemma), where electrical conduction and action potentials physically occur, with the internal cytoplasm (axoplasm).

NCERT-Based Explanation
According to NCERT, during depolarisation, the rapid influx of Na+ ions is extremely short-lived because it is quickly followed by a rise in permeability to K+. Voltage-gated Na+channels rapidly inactivate after opening. Potassium ions, on the other hand, move continuously across the membrane—leaking at rest through potassium leak channels, exiting rapidly during repolarisation, and being actively pumped back inside by the Na+/K+ pump. Thus, both statements are scientifically true, but continuous potassium movement is not the physiological cause of the brief duration of sodium influx.
Pedagogical Value
Concept Reinforcement: Distinguishes between the distinct channel kinetics controlling short-lived sodium influx (voltage-gated channel inactivation) and the multi-phase, continuous flux of potassium across the axonal membrane.

NCERT-Based Explanation
Assertion is True: Post-synaptic potentials (EPSPs) are graded potentials. Releasing more neurotransmitter opens a greater number of ligand-gated channels, increasing the amplitude and likelihood of detection of the local post-synaptic potential.
Reason is False: Action potentials strictly obey the All-or-None Law. Once the threshold is reached, the amplitude (strength) of an action potential remains constant regardless of the intensity of the stimulus or the amount of neurotransmitter released. Higher neurotransmitter concentration increases action potential frequency, not amplitude.
Pedagogical Value
Graded vs. Action Potential Misconception: Tests whether students can distinguish between graded potentials (which vary in amplitude with neurotransmitter quantity) and action potentials (which maintain fixed amplitude).

NCERT-Based Explanation
Assertion is False: The statement is logically and anatomically inverted. A synaptic cleft is a fluid-filled space (found in chemical synapses), not an entity that can “lack” a synapse. The true statement is that an electrical synapse lacks a synaptic cleft. Students who skim the sentence will mentally invert it to mean “electrical synapses don’t have clefts” and mistakenly mark it true.
Reason is True: According to NCERT, at an electrical synapse, the pre- and post-synaptic membranes lie in very close proximity (connected directly by gap junction channels), so no fluid-filled space exists between them.
Pedagogical Value
Subject–Predicate Inversion Trap: Directly targets surface-level readers and keyword matchers. It forces students to read with extreme structural precision rather than relying on familiar word associations (“synaptic cleft” + “electrical synapse” + “lacks”), ensuring they process both grammatical structure and biological meaning accurately.

NCERT-Based Explanation
According to NCERT, there are two types of synapses: electrical synapses and chemical synapses, both of which serve to transmit impulses from one neuron to another. At chemical synapses, neurotransmitters are released across the synaptic cleft, whereas electrical synapses transmit signals directly via electrical current without neurotransmitters. Thus, “synapses sometimes release neurotransmitters” is scientifically true, but this mechanism applies only to chemical synapses and does not explain why both types function to transmit impulses.

Pedagogical Value
Terminology Trap: Evaluates whether students recognise that chemical transmission is only one of two functional synaptic modalities described by NCERT.

NCERT-Based Explanation
Assertion is False: According to NCERT, a multipolar neuron is defined as having “one axon and two or more dendrites” (found in the cerebral cortex). Therefore, a multipolar neuron can have exactly two dendrites (giving it 3 total processes: 1 axon + 2 dendrites).
Reason is True: According to NCERT, a bipolar neuron consists of one axon and one dendrite, giving it exactly two protoplasmic processes (found in the retina of the eye).
Pedagogical Value
NCERT Definition Trap: Targets students who incorrectly assume that having “two dendrites” conflicts with being multipolar, testing exact recall of NCERT’s “two or more dendrites” threshold.

NCERT-Based Explanation
According to NCERT, impulse transmission across an electrical synapse is very similar to impulse conduction along a single axon, whereas transmission across a chemical synapse involves a synaptic cleft and chemical messengers. NCERT also explicitly states that the new potential developed in the post-synaptic neuron may be either excitatory or inhibitory. While both statements are true, the nature of the post-synaptic potential (excitatory vs inhibitory) does not explain the structural and functional similarity/dissimilarity between axonal conduction and synaptic transmission.

Pedagogical Value
NCERT Wording Trap: Combines NCERT’s explicit comparison of axonal vs synaptic conduction with its exact statement regarding post-synaptic potential variations.

NCERT-Based Explanation
Larger amounts of released neurotransmitters bind more post-synaptic receptors, producing larger graded potentials (increasing the likelihood of reaching a detectable potential). However, if the neurotransmitter released is inhibitory, it hyperpolarises the post-synaptic membrane and will never induce an action potential, regardless of the quantity released. Thus, the Reason statement is scientifically false.
Pedagogical Value
Consciousness Check: Traps students who overlook neurotransmitter functional diversity (excitatory vs inhibitory) and assume all neurotransmitters induce action potentials when released in large amounts.

NCERT-Based Explanation
According to NCERT, at a chemical synapse, the membranes of pre- and post-synaptic neurons are separated by a fluid-filled space called the synaptic cleft. However, at electrical synapses, the pre- and post-synaptic membranes are in very close proximity without an intervening synaptic cleft. Thus, a synaptic cleft is absent at electrical synapses, explaining why it cannot be observed between all pairs of communicating neurons.
Pedagogical Value
Question directly tests structural differences between chemical and electrical synapses, catching students who assume all neuronal connections possess a synaptic cleft.

NCERT-Based Explanation
Assertion is True: According to NCERT, binding of a neurotransmitter to specific receptors on the post-synaptic membrane opens ligand-gated ion channels. If no neurotransmitter binds, these channels stay closed.
Reason is False: Presynaptic depolarization (action potential generation) occurs prior to neurotransmitter release and is completely independent of post-synaptic receptor binding. Receptor non-binding at the post-synaptic membrane does not cause or imply an absence of potential generation in the presynaptic neuron.
Pedagogical Value
Sequential Logic Trap: Directly catches students who confuse the forward cause-and-effect flow of synaptic transmission by assuming post-synaptic events retroactively dictate presynaptic electrical events.