NCERT-Based Explanation
The Assertion is true. During nerve impulse conduction, current on the inner surface of the axonal membrane flows from the depolarised site (site A) to the resting site (site B). The nerve impulse (action potential) is also conducted in this same forward direction (site A to site B).
The Reason is false. It is not a “perfect coincidence.” It is governed by the physical laws of bioelectricity, where local circuit flow brings the adjacent membrane to the threshold, causing the impulse to propagate in the direction of the internal current.
Pedagogical Value
This question discourages students from attributing physiological phenomena to “coincidence.” It forces them to recognize that the direction of impulse propagation is a direct physical consequence of internal local current flow.

NCERT-Based Explanation
The Assertion is false. Impulse transmission within a functional neuron is strictly unidirectional (from dendrites → cell body → axon → axon terminal). A neuron does not relay signals in “many directions.”
The Reason is true. Direct NCERT definition: A multipolar neuron has “one axon and two or more dendrites.”
Pedagogical Value
This question addresses a common misconception that having multiple dendrites allows a neuron to conduct impulses in multiple directions along its body, reinforcing the fundamental principle of unidirectional nerve impulse conduction.

NCERT-Based Explanation
The Assertion is true. NCERT explicitly states that “the somatic neural system relays impulses from the CNS to skeletal muscles.”
The Reason is false. While their nerve endings do form neuromuscular junctions with skeletal muscle fibers, somatic motor neurons originate from both the brain (cranial motor nerves) and the spinal cord (spinal motor nerves). Stating that they originate strictly from the brain is incorrect, as the majority of somatic motor neurons controlling body muscles arise from the ventral horn of the spinal cord.
Pedagogical Value
This question tests whether students recognize that the Central Nervous System (CNS) includes both the brain and the spinal cord, preventing them from assuming all motor nerves originate solely in the brain.

NCERT-Based Explanation
The Assertion is true. NCERT highlights that during physical/muscular activity, multiple organ systems (neural, respiratory, circulatory, and endocrine) function in a coordinated manner to sustain muscle function.
The Reason is true. Neuromuscular transmission (via acetylcholine) initiates contraction; the respiratory and circulatory systems increase rates to deliver required oxygen and nutrients (glucose); and hormones (e.g., epinephrine) help adjust heart rate and metabolic output.
Since these specific roles describe how the systems jointly regulate muscle function, the Reason correctly explains the Assertion.
Pedagogical Value
This question encourages students to integrate concepts across multiple physiology chapters (Neural, Circulation, Respiration, Endocrine, and Locomotion) rather than treating muscle activity as an isolated neural event.

NCERT-Based Explanation
The Assertion is true. NCERT states that afferent fibres conduct impulses from tissues/organs to the CNS, whereas efferent fibres conduct regulatory impulses from the CNS to peripheral tissues. Relative to the CNS, their conduction directions are opposite.
The Reason is false. Afferent and efferent classifications are based on direction relative to the CNS, not the cyton. In both sensory (afferent) and motor (efferent) neurons, dendrites/receptors carry signals toward the cyton and axons conduct signals away from the cyton toward synaptic terminals.
Pedagogical Value
This question addresses a common misconception regarding neuronal polarity versus systemic signal flow, clarifying that “afferent” and “efferent” refer to direction relative to the Central Nervous System.

NCERT-Based Explanation
The Assertion is true. NCERT states that to complete the circuit of current flow, current flows on the inner surface from site A to site B, and on the outer surface from site B to site A. Thus, they are opposite.
The Reason is false. A “nerve impulse” is the transmembrane propagation of the action potential along the axon. It is a singular wave of depolarization that travels down the neuron. Describing the nerve impulse as having separate “inside” and “outside” directions is scientifically inaccurate and meaningless terminology.
Pedagogical Value
This question tests the student’s ability to differentiate between “current flow” (which completes a local circuit and moves in opposite directions inside and outside) and the “nerve impulse” (which is a singular directional wave).

NCERT-Based Explanation
The Assertion is false. NCERT explicitly states: “The visceral nervous system is the part of the peripheral nervous system that comprises the whole complex of nerves, fibres, ganglia, and plexuses…”
The Reason is true as an etymological fact. “Visceral” pertains to the internal organs (viscera), which is linguistically distinct from “peripheral”, even though the visceral nervous system is structurally classified as a division of the PNS.
Pedagogical Value
This question prevents students from falling into word-association traps where literal English definitions (visceral vs. peripheral) are confused with formal anatomical classifications.

NCERT-Based Explanation
The Assertion is true. Endocrine glands are ductless and release their hormones directly into the blood, meaning almost all classical hormones travel through the bloodstream.
The Reason is true. Paracrine/autocrine factors (local hormones like certain growth factors) are secreted into the interstitial fluid to act on nearby cells and do not enter the systemic circulation in significant amounts.
However, the Reason (discussing local tissues) does not explain the Assertion (why classical hormones are in the blood). Therefore, the correct answer is B.
Pedagogical Value
This question requires students to differentiate between classical endocrine signaling (bloodborne) and paracrine signaling (local), ensuring they don’t incorrectly link two disparate facts as cause and effect.

NCERT-Based Explanation
The Assertion is true. NCERT states that the functions of the organs/organ systems in our body must be coordinated to maintain homeostasis.
The Reason is true. Coordination is the process through which two or more organs interact and complement the functions of one another, meaning they depend on each other.
Since organs must work together and complement each other’s distinct functions to sustain the body’s internal environment, the Reason correctly explains the Assertion.
Pedagogical Value
This question tests the foundational definition of coordination and its ultimate physiological goal (homeostasis). It reinforces that no organ works in isolation.

NCERT-Based Explanation
The Assertion is true. Lower vertebrates generally have less complex neural organisation compared to the highly developed human brain. (Note: NCERT specifically highlights that neural organization is very simple in lower invertebrates like Hydra, but the statement holds true for vertebrates as well).
The Reason is true. Humans are highly evolved vertebrates with a highly developed neural system.
However, stating humans are “evolutionarily advanced” is a broad fact that does not mechanistically explain why lower vertebrate brains are simpler. Therefore, it is not the correct explanation for the Assertion.
Pedagogical Value
This question teaches students to distinguish between a general evolutionary statement and a specific mechanistic explanation, discouraging them from linking two true facts simply because they share a theme.

NCERT-Based Explanation
The Assertion is true. NCERT explicitly states that afferent nerve fibres transmit impulses from tissues/organs to the CNS (whereas efferent fibres transmit from the CNS).
The Reason is false. Afferent fibres are sensory neurons; they generate action potentials upon receiving threshold stimuli from sensory receptors in order to conduct signals to the CNS.
Pedagogical Value
This question tests whether students understand the directionality of afferent versus efferent transmission without confusing sensory signal generation with motor output.

NCERT-Based Explanation
The Assertion is true. Direct NCERT statement: “The neural system provides an organised network of point-to-point connections for a quick coordination.”
The Reason is true as a logical inference. When the respiratory rhythm center in the medulla regulates pulmonary ventilation, direct motor neurons connect the medulla to the respiratory muscles (diaphragm/intercostals), allowing rapid nerve impulse transmission.
Since this physiological example directly demonstrates a point-to-point connection producing rapid action, the Reason correctly explains the Assertion.
Pedagogical Value
This question helps students translate an abstract NCERT definition (“point-to-point connections”) into a concrete physiological example (medullary regulation of respiration).

NCERT-Based Explanation
The Assertion is true. Direct NCERT statement: “The visceral nervous system is the part of the peripheral nervous system that comprises the whole complex of nerves, fibres, ganglia, and plexuses…”
The Reason is true as a general anatomical definition. A plexus is a branching network of intersecting nerves, blood vessels, or lymphatic vessels.
However, defining what the word “plexus” means does not provide the physiological/anatomical reason why the visceral nervous system contains them (which is to provide localized, interconnected autonomic regulation to internal organs). Therefore, the Reason does not correctly explain the Assertion.
Pedagogical Value
This question teaches students to distinguish between a dictionary definition of a term and a mechanistic physiological explanation for why a specific organ system possesses that structure.

NCERT-Based Explanation
The Assertion is true. NCERT directly states that “the neural coordination is fast but short-lived.”
The Reason is true. Action potentials are measured in milliseconds, and neurotransmitters are rapidly degraded or reuptaken from the synaptic cleft. This rapid initiation and termination explain why neural coordination cannot sustain long-term continuous regulation (which is why hormones are needed). Thus, the Reason correctly explains the Assertion.
Pedagogical Value
This question connects the macroscopic concept of “short-lived coordination” with its microscopic molecular mechanisms (temporary electrical and chemical signals).

NCERT-Based Explanation
The Assertion is true. NCERT states: “The neural system provides an organised network of point-to-point connections for a quick coordination.”
The Reason is true. Neurons form direct synaptic connections with their target organs/tissues (like muscles or glands), and nerve impulses propagate rapidly along axons. Because of these direct physical connections and fast conduction, the system achieves point-to-point rapid coordination.
Pedagogical Value
This question reinforces the relationship between anatomical structure (direct point-to-point synaptic wiring) and physiological function (speed and specificity of coordination).

NCERT-Based Explanation
The Assertion is true. NCERT explicitly uses the example of physical exercise, stating that increased muscular activity leads to an increased demand for energy and oxygen.
The Reason is true. Muscle contraction requires continuous ATP. To meet this heightened energy demand, cellular respiration must increase, which in turn requires more oxygen.
Therefore, the Reason correctly explains why oxygen demand spikes during increased muscle activity.
Pedagogical Value
This question encourages students to link macroscopic physiological changes (increased breathing/oxygen demand) with their microscopic cellular causes (ATP requirement for muscle contraction).

NCERT-Based Explanation
The Assertion is false. NCERT explicitly states that “the nerve fibres do not innervate all cells of the body.” This is precisely why the endocrine system is required for chemical integration.
The Reason is false. The neural system is not “solely” responsible for homeostasis; NCERT states that the neural system and the endocrine system jointly coordinate and integrate all activities to maintain homeostasis.
Pedagogical Value
This question highlights a critical NCERT trap. Students often assume the nervous system controls absolutely everything. It reinforces the limitations of neural point-to-point connections and emphasizes the necessity of the endocrine system.

NCERT-Based Explanation
The Assertion is true as a logical inference. The Somatic Neural System (SNS) is a subdivision of the Peripheral Nervous System (PNS). Therefore, all somatic neurons belong to the PNS, but peripheral neurons also include autonomic neurons.
The Reason is true. NCERT states that the PNS is divided into two divisions: the somatic neural system and the autonomic neural system (ANS).
Since the inclusion of the ANS in the PNS accounts for the non-somatic peripheral neurons, the Reason correctly explains the Assertion.
Pedagogical Value
This question tests set-subset logic in biological classification, ensuring students understand the structural subdivisions of the Peripheral Nervous System.

NCERT-Based Explanation
The Assertion is true. While the two systems overlap, they are not completely mutually exclusive, nor are they identical (e.g., insulin is only a hormone; acetylcholine is generally only a neurotransmitter).
The Reason is true. Epinephrine (adrenaline) is secreted by the adrenal medulla as a circulating hormone, but it also functions as a neurotransmitter in the sympathetic nervous system.
Because there are overlapping molecules like epinephrine, it proves that the two categories are not mutually exclusive, thereby correctly explaining the Assertion.
Pedagogical Value
This addresses a common student misconception that neural and endocrine systems use entirely distinct sets of chemicals. It bridges Neural Control and Chemical Coordination.

NCERT-Based Explanation
The Assertion is true. NCERT states that in insects, the neural system consists of a brain along with a number of ganglia, while in humans, ganglia are present in the peripheral nervous system (e.g., dorsal root ganglia, autonomic ganglia).
The Reason is true as a biological fact. Nervous tissue and ganglia develop from the embryonic ectoderm (neural crest / neural tube).
However, embryonic germ layer origin (ectoderm) does not explain why both humans and insects possess organized ganglia in their neural systems. Therefore, the Reason does not correctly explain the Assertion.
Pedagogical Value
This question tests cross-chapter integration by linking animal kingdom/neural organisation with embryological tissue origins, while assessing whether students can differentiate between an anatomical fact and a causal explanation.