Neural Control and Coordination — Class 11 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 11 Biology chapter "Neural Control and Coordination" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Neural Control and Coordination" — 8 important questions with detailed answers for CBS…
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NCERT Solutions for Class 11 Biology — Neural Control and Coordination. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Neural Control and Coordination — All 8 Questions Solved
Q1. What is a neuron? Name its three main parts and their functions.
Neuron is the structural and functional unit of nervous system.
Three main parts:
- Dendrite: receives signals from other neurons via neurotransmitters; increases surface area
- Cell body (soma): contains nucleus; site of protein synthesis
- Axon: transmits electrical signals away from cell body; ends in synaptic terminal
Q2. Differentiate between myelinated and unmyelinated nerve fibers.
Myelinated fibers:
- Covered by myelin sheath formed by Schwann cells; segmented
- Saltatory conduction (jump along nodes of Ranvier)
- Conduction velocity: 100+ m/s
- Found in somatic and autonomic nervous systems
Unmyelinated fibers:
- No myelin sheath; multiple axons embedded in single Schwann cell
- Continuous conduction along entire axon
- Conduction velocity: 0.5-2 m/s
- Found in parasympathetic and visceral sensory nerves
Q3. Explain the all-or-none principle in nerve impulse transmission.
All-or-none principle:
- If stimulus intensity reaches threshold, action potential fires completely
- If stimulus is below threshold, no action potential occurs
- Once threshold is reached, further stimulus increase does not alter magnitude of action potential
- Intensity of stimulus is conveyed by frequency of action potentials, not by amplitude
- This ensures reliable nerve signaling
Q4. What is a synapse? Describe the mechanism of synaptic transmission.
Synapse is junction between axon terminal of one neuron and dendrite/soma of next neuron.
Synaptic transmission:
- Action potential reaches presynaptic terminal
- Voltage-gated Ca2+ channels open; Ca2+ influx
- Synaptic vesicles fuse with membrane; neurotransmitter released
- Neurotransmitter diffuses across synaptic cleft
- Binds to receptors on postsynaptic membrane
- Opens ion channels; depolarization or hyperpolarization occurs
Q5. Define reflex arc. Give an example of a spinal reflex.
Reflex arc is the pathway of nerve impulse in a reflex action from receptor to effector.
Sequence: Receptor → sensory neuron → spinal cord → motor neuron → effector
Example - withdrawal reflex on touching hot object:
- Sensory receptors detect heat
- Sensory neuron conducts impulse to spinal cord
- Synapse with motor neuron in cord (no brain involvement)
- Motor neuron sends impulse to flexor muscles
- Arm withdraws immediately; pain sensation follows
Q6. What is the difference between the sympathetic and parasympathetic nervous systems?
Sympathetic nervous system:
- Fight or flight response
- Increases heart rate, BP, pupil dilation
- Decreases digestion
- Arises from thoracolumbar region
Parasympathetic nervous system:
- Rest and digest response
- Decreases heart rate, BP
- Increases digestion
- Arises from craniosacral region
- Generally antagonistic effects
Q7. What is the resting membrane potential? How is it maintained?
Resting membrane potential (RMP) is -70 mV across nerve membrane at rest.
Maintained by:
- Na+/K+ ATPase pump: extrudes 3 Na+ for every 2 K+ in; uses ATP
- Unequal ion distribution: more K+ inside, more Na+ outside
- Selective permeability: membrane more permeable to K+ at rest
- Negatively charged proteins trapped inside
- This potential allows rapid depolarization for action potentials
Q8. Describe the phases of an action potential.
Phases of action potential:
- Resting state (-70 mV): stable membrane potential
- Depolarization: stimulus reaches threshold (-55 mV); Na+ channels open; rapid inward Na+ current; membrane potential becomes positive (+30 mV)
- Repolarization: Na+ channels close; K+ channels open; outward K+ current; return to negative potential
- Hyperpolarization: brief overshoot below resting potential (-90 mV)
- Return to resting: K+ channels close; Na+/K+ pump restores distribution
Neural Control and Coordination — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which part of the neuron transmits impulses away from the cell body?
- A. Dendrite
- B. Axon
- C. Soma
- D. Myelin sheath
Answer: B. Axon — The axon is a long, slender projection of a nerve cell that typically conducts electrical impulses away from the neuron's cell body. Dendrites primarily receive signals.
MCQ 2. What is primarily responsible for maintaining the resting membrane potential in a neuron?
- A. Passive diffusion of ions
- B. Na+/K+ pump
- C. Voltage-gated Na+ channels
- D. Leakage channels for Ca2+
Answer: B. Na+/K+ pump — The Na+/K+ pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, consuming ATP, thus maintaining the electrochemical gradient necessary for the resting potential.
MCQ 3. In a chemical synapse, the influx of which ion into the presynaptic terminal triggers the release of neurotransmitters?
- A. Na+
- B. K+
- C. Ca2+
- D. Cl-
Answer: C. Ca2+ — When an action potential reaches the presynaptic terminal, voltage-gated Ca2+ channels open, allowing Ca2+ ions to flow into the terminal, which then triggers the fusion of synaptic vesicles with the presynaptic membrane and the release of neurotransmitters.
MCQ 4. The Central Neural System (CNS) in humans consists of:
- A. Brain and spinal nerves
- B. Spinal cord and cranial nerves
- C. Brain and spinal cord
- D. Brain and autonomic nerves
Answer: C. Brain and spinal cord — The Central Neural System (CNS) is the processing center of the body and consists of the brain and the spinal cord.
MCQ 5. Which part of the human brain is primarily responsible for maintaining posture and balance?
- A. Cerebrum
- B. Thalamus
- C. Cerebellum
- D. Medulla oblongata
Answer: C. Cerebellum — The cerebellum is crucial for motor control, including coordination, precision, accurate timing, and especially maintaining posture and balance.
MCQ 6. Acetylcholine is an important neurotransmitter. Which of the following statements about acetylcholine is correct?
- A. It is exclusively an inhibitory neurotransmitter
- B. It is released at the neuromuscular junction
- C. It acts solely on adrenergic receptors
- D. It is synthesized from dopamine
Answer: B. It is released at the neuromuscular junction — Acetylcholine is a major neurotransmitter released at the neuromuscular junction, where it triggers muscle contraction. It can be both excitatory and inhibitory depending on the receptor type.
MCQ 7. The protective membranes covering the brain and spinal cord are called:
- A. Pleura
- B. Pericardium
- C. Meninges
- D. Peritoneum
Answer: C. Meninges — The brain and spinal cord are protected by three layers of connective tissue membranes collectively called meninges: dura mater, arachnoid mater, and pia mater.
MCQ 8. In a reflex arc, which component typically transmits impulses from the CNS to the effector organ?
- A. Receptor
- B. Afferent neuron
- C. Interneuron
- D. Efferent neuron
Answer: D. Efferent neuron — An efferent (motor) neuron carries nerve impulses from the central nervous system to effector organs like muscles or glands, initiating a response.
MCQ 9. During the repolarization phase of an action potential, which ion channels are primarily responsible for restoring the membrane potential?
- A. Voltage-gated Na+ channels opening
- B. Voltage-gated K+ channels opening
- C. Voltage-gated Na+ channels closing
- D. Na+/K+ pump activity
Answer: B. Voltage-gated K+ channels opening — Repolarization occurs primarily due to the opening of voltage-gated K+ channels, allowing K+ ions to rush out of the cell, making the inside more negative again. While Na+ channels close, the outflow of K+ is the main event.
MCQ 10. The autonomic neural system (ANS) is a part of the:
- A. Central Neural System
- B. Somatic Neural System
- C. Peripheral Neural System
- D. Sensory Neural System
Answer: C. Peripheral Neural System — The Peripheral Neural System (PNS) includes all nerves outside the brain and spinal cord and is divided into the somatic neural system and the autonomic neural system.
MCQ 11. The diencephalon, a part of the forebrain, includes:
- A. Cerebrum and cerebellum
- B. Pons and medulla
- C. Thalamus and hypothalamus
- D. Midbrain and spinal cord
Answer: C. Thalamus and hypothalamus — The diencephalon is the posterior part of the forebrain, connecting the midbrain with the cerebral hemispheres, and it primarily includes the thalamus and hypothalamus.
MCQ 12. What is the primary advantage of saltatory conduction in myelinated nerve fibers compared to unmyelinated fibers?
- A. Reduced energy consumption by the Na+/K+ pump
- B. Slower propagation of nerve impulses
- C. Increased diameter of the axon
- D. Continuous depolarization along the axon
Answer: A. Reduced energy consumption by the Na+/K+ pump — Saltatory conduction allows the action potential to 'jump' between nodes of Ranvier, significantly increasing the speed of impulse transmission and reducing energy consumption because ion channels only need to be activated at the nodes.
MCQ 13. A neuron with one axon and two or more dendrites is classified as:
- A. Unipolar
- B. Bipolar
- C. Multipolar
- D. Pseudounipolar
Answer: C. Multipolar — Multipolar neurons have one axon and two or more dendrites, making them the most common type of neuron in the CNS.
MCQ 14. Which brain structure is responsible for controlling body temperature, thirst, and hunger?
- A. Cerebrum
- B. Thalamus
- C. Hypothalamus
- D. Medulla oblongata
Answer: C. Hypothalamus — The hypothalamus is a vital part of the brain that plays a crucial role in regulating essential homeostatic functions such as body temperature, hunger, thirst, and various endocrine functions.
MCQ 15. The blood-brain barrier is primarily formed by tight junctions between endothelial cells of capillaries and is maintained by which glial cells?
- A. Microglia
- B. Astrocytes
- C. Oligodendrocytes
- D. Schwann cells
Answer: B. Astrocytes — Astrocytes, a type of glial cell, play a critical role in forming and maintaining the blood-brain barrier by sending signaling molecules to endothelial cells that induce the formation of tight junctions.
MCQ 16. Which division of the autonomic nervous system is typically activated during "fight-or-flight" responses?
- A. Somatic
- B. Central
- C. Parasympathetic
- D. Sympathetic
Answer: D. Sympathetic — The sympathetic nervous system prepares the body for stressful situations or emergencies, triggering the 'fight-or-flight' response, which includes increased heart rate, dilated pupils, and inhibited digestion.
MCQ 17. What is the primary function of neuroglia (glial cells) in the nervous system?
- A. Generating nerve impulses
- B. Transmitting nerve impulses
- C. Providing support and protection to neurons
- D. Synthesizing neurotransmitters
Answer: C. Providing support and protection to neurons — Neuroglia are non-neuronal cells that provide essential support, nutrition, insulation, and protection for neurons, and do not generate or transmit nerve impulses themselves.
MCQ 18. Which of the following is a characteristic feature of an electrical synapse?
- A. Presence of a synaptic cleft
- B. Release of neurotransmitters
- C. Unidirectional flow of impulses
- D. Gap junctions
Answer: D. Gap junctions — Electrical synapses are characterized by the direct physical connection between neurons via gap junctions, allowing for rapid and often bidirectional flow of ions and small molecules, unlike chemical synapses.
MCQ 19. The brainstem consists of:
- A. Cerebrum, cerebellum, and pons
- B. Thalamus, hypothalamus, and midbrain
- C. Midbrain, pons, and medulla oblongata
- D. Spinal cord, midbrain, and medulla
Answer: C. Midbrain, pons, and medulla oblongata — The brainstem is composed of the midbrain, pons, and medulla oblongata, and it connects the cerebrum and cerebellum to the spinal cord.
MCQ 20. What is the main function of cerebrospinal fluid (CSF)?
- A. Transporting oxygen to brain cells
- B. Producing neurotransmitters
- C. Protecting the brain and spinal cord from mechanical shock
- D. Facilitating nerve impulse conduction
Answer: C. Protecting the brain and spinal cord from mechanical shock — Cerebrospinal fluid (CSF) acts as a cushion, protecting the brain and spinal cord from trauma and mechanical shocks, and also helps in nutrient delivery and waste removal.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.