CBSE Class 11 Biology Chapter 21 Neural Control and Co-ordination NCERT Solutions

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NCERT Solutions PDF Class 11 PDF

This chapter delves into the intricate mechanisms of Neural Control and Co-ordination in Class 11 Biology, as explained through NCERT Solutions. It covers the fundamental aspects of the nervous system, including the structure and function of neurons, the generation and propagation of nerve impulses, and synaptic transmission. The solutions also explore the human nervous system, differentiating between the central and peripheral nervous systems, and detailing the roles of the autonomic and somatic nervous systems. Key concepts like resting potential, action potential, and reflex actions are explained with clarity. These solutions are designed to help students grasp complex neurological processes, understand the roles of various neural components, and prepare effectively for their examinations by providing clear, step-by-step explanations for all questions.

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BoardCBSE
ClassClass 11
SubjectBiology Exemplar
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 21

Chapter summary

Chapter 21 of the CBSE Class 11 Biology NCERT Solutions focuses on Neural Control and Co-ordination. It provides detailed explanations for multiple-choice questions covering neurotransmitters, resting membrane potential, ion distribution, and the functions of different neural systems like sympathetic and parasympathetic. The solutions also clarify the components involved in reflex actions, such as the knee-jerk reflex, and highlight the roles of neurons and neural pathways. This chapter is crucial for understanding how the body's functions are regulated and coordinated through the nervous system.

Learning outcomes

  • Understand the role of neurotransmitters in synaptic transmission.
  • Explain the ionic basis of resting membrane potential.
  • Differentiate between the functions of sympathetic and parasympathetic nervous systems.
  • Identify the components involved in a reflex arc.
  • Describe the mechanism of nerve impulse generation and propagation.
  • Recognize the parts of the human neural system.

Topics covered

Paper topics

  • Neural System
  • Neuron Structure and Function
  • Generation and Conduction of Nerve Impulses
  • Synaptic Transmission
  • Human Nervous System
  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
  • Autonomic Nervous System (ANS)
  • Sympathetic Nervous System
  • Parasympathetic Nervous System
  • Somatic Nervous System
  • Reflex Actions and Reflex Arcs

Important topics

  • Generation and Conduction of Nerve Impulses
  • Synaptic Transmission
  • Resting Membrane Potential
  • Autonomic Nervous System (Sympathetic & Parasympathetic)
  • Reflex Arc Components

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Questions and Solutions

MCQ 1

Chemicals which are released at the synaptic junction are called
  1. hormones
  2. neurotransmitters
  3. cerebrospinal fluid
  4. lymph
Solution: The correct option is (b) neurotransmitters. Neurotransmitters are specialized chemical messengers that are released from the axon terminal of a presynaptic neuron into the synaptic cleft. They bind to specific receptors on the postsynaptic membrane, thereby transmitting the nerve impulse across the synapse. Hormones are signaling molecules produced by endocrine glands. Cerebrospinal fluid is found in the central nervous system and provides cushioning. Lymph is a fluid involved in the immune system and fat transport.

MCQ 2

Potential difference across resting membrane is negatively charged. This is due to differential distribution of the following ions.
  1. Na+ and K+ ions
  2. CO_3^{2-} and Cl^- ions
  3. Ca2+ and Mg2+ ions
  4. Ca+4 and Cl- ions
Solution: The correct option is (a) Na+ and K+ ions. Neurons maintain a resting membrane potential, which is typically negative inside relative to the outside. This potential is established and maintained by the unequal distribution of ions across the plasma membrane. Specifically, there is a higher concentration of K+ ions inside the neuron and a higher concentration of Na+ ions outside. The selective permeability of the membrane to these ions, facilitated by ion channels and actively maintained by the sodium-potassium pump, results in the negative resting potential. Other ions like Ca2+, Mg2+, and Cl- play roles in cellular functions but are not the primary determinants of the resting membrane potential.

MCQ 3

Resting membrane potential is maintained by
  1. hormones
  2. neurotransmitters
  3. ion pumps
  4. None of these
Solution: The correct option is (c) ion pumps. The resting membrane potential is actively maintained by ion pumps, primarily the sodium-potassium pump (Na+/K+-ATPase). This pump uses energy to transport ions against their concentration gradients, moving three sodium ions (Na+) out of the cell for every two potassium ions (K+) pumped into the cell. This action helps establish and preserve the ionic gradients that define the resting potential.

MCQ 4

The function of our visceral organs is controlled by
  1. sympathetic and somatic neural system
  2. sympathetic and parasympathetic neural system
  3. central and somatic nervous system
  4. None of the above
Solution: The correct option is (b) sympathetic and parasympathetic neural system. The sympathetic and parasympathetic nervous systems are the two main divisions of the autonomic nervous system, which controls involuntary bodily functions, including the activity of visceral organs. The somatic neural system controls voluntary movements of skeletal muscles, and the central nervous system (brain and spinal cord) is the processing center but does not directly control visceral organs in the same way the autonomic system does.

MCQ 5

Which of the following is not involved in knee-jerk reflex?
  1. Muscle spindle
  2. Motor neuron
  3. Brain
  4. Inter neurons
Solution: The correct option is (c) Brain. The knee-jerk reflex is a monosynaptic or polysynaptic reflex arc that is processed at the spinal cord level and does not involve conscious processing by the brain. The reflex arc includes sensory receptors like the muscle spindle, sensory (afferent) neurons, interneurons (in polysynaptic reflexes), motor (efferent) neurons, and the effector muscle. The brain is aware of the reflex after it has occurred but does not initiate or control it.

Common mistakes

  • Confusing hormones with neurotransmitters.
  • Misunderstanding the specific ions responsible for resting membrane potential.
  • Incorrectly identifying the components of a reflex arc, especially the role of the brain.
  • Failing to distinguish between the somatic and autonomic nervous systems' functions.

Revision tips

  • Focus on the key differences between chemical and electrical synapses.
  • Memorize the ions involved in maintaining resting and action potentials.
  • Draw and label diagrams of reflex arcs to understand the pathway.
  • Review the functions of the sympathetic and parasympathetic nervous systems for visceral organ control.

Practice MCQs

Q1. What are the chemicals released at the synaptic junction called?

Q2. The potential difference across a resting neuron's membrane is negative primarily due to the differential distribution of which ions?

Q3. What is primarily responsible for maintaining the resting membrane potential in a neuron?

Q4. The functions of visceral organs are regulated by which pair of neural systems?

Q5. Which of the following components is NOT involved in the knee-jerk reflex?

Frequently asked questions

What is the main function of neurotransmitters?

Neurotransmitters are chemical messengers released at synaptic junctions that transmit nerve impulses from one neuron to another or to an effector cell, enabling communication within the nervous system.

What causes the negative charge across the resting membrane of a neuron?

The resting membrane potential is negative due to the differential distribution of ions, primarily the higher concentration of K+ ions inside the neuron and Na+ ions outside, along with the selective permeability of the membrane and the action of ion pumps.

How do ion pumps maintain the resting membrane potential?

Ion pumps, like the sodium-potassium pump, actively transport ions across the membrane, moving 3 Na+ ions out for every 2 K+ ions in. This maintains the ionic gradients essential for the resting potential.

Which neural systems control the visceral organs?

The visceral organs are controlled by the sympathetic and parasympathetic neural systems, which are parts of the autonomic nervous system.

Is the brain involved in a simple reflex action like the knee-jerk reflex?

No, the brain is not directly involved in simple reflex actions like the knee-jerk reflex. These reflexes are processed at the spinal cord level through a reflex arc.

What are the key components of a reflex arc?

A reflex arc typically includes a receptor (e.g., muscle spindle), an afferent neuron, an integration center (often in the spinal cord, involving interneurons), an efferent neuron, and an effector (e.g., muscle).

Important links

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