Directions: In the following questions, a statement of assertion is followed by a statement of reason.
Mark the correct choice as:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
Q.1. Assertion : Nerve conduction is the one way conduction.
Reason : Nerve impulse is transmitted from dendrite terminals to axon terminals.
Q.2. Assertion : The chemical stored in the synaptic vesicles are termed as neurotransmitters.
Reason : Synaptic vesicles release these chemicals in the synaptic cleft.
Q.3. Assertion : The imbalance in concentration of Na+, K+ and proteins generates resting potential.
Reason : To maintain the unequal distribution of Na+ & K+, the neurons use electrical energy.
Q.4. Assertion : Transmission of nerve impulse across a synapse is accomplished by neurotransmitters.
Reason : Transmission across a synapse usually requires neurotransmitters because there is a small space, i.e., synaptic cleft, that separates one neuron from another. [AIIMS 1999]
Q.5. Assertion : The axonal membrane of the neuron is more permeable to sodium ion (Na+) and nearly impermeable to potassium (K+).
Reason : In a resting state, neuron conducts impulses. [AIIMS 2016]
Q.6. Assertion: Electrical synapses are rare in our system.
Reason: Impulse transmission across an electrical synapse is slower than that across a chemical synapse.
Q.7. Assertion: Multipolar neurons have two or more axons and one dendrite.
Reason: Multipolar neurons are found usually in the embryonic stage.
Q.8. Assertion: Myelinated nerve fibres are present in spinal and cranial nerves.
Reason: Myelinated nerves conduct impulses more rapidly than unmyelinated nerves.
Q.9. Assertion: The resting membrane of the neuron exhibit polarity of charges.
Reason: The outer surface of the axonal membrane possesses a negative charge while its inner surface becomes positively charged.
Q.10. Assertion: Nerve fibre can become excited through touch, smell, pressure and chemical changes and there is a change in polarity.
Reason: It is called action potential.
Q.11. Assertion : The membrane of a neuron is polarised.
Reason : Ion channels on the neural membrane are selectively permeable to different ions.
Q.12. Assertion : The presynaptic neuron transmits an impulse (action potential) across the synaptic cleft to the postsynaptic neuron.
Reason : For the transmission of impulses at synapse, chemicals called neurotransmitters are responsible.
Q.13. Assertion : Neurons are excitable cells.
Reason : The membrane of neurons in a depolarised state is responsible for excitability.
Q.14. Assertion : Neurons regulates the endocrine activity but not vice-versa.
Reason : Endocrine gland regulates neural activity and neural activity regulates endocrine gland.
Q.15. Assertion : During physical exercise, the demand of oxygen is increased, which compels the lungs and heart to increase the rate of respiration and to increase the blood flow for proper supply of oxygen respectively.
Reason : Coordination is the process through which two or more organs interact and complement the functions of each other.