Correct Option
The correct option is (a).
Explanation
Nerve impulses are electrochemical signals that transmit information throughout the nervous system. They travel along neurons (nerve cells) and enable the body to react to stimuli by coordinating with effectors such as muscles and glands.
Statement-wise Analysis
- Statement 1 is Correct: A nerve impulse is a signal transmitted along a nerve fiber (axon). It propagates as a wave of electrical activity (action potential) along the membrane of the neuron.
- Statement 2 is Incorrect: While nerve impulses are electrical signals, they do trigger muscle movement. When an impulse reaches the neuromuscular junction (the interface between a nerve and a muscle), it causes the release of neurotransmitters that stimulate the muscle fibers to contract.
- Statement 3 is Incorrect: The functional combination of nerve and muscle tissue is present and is a fundamental characteristic of most animals. This coordination is essential for rapid movement in response to environmental stimuli.
Key Takeaway: Nerve impulses are the primary mechanism for rapid internal communication in animals, directly facilitating muscle contraction and coordinated physical movement.