Nervous System and Reflex Arc

Which part of the nervous system is the Coordination Center?

• Receptors

• Motor neurons

• Central nervous system

• Sensory neurons

Answer explanation

The central nervous system is the coordination center of the body. It includes the brain and spinal cord, which are responsible for processing information received from all parts of the body and coordinating activity. The other options, receptors, motor neurons, and sensory neurons, are parts of the nervous system but they do not serve as the coordination center.

What is the role of effectors in the nervous system?

• To detect stimuli

• To bring about a response

• To release chemicals

• To sense the environment

Answer explanation

Effectors in the nervous system play a crucial role in bringing about a response to stimuli. They receive signals from the brain or spinal cord and act accordingly, causing muscles to contract or glands to secrete hormones. Therefore, the correct answer is 'To bring about a response'.

What is the purpose of the reflex arc?

• To minimise harmful stimuli

• To secrete hormones

• To detect stimuli

• To maintain homeostasis

Answer explanation

The purpose of the reflex arc is to minimise harmful stimuli. This is achieved by allowing the body to respond quickly to potentially harmful situations without the need for conscious thought. The reflex arc is a neural pathway that controls an action reflex. The other options, such as secreting hormones, detecting stimuli, or maintaining homeostasis, are not the primary functions of the reflex arc.

What is the stimulus in the reflex arc when you touch a hot object?

• Heat

• Light

• Sound

• Pressure

Answer explanation

The reflex arc is a neural pathway that controls an action reflex. In the given question, the stimulus is the change detected by the body, which is the heat from the hot object. This heat triggers a response, causing you to quickly withdraw your hand. Therefore, the correct answer is 'Heat'.

What is the role of sensory neurons in the reflex arc?

• To detect stimuli

• To bring about a response

• To release chemicals

• To communicate information to the coordinating centre

Answer explanation

The role of sensory neurons in the reflex arc is to communicate information to the coordinating centre. They detect stimuli and transmit this information to the central nervous system. This is why the correct answer is 'To communicate information to the coordinating centre'. The other options, while related to general functions of neurons, do not specifically describe the role of sensory neurons in the reflex arc.

What triggers an electrical impulse in the motor neuron in the reflex arc?

• Heat

• Chemicals

• Pressure

• Light

Answer explanation

In the reflex arc, an electrical impulse in the motor neuron is triggered by chemicals. These chemicals, or neurotransmitters, are released from the sensory neuron and bind to the motor neuron, causing it to fire an impulse. This is not triggered by heat, pressure, or light.

What is the effector in the reflex arc when you touch a hot object?

• Receptor

• Motor neuron

• Sensory neuron

• Muscle

Answer explanation

The effector in the reflex arc when you touch a hot object is the muscle. This is because, in response to the stimulus (touching a hot object), the sensory neuron sends a signal to the spinal cord, which then sends a signal via the motor neuron to the effector (muscle) to pull the hand away.