OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What role does the central nervous system play after receiving information?

1. It ignores the stimulus

2. It co-ordinates the response and decides the action

3. It directly performs the action

4. It sends a signal to the sensory receptors

The correct answer is: It co-ordinates the response and decides the action

After receiving information, the central nervous system (CNS) processes this information and integrates it to coordinate an appropriate response. The CNS consists of the brain and spinal cord, which together analyze sensory inputs and determine the most suitable actions to take. This enables the body to respond to stimuli effectively and appropriately, whether it involves moving a muscle, secreting a hormone, or any other response necessary to maintain homeostasis or react to environmental changes. The first choice, ignoring the stimulus, does not reflect the role of the CNS, as it is specifically designed to process and respond to stimuli. The third choice, performing the action directly, misrepresents the role of the CNS because it does not carry out physical actions itself; instead, it sends signals to other parts of the body, such as muscles or glands, to execute the actions. The fourth choice, sending a signal to the sensory receptors, is incorrect because the sensory receptors gather information and send it to the CNS, rather than the other way around. The CNS functions to coordinate and decide on responses after processing the incoming stimuli.