Question

which of the following is true about cnidarian nervous systems? cnidarians have a complex spinal cord. cnidarians have a centralized brain. cnidarlans lack any form of nervous system. cnidarians have a nerve net without a brain.

Explanation:

To determine the correct answer, we analyze each option based on knowledge of cnidarian nervous systems:

• Option 1: Cnidarians (like jellyfish, corals) are simple organisms and do not have a spinal cord (spinal cords are part of more complex vertebrate nervous systems). Eliminate this.
• Option 2: Cnidarians do not have a centralized brain. Their nervous system is decentralized. Eliminate this.
• Option 3: Cnidarians do have a nervous system (a nerve net), so they do not lack any form of nervous system. Eliminate this.
• Option 4: Cnidarians have a nerve net, which is a decentralized network of neurons, and they lack a centralized brain. This matches their biological characteristics.

Answer:

D. Cnidarians have a nerve net without a brain.