Problem 9 - Biology the Easy Way (E-Z Biology)

Question

Write "true" for your answer. If a statement is incorrect, change the underlined expression to one that will make the statement true. The nerve net is associated with sponges.

Step-by-Step Solution

Answer

The nerve net is associated with cnidarians.

Step 1: Identify the Incorrect Statement

The statement provided is: "The nerve net is associated with sponges." Let's analyze whether this statement is true. A nerve net is a simple type of nervous system commonly found in animals like cnidarians (such as jellyfish) but not in sponges. Sponges lack a nervous system altogether.

Step 2: Correcting the Incorrect Expression

Since sponges do not have a nervous system, the statement is incorrect. The underline part should refer to organisms that possess a nerve net. Cnidarians, like jellyfish or hydra, have a nerve net. Thus, replace 'sponges' with 'cnidarians' to correct the statement.

Step 3: Write the Corrected Statement

The corrected statement should read: "The nerve net is associated with cnidarians." Now, the statement is accurate.

Key Concepts

Nervous System

The nervous system is a network that coordinates and controls the functions and activities within an organism's body. It is made up of nerve cells, also known as neurons, which communicate information via electrical and chemical signals. In animals, the nervous system can vary from simple to incredibly complex structures.

• In higher animals, like humans, the nervous system is highly complex and organized into the central and peripheral nervous systems.
• The central nervous system is composed of the brain and spinal cord, while the peripheral consists of all other neural elements.
• In lower animals, such as cnidarians, the nervous system takes simpler forms, like the nerve net.

In general, the nervous system allows organisms to interact with and adapt to their environment, a crucial element for survival and reproduction.

Cnidarians

Cnidarians are a group of simple aquatic organisms that include jellyfish, sea anemones, corals, and hydra. These creatures have a unique structure called a nerve net, which acts as their nervous system. The nerve net is a decentralized network of interconnected neurons found in the body walls of cnidarians.
Instead of having a central brain, this network allows them to respond to environmental stimuli, ensuring their survival.

• The nerve net enables basic functions, such as contracting their bodies and coordinating movements.
• This system is essential for activities like feeding, defense, and locomotion.
• Advantages of having a nerve net include flexibility and the ability to respond to different stimuli quickly.

Cnidarians do not have a complex nervous system like higher animals, but their nerve net is perfectly suited to their simple life requirements.

Sponges

Sponges are among the simplest multicellular organisms, and unlike cnidarians, they do not possess a nervous system or any nerve nets. These organisms have a porous body structure and rely on the flow of water to obtain nutrients and remove wastes.
Their anatomy is very basic, consisting primarily of two layers of cells, with a jelly-like substance in between.

• Sponges do not respond to stimuli in the way organisms with nervous systems do. Instead, they depend largely on passive filtration for survival.
• The lack of a nervous system means that sponges cannot perform complex interactions or exhibit rapid behavioral responses to their environment.
• Despite this simplicity, sponges are very successful in their ecological niches, often dominating marine environments.

This simplicity underlines the diversity of life and the various survival strategies found in the animal kingdom.