One of the following organisms exhibits a closed and single circulatory system

Explanation

This question is asking which organism has a closed and single circulatory system. The options given are Insect, Earthworm, Fishes and Mammals. A circulatory system is the system in our bodies that carries blood and oxygen to all the organs and tissues in our body. There are two types of circulatory systems, open and closed. An open circulatory system is when blood is not contained in vessels and flows freely through the body cavity, while a closed circulatory system is when blood is contained in vessels and pumped by the heart. In this question, the organism that exhibits a closed and single circulatory system is Fishes. Fish have a heart that pumps blood throughout their body in a closed system of blood vessels. This is different from an open circulatory system, which is found in insects and earthworms. In an open circulatory system, blood is pumped by the heart into a body cavity where it bathes the organs and tissues. It's important to note that mammals also have a closed circulatory system, but they have a double circulatory system, which means the blood flows through two separate circuits. This is different from Fishes, which have a single circulatory system. In summary, the organism that exhibits a closed and single circulatory system is Fishes. Insects and earthworms have an open circulatory system, while mammals have a closed double circulatory system.