Why do multicellular organisms need a constant, rapid supply of glucose and oxygen?

What are the different types of circulatory systems?

What is a single circulatory system?

Give an example of an organism with a single circulatory system

What is a double circulatory system?

Give an example of an organism with a double circulatory system

What is a closed circulatory system?

TRUE OR FALSE:
All vertebrates have a closed circulatory system where blood is enclosed inside blood vessels

What is an open circulatory system?

TRUE OR FALSE:
All invertebrates have an open circulatory system

Complete the sentence:
An insect's heart is ___________; it contracts in a ________, pumping blood into the main artery (which opens up into the ______ ________)