Answer:
chitin
Explanation:
chitin is a complex carbohydrates, similar to cellulose, that makes up organic structure, such as the cell walls of fungi and exoskeletons of insects and other arthropods.
Ribose
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Blood flows through your heart and lungs in four steps: The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle through the tricuspid valve. The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve.