The kidney is referred to as an excretory organ because it excretes:

• A. carbon dioxide
• B. oxygen
• C. nitrogenous wastes such as urea
• D. digestive enzymes

Answer: (C)

Verified step by step guidance

1. Understand the role of the kidney in the human body: The kidney is part of the excretory system, which is responsible for removing waste products from the blood and maintaining homeostasis.
2. Identify the types of waste products excreted by the kidney: The kidney primarily excretes nitrogenous wastes, such as urea, creatinine, and uric acid, which are byproducts of protein metabolism.
3. Clarify why carbon dioxide and oxygen are not excreted by the kidney: Carbon dioxide is excreted by the respiratory system (lungs), and oxygen is utilized by cells for energy production, not excreted as waste.
4. Explain why digestive enzymes are not excreted by the kidney: Digestive enzymes are produced by the digestive system to break down food and are not considered waste products excreted by the kidney.
5. Conclude that the kidney is referred to as an excretory organ because it removes nitrogenous wastes, such as urea, from the blood and excretes them in urine.