The correct option is
B. Production of hormones.
Detailed Explanation:
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Understanding Blood Functions: Blood in mammals serves several critical functions, including transportation, regulation, and protection. Let's break down each of the options to see how they relate to these functions.
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Option A: Engulfing bacteria
- Function: This refers to the role of white blood cells (leukocytes), particularly phagocytes, which are part of the immune system. They engulf and digest pathogens, including bacteria, to protect the body from infections.
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Conclusion: This is indeed a function of blood, as it plays a crucial role in the immune response.
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Option B: Production of hormones
- Function: While blood does transport hormones produced by glands (like the thyroid or adrenal glands) to various parts of the body, it does not produce hormones itself. Hormones are synthesized and secreted by specific endocrine glands.
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Conclusion: This is the correct answer because the production of hormones is not a function of blood; rather, blood serves as a medium for transporting hormones.
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Option C: Transporting ureas
- Function: Blood is responsible for transporting waste products, including urea, which is a byproduct of protein metabolism. Urea is carried from the liver (where it is produced) to the kidneys (where it is excreted).
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Conclusion: This is a valid function of blood, as it helps in the removal of metabolic waste.
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Option D: Distribution of heat
- Function: Blood plays a significant role in thermoregulation. It helps distribute heat generated by metabolic processes throughout the body and can also help dissipate heat through the skin.
- Conclusion: This is also a function of blood, as it helps maintain a stable internal body temperature.
Why Other Options Are Incorrect or Weaker:
- Option A: Engulfing bacteria is a direct function of blood through its white blood cells, making it a strong and valid function.
- Option C: Transporting ureas is a critical waste management function of blood, which is essential for maintaining homeostasis.
- Option D: The distribution of heat is vital for thermoregulation, which is crucial for the survival of mammals, especially in varying environmental conditions.
Summary of Key Points:
- Blood has multiple functions, including transportation of gases, nutrients, hormones, and waste products, as well as regulation of body temperature and immune response.
- The production of hormones is not a function of blood; hormones are produced by endocrine glands and transported by blood.
- White blood cells in blood are responsible for engulfing bacteria, while blood also transports metabolic wastes like urea and helps regulate body temperature.
Revision Summary:
- Blood functions include transportation, regulation, and protection.
- It does not produce hormones; it only transports them.
- White blood cells in blood are responsible for immune responses.
- Blood helps in waste removal and thermoregulation.