______ refers to the protection of the internal environment against the harms of changes in the external environment. 

• A. Thermoregulation
• B. Homeostasis 
• C. Defecation 
• D. Evaporation

Answer: (A)

Verified step by step guidance

1. Begin by understanding the concept of homeostasis, which is the process by which living organisms maintain a stable internal environment despite changes in the external environment.
2. Consider the role of thermoregulation, a specific aspect of homeostasis, which involves maintaining a stable internal temperature.
3. Evaluate the options provided: Thermoregulation, Homeostasis, Defecation, and Evaporation. Determine which term best describes the overall protection of the internal environment.
4. Recognize that defecation and evaporation are processes that do not directly relate to maintaining internal stability against external changes.
5. Conclude that homeostasis is the broad term that encompasses various processes, including thermoregulation, to protect the internal environment from external fluctuations.

Key Concepts

Homeostasis

Homeostasis is the biological process through which living organisms maintain a stable internal environment despite external changes. This involves regulating factors such as temperature, pH, and ion concentrations to ensure optimal functioning of cells and systems. For example, humans maintain a body temperature around 37°C, adjusting through mechanisms like sweating or shivering.

Thermoregulation

Thermoregulation is a specific aspect of homeostasis that focuses on maintaining an organism's body temperature within a certain range. This process can involve physiological responses such as altering blood flow, sweating, or shivering to either dissipate or conserve heat. It is crucial for the survival of endothermic (warm-blooded) animals, which rely on internal mechanisms to regulate their temperature.

External Environment

The external environment refers to all the external factors that can influence an organism's internal conditions, including temperature, humidity, and availability of resources. Changes in the external environment can pose challenges to homeostasis, prompting organisms to adapt through behavioral or physiological changes. Understanding these interactions is essential for studying how organisms survive and thrive in varying conditions.