TeXes Science Test 2025 – 400 Free Practice Questions to Pass the Exam

Living systems are designed to respond to a variety of stimuli, which can be categorized into two main types: internal and external stimuli. Internal stimuli refer to changes occurring within the organism, such as hunger, thirst, or hormonal fluctuations, prompting responses to maintain homeostasis. External stimuli include environmental factors like light, temperature, and sound, which can influence behavior and physiological processes.

The ability to respond to both types of stimuli is crucial for survival, allowing organisms to adapt to changing conditions, seek resources, and avoid dangers. For instance, the process of responding to light is essential for plants, which adjust their growth patterns, while animals may modify their behavior based on internal states like hunger and external threats. This dual responsiveness enhances overall adaptability, making it possible for living systems to thrive in diverse environments.