Organisms respond to environmental signals to adapt and survive. These signals can include changes in temperature, light, or the presence of predators. For example, plants may grow towards light sources, a process known as phototropism, while animals might alter their behavior in response to seasonal changes. The ability to respond to these signals is crucial for maintaining homeostasis. In humans, sensory systems detect stimuli, allowing for quick reactions, such as pulling away from a hot surface. This responsiveness helps ensure survival by enabling organisms to adjust to their surroundings effectively.