Responses to stimuli refer to how living organisms react to changes in their environment. For example, when a plant senses sunlight, it grows towards it, a process known as phototropism. This ability to respond helps organisms survive by adapting to their surroundings, whether it's finding food, avoiding danger, or seeking optimal conditions for growth. Animals also exhibit responses to stimuli, such as a dog barking when it hears a loud noise. This reaction is part of their instinctual behavior, helping them communicate and protect themselves. Overall, responses to stimuli are essential for survival and play a crucial role in the behavior of both plants and animals.