Movement and Response to Stimuli

Core concept

Plants show responses called tropisms — phototropism is growth towards light, while geotropism (or gravitropism) is growth in response to gravity, with roots growing downward and shoots growing upward. Animals show much faster responses through their nervous system — for example, quickly pulling a hand away from something hot is a reflex action, an automatic and very fast response that does not require conscious thought, helping protect the body from harm.