Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Question: What is the touch response in plants called? Answer: thigmotropism
The surface temperature of most stars is due to their size. Bigger stars produce more energy, so their surfaces are hotter. But some very small stars are very hot. Some very big stars are cool.

Question: What effect causes winds and currents to form circular patterns? Answer: coriolis effect
The Coriolis effect causes winds and currents to form circular patterns. The direction that they spin depends on the hemisphere that they are in.

Question: What is anything that causes cancer called? Answer: carcinogen
A carcinogen is anything that causes cancer. Most carcinogens produce mutations in genes that control the cell cycle.