Given a scientific passage and an answer, generate a question for the given answer.

Passage: Hydraulic car lifts also use fluid to transmit pressure and increase force. The lifts are used to raise cars, which are very heavy, so mechanics can work on them from underneath. Controls in airplanes use fluids to transmit pressure and increase force so a flick of a switch can raise or lower heavy landing gear. To see animations of hydraulic systems such as these, go to URLs:. Answer: hydraulic systems
What kind of systems use fluid to transmit pressure and increase force?

Passage: The amount of material left over after a certain number of half-lives can be easily calculated. Answer: pheromone
What term is used to describe a chemical released by an animal that affects the behavior or physiology of animals of the same species?

Passage: In endothermic reactions, the temperature of the products is typically lower than the temperature of the reactants. The drop in temperature may be great enough to cause liquids to freeze. That's what happens in the endothermic reaction at this URL: http://www. bbc. co. uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev1. shtml . Answer: endothermic
The temperature of the products is typically lower than the temperature of the reactants in what type of reaction?