Which of the following best describes what happens to an enzyme after it catalyzes a chemical reaction?
its mass decreases since part of the molecule is used up.
it is unchanged and can be used again for the same chemical reaction.
it becomes chemically bonded to the products of the reaction.
its shape changes, giving it different chemical and physical properties.

In 2015, about ten percent of total u.s. energy consumption was from renewable energy sources. renewable energy plays an important role in reducing greenhouse gas emissions. when renewable energy sources are used, the demand for fossil fuels is reduced. sanjay and his family want to cut back on their use of non-renewable resources at home. they are thinking of an alternate way to heat their home without adding more greenhouse gases or pollutants to the environment. which renewable resource would not fit into their plan? a) solar power b) burning wood c) constructing a wind turbine eliminate d) generating hydroelectric power