Answer the following question given this paragraph: Reactions can proceed by themselves if they are exergonic or exothermic, that is if they release energy. The associated free energy of the reaction is composed of two different thermodynamic quantities, enthalpy and entropy. Enthalpy is a measure of the total energy of a thermodynamic system. The change in enthalpy is positive in endothermic reactions, and negative in exothermic processes. Q: Enthalpy is a measure of the total energy of what kind of system? Choices: - macroscopic - planetary - hypodermic - thermodynamic A:
thermodynamic

Answer the following question given this paragraph: The light reactions occur in the first stage of photosynthesis. This stage takes place in the thylakoid membranes of the chloroplast. In the light reactions, energy from sunlight is absorbed by chlorophyll. This energy is temporarily transferred to two molecules: ATP and NADPH. These molecules are used to store the energy for the second stage of photosynthesis. The light reactions use water and produce oxygen. Q: Light reactions occur during which stage of photosynthesis? Choices: - intermediate stage - third stage - final stage - first stage A:
first stage

Answer the following question given this paragraph: In the absence of a net force, objects move in a straight line. If they turn that is, if their velocity changes, even only in direction there must be an applied force. Forces which cause objects to turn around continuously in a circle are known as centripetal forces. When an object moves in a circle its velocity at any particular instant points in a direction tangent to the circle. The acceleration points towards the center of the circle, and so does the force acting on it. This is only natural, when you think about it if you feel a force pushing you towards your left as you walk forward, you will walk in a circle, always turning left. Q: Forces which cause objects to turn around continuously in a circle are known as? Choices: - frictional forces - tension forces - hydrodynamic forces - centripetal forces A:
centripetal forces