BIOL 101 Homework Learn It Exergonic and Endergonic Reactions solutions complete answers

BIOL 101 Homework Learn It Exergonic and Endergonic Reactions solutions complete answers 

 

Learn It: Differentiate between exergonic and endergonic reactions.
The first law of thermodynamics states that energy is neither created nor destroyed. The second law of thermodynamics states that energy tends to spontaneously move toward molecular disorder. This means that a highly ordered organism like you requires a constant input of energy to remain ordered. The nutrients contained within the foods that you consume provide the energy necessary to keep you in an ordered state. For instance, what happens if we stop eating? We would begin to lose mass; we would become less ordered as our bodies began to break down stored nutrients for energy.

Energy is stored within the chemical bonds holding the molecules in our bodies together. When broken, those chemical bonds can release energy. This process takes the energy of an ordered state (i.e., in a chemical bond) and releases it, increasing molecular disorder. What happens when we consume more nutrients or energy than we need to maintain our current mass? We make more chemical bonds and increase in mass; we gain weight.

So, as we can see, energy can be both released from chemical bonds and stored in chemical bonds. The releasing of energy from chemical bonds is driven by the second law of thermodynamics and therefore tends to be spontaneous. Reactions that release energy and increase disorder are called exergonic reactions. While a portion of the energy released by exergonic reactions is lost to the environment in the form of heat, some of the energy released can be used to drive reactions that form chemical bonds and therefore store energy. The process of storing energy in chemical bonds increases order and therefore tends to be nonspontaneous. As such, this process requires an input of energy and is endergonic.

 

Exergonic and endergonic reactions are often coupled for this reason; some of the energy released by an exergonic reaction provides the energy necessary to drive an endergonic reaction. Some of the energy released by breaking chemical bonds can therefore be stored within new chemical bonds. In an exergonic reaction, energy is released and the products have less energy than the reactants. In an endergonic reaction, energy is consumed and the products have more energy than the reactants.

 

Endergonic reactions do which of the following? Select all that apply.

     Are nonspontaneous

   Release energy

   Consume energy

   Are spontaneous

 

Which two of the following apply to the products of an exergonic reaction?

     Are more ordered than the reactants

   Have more energy than the reactants

   Have less energy than the reactants

   Are less ordered than the reactants

 

Which of the following apply to some of the energy released by an exergonic reaction? Select all that apply.

     Cease to exist after the reaction is complete

   End up being stored into new chemical bonds

   Provide energy to drive an endergonic reaction

   Be lost to the environment in the form of heat

 

Endergonic and exergonic reactions are often coupled, with the energy released by the  reaction used to power the  reaction.

 

Where is the energy used to power our bodies stored?

     As exergonic reactions

   As endergonic reactions

   Free in the cytosol

   Chemical bonds