Question

Identify the endergonic reaction from the following reactions?
A. The synthesis of sugar in photosynthesis
B. The breakdown of sugar in cellular respiration
C. The breakdown of fats to release energy
D. Break down of sugar in photosynthesis
E. Break down of ATP

Answer 1

Hint: Endergonic reaction is a type of non-spontaneous reaction in which energy needs to be provided externally to carry the reaction forward. Also, the breakdown of bonds releases energy and are exothermic in nature.

Complete step by step answer:
To identify the correct answer we need to have detailed information on Endergonic reaction.
In chemical thermodynamics, an endergonic reaction which is also coined as heat absorbent Non spontaneous reaction or an unfavourable reaction. It is a chemical reaction in which the standard change in free energy is positive and an additional driving force or external energy is needed to perform this reaction. In other terms, it is a type of reaction that takes more energy to start the reaction than what is received out of it. This means that the total amount of useful energy is negative so the total energy is negative net result. In this reaction energy must be absorbed from the surroundings into the workable system for the reaction to happen.

At standard state, at constant temperature and constant pressure conditions, the change in the standard Gibbs free energy would be positive. In metabolism, an endergonic reaction is anabolic meaning energy is stored. In many such anabolic processes energy is supplied by coupling the reaction to ATP or adenosine triphosphate resulting in high energy.

Now, according to the options we need to find out in which reaction we need to supply energy externally.
-> According to the first option, photosynthesis is a synthesis of sugar which takes sunlight, water and air as input. As energy is supplied from outside from sunlight, therefore it is an endergonic reaction.
-> Now, according to the next four options, a breakdown is taking place. Whether it is sugar or fats or ATP, break down is taking place in the reactions. We know that when a bond is broken in a compound, energy is always released. Therefore, the breakdown reactions are exothermic reactions.

Therefore, the correct answer is option A.

Note:
Endergonic reactions are reactions which need external energy to reach to the final phase and get the products. Also, the breakdown in reactions releases energy and is exothermic and nature.