Question

Energy is required for maintenance of life. It is obtained by a process called ___________.
A. Metabolism
B. Phagocytosis
C. Photorespiration
D. Decomposition

Answer 1

In our world we know that all living beings need an energy source to do work and for survival. So we can simply define energy as the ability to work. Where the work is said to be done when a force moves an object. On our earth energy ultimately comes from the sun. Even energy is necessary for maintenance of life.

Complete step by step answer:
For the maintenance of life we need energy. We get this energy by food. So some chemical reactions are involved in converting the food we eat into energy. We can call these chemical reactions which take place in our body to convert food into energy as metabolism. So we can define metabolism as chemical reactions in the body cell that change the food into energy. Some specific proteins in our body will help to control the chemical reactions.
Our body uses sugar, amino acids, fatty acids etc as energy sources. After having food, the enzymes in our body breaks proteins into amino acids, fats into fatty acids and carbohydrates into sugars. So these compounds are absorbed into the blood, blood carries them to the cell where the metabolism reactions take place. Once they enter the cell, the enzymes regulate the chemical reactions that are involved with the metabolism. The energy from the compounds is then released and stored for the living process.
So metabolism is the process which is used for producing energy in the body and for maintenance of life.

So, the correct answer is option A.

Note:
We already know that the sun is the main energy source in our earth. Green plants use the energy from sunlight for photosynthesis. By photosynthesis plants produce their foods. Therefore green plants known as producers or autotrophs. Other organisms that eat green plants (which have stored a part of energy they produced) will get energy, they are known as consumers or heterotrophs.