Define Nutrition.

Hint: Nutrition refers to the basic energy source for the organism. Nutrition comprises the whole process through which an organism obtains its food. It comprises ingestion, digestion, and absorption. Deprivation of nutrition can lead to faulty body functions.

Complete answer:Nutrition comprises all the required and essential nutrients required to support and maintain good health. Human life is sustained by the nutrition we get. A balanced diet makes a proper nutritious meal whereas poor nutrition leads to various deficiencies. Nutrition is not only about ingesting the food but it deals with a large field of scheduled diet that assists what food should be eaten at what stage.
The general requirements for energy are derived from nutrition. Some organisms utilize simple food materials that are obtained from inorganic sources. These organisms that use carbon dioxide and oxygen are called autotrophs. On the other hand, some organisms use complex substances that are broken down into simpler ones in the body. These are called heterotrophs. Heterotrophs are directly or indirectly dependent on the autotrophs for their nutrition.
Different animals obtain food in different ways. Also, every organism has a distinct processing mechanism for the food they eat. The complex organism has more developed and specialized forms of processing. In heterotrophs, various stages are involved in food processing. Ingestion means taking up food is the first and the most essential part of nutrition. After ingestion, the food eaten is processed by various enzymes and chemicals in the body. This is called digestion. Once the food is digested, the essential nutrients are absorbed from it. These nutrients are then circulated throughout the body. Further processing happens at cellular levels where energy is produced.
Hence, nutrition is the key sustaining process of all life forms.

Note: Malnutrition is the condition where an individual is deprived of the required and essential nutrients. Malnutrition results in various diseases and dysfunctions. The energy is not made at sufficient levels that lead to faulty metabolism and functioning.