Some terms in Nutrition

Ingestion: Intake of food into the body (Feeding)
Digestion: Process where large food molecules are broken down into soluble and diffusible molecules that can be absorbed into the body cells. Alimentary canal usually has a section with a storage function (eg. Stomach)
Absorption: Process where digested food materials are taking into the body cells
Assimilation: Process where some of the absorbed food materials are converted into new protoplasm or used to provide energy
Egestion: Removal of undigested matter from the body (Defaecation)

Distinguish clearly between the following pairs of terms:
A) Nutrition & Tissue Respiration
Nutrition is changing food into part of the body (protoplasm); [1]
Respiration is changing food into energy by oxidation; [1]

Nutrition includes ingestion / the intake of food, respiration does not; [1]
Nutrition results in growth, whereas respiration does not result that; [1]

B) Digestion & Assimilation
Digestion is the Breakdown of complex food substances in the digestive system (in the mouth / stomach / small intestine or alimentary canal) into simpler substances; [1]
Assimilation is the synthesis of complex organic compounds (from simple substances); [1]
Assimilation involves chemical reactions that take place in living cells, therefore it is a metabolic reaction, whereas digestion is not taking place in living cells, thus it is not a metabolic reaction; [2]

C) Metabolic wastes & faeces
Metabolic wastes - waste products produced by chemical reactions, taking place in living cells;
Faeces - referring to the undigested, unabsorbed matter;