Life processes are the processes that perform maintenance functions in living organisms even when they are not actively doing anything
Energy is needed for these maintenance processes to preventdamage and breakdown
Energy for life processes comes from outside the body of the organism
The process of transferring energy from outside the body to the inside is called nutrition
Additional raw material from outside is needed for the growth of the body size of organisms
Most food sources for organisms are carbon-based
Different organisms use different nutritional processes depending on the complexity of the carbon sources
Outside sources of energy need to be broken down or built up in the body and converted to a uniform source of energy for various molecular movements and growth
Chemical reactions in the body, such as oxidising-reducing reactions, are necessary to break down molecules
Many organisms use oxygen sourced from outside the body for oxidising-reducing reactions
The process of acquiring oxygen from outside the body and using it in the breakdown of food sources for cellular needs is called respiration
In multi-cellular organisms, specialised tissues are needed for the uptake of food and oxygen
A transportation system is required in multi-cellular organisms to carry food and oxygen from one place to another in the body
Waste byproducts created from chemical reactions in the body need to be removed and discarded outside the body by a process called excretion