Life Processes
- The basic functions performed by living organisms to maintain their life on this earth are called life processes.
- For life to continue, processes like nutrition, respiration, transport of materials within the body and excretion of waste products are necessary.
- Food is a kind of fuel which provides energy to all the living organisms.
- A nutrient can be defined as a substance which an organism obtains from its surroundings and uses it as a source of energy or for the biosynthesis of its body constituents.
- Nutrition is a process of intake of nutrients by an organism as well as the utilisation of these nutrients by the organism. There are mainly two modes of nutrition: Autotrophic and heterotrophic.
- Different steps in the process of nutrition in animals are ingestion, digestion, absorption, assimilation and egestion.
- Autotrophic nutrition involves the intake of simple inorganic materials from the environment and using energy source from the sun to synthesise complex, high energy organic material.
- Photosynthesis is the process by which plants, capture solar energy to convert\[C{{O}_{2}}\]into simple sugars.
\[6C{{O}_{2}}+12{{H}_{2}}O\xrightarrow[Chlorophyll]{Sunlight}{{C}_{6}}{{H}_{12}}{{O}_{6}}+6{{O}_{2}}+6{{H}_{2}}O\]
- Heterotrophic nutrition involves the intake of complex materials prepared by other organisms. The heterotrophic mode of nutrition is of three types: Saprotrophic, parasitic and holozoic nutrition.
- The food eaten by human beings is broken down by various steps along the alimentary canal by the action of digestive enzymes.
- The process of releasing energy from food is called respiration.
- During the process of respiration complex organic compounds such as glucose is broken down to provide energy in the form of ATP. ATP is used to provide energy for other reactions in the cell.
- Respiration in organisms is of two types aerobic and anaerobic respiration.
- The transport of materials such as food, oxygen, energy and excretory products is a function of the circulatory system in human beings.
- The transport of water, minerals, food and other materials is a function of the vascular tissues like xylem and phloem in plants.
- Excretory products in the form of soluble nitrogen compounds are removed by the nephrons in the kidneys of human beings.
- Plants store waste material such as gum and resin in the vacuoles of cells.
