The processes which are absolutely necessary to maintain life in a living being are called life processes.
Nutrition, respiration, transportation of substances and excretion are categorized as life processes.
The process of taking and utilizing food by living beings is called nutrition. There are two types of nutrition, viz. autotrophic nutrition and heterotrophic nutrition.
During photosynthesis, a green plant takes carbon dioxide and water to make carbohydrate by utilizing energy from sunlight.
The heterotrophic nutrition is of two types, viz. saprotrophic nutrition and holozoic nutrition.
Nutrition in amoeba can be divided into following steps: Ingestion, digestion, absorption, assimilation and egestion.
The human digestive system is composed of an alimentary canal and some accessory glands.
The main parts of alimentary canal are; mouth (buccal cavity), oesophagus, stomach, small intestine, large intestine and rectum.
Respiration is the process during which food is utilized to produce energy.
The first step of respiration happens in cytoplasm and results in breakdown of glucose (6 carbon molecule) into pyruvate (3 carbon molecule).
The next step depends on the presence of absence of oxygen. Based on this fact, there are two types of respiration, viz. aerobic respiration and anaerobic respiration.
The main parts of the respiratory system are; nasal chamber, pharynx, larynx, trachea, bronchi, bronchioles, alveoli and lungs.
In human beings, transportation of substances takes place through the blood circulation system. The circulation system is composed of the heart, blood vessels and blood.
There are three types of blood vessels, viz. arteries, veins and blood capillaries.
Transport of water takes place through xylem in plants. This is a complex tissue which forms a continuous pipeline through different parts of a plant.
Transport of water in plants is facilitated by root pressure, capillary action, adhesion-cohesion and transpiration pull.
Removal of wastes from the body is called excretion.
The human excretory system is composed of a pair of kidneys, ureters, a urinary bladder and urethra.
These main points are highly helpful for last minute preparation for examination. You can glance through them while going for examination. You can view them in the school bus, in car, in elevator, etc.