CHARACTERISTICS OF LIVING THINGS
Everything in nature can be classified into two groups: living and non -living things.
The living things can be distinguished from their nonliving counterparts through the following characteristics observable in all living things:
- MOVEMENT: Animals can move from place to place on their own in search of food. Higher plants move certain parts of their body in response to growth or external stimuli
- RESPIRATION: In order to perform the numerous life processes, living things need much energy. The energy can only be obtained when the organism respires. Therefore, respiration is the oxidation of food substances in the presence of oxygen to produce energy with carbon (iv) oxide and water released as by products.
- NUTRITION: The act of feeding is called nutrition. All organisms need food to carry out their biological activities. Green plants can manufacture their food. Hence, they are autotrophs while animals are dependent on plants for their food, so they are heterotrophs.
- IRRITABILITY: Is the ability of living things to respond to external and internal stimuli in order to survive. External stimuli may be light, heat, water, sound or chemical substances.
- GROWTH: this is the tendency of organisms to increase irreversibly and rapidly in length and size and in mass. The essence of growth is to enable organisms to repair or replace damaged or old tissues in their bodies. The food eaten by an organism provides the basis of growth.
- EXCRETION: Toxic waste products of metabolism & other unwanted materials have to be eliminated to ensure proper functioning of the bodies of organisms. Such wastes include water, carbon (iv) oxide etc.
- REPRODUCTION: Is the ability of a living organism to give birth to young ones (off springs). The essence is to ensure life continuity. Reproduction can be sexual (involving two organisms) or asexual (involving one organism)
- LIFE SPAN / DEATH: Every organism has a definite and limited period of existence. Life , for all organism has five main stages , namely : origin ( birth ) , growth, maturity, decline and death.
- COMPETITION: Living things tend to struggle for the basic things of life in order to survive. Hence, they compete for food, water, light, mates and space.
- ADAPTATION: To survive, every organism possesses ability to get used to change in its environment.
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