Recognizing Living Things SS1 Biology Lesson Note

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:

i. 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

ii. RESPIRATION: To perform the numerous life processes, living things need a lot of 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.

iii. 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.

iv. IRRITABILITY: Is the ability of living things to respond to external and internal stimuli to survive. External stimuli may be light, heat, water, sound or chemical substances.

v. GROWTH: this is the tendency of organisms to increase irreversibly and rapidly in length size and 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 for growth.

vi. EXCRETION: Toxic waste products of metabolism & other unwanted materials have to be eliminated to ensure the proper functioning of the bodies of organisms. Such wastes include water, carbon (iv) oxide etc.

vii. REPRODUCTION: This is the ability of a living organism to give birth to young ones (offspring). The essence is to ensure life continuity. Reproduction can be sexual  (involving two organisms) or  asexual (involving one organism)

ix. LIFE SPAN / DEATH: Every organism has a definite and limited period of existence. Life, for all organisms, has five main stages, namely: origin ( birth ), growth, maturity,  decline and death.

x. COMPETITION: Living things tend to struggle for the basic things of life to survive. Hence, they compete for food, water, light, mates and space. 

xi. ADAPTATION: To survive, every organism possesses the ability to get used to change in its environment. 

DIFFERENCES BETWEEN PLANTS AND ANIMALS 

All living organisms can be generally classified as plants or animals. However, plants can be distinguished from animals in the following ways:

ASSIGNMENT:

1. Explain the differences between growth in plants and animals
2. Define the following characteristics of living things :

(a) respiration   

(b) irritability                          

(c) excretion

3. What are the similarities between living and non-living things
4. What are the similarities between plants and animals