Senior one biology-Diversity of living things

Biology 

SENIOR ONE BIOLOGY
TOPIC
DIVERSITY OF LIVING THINGS
INTRODUCTION TO BIOLOGY

Biology is the study of living things. The word biology comes from twp Greek words, Bios- which means life and Logos which means the study of.
Biology is a subject, which is very wide and has a number of branches.
These include:-

Zoology. This is study of animal.
Botany: It deals with the study of plants (flora).
Anatomy: it handles the study of the structure of living things.
Physiology: This deals with the study of functioning of the body's parts.
Taxonomy.  It deals with the study of the clasification of organisms.
Nutrition. Tackles the study of food and feeding in organisms.
Genetics. It study the inheritance.
Ecology.  It study the organisms in relation rmto their environment.
Ethiology. Is the study of the behavior of animals.

LIVING THINGS
Living things (also called organisms) differ from non-living things like wood, stones and others because living things have the ability to carry out many life processes which are their main characteristics.

CHARACTERISTICS OF LIVING THINGS.
Let look at what are the things that make living things (organisms) to be called living.

1. Nutrition: From the above,  we saw the nutrition is the study of food and feeding in organism. All living things carry out nutrition by taking in substance from their environment, from which they obtain material for energy production, body growth and repair of worn out tissues.
Green plants are able to make their own food in the process of photosynthesis.

2.  Respiration: All living things respires.  During respiration they take in air containing oxygen which is used to oxidize food in order to release energy. Energy is used by body to perform work. In the process carbodixe CO2  is produced as a waste product and is eliminated (removed) from the body (e.g by lungs in mammals).

3. Excretion: The many chemical reactions, which take place in the bodies of living organisms (called metabolism ) produced waste products. Which are toxic (poisonous ) to the cells if allowed to stay in them. They are therefore removed from the body in the process of excretion by the excretory organs like skin, kidneys and lungs. In animals these wastes include carbondioxide, urea, uric acid and ammonia.

4. Locomotion:Living things are able to move,  through this movement is limited in plants. In animals movement is particularly necessary if they are to find food, shelter, mates and escape from their enemies.

5. Reproduction: All living things produce others of the same kind by the process of reproduction. This is important if they are to maintain their numbers by replacing those who might have died. Reproduction may be either asexual or sexual.

6. Growth: Every living thing grows. Life usually starts from a single cell and growth continues by addition of New material and cells together with changes in the shape and form of the organism. This continues until the organism reaches the end of its life span and dies.
Irritability: Living things are able to respond (react) to changes in their external environment (i. e their surroundings). This is particularly done in animals with the help of the nervous system and in plants by growth movement.
Irritability is essential for survival of organism in their environment.

DIFFERENCES BETWEEN PLANTS AND ANIMALS
Most living things fall in to two broad divisions:- plants and animals which have the following differences as shown in table below.

Table showing the differences between green plants and animals.
Green plants
Animals

Methods of feeding :
-Make their own food from CO2 and water in the presence of sunlight.
-Do not make their own food,  they depend on plants and other animals for food.

-They have chlorophyll
-Do not have chlorophyll.

-They have cell walls made of cellulose.
-Have large cell vacuoles.
-Do not have cell wall.
-Do not have vacuoles.

-Most have limited movement.
Most have free movement.

-They grow continously. This is because plants do not have fixed number organs.
-Growth is limited to the growing points at the tips of the stems and roots called Apical meristems. 
-Grow to a definite shape and stop.
-They have a fixed number of organs.

-They respond by growth and therefore slow.
-Growth is not limited to a particular region.