Introduction to biology

Welcome to O’level Biology notes.

In this course we will provide you with all the notes of biology from from 1 to form 4.

Biology

Biology is a word derived from two Greek words i.e. “Bios”meaning life and “logos” meaning knowledge.

Therefore Biology is a branch of science which deals with the study of life or living things. All living things are called organisms.

BRANCHES OF BIOLOGY

Biology as a science is very wide and has many branches which include the following;

1.Botany, the study of plants.

2.Zoology, the study of animals.

3.Anatomy, the study of the structure of living things.

4.Nutrition, the study of food and how living things feed.

5.Ecology, the study of how organisms are related to their environment / surrounding.

6.Mycology, the study of fungi.

7.Virology,the study of virus.

8.Bacteriology, the study of bacteria.

9.Entomology, the study of insects.

10.Microbiology, the study of microorganisms.

11.Physiology, the study of process and functioning of the body parts.

12.Genetics, the study of inheritance.13.Taxonomy, the study of classification of organisms

14.Ornithology, the study of birds.

15.Ichthyology, the study of fish.

WHY DO WE STUDY BIOLOGY? (IMPORTANCE OF STUDYING BIOLOGY)

  • To get knowledge on how to treat the sick
  • To shape for our future careers such as doctors, opticians and nurses
  • To get knowledge on how to manufacture drugs(pharmacists)
  • To get knowledge on how to conserve the environment
  • To know how our body functions.

CHARACTERISTICS OF LIVING THINGS

A living thing is biologically known as an organism, for example man, plants, animals, birds, insects.

All living things share certain basic features called characteristics of living things.

1.Nutrition/feeding.

It’s a process by which living things obtainfood from the environment.All living things take in food from which they obtain materials for energy production, body growth, and Repair. Green plants make their own food while the rest obtain already made food from the environment.

2.Respiration.

This is the breakdown of food to release energy in the bodyusing oxygen obtained from the environment.

3.ExcretionIs.

the process by which waste products are removed from the body e.g. urea in urine, carbon dioxide, etc.

4.Reproduction

This is the ability of an organism to give rise to new organismssimilar to the parent.

5.Movement

This is the ability of an organism to transfer its body from one place to another. They move in search for food, water, shelter, mates, and run away from predators.

6.Growth

Growth is a permanent increase in size of an organism. It is followed by development.

7.Irritability / sensitivity

It is the ability of an organism to respond to changes in its environment.

DIFFERENCES BETWEEN PLANTS AND ANIMALS

PlantsAnimals
i)Have cell wall.Lack cell wallLack cell wall.
.ii)Have chlorophyll.Lack chlorophyllLack chlorophyll.
iii)Movement is by growth of plant parts.Movement involves the whole organism.
iv)They make their own food by photosynthesis.Feed on already made food
v)Respond to stimulus slowly since it involves growth.Quick / immediate response to stimulus.
vi)Growth occurs throughout lifeGrowth is up to maturity and no further growth after
vii)Growth occurs in particular plant partsGrowth occurs allover the body.