TOPIC 1:INTRODUCTION TO BIOLOGY
The concept of Biology
Biology is the branch of science that deals with the study of living things.
The word Biology is derived from two Greek words, Bios which means Life, and logos which means study of.
Thus biology is a study of life and living organisms.
BASIC CONCEPTS AND TERMINOLOGIES OF BIOLOGY
Biology is derived from two Greek words, that is, bios which means life and logos or logia which means study or knowledge. So biology can be defined as a branch of science which deals with the study of life. The term biology can also be defined as a branch of science which deals with the study of living things or organisms.
Biologist A person specialized in the study of biology
Life means being alive or existing. Something is alive or existing if it possesses life processes. The life processes are growth, movement or locomotion, respiration, excretion, reproduction, sensitivity and nutrition.
Organism is anything which has life. It is the other name of a living thing. Organisms are made up of cells.
A cell is a basic unit of living things. The cell has three main parts, cell membrane, cytoplasm and nucleus. Cells which make up plants are called plant cells and those which make up animals are called animal cells. Some organisms are made up of one cell. They are called unicellular or single-celled organisms e.g. amoeba, euglena and yeast. Some organisms are made up of many cells, they are called multicellular organisms e.g. animals, plants, and most fungi.
THE CHARACTERISTICS OF LIVING THINGS
Movement/locomotion
All living organisms are capable of movement. Movement is the change of position of the whole organism or just part of an organism. For animals and unicellular organisms the movement is of the whole body. This is known as locomotion. Most animals move about using legs, wings or fins. Unicellular organisms such as amoeba, paramecium and euglena use the locomotory structures pseudopodia, cilia and flagella respectively.
In plants only part of it may move towards different factors such as light, water, gravity etc. They move by growing. Their roots grow down in the soil and their shoots grow up into the air or towards a source of light.
Irritability (sensitivity)
Irritability is the ability of an organism to respond to a stimulus. Stimulus (plural; stimuli) is anything that causes a response in an organism.
Examples of stimuli include: an alarm clock, a smell of breakfast cooking and a fly landing on your skin.
All living things are sensitive to certain changes in their surroundings, that is, they are aware of what is happening around them. This is possible because they have special organs known as sense organs by which they detect these changes.
Examples of sense organs include: eyes for vision (sight); skin for temperature, touch, pressure detection; tongue for tasting; nose for smelling; and ears for hearing and body balance. Plants do not have sense organs but are still able to detect and respond to things like gravity, water and light.