Biology-classification of living things

Biology 

SENIOR ONE BIOLOGY
CLASSIFICATION OF LIVING THINGS
Classification is the grouping of organisms basing on the their similarities and differences.
It should probably have come to your notice already that living things are many.
Now if you take a coser look at living things in your immediate vicinity you will establish that they of many different types too. That is, they vary. With these observations in mind biologists have come up to the science of classification whose major aim is to enable any biologists to use similarities and differences in organisms to quickly identify them and be able to group them together with the others with which they resemble. Classification also involes the naming of organisms (also called nomenclature) by assigning them particular names so That identification can be done with exactness. The science that deals with classification of organisms and their naming is called Taxonomy.
IMPORTANCE OF CLASSIFICATION
Let us look at why there is need to group and name organisms

• It shorts out living things into groups for easy reference minimising confusion.
• Provides organisms with names that are internationally accepted by all biologists.
• It enables biologists to communicate information about organisms precisely world wide
• It enables biologists to understand evolutionary relationship between different organisms.
• It enables biologists to predict the characteristics of any newly discovered organisms.
• It enables the classification of new species basing on the specific characteristics they have and share with other groups.
• It allows generalization to be made about groups of organisms because they are likely to behave like others in their group. This can help to solve biologically related problems like providing clues about the origins and spread of a new pathogens.

All this help to simplify the study of living things.
During classification organisms are grouped into groups according to their resemblance and differences known as Taxa. The members of each group have certain features in common which distinguish them from those of other groups. The largest of this is called kingdom. Today organisms have been grouped into 5 kingdom. i.e Protista, Monera, Fungi, Plantae, and Animalia.
The kingdoms are subdivided into Phyla (singular phylum), the phyla again divided into classes, the classes into orders, orders into families, the families into genera(singular generus), and genera into species which are the smallest of the biological groupings. This order of arrangement of the different subgroups (taxa) in the kingdoms from the largest to the smallest is known as the Taxonomic Hierarchy.
The last two of these biological groupings can be defined with a good degree of accuracy but other groupings are usually too broad to be defined precisely. Thus the genus is a group of organisms which show resemblance, e.g Man, Ape, Gorilla, Monkey, all belong to the same genus while a a species is a group of organisms which can interbreed and produce viable offspring. e.g all mankind belongs to the same species.
The Binomial system of naming organisms
This is the most widely used system of naming organisms. It was first suggested and used by carolus Linneaus in the 18th century.
In this system each organism is given two names (hence the word Binomial ) usually in Latin i.e a genus name and species name.
The first name is the genus name and is written beginning with capital letter while the second is the species name and is written beginning with a small letter. Both names are typed in italic but If written by hand must be underlined each one separately. Examples of such names are:- Homo sapiens (man), Feils leo (lion). Mangifera indica (mango tree ).
CHARACTERISTICS OF THE ORGANISMS IN THE KINGDOMS
KINGDOM MONERA
This kingdom consists of only the bacteria

Characteristics

1. Microscroscopic single celled organisms with a variety of shape and size.
2. Are prokaryotic. i.e do not have true nuclei.
3. Genetic material is not found in chromosomes and normally attached to the cell wall.
4. Feed either heterotrophically or autotrophically.
5. Adapted to almost every environment.
6. Reproduce sexually by binary fission and rarely by sexual means. Bacteria are further classified according to their shape into Cocci (spherical). Bacilli (rod Shape), spirilla (spiral) etc. And by the biochemical differences they have into Gram +ve and Gram -ve.

A typical bacterial cell

A typical bacterial cell
ECONOMIC IMPORTANCE OF BACTERIA
Useful bacteria

1. Saprophytic bacteria are decomposer in nature breaking down organic matter, contributing to the recycling of matter.
2. Nitrogen fixing bacteria convert nitrogen to nitrates in the soil making it available for plants.
3. In industry, bacteria are used to make milk products, like cheese, butter yogurt and alcohol by fermentation, making soap powders, etc.
4. Production of vaccines for immunization against bacterial diseases like dipteria, tetanus and pneumonia.
5. Digestion of plant material cellulose in the gut of ruminant herbivores by cellulase producing bacteria living there symbiotically.
6. Breakdown of waste in sewage works.
7. Scientific research in genetic biotechnology etc.

Harmful bacteria

• Cause many diseases to plants and animals. Some human bacterial diseases include cholera, diphtheria, tuberculosis, pneumonia, tetanus and gonorrhea.
• Spoilage of stored food especially milk and milk products.
• Damage of buried metal pipe caused by sulphuric acid produced as a result of bacterial action.