Biology is the science that deals with the study of living things. The word is derived from two Greek words: Bios, which means Life, and logos, which means study. Thus, biology is the study of life and living organisms.
Basic
Concepts and Terminologies of Biology
Biology
Biology is derived from
two Greek words: 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 specialised in
the study of biology
Life
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
The organism is anything
which has life. It is another name for a living thing. Organisms are made up
of cells.
Cell
A cell is a basic unit of living things. The cell has three main parts: the 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 multicelled 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, and 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.
Feeding
(Nutrition)
All living things need
food to provide energy for such activities as growth, repair and health.
Animals get their food by eating other living things or food materials that were once living things. Herbivores (e.g. rabbits) eat plants, carnivores (e.g. lions) eat other animals, and omnivores (e.g. humans) eat animals and plants. Plants make their own food through the process called photosynthesis.
The process of taking in
food, synthesising it, digesting and oxidising it to release energy or build
the body is called nutrition.
Respiration
Respiration is the
breaking down of food materials within cells to release energy.
Respiration usually
involves the use of oxygen. All living things need energy for movement, growth
and development, and the functioning of body organs.
Excretion
All living things produce wastes such as carbon dioxide, water, urea, ammonia, etc.. Some of these chemicals, if left to accumulate in the cells, would seriously poison the living organism; hence, they need to be removed. The process of removing metabolic waste products from the body of living organisms is called excretion.
Waste products are
removed from the body by excretory organs such skin, kidneys, lungs and liver.
Reproduction
Reproduction is the process by which living things produce new individuals of their own kind. All living things reproduce to replace organisms lost by death. If a group of organisms does not reproduce fast enough to replace those which die, the group becomes extinct. Reproduction ensures the continuation of life when the parent generation dies.
Human beings bear babies;
birds hatch chicks; and plants produce seedlings as new organisms, which
eventually grow to mature organisms to replace those lost by death.
Growth
Growth is defined as an irreversible (permanent) increase in size and dry weight of an organism involving differentiation. All living things need food to grow and build up their bodies.
Animals grow until they
reach a certain adult size, but most plants can grow continuously throughout
their lives.
A table of differences between
living things and non-living things
|
Living things |
Non-living things |
|
They respire |
Do not respire |
|
They grow |
Do not grow |
|
They respond to stimuli |
Do not respond to stimuli |
|
They reproduce |
Do not reproduce |
|
They excrete |
Do not excrete |
|
They feed |
Do not feed |
|
They move |
Do not move |
Branches
of biology
Biology is a subject, and
it has many branches. The main branches are botany and zoology. Botany is a branch of biology which deals with
the study of plants. A person who studies botany is called a botanist. Zoology
is a branch of biology which deals with the study of animals. A person who
studies zoology is called a Zoologist
Other
branches of biology
Mycology:
This is the study of fungi. A person who studies mycology is called a
mycologist
Bacteriology:
This is the study of bacteria. A person who studies bacteriology is called a
bacteriologist.
Virology:
This branch of biology deals with the study of viruses. A person who studies
virology is called a virologist.
Immunology is concerned with the body's defence against diseases and foreign substances. A
person who studies immunology is called an immunologist.
Entomology refers to the study of insects. A person who studies entomology is called an
entomologist.
Parasitology:
This branch deals with the study of parasites and their effects on living
organisms. A person who studies parasitology is called a parasitologist.
Dermatology:
It is concerned with the medical study of skin and its diseases. A person who
studies dermatology is called a dermatologist
Ecology is a branch of biology that deals with relationships among living things and
between organisms and their surroundings. A person who studies ecology is
called an ecologist
Anatomy is the study which deals with the structure of living things. A person who studies
anatomy is called an anatomist
A diagram representing the branches of Biology
Endocrinology:
This is the study of the structure of endocrine glands and the hormones associated
with them. A person who studies endocrinology is called an endocrinologist.
Histology is the study of the structure of tissues. A person who studies histology is called
a histologist
Cytology:
Is the study of the structure, composition and function of cells. A person who
studies cytology is called a cytologist.
Microbiology is devoted to the study of organisms that can be seen only with a microscope, e.g. bacteria, viruses, some fungi and some protozoans. A person who studies
microbiology is called a microbiologist.
Taxonomy is the scientific classification of organisms. A person who studies taxonomy is
called a taxonomist.
Genetics:
Study of heredity and variation in organisms. A person who studies genetics is
called a geneticist.
The
Importance of Studying Biology
The study of biology is
very important to man.
The following is an
outline of why the study of biology is important:
1. It helps us to
understand ourselves better since we are living things.
2. Skills and knowledge
of biology can be applied to other scientific fields such as agriculture,
forestry, medicine, nutrition, pharmacy and veterinary science.
3. It helps us to
understand our environment better and the principles of conserving it.
4. Biology helps to
answer some important questions, such as what living things need, why we
resemble a monkeys, and why do frogs lay many eggs but only a few become adults?
5. Knowledge of biology
helps us to improve our health since causes, symptoms, transmission, and
treatment of various diseases are studied in biology.
6. Knowledge of biology
helps us to avoid being influenced by magical beliefs, superstitions and other
traditional taboos.
7. Knowledge of genetics
helps us to clear some common doubts about certain inherited characteristics, e.g. albinism, sickle cell anaemia, haemophilia, etc.
8. Knowledge of the
structure and chemical composition of the organisms enables us to acquire food,
clothes and shelter from them.
Relationship
between Biological Science with Other Related Fields
Veterinary science
(Veterinary medicine)
Veterinary medicine is
the branch of medicine that deals with the diseases of animals. Doctors who
treat animals are called Veterinarians. Veterinarians are trained to prevent,
diagnose and treat illness in large and small animals. Their work is valuable
because many animal diseases can be transmitted to human beings, e.g. rabies,
tuberculosis, tularemia (rabbit fever), anthrax, etc. Basic knowledge of biology
is required for the successful study of veterinary science.
Agriculture
Agriculture is concerned
with the production of useful plants and animals through farming system.
Agriculture provides us with almost all our food. It provides materials for
clothing and shelter. It provides materials used for making many industrial
products, such as paints and medicines. Agriculture uses knowledge of biology to
improve plant and animal breeding. Genetically modified organisms (GMOS) ensure
better quality, early maturity and high yield products. Crop and animal
diseases and pests can only be overcome by applying biological knowledge.
Forestry
A forest is a large area
of land covered with trees. It is much more than just trees. It also includes
smaller plants such as mosses, shrubs and wild flowers. Forestry is the science
of managing forest resources for human benefit. The practice of forestry helps
maintain an adequate supply of timber and management of such valuable forest
resources as water, wildlife, grazing areas and recreational areas.
Biology helps in
improving the qualities of the trees through manipulating the genetic
constitution of the particular plant species.
Climate, soil and water
determine the type of plants to be grown, which entirely applies biological
knowledge. The use of biological control to combat tree pests applies biological
principles.
Pharmacy
Pharmacy is the
profession concerned with the preparation, distribution and use of drugs.
Members of this profession are called pharmacists or druggists. A pharmacy also
refers to a place where drugs are prepared or sold. The drugs are made depending
on the chemical composition of the body of an organism and how they can react
with such medicines. Knowledge of biology also helps to know the effects of
drugs on living things (pharmacology) and possible remedies to be taken.
Medicine
Medicine is the science
and art of preserving health and treating illness. Medicine is a science
because it is based on knowledge gained through careful study and
experimentation. It is an art because its success depends on how skilfully
medical practitioners apply their knowledge in dealing with patients. The goal
of medicine includes saving lives, relieving suffering and maintaining the dignity
of sick people. Biological knowledge helps doctors, surgeons and nurses to
diagnose, treat and prescribe the right medicine to cure the disease.
Biological knowledge will
also help them to offer education to the patients on how to prevent themselves
from the diseases, e.g. purifying drinking water, vaccination against polio,
measles and other diseases.
Nutrition
Nutrition is the science
which deals with food and how the body uses it. People, like all living things, need food to live. Food provides substances that the body needs to build and
repair its tissues and to regulate its organs and systems. Food also supplies
energy for every action we perform. Knowledge of biology helps to identify the
type of food required by an individual based on its quality and quantity.
| PLANTS | ANIMALS |
|---|---|
| (i) They are autotrophic, i.e. they can make their own food | They are heterotrophic, i.e. they feed on complex organic compounds |
| (ii) Contain chlorophyll and can undergo photosynthesis | No chlorophyll, cannot undergo photosynthesis |
| (iii) Growth occurs in some parts only (e.g. root and shoot tips) | Growth occurs in all parts of the body |
| (iv) They have branched bodies | They have compact bodies |
| (v) No nerves, muscles, blood system or special sensory cells | Have nerves, muscles, blood system and special sensory cells |
| (vi) Usually rooted in the ground and do not move from place to place | Not rooted in the ground, move to get food and escape enemies |
| (vii) Have no digestive system | Have a digestive system to break down food |
| (viii) Cells of plants have cell walls | Cells of animals have no cell walls |
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