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What is Biology?
What is Biology?
“Biology is defined as the study of living organisms, their origins, anatomy, morphology, physiology, behaviour, and distribution.”
Basic concepts and terminologies of Biology
The term ‘Biology’ comes from two Greek words, bios that means ‘life’ and logos that means ‘study’. Therefore, Biology is a branch of science that deals with the study of life. A person who studies Biology is called a Biologist. Living things are also called organisms. They include, plants, animals, fungi, and microorganisms. Microorganisms are very small living things such as bacteria and some protozoans which cannot be seen with the naked eyes. The size of organisms varies and ranges from very small ones like bacteria to very large ones like trees, birds, hippopotamus, and whales as shown in Figure 1.1.
Life
Life is the state of living in which plants, animals, and other living organisms have and non-living things do not have. The basic unit of life is cell. All living things are made up of cells. Cells are so small that they cannot be seen with the naked eyes but can be seen by using a microscope. Microscope is an instrument that is used in scientific studies to enlarge very small things so that they can be easily seen and examined. This processis called magnification. The simplest living things consist of one cell, thus, are known as unicellular organisms, for instance bacteria and amoeba. Larger and more complex organisms, for example human beings, fish, and trees are made up of millions of cells. They are known as multicellular organisms.
Branches of Biology
There are two main branches of Biology, namely Botany and Zoology.
Botany is the study of plants and zoology is the study of animals. A person who is specialised in the study of plants is called a Botanist, whereas a person who deals with the study of animals is called a Zoologist. However, there are many minor branches of Biology that deal with different aspects of living things.
Other branches of Biology
Characteristics of living things
Living things have characteristics that make them different from non-living things.
Activity 1.1: Identifying the characteristics of living things
Materials: A variety of living and non-living things
Procedure
1. Walk around the field or the school compound. Observe all the living and non-living things that you see.
2. Make a list of the observed things in your notebook.
3. Divide the things that you have observed into two groups; living and non-living
4. In your groups, discuss the things that you have observed by answering the following questions.
(a) Which ones are living? Why?
(b) Which ones are non-living? Why?
5. Compare your findings with those from other groups.
Living things have seven characteristics which distinguish them from non-living things. These characteristics are:
Nutrition
Nutrition is the process by which living things feed on materials from the environment. Plants, blue-green algae, and some protoctists make their own food using sunlight, water, and carbon dioxide as shown
Animals and some protozoans feed on ready made food .They may feed on plants, other animals, or microorganisms.
Example of an animal that feeds on other
animals is lion as shown. Food enables living things to grow,
develop, and carry out other life processes.
Respiration
The food eaten by organisms contains energy. However, this energy is not in a directly usable form. The food has to be broken down within living cells in order to release the energy. This process is called respiration. In this process, food substances are broken down in the living cells to produce useful energy. The energy released can be used for growth, movement, and other activities.
Excretion
Processes such as nutrition and respiration are known as metabolism. They produce useful substances and by-products. Some of the by-products are harmful if left to accumulate in the body of an organism. Excretion is the process by which metabolic by- products are removed from the body of an organism. The by-products are also called excretory products. Examples of excretory products are urea, excess water, and carbon dioxide. Urea and excess water are removed in the form of urine and small amounts are removed as sweat through the skin. Water vapour and carbon dioxide are removed during exhalation or breathing out.
Growth and development
Growth is caused by an increase in the number of cells that make up an organism. Therefore, growth is an increase in the size and weight of an organism. Development occurs when cells become specialized to perform specific functions. This causes an organism to change in shape and form, and becomes more complex.
Sensitivity or irritability
Living things detect and respond to changes in their environment. The ability of an organism to detect and respond to changes in its environment is called sensitivity or irritability. The changes that organisms detect and respond to are called stimuli (singular: stimulus). For example, human beings can feel and react to heat, cold and pain. A snail hides its body inside its shell when touched. Heat, touch, and pain are examples of stimuli.
Movement
All organisms can move on their own in response to their environment. Non-living things only move when pushed or pulled by someone or something. Some living things move from place to place in search for food, water, shelter, mates, or suitable environment. Movement involving the whole body of an organism is called locomotion. For example, animals can walk, run or crawl. Plants show movement in terms of
growth of their body parts, for instance
movement of plant roots towards water
and shoots towards light.
Reproduction
Living things produce new individuals of their own kind. For example, human beings give birth to human beings, maize seeds grow into maize plants, and chicks hatch from eggs of chicken. Reproduction ensures the continuity of organisms. Non-living things do not reproduction.
Activity: Finding out life processes and their importance Key question Can you tell a life process?
What you need
pictures of living things involved in life processes
What you do
The pictures below show living things involved in life processes.
i) In pairs, study the pictures carefully.
ii) Identify the life process shown in each picture and state its importance(s) to the living organism. Fill the answers in the table provided below the pictures.
Importance of studying biology
(a) Helps to understand and care for the environment properly. It helps to learn about the plants, animals, and microorganisms that surround us and how they affect us.
(b) Helps to identify and group living things which makes it easier to learn more about them.
(c) Helps to appreciate the nature. Many fascinating things about different organisms and how they function are learnt through Biology
(d) Helps to understand our bodies better.
(e) Helps to acquire research skills that are useful when carrying out scientific investigations. Such skills include measuring, observing, analysing, and making conclusion.
(f) Helps to improve food production. Scientists can use biological skills to develop higher-yielding and disease-resistant varieties of plants and animals. These new breeds of plants and animals are called hybrids.
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