Biology is the branch of science that studies living things.Biologists are scientists who investigate life.Biology being a science is studied by the use of the scientific method. The scientific method includes these steps

A theory, which has been tested for a long time and found to be consistent with new discoveries, is taken to be a law or a principle. In carrying out experiments, care must be taken to eliminate all bias that can lead to false results and conclusions. this informs the need for a control experiment A control experiment is an experimental set up which has all factors affecting the result of the experimental subject to be constant except the one that is being tested which is the variable. Biological science finds its applications and usefulness in various fields and areas such as medicine, Agriculture, genetic Engineering, food production industries etc.

Characteristics of Life

Understanding biology as a science poses the question: How do we recognize life? Certainly, living and non living things have some features, but there are some characteristics that are found in living things only. As it is difficult to define life, a description of these activities and properties that charactercterize living things gives biologists an understanding of life and things that are living. These characteristics are:

• (1) MOVEMENT
• (2) RESPIRATION
• (3) NUTRITION
• (4) IRRITABILITY OR SENSITIVITY
• (5) GROWTH FROM WITHIN
• (6) REPRODUCTION
• (7) EXCRETION
• (8) ADAPTATION TO THE ENVIRONMENT

While a non living thing may have one or a few of these characteristics, only living things have all of them, therefore any thing that has all the characteristics of life must be living.

Energy and Living Organisms

Energy is the ability to do work. All living things need energy which they take in from their surroundings and food and use for their life activities. All life on earth depends on energy from the sun (solar energy). This energy through photosynthesis in green plants is transformed to chemical energy.All animals depend on plants for their foods directly or indirectly. Both plants and animals utilize the chemical energy contained in food to carry out life activities including growth and reproduction. The process of photosynthesis, which involves energy consumption, storage and transformation, is a building up process (anabolism). On the other hand, respiration, which involves the release of chemical energy in mechanical work, and heat energy during work, is a breaking down process (catabolism). Both anabolism and catabolism comforms to the first and second laws of thermodynamics. the first law state that: Energy can neither be created no destroyed but can be converted from one form to another.The second law states that Energy transformation is never 100% efficient as energy is always lost to the surroundings as heat energy

General Questions

1. is the name of the procedure scientists follow to solve problems.
2. A preliminary explanation scientists give for a particular question is called .
3. In any experiment, the factor that changes is called .
4. A can be regarded as a scientific explanation supported by a large number of experimental results.

10. In an experimental procedure, a is set up in order to eliminate bias.

Using the characteristics of living things state the distinctions you can make between something that is dead and something that is alive.

12. Alighted candle flame utilize energy in its burning and living things too need energy. But how is the use of energy by a candle flame different from the use of energy by living things?

Practical Activities

Collect the following from the environment or your teacher will make them available for you. A living rat, A dead rat, stone, a plastic cup. Check for the activities of life in all these collected items and record your observations in the table provided below.

Observing growth as an activity of a living thing
1. Your teacher will provide you with a warm saturated solution of a crystalline salt e.g. potassium trioxonitrate (V), evaporating dish. Display it on a table and allow it to cool slowly. Observe it every two or three minutes intervals for about 30minutes.Dip a glass rod into the saturated solution. draw it out and hold it in the air.

Questions

What do you observe as the solution cools in the air?
How do you differentiate this increase in size here, with that of growth in living things

2. Each member of the class is to be provided with bean seeds or maize grain, tins or container, garden soil, water and ruler. Fill the tins with wet garden soil and sow two or three seeds in a tin. After the seed is germinated in a few days, keep watering it and continue to observe the seedling for about two or three weeks more. In each round of observation, note the number of leaves and the increase in height.
Record your observations in the table below:

Projects

1. Formulate a hypothesis about the effect of sun light on plant growth. Design and carry out an experiment and a controlled experiment to test your hypothesis.
2. Research the history of a particular biological discovery and describe how the scientist or scientists involved arrived at their conclusion. (Do the work in your Biology practical note book and submit the work to your teacher.)