Activities of Living Things

Introduction

This unit on activities of living things presents the organism, plant or animal as an entity that is capable of existing. To say an organism exists, is the same thing as saying that it is busy, it is full of life, it is going on, it is alive, it is full of energy. If you look into any biology textbook (see reference at the end of the unit), it will give you list of things that living things do to qualify them as living things and differentiates them from non living things.

 Objectives:

When you complete this unit successfully, you will be able to:

1. Differentiate living things from non-living things. 
2.  List the characteristics of living things. 
3. Describe in detail those activities that distinguish living things from non living things. 
4.  Give examples of living things. 
5. Explain how energy is transformed by living things. 
6. Classif y living things based on oxygen requirement. 

 Activities of Living Things

All living things manifest certain characteristics. They demonstrate the ability to use energy from the environment for survival and carry out their various activities. For continuous survival, protoplasm must be added. Waste must be gotten rid off. New ones or offspring must be produced. Nine characteristics distinguish living things from non-living things.

These are:

1.  Ingestion 
2.  Assimilation 
3. Growth 
4. Reproduction 
5. Waste elimination 
6.  Responsiveness 
7. Co-ordination 
8.  Regulation 
9.  Movement 

Ingestion

All living things feed one way or the other. They take in food for many reasons, chief among these is for energy purposes. The organism needs energy to carry out all the other activities associated with living things. There are two kinds of living things, plant and animal. Plant manufacture food, i.e. basic materials are secured, light energy is utilised to convert the materials to complex nutritive substances, which are used as food. Animals depend on plants for food.

Assim ilation

Living organisms utilise food (nutrients) to maintain life. This is done by a process called metabolism. It is a chemical process involved in keeping the life of the organism going. There are two aspects of metabolism, (a) anabolism (substances are synthesised from simpler substances, e.g. photosynthesis..... (b) catabolism (the breakdown of the substances).

Growth

Growth simply put is increase of materials in an organism. This is done in stages, a unicellular organism increases its protoplasm while a multicellular organism increases the number of cells, and every living cell is made up of protoplasm.

 Excretion

All living organisms get rid of unwanted products (waste). As a result of cell activities in the protoplasm, many materials formed (byproducts) which are not beneficial to the cell and if left will cause harm to the cell.

 Reproduction

All cells of living organisms multiply or divide. This multiplication or division enables the organism to perpetuate their species. Reproduction can take different forms. (a) fission into two or more parts, (b) fusion of protoplasmic material from two sources (i.e. male and female gametes) resulting in an offspring.

Responsiveness

Living organisms respond to forces or anything external, even internal, i.e. any stimuli in the environment, it could be change of weather. Organisms do this by many methods. You will learn some of these in detail as your study progresses.

 Co-ordination and Regulation

Chemical and physical changes in the organism are involved in all these activities. There is a general process of co-ordination and regulation by enzymes to keep the system of the organisms balanced and unified. Materials are exchanged, energy is exchanged between the organism and its environment.
You have gone through the various activities most living things carry out. Now think of some living things around you, check through the list of activities and see if your example of a living thing (say, yourself or an insect) manifest these characteristics, non-living things such as wood.

 Energy Transform ation in Living Things

Looking through all the activities of living things, energy seems to be a linking factor between all the activities. Each of the activities expend energy to be carried out.

Classification of Living things Based on Oxygen utilization

Living things can be classified into three groups, based on their oxygen requirement (a) those that use free oxygen to breakdown complex compound - aerobic, (b) those that can respire without oxygen ,.J anaerobic, (c) those that can exist with or without oxygen, e.g. yeast. Energy is needed for the organism to move from place to place (locomotion). Plant cells do not move like animal cells, but there is movement within the cells of a plant i.e. movement of the protoplasm.