Introduction To Biology

• Biology derived from Greek words-BIOS meaning LIFE and LOGOS meaning STUDY or KNOWLEDGE.
  
• Biology means “life knowledge”.
  
• It is the study of living things/organisms.
  

Branches of Biology

• Botany – the study of plants.
  
• Zoology – the study of animals.
  
• Microbiology – the study of microscopic organisms.
  
• Morphology – the study of external structure of organisms.
  
• Anatomy – the study of the internal structure of organisms.
  
• Physiology – the study of the functioning or working of the cells or body.
  
• Biochemistry – the study of the chemistry of materials in living organisms.
  
• Cytology – the study of cells.
  
• Genetics – the study of inheritance.
  
• Ecology- the study of the relationship between organisms and their environment.
  
• Taxonomy – sorting out of organisms into groups.
  
• Histology – the study of fine structure of tissues.
  
• Virology – the study of viruses.
  
• Bacteriology – the study of bacteria.
  
• Entomology – the study of insects.
  
• Ichthyology – the study of fish.
  

Importance of Biology

• One learns about the functioning of the human body.
  
• One understands the developmental changes that take place in the body.
  
• It contributes immensely to improved life.
  
• It enables one to enter careers such as:
  
  • Medicine,
    
  • Nutrition,
    
  • Public Health,
    
  • Dentistry,
    
  • Agriculture
    
  • Environmental Studies.
    
  • Teaching
    

Characteristics of Living Things

Life defined through observations of activities carried out by living things;

Nutrition –

• Nutrition is the processes by which food/nutrients are acquired/made and utilized by living organisms.
  
• Green plants and certain bacteria make their own food.
  
• All other organisms feed on complex organic materials.
  

Respiration –

• This is the breakdown of food to provide energy.
  
• The energy released is used for various activities in the organism.
  

Gaseous Exchange –

Process throw which respiratory gases(CO₂&O₂) are taken in and out through a respiratory surface.

Excretion –

• Excretion is the removal of metabolic wastes from the body.
  
• Substances like urea, carbon dioxide (Carbon (IV) oxide).
  
• These substances are poisonous if allowed to accumulate in the body.
  

Growth and Development –

• Growth means irreversible change in size.
  
• All organisms increase in size that is, they grow.
  
• Development is irreversible change in complexity.
  
• As they do so, they also become differentiated in form.
  

Reproduction-

Reproduction is the formation of new individuals of a species to ensure continued existence of a species and growth of its population.

Irritability –

• The ability of organisms to detect and respond to changes in the environment. This is of great survival value to the organism.
  

Movement –

• Is the progressive change in position from one place to another.
  
• Some organisms are sessile (i.e. fixed to the substratum).
  
• The majority of plants move only certain parts.
  

Collection and Observation of Organisms

Biology as a practical subject is learnt through humane handling of organisms.

Materials needed for collection of organisms:-

• Knives to cut portions of plant stem/root or uproot.
  
• Polythene bags to put the collected plant or specimens.
  
• Insect collecting jars.
  
• Insect killing jars.
  
• Hand gloves.
  
• Sweep nets
  
• Pooters
  
• Traps
  

Observation of Organisms

• Observe the plant/animal in its natural habitat before collecting.
  
• Identify the exact place -on surface, under rock, on tree trunk, on branches.
  
• What does it feed on?
  
• How does it interact with other animals and the environment?
  
• How many of that kind of plant or animal are in a particular place?
  
• Plant specimens placed on the bench and sorted out into;- seeds/stems/roots/leaves/fruits.
  
• Animal specimens may be left inside polythene bags if transparent.
  
• Others (killed ones) are put in petri dishes.
  
• Use hand lens to observe the external features of small animals.
  

Presenting the Results of Observations

• Organisms are observed and important features noted down: colour, texture hard or soft; if hairy or not. Size is measured or estimated.
  
• 
  Biological Drawings – It is necessary to draw some of the organisms.
  
  • In making a biological drawing, magnification (enlargement) is noted.
    
  • Indicate the magnification of your drawing.
    
  • i.e how many times the drawing is larger/smaller than the actual specimen MG=length of drawing/length specimen
    

How to Draw

• Several drawings of one organism may be necessary to represent all features observed, e.g.
  
• Anterior view of grasshopper shows all mouth parts properly, but not all limbs.
  
• Lateral (side) view shows all the legs.
  

Collection, Observation and Recording of Organisms

Collection

• Plants and animals collected from the environment, near school or within school compound using nets, bottles and gloves.
  
• Animals collected include:-arthropods, earthworms and small vertebrates like lizards/chameleons/ rodents.
  
• Place in polythene bags and take to the laboratory.
  
• Stinging/poisonous insects killed using ether.
  
• Other animals are observed live and returned to their natural habitat.
  
• Plant specimens collected include:- leaves, flowers and whole plants.
  
• Observations are made to show the following:-
  
  • Plants have roots, stems, leaves and flowers.
    
• Animals have legs, hair, hard outer covering, feathers, eyes, mouth, limbs, and other appendages,
  

The differences between animals and plants collected

Comparison Between Plants And Animals

	Plants		Animal
l.	Plants are fixed in position and do not” move.	l.	Most animals move in search of food, shelter and mates.
2.	Respond slowly to stimuli.	2.	Respond quickly to stimuli.
3.	Cells have cellulose cell walls.	3.	Cells have no cell walls only a cell membrane
4.	Plants make their own food from simple	4.	Animals feed on already made food.
	materials such as CO2 and water using
	light energy.

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