INTRODUCTION 

Living things are also known as living organisms. 

Organisms (forms of life) have distinguishing characteristics and 

therefore are grouped. 

The Magnifying lens 

-Is used for enlarging small objects. 

(Diagram) 

Procedure of its use 

• Place the object on the bench.

• Move the hand lens from the object to the eye.

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• An enlarged image is seen.

Drawing magnification = Length of the drawing/ drawing Length

 Length of the object/Actual Length 

 (Diagram) 

External features of plants and animals

External features of plants 

i) Rhizoids as in moss plant. 

ii) Fronds in ferns. 

iii) Roots, stems, leave, flowers, seeds, fruits, and cones in higher 

plants. 

External features of animals 

i) Tentacles in hydra 

ii) Feathers in birds 

iii) Shells in snails 

iv) Wings in birds 

v) Fur and hair in mammals 

vi) Scales and fins in fish 

vii) Proglotids in tapeworms 

viii) Mammary glands in mammals 

ix) Locomotory Structures e.g. limbs in insects 

x) Body pigmentation 

Practical activity 1 

To collect and observe animal specimens

To collect and observe plant specimens 

What is classification? 

-Is an area of biology that deals with the grouping of living organisms 

according to their structure. Organisms with similar structures are put 

under one group referred to as a taxon—taxa (plural). 

The groupings also consider evolutionary relationships (phylogeny)—

since all living organisms had a common origin at one time. 

Taxonomy—Science of classification. 

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Taxonomist—Biologist who studies taxonomy. 

Need for classification. 

Reasons 

1. To identify living organisms into their correct groups for 

reference and study 

2. To bring together living organisms with similar characteristics but 

separate those with different features. 

3. To arrange information of living organisms in an orderly manner. 

This avoids chaos and confusion. 

4. To understand the evolutionary relationship between different 

organisms 

Taxonomic Units 

Are groups (taxa) into which organisms are placed as a matter of 

convenience. 

Groups are based on observable characteristics common in the group. 

In a classification scheme (taxonomic units or groups, a hierarchy of 

groups are recognized starting with the first largest and highest group; 

the Kingdom to the smallest and lowest unit; the species. 

There are 7 major taxonomic units. 

The Kingdom

There are five Kingdoms of living organisms, namely: 

1. Kingdom Monera: bacteria 

2. Kingdom protoctista: algae, protozoa, amoeba, paramecium 

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3. Kingdom Fungi: Moulds, Yeast, Mushrooms 

4. Kingdom Plantae: Moss plants, ferns, maize, garden pea, pine, 

meru oak, bean etc. 

5. Kingdom Animalia: hydra, tapeworms, bees, human beings etc. 

A kingdom is divided into Phyla in animals or divisions in plants and 

sorts out organisms based on body plan and form. 

Plan is the adaptation to a special way of life. 

The Class is further divided into small groups; Orders using structural 

features. 

Orders are divided into families using structural features, then 

Families into Genera (singular genus) –based on recent common 

ancestral features that are less adaptive. 

Genus is divided into species i.e. kind of plant, or animal. 

Down the hierarchy, the number of organisms in each group decreases 

but their similarities increases. 

The Species group members naturally interbreed to produce fertile off 

springs. 

Minor differences are exhibited in the species groups e.g. on colour of 

the skin in human beings and varieties of plants. 

The groups of the species are termed to as varieties, races or strains. 

Scientific Naming Of Living Organisms 

Present naming was developed by carolus Linnaeus 18th c, where 

organisms were given 2 names in Latin language. 

Living organisms have their scientific names and common names i.e. 

local or vernacular names. 

Scientific naming uses the double naming system—Binomial system. 

In binomial system, an organism is given both the genus and species

name. 

Binomial nomenclature (Double –naming system)-Is the assigning of 

scientific names to living organisms governed by a definite set of rules 

recognized internationally. 

Principles of binomial nomenclature 

a) The first, genus name, should begin with a capital letter and the 

second name, species, should begin or written in small letters e.g. 

Lion---- Panthera leo

Leopard----- Panthera pardus

Domestic dog----- Canis farmiliaris

Human being--- Homo sapiens

Maize plant---Zea mays

Lion and Leopard are closely related ---Same genus but distantly 

related—different species. 

b) The scientific names must be printed in italics in textbooks and 

where hand written to be underlined e.g. Panthera leo.

c) The specific name (species) is frequently written with the name of 

the scientist who first adequately described and named the 

organism e.g.Phaseolus vulgaris i.e. Vulgaris is the scientist who 

described and named the bean plant. 

d)Biologists should give a Latinized name for a newly described 

animal or plant species where Latin name is missing e.g. 

Meladogyne kikuyuensis – Is a scientific name of a nematode 

from kikuyu. 

Aloe kilifiensis --- A member of Aloeceae family from Kilifi 

discovery. 

Garinsoga parviflora waweruensis --- a member of Macdonald 

eye family discovered by Waweru.