CLASSIFICATION OF LIVING THINGS.  
Classification-Is the branch of science which deals with the process of  
sorting, grouping and naming living organisms according to their  
similarities and differences. The study of classification is known as  
Taxonomy  
Importance of classification  
❖ It helps to reduce large number of groups of dissimilar organisms  
into small number of manageable groups of organisms with more  
features in common.  
❖ It makes easy to classify all known organisms and predict the  
placement of the yet to be discovered based on already known  
features.  
❖ Classification  
simplifies  
communication  
among  
taxonomists  
worldwide.  
❖ It helps to show evolutionary relationship between organisms.  
❖ Organisms grouped in the same taxon, such as at genus level,  
normally have many common features.  
❖ It paves a way towards understanding other disciplines, such as  
ecology, medicine and pharmacy.  
Types of classification systems  
There are two types of classifications namely;  
❖ Natural classification- Is the type of classification which is based  
on external and internal features.  
❖ Artificial classification- Is the type of classification which is  
based on external features only.  
Features of natural classification.  
❖ Considers both internal and external features  
❖ Requires scientific skills  
❖ Based on international standards  
❖ More accurate  
❖ Consumes time and is costly  
Features of artificial classification  
❖ Based on external features only  
❖ Requires simple skills  
❖ Less accurate  
❖ They have chitin as a structural carbohydrate in the cell wall. This  
is a feature typical of animals such as arthropods; example insects.  
❖ They store carbohydrates in the form of glycogen.  
❖ They are heterotrophs. Thus, they cannot manufacture their own  
food since they are either saprophytes or parasites. The parasitic  
fungi can be facultative or obligate.  
Similarities between fungi and plants  
❖ Their cells have cell wall.  
❖ Some fungi have vegetative bodies that are superficially  
differentiated into shoot-like and root-like systems.  
❖ Most fungi’s growth is restricted to apical cells.  
❖ They are non-motile.  
❖ They reproduce sexually by formation of spores such as ascospore  
in yeast and basidiospores in mushrooms. Some fungi reproduce  
asexually by producing spores such as sporangiospore.  
❖ They lack centrioles in their cells.  
Phyla of kingdom fungi  
a) Phylum Zygomycota  
b) Phylum Ascomycota  
c) Phylum Basidiomycota  
Phylum Zygomycota  
Phylum Ascomycota Members Of this phylum are commonly called  
ascomycetes or sac fungi. This is because their spores are enclosed in sac  
like structures known as asci (singular Ascomycetes can reproduce both  
sexually through spores or asexually by budding. Some are single-celled  
(unicellular) organisms such as yeast.  
Representative organisms are mucor and black breadmould (Rhizopus).  
Characteristics of Zygomycetes  
❖ They are multicellular.  
❖ They are saprophytic, growing on decaying organic materials.  
❖ They reproduce sexually through zygospores or asexually through  
sporangiosphores.  
❖ Have hyphae without cross walls.  
Distinctive features of phylum Zygomycota  
Members of the phylum Zygomycota have the following features that  
differentiate them from other phyla:  
❖ They have aseptate hyphae which lack cross walls between  
adjacent cells. They are therefore coenocytic in structure.  
nuclei in their cell. The nuclei will fuse only after the  
formation of ascus. The diploid nucleus will later undergo  
meiotic and mitotic divisions to form ascospores.  
❖ Some ascomycetes such as yeasts are unicellular and reproduce  
asexually by budding (new cells form on the surface of the old  
ones).  
Distinctive features of phylum Ascomycota  
The following are the distinctive features of the phylum Ascomycota:  
❖ They have specialised spore producing structures called  
ascocarps.  
❖ They reproduce asexually using conidia formed on the tips of  
conidiophores; in some members asexual reproduction is  
through budding.  
❖ Some are unicellular heterotrophs, and lack typical hyphae,  
for example Saccharomyces.  
Figure;2.3: Yeast  
Habitat of yeast  
They grow on flowers, ripen fruits, juices and slim wax from the trees.  
Economic importance of yeast to industries  
❖ It is a reach source of vitamins B and proteins  
❖ Used in fermentation of various carbohydrates  
❖ Yeast cells are used in production of lactic acid and citric acids  
❖ It is used in baking to make dough rise.  
Adaptations of Saccharomyces(yeast) to its mode of life  
Saccharomyces(yeast) species have the following adaptive features that  
enable them suit to their mode of life:  
❖ They store carbohydrates in the form of glycogen for use  
during shortage of food supply.  
❖ They have permeable cell walls to allow entry of nutrients that  
are obtained from external digestion. Thus, they can absorb  
simple monosaccharides and vitamins directly from their  
environment.  
❖ They secrete extracellular enzymes such as sucrase and  
cellulase for digestion of carbohydrate, and protease for  
digestion of protein.  
❖ They have high reproductive rate through budding, to produce  
new cells hence increase in number.  
❖ Spores’ ability to remain dormant in unfavourable conditions  
ensures their existence.  
❖ Some Saccharomyces are facultative anaerobes. They have an  
ability to respire anaerobically or aerobically, which ensures  
survival in both aerobic and anaerobic conditions.  
Economic importance of kingdom fungi  
❖ They are source of food for example mushroom  
❖ They are decomposers for example.  
❖ Fermentation of carbohydrates  
❖ Source of vitamin B  
❖ Used in production of phytohormones.  
❖ Used in food industry  
❖ Increase soil fertility  
❖ Used in making medicine for example peniciline from  
penicilium  
❖ Used in treatment of polluted water and soil.  
❖ They are poisonous e.g. some of Mushroom (Amanita spp)  
❖ They cause diseases to human e.g., Athletes foot disease  
❖ They cause damage to crop plants during growth e.g. puccinia.  
❖ They cause damage to woods on both living and stored timber  
e.g. bracket fungi  
❖ Cause food spoilage  
Kingdom Plantae  
Kingdom plantae- Is comprised of green plants that are able to make their  
own food by the process known as photosynthesis. They include fern  
plant, maize, pines, bean plants etc  
General characteristics of kingdom plantae  
❖ They possess chlorophyll  
❖ Plants have cell wall made cellulose  
❖ They are multi-cellular organism  
❖ Their life cycle involves alteration of generation which is more  
prominent in lower plants.  
❖ They have well vegetative bodies and are sometime  
differentiated into roots, stems and leaves.  
❖ They have prominent large vacuoles in their cells and store  
carbohydrate in form of starch.  
Divisions of Kingdom Plantae  
1. Division Bryophyta  
2. Division Filicinophyta (Pteridophyta)  
3. Division Coniferophyta  
4. Division Angiospermophyta  
Division Bryophyta  
Members of the division Bryophyta are called bryophytes, which are the  
most primitive plants. They are found in wet and shaded environments,  
such as on forest floors, rock surfaces, bare soil, cracks of paved surfaces,  
bricks, on trunks, and branches of trees. The reproduction process in  
bryophytes depends on availability of water that is why their distribution  
is restricted to shady and moist places. Examples of bryophytes are mosses  
and hornworts.  
The structure or mosses Mosses are primitive plants believed to be among  
the plants to develop the ability to live on land.  
Characteristics of bryophytes  
❖ They show alternation of generations in which the haploid  
gametophyte generation is dominant over the diploid sporophyte  
generation.  
❖ The sporophyte is attached on the gametophyte generation, and it  
depends upon it for support and nutrition.  
❖ The gametophyte generation is anchored by filamentous rhizoids  
which provide support and used for absorption of water and  
mineral salts.  
❖ They lack vascular tissue, meaning that they have no xylem and  
phloem.  
❖ They have a thallus body which shows low level of differentiation;  
hence, they lack true leaves, stems, and roots.  
Figure;2. 5: Fern Plant  
Advantages of fern plants  
❖ They constitute ground-cover in moist areas; they are primary  
producers, thus produce food for themselves and for heterotrophic  
organisms in an ecosystem;  
❖ They are used for decoration in homes and offices;  
❖ They are the major components of coal, a fossil fuel which is made  
up of the remains of primitive plants;  
Adaptations of fern plants to its mode of life  
Fern plant possess the following features which enable them to adapt to  
their environment:  
❖ They have chloroplasts containing chlorophyll for capturing light  
energy needed for photosynthesis.  
❖ They have roots for anchorage and absorption of water and mineral  
salts.  
❖ They have stomata which facilitate gaseous exchange.  
❖ They have xylem responsible for transportation of water and  
dissolved minerals and also, they have phloem for translocation of  
manufactured food.  
❖ Rhizomes play part in storing food and propagating new plants,  
and can remain viable in the soil for a long time to ensure survival.  
❖ They have a well-developed and independent sporophyte  
generation, since the gametophyte withers and dies as the young  
leaves of sporophyte grow.  
❖ They have cuticle in their leaves to prevent excessive water loss.  
❖ Archegonia secrete chemical which attracts antherozoids to swim  
towards the egg during fertilization.  
Division coniferophyta  
Coniferophyta is a division of kingdom Plantae which belongs to a broad  
group of non-flowering seed-bearing plants, referred to as gymnosperms.  
The word gymnosperms originated from a combination of two Greek  
words Gymno meaning ‘naked’ and sperma meaning ‘seed.’ Theophrastus  
was the first person to use this term in his book “Enquiry into plants”  
referring to plants producing naked seeds.  
Characteristics of division Coniferophyta  
❖ They are non-flowering, seed-bearing plants, producing naked  
seeds which are not enclosed in ovaries or fruit tissues.  
❖ Sexual reproduction involves microspores (male gametophyte) and  
megaspores (female gametophyte) which are found in male and  
female cones or strobili respectively.  
❖ Fertilisation does not require water; instead, they develop pollen  
tubes which carry sperms to the ovule for fertilisation.  
❖ They have poor xylem with only tracheids as conducting elements  
but no vessel elements. This is the reason why most coniferophytes  
produce soft wood.  
❖ Leaves are reduced into spiny or needle-like leaves to minimize  
water loss through transpiration.  
Distinctive features of division Coniferophyta  
Presence of the following features in members of division Coniferophyta  
differentiate them from members of other divisions:  
❖ The pollen grains are winged to provide buoyance; hence they are  
wind pollinated.  
❖ They have seeds which are not enclosed within the ovary; thus, no  
ovaries, and no formation of fruits.  
❖ Their phloem tissues are associated with albuminous cells instead  
of companion cells.  
❖ The majority produce resin in special ducts called resin canals.  
Such resin is useful in wound healing and deterring browsers.  
❖ Most are evergreen plants with needle-like shaped leaves.  
❖ Fertilisation in conifers does not require water, instead male  
gametes are carried by wind or insects to the female reproductive  
organs  
❖ They have simple xylem with only tracheids as conducting  
elements but no vessel elements. This is the reason why most  
coniferophytes produce soft wood.  
❖ Their phloem tissues lack companion cells; instead, they are  
associated with albuminous cells  
Adaptations of Pinus to its mode of life  
Pinus are able to adapt to their environment due to presence of the  
following features:  
❖ The root and shoot systems are well developed to provide the plant  
with a good contact to the soil and atmosphere.  
❖ They have roots for absorption of water and nutrients from the soil.  
❖ The plant has mechanical tissues for support and vascular tissues  
for transportation of water and food.  
❖ They have an elaborate mechanism for reducing water loss through  
transpiration. This becomes possible due to presence of thick  
cuticle, needle-like leaves to reduce their surface area and a  
reduced number of stomata pores.  
❖ They produce lighter pollen grains, each with two wing-like  
structures which make them to float in air, hence easily to be  
carried by wind for pollination.  
❖ They can reproduce sexually without necessity of using water,  
because the transfer of male gametes to female gametes is through  
pollen tube, which ensures reproduction in terrestrial environment  
where water is limited.  
❖ The seeds are winged; hence, they can female cones. Normally,  
male cones are borne in clusters at the axils of lower branches.  
Take some pollen grains from the male cones and mount a few in a  
drop of water on a slide for examination under the light  
microscope to observe the wings on each.  
Economic Importance of Conifers  
•
•
•
•
Provide soft woods for construction  
Used in making drugs  
Prevent soil erosion  
Production of turpentine and resin from pines  
•
They are ornamental plants  
Figure; 2.6: Conifers  
Adaptation of conifers(pine) to its habitats  
❖ They have extensive roots for absorption of water  
❖ They have needle-like to reduce transpiration  
Disadvantages of the division Coniferophyta  
❖ Coniferous forest completely shades the ground and prevents the  
growth of other plants.  
❖ Wood products from conifers are soft and can be easily attacked by  
termites if not treated.  
❖ They have needle like thorny leaves that can prick and cause  
injury.  
❖ Resins which are produced by pines catch fire easily. Thus, in case  
of fire outbreak in a Pinus forest, fire is likely to spread rapidly  
because of the resins.  
Division Angiospermophyta  
Angiospermophyta is the division in Kingdom Plantae which comprises  
plants commonly known as flowering plants or angiosperms. Angiosperms  
are the most diverse and a successful group of all the plants.  
Distinctive features of Angiospermophyta.  
❖ They show alternation of generation  
❖ Fertilization does not depend on water  
❖ Have well developed vascular tissue  
❖ They produce flowers  
❖ They undergo double fertilization  
❖ Their seeds are enclosed in an ovary  
Classes of division Angiospermophyta  
Old system of classification recognised two classes based on the number  
of cotyledons; Monocotyledon and Dicotyledon.  
Class Monocotyledoneae  
This class contains plants with one cotyledon. Examples of monocots are  
maize, sugarcane, wheat, millet, sisal, coconuts and banana plants.  
Features possessed by members of the class Monocotyledoneae  
❖ Monocots have parallel leaf venation.  
❖ Flower parts normally occur in multiples of three.  
❖ The embryo of monocot seeds bears one cotyledon.  
❖ Monocot leaves are composed of an open or closed sheath which  
encloses the stem.  
❖ Their vascular bundles in stems are scattered.  
❖ They have fibrous root system.  
❖ They have long and thin leaves.  
Figure;2.7: Maize Plant  
Class Dicotyledoneae  
This class contains plants with two cotyledons. Examples of dicots are  
beans, mangoes, coffee, groundnuts and sunflower plants.  
Distinctive features of class Dicotyledoneae  
❖ Dicot leaves have net like venation.  
❖ Their stems have vascular bundles which appear in a ring form.  
❖ They have tap root system.  
❖ Their seed embryo has two cotyledons.  
❖ Floral parts are normally in multiples of four or five.  
❖ Dicot plants have petioles that support the leaf.  
❖ They have short and broader leaves  
Tap root (Primary ro  
seed  
Figure; 2.8: Bean Plant  
Economic importance of angiosperms  
❖ Are vital for the existence and economy of humans  
❖ Source of medicines  
❖ Fibres of plants are used in textile industries  
❖ Rubber tyres are produced from sap of tropical rubber trees  
❖ Prevent soil erosion  
Adaptation of cactus plant to its habitat  
❖ They have thorny for protection  
❖ They have thick cuticle to reduce water loss  
❖ They have long roots for absorption of water  
❖ They have chlorophyll for photosynthesis  
Kingdom Animalia  
Animals are a diverse group of organisms that make up the kingdom  
Animalia. This kingdom comprises of animals, which are multicellular  
eukaryotic organisms.  
It is the largest kingdom composed of variety of animals.  
General and distinctive features of the kingdom  
❖ They have nervous system with sense organs except sponges  
❖ They are multi-cellular organism  
❖ They are heterotrophs  
❖ They are eukaryotes  
❖ They store food in form of glycogen  
❖ They have mainly sexual reproduction  
❖ Their cells lack cell wall  
❖ They have no chlorophyll  
❖ Most animals are mobile  
❖ Most animals have higher degree of differentiation  
Phyla of the kingdom Animalia;  
(a) Phylum Arthropoda  
(b) Phylum Platyhelminthes  
(c) Phylum Aschelminthes(Nematoda)  
(d) Phylum Annelida  
(e) Phylum Chordata  
Phylum Arthropoda  
This is the largest group in the Kingdom Animalia, with high species  
diversity. Arthropods represent about three-quarters of all known living  
organisms. Some of the well- known arthropods include insects,  
crustaceans, and arachnids. Arthropoda comes from two Greek words  
arthro that means ‘joint’ and podos that means ‘foot’. Therefore, all  
arthropods have jointed appendages. Arthropods are found in almost every  
known environment including marine, freshwater, and terrestrial  
ecosystems. They vary extremely in their habitats, life histories, and  
feeding habits  
Characteristic features of Arthropods  
❖ Have jointed appendages or legs  
❖ Have exoskeleton made of chitin  
❖ If wings present are in pairs  
❖ Body division are in two (i.e. head and thorax) called cephalothorax  
or in three (i.e. head, thorax and abdomen)  
❖ Their hearts are dorsally located  
❖ Some have antennae  
❖ Have open circulatory system (i.e. blood not enclosed in blood  
vessels)  
❖ Gaseous exchange- terrestrial arthropods used trachea system, book  
lungs and Aquatic arthropods use gills (i.e. book gills)  
❖ Their body plan is bilaterally symmetrical.  
❖ They have a ventral nervous system and open circulatory system,  
which is dorsally positioned.  
❖ They are triploblastic coelomate animals, which are metamerically  
segmented.  
❖ Their coelom is reduced and confined to cavities of excretory organs  
and reproductive ducts during their development and form another  
cavity called haemocoel.  
❖ They have an open circulatory system.  
Classes Phylum Arthropoda: -  
(a) Class Insecta  
(b) Class Arachnida  
(c) Class Crustacea  
(d) Class Diplopoda  
(e) Class Chilopoda  
1. Class Insecta  
The members of class insecta are called insects.  
Distinguishing characteristics of insects: -  
Insects have the following features that differentiate them from other  
arthropods:  
❖ Their bodies are divided into three main regions or tagmata,  
namely the head, thorax, and abdomen.  
❖ They have three pairs of walking legs on the thorax (one pair per  
thoracic segment).  
❖ They usually have one or two pairs of wings on the thorax, some  
members may lack wings.  
❖ They use the tracheal system as their respiratory surface with  
segmental spiracles.  
❖ They undergo metamorphosis during their development through  
the molting process.  
❖ They have a pair of compound eyes and simple eyes.  
❖ They usually have three pairs of mouthparts, which are maxillae,  
mandible, and labrum  
Grasshopper  
Habitat: Grassland, plants  
Economic importance of grasshopper  
❖ Source of food to birds and other animals  
❖ Used for biological studies  
❖ Destroy crops e.g. locusts.  
❖ Increase soil fertility