BIODIVERSITY

Diversity refers to variety of living things.

Organisms are grouped according to common characteristics. Grouping of organisms according to characteristics is
called CLASSIFICATION or TAXONOMY. The main characteristics used to group living things are:
 Feeding
 Structure
 Reproduction
There are 5 major groups (kingdoms) used to classify organisms which are as follows;
1. MONERA e.g. bacteria and blue green algae
2. PROCTISTA e.g. protozoa (animal like) and protophyta (plant like)
3. FUNGI e.g. mushroom, toadstools etc.
4. ANIMALS e.g. vertebrates and invertebrates
5. PLANTS e.g. flowering and non-flowering.

Kingdom is the largest groups of organisms. Species is the smallest group of organisms” capable of producing fertile
offspring”

Viruses do not feed, respire or reproduce on their own as such it is debatable whether they are living or non-living
organisms. They are just in their own class.

BACTERIA
(blue green algae, ecoli, spirilium, bacillus)

STRUCTURE

A) Structural characteristics
 It is a unicellular organism
 Has no nucleus but rather have chromosome which are not enclosed in any membrane
 Their cell walls are made up of lipids, proteins and sugars instead of cellulose
 Each bacteria cell contains a single chromosome consisting of circular strands of DNA
 Some have filaments (whip like structures) called flagella which aid in movement
 Some bacteria have slime capsule outside their cell walls
 They have different shapes. Some rods, spheres and spirals.
 Some have chlorophyll but not chloroplast.
B) Feeding characteristics
 Some bacteria contain a photosynthetic pigment (chlorophyll) and can build up their own food by
photosynthesis.
Light
(Hydrogen sulphide + carbon dioxide Carbohydrates + water)
Bacteria Chlorophyll

 Most bacteria do not have chlorophyll hence they do not photosynthesize and they can obtain food
from;
a) Other living things (parasitic)
b) Dead organic matter (saprophytic)

The saprophytes secrete enzymes onto the organic matter so that digestion is outside the organism. The organism
then absorbs the soluble product of digestion.

C) Reproduction

1. They reproduce asexually by binary fission; each cell dividing in to 2 daughter cells. E.g. each cell division takes
place every 20 minutes.

2. Sexually by genetic recombination (transfer of DNA between bacteria through special tubes). DNA bodies divide
equally during cell division with half going to each daughter cell.

USEFUL AND HARMFUL BACTERIA

Only a tiny minority of bacteria are harmful. Most of them are harmless or extremely useful. Bacteria which feed
saprotrophically bring about decay. They secrete enzymes into dead organic matter and liquidify it. The decay bacteria
also release essential elements from dead remains.
Humans exploit bacterial physiology in the course of BIOTECHNOLOGY.

The bacteria which cause diseases are called PATHOGENS. The organism in which they live and reproduce is called
a HOST. Most bacteria also produce poisonous waste products called TOXINS. The toxins are produced by the
CLOSITRIDIUM bacteria (which causes tetanus). It is as little as 0.0002g and is very fatal.
 VIRUSES

STRUCTURE

They are on the border line between living and non-living because they can only survive and reproduce inside the living
cells e.g. herpes, influenza and polio viruses.

A) Structural characteristics
 Non cellular (not cells) and do not have nucleus , cytoplasm, cell organelles or cell membranes
 Very tiny particles, much smaller than bacteria ( 50 times smaller than bacteria) and can only be seen by an
electron microscope( 20-300 nm)
 Consists of genetic material (either DNA or RNA) forming the central core of the virus
 DNA or RNA is surrounded by a protein coat called capsid
 Found in different shapes; can be rod like, spherical or hexagonal (has a tail).
B) Reproduction
In order for the virus to reproduce they must penetrate into a living cell by first attaching to the cell membrane of the
host cell & then either;
 Injects its DNA / RNA into the cell’s cytoplasm or
 The whole virus may be taken in, after which it gets uncoated in the host cell.

The genetic material replicates & multiplies inside the host cell; it takes over the cell’s activities. Eventually the cell
bursts & releases the new virus which can infect other cells.

C) Nutrition
Viruses do not feed.

Human viruses include the common cold, poliomyelitis, measles, mumps, chickenpox, rubella, influenza & HIV.

How viruses are useful to man;

 They are used to make vaccines for hepatitis
 Viruses may be used to deliver recombinant DNA in genetic engineering.

How viruses are harmful to man;

 They cause diseases such as HIV / AIDS, influenza etc.
 FUNGI
Fungi range from the unicellular yeast to the large toadstools, puffballs, and mushrooms etc, which occupy a very wide
range of habitats, both aquatic & terrestrial.

Structure

A) Structural Characteristics
They lack chlorophyll
Have rigid cell walls containing chitin (a nitrogen – containing polysaccharide)
Body is usually a mycelium, a network of fine tubular filaments called Hyphae
They are non-motile (cannot move)

B) Reproduction
Some reproduce sexually by conjugation e.g. moulds
Some asexually by forming spores e.g. penicillium, mushroom etc. when a spore lands on a suitable organic
matter or new host it germinates to produce mycelium without involvement of gametes.
Some through budding e.g. yeast an outgrowth from the cell appears, enlarges and is finally cut off as an
independent cell

C) Nutrition
Since fungi do not contain chlorophyll they cannot make their own food, hence depend on other organisms for food.
Unlike animals which ingest food & later digest before absorption, fungi absorb soluble food products which they do not
need to digest. If digestion is required then it is done externally using extra cellular enzymes (enzymes secreted onto
the food material to digest it outside their cells).
Some fungi are saprotrophs (saprophytes); they feed on dead organic matter. This kind of fungi produces a
variety of digestive enzymes. E.g. Penicillium, mucor, yeast etc.
Some are parasites which feed on living plants & animals. Some of these parasites may cause diseases or
eventually kill the host & feed on the dead remains. E.g. ringworm is caused by fungi.
Penicillium is a genus of a mould, fungi that grow on decaying vegetable matter, damp leather and citrus fruits. The
mycelium grows over the food, digesting it & absorbing nutrients. The vertical Hyphae grow from mycelium & at their
tips produce chains of spores.

PROTOCTISTA

Protoctista is made up of Protozoa( animal like) and Protophyta ( plant like).

Examples;

Protozoa eg. amoeba and paramecium Protophyta eg. Chlamydomonous and spirogyra

Some protoctists show both protozoa and protophyta characteristicts eg. euglena
A) Structural Characteristics
 They are unicellular
 They do not contain chlorophyll
 They have a nucleus, cell membrane but no cell wall.
 They have vacuole by which they remove excess water (contractile vacuole)

 They move by flowing movements of their cytoplasmic fluids(pseudopodia) and by the use of cilia (tiny hairs found
on their surfaces)

B) Nutrition
They are heterotrophic – they feed on ready made food materials or other organisms such as bacteria, algae, decaying
organic matter.

C) Reproduction
They reproduce asexually by binary fission whereby – the parent organism duplicates its genetic material & then
separate into two organisms.
(Diagram of fission)

Protozoa can cause diseases such as malaria.

Malaria
It is a disease caused by a protozoan parasite called plasmodium. The plasmodium is transferred from one person to
the next by a female mosquito called Anopheles mosquito. An adult mosquito bites an infected person and takes the
blood, thus ingesting the parasite.

The
The parasite
parasite enters
enters thethe mosquito
mosquito intestines
intestines and
and develops
develops
Parasites
Parasites move
move toto the
the salivary
salivary glands
glands of
of the
the mosquito
mosquito
Infected
Infected mosquito
mosquito bites
bites another
another human
human being,
being, secretes
secretes
saliva
saliva to
to prevent
prevent blood
blood from
from clotting(acts
clotting(acts asas anti
anti coagulant)
coagulant)
Parasite
Parasite inin mosquito
mosquito saliva
saliva enters
enters the
the blood
blood circulation
circulation &&
and
and reaches
reaches the
the liver
liver
Plasmodium
Plasmodium enters liver
enters liver cells
cells && reproduce
reproduce asexually
asexually
Daughter
Daughter plasmodium produced break
plasmodium produced break out
out of
of the
the liver
liver cells
cells
and invade red blood
and invade red blood cells cells
Infected
Infected red
red blood
blood cells
cells are
are destroyed
destroyed whenever
whenever new new cells
cells
are
are produced
produced

i) Symptoms of Malaria

Chills
Violent shivering
Profuse (excessive) sweating
Fever
Tiredness, increased pulse rate and anaemia
ii) Cure
Malaria can be treated through the use of drugs, e.g. chloroquine, quinine kill parasites in
bloodstream

iii) Prevention & Control

Through the use of drugs
Disturbing the life cycle
Prophylactic drugs are taken by a healthy person as a precaution. Kills parasite as soon as it
enters the body
iv) Life cycle of a mosquito

v) Ways of disturbing the life cycle

Spraying insecticides or oil over stagnant water disables the pupa from breathing thus killing it.
The use of this approach can problematic in that the insecticides & oil might pollute the water OR kill
other organisms indiscriminately. Also the mosquito larva / pupa can eventually develop resistance to
the insecticides, making control difficult.

By draining swamps, this prevents the mosquito from breeding, i.e. no where to lay eggs.
This can be a problem in that livestock will not have water to drink.
 ANGIOSPERMS (FLOWERING PLANTS)
More than 80% of plants are angiosperms.

A) Structural Characteristics
Have large leaf surface which allows high rate of photosynthesis
Have vascular system – to transport water, ions & organic solutes
Have cuticle (water proof) – to reduce water loss to the atmosphere
Have ovary – to protect the ovules & developing embryo
They range small herbs to big trees

There are two groups of angiosperms

1) Monocotyledons
2) Dicotyledons

MONOCOTYLEDONS DICOTYLEDONS
Have one seed leaf (1 cotyledon) Have two seed leaves (2 cotyledons)

Vascular bundles are scattered on the stem The vascular bundles are arranged in a ring

Have narrow leaves with parallel veins They have broad leaves with a branching network of
veins

Have adventitious roots from the base of the stem giving Have a tap root system that develops lateral roots
rise to a fibrous root system

B) Nutrition
There are autotrophic, i.e. can photosynthesize to produce their own food

C) Reproduction
They reproduce sexually because they produce male & female gametes.
 GREEN ALGAE
They are believed to be the most immediate relatives of the green land plants. They belong to the phylum chlorophyta,
can live virtually wherever there is sunlight and adequate moisture. Algae are found in freshwater lakes, ponds,
streams, swamps, on moist soil, wood, and throughout the sunlit zones of the marine environment, as well as on the
snowfields and in thermal hot springs.

DRAW -CHLAMYDOMONOUS AND SPIROGYRA

A) Structure
Have photosynthetic pigment called chlorophyll in chloroplasts
Store carbohydrates as starch
They are of a large range of types e.g. unicellular, filamentous, colonial & thylloid
They have cellulose cell wall
Some have pigment spot (red eye spot) to detect light sand move towards it. E.g. Chlamydomonas

Examples of green algae

Chlamydomonas – a unicellular motile algae
Spirogyra – filamentous algae
Alva (seed weed) – a thylloid marine algae

B) Reproduction
This can either be (i) sexual or (ii) asexual

(i) Sexual reproduction – This involves the combination of genetic material from two individuals of the same
species as in spirogyras & Chlamydomonas.

(ii) Asexual reproduction

a) Fragmentation – this occurs in filamentous algae such as spirogyra. The filament breaks in a
controlled manner somewhere along its length to form two filaments.
b) Binary fission – a unicellular organism divides into equal halves. The nucleus divides through
mitosis.
c) Zoospores – these are motile flagellate spores produced by algae e.g. Chlamydomonas.
C) Nutrition
They are autotrophic – can make their own food through photosynthesis.
 VERTEBRATES
General Characteristics
Have endoskeleton
Have backbone (vertebral column)
FISH AMPHIBIANS REPTILES BIRDS MAMMALS

- Have 4 fins - 4 limbs in adults - 4 limbs except in - 2 legs & front limbs - Have 4 limbs
STRUCTURE - Wet scaly skin - wet smooth skin snakes which form wings - Hair (fur) on skin
- Have gills for breathing - Gills in tadpoles & lungs - Dry scaly skin - Have feathers - Have lungs
in adults - Have lungs

- Carnivores & herbivores - Carnivores - Carnivores - Omnivores - Carnivores

NUTRITION e.g. feed on plankton - Herbivores - Herbivores - Herbivores
-Omnivores

- Lay eggs - Lay hard shelled - Lay hard shelled - Eggs develop inside
- lay eggs in water - Fertilization is external eggs on land eggs on land the females
REPRODUCTION - Fertilization is external - Little or no care for - Fertilization is - Fertilization is - Internal fertilization
- Little or no care for young ones internal internal - Embryo grow inside
young ones - There is little care - The eggs & young the female’s body until
for the young ones ones are fully cared birth
for - Much care given to
young ones
 ARTHROPODS
General Characteristics
Have exoskeleton
Have segmented body
Have jointed legs

INSECTS ARACHNIDS MYRIAPODS CRUSTACEANS

Examples Roaches, beetles, butterflies, Spiders, scorpions, ticks, etc Centipedes, millipedes Crabs, lobsters, crayfish
houseflies, ants, bees

- Have 3 body segments; Head, - Have 2 body sections; - Have 2 body sections; - Have 2 body sections
Thorax, Abdomen Cephalothorax, Abdomen Head, segmented body - No wings
STRUCTURE - Have 6 legs (3 pairs) - Have 8 legs (4 pairs) - No wings - 2 pairs of antennae
- Have 2 pairs of wings - No antennae but have - Many legs
- Have a pair of antennae chelicerae instead - One pair of antennae
- Compound eyes - No wings - Have simple eyes

REPRODUCTION - Sexually - Sexually - Sexually - Sexually

- Heterotrophic , i.e. some feed on - Heterotrophic - Carnivores i.e. centipedes - Saprotrophic

NUTRITION leaves, nectar, plant sugar, blood
- Herbivores, i.e. millipedes