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Characteristics Of Living Organisms
In order to identify living organisms, scientists listed 7 characteristics which all living organisms have:
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7
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The Binomial System:
Each organism has two names written in Latin, the first name is the name of the genus it belongs to and the second
name is the name of its species
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The name of the species must begin with a small letter
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For example, we humans belong to the genus Homo and our species is sapiens
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sapiens for short
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They are very small and measured in nm (nanometers), they could only be seen through an electronic microscope
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Viruses are not considered a living organism because they don’t have any of the seven characteristics, except that
they reproduce by replication, but that only happens inside the host cell
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It can only be seen by a microscope
Structure of bacteria:
Cell Wall: It’s made of a substance called peptidoglycan, which contains glycogen and sugars
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Cytoplasm: It’s where the chromosomes are kept and it stores granules of various materials
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Slime Capsule: This is an extra feature that is not present in all bacteria, it is created by the bacterium when the
external conditions are not favourable
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Adaptation:
Bacteria have managed to adapt its self in order to survive in various conditions
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Heterotrophic Bacteria: They feed on ready made food, they are unable to create their own
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Mutualistic Bacteria: These live on the roots of plants, they use Nitrogen in the airspaces between the soil to convert
it to nitrate ions which they feed on
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Bacteria also reproduce extremely quickly by binary fission producing numerous offspring in a short time
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Some bacteria respire aerobically while others respire anaerobically
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Some fungi are not made of cells,
but rather of microscopic threads called hyphae
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Feeding hyphae: They form a network which grows over or through the food materials, they are called mycelium
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It doesn’t contain chloroplasts neither starch granules
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Large numbers of hyphae grow together through
whatever the fungus is feeding on making a branching network called mycelium
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The hyphae secretes enzymes which digests dead
organic matter or animal waste which is then absorbed by the hyphae to be used by the fungi
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Adaptations Of Fungi
Fungi are adapted to perform their functions easily by the following ways:
They grow long mycelium of hyphae on whatever they feed on, these secret enzymes which digests what the fungi
feeds on
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Why Fungi Are Not Plants:
Long ago, fungi were classified as plants, but in details, fungi are actually different to plants, firstly, they do not
contain chloroplasts and they do not undergo photosynthesis
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Thirdly, their extra supplies of sugar is stored as glycogen not starch
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Kingdom Plant:
Plants are multicellular organisms
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Plants are green because they contain a lot of chlorophyll which is a green pigment which traps sunlight for
photosynthesis, plants are autotrophic organisms, they make their own food
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The Plants Kingdom contains several different phyla, but we will discuss only one of them, which is flowering plants
or Angiosperms
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The main difference between both types is the number of cotyledons in their seeds, monocots contain only one
cotyledons in their seeds
while dicots contain two in theirs
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One could differentiate between the two classes (monocots and dicots) just by looking at their external features
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), while dicots have
number of parts of the flower divisible by 4 or 5 (4 petals – 10 leaves etc
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To study this kingdom study the
following tables
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Tail helps
movement, gills
direction

AMPHIBIA
Moist skin
4 limbs

REPTILES
Dry Scales
4 limbs

BIRDS
Feathers
4 limbs (wings)

Cold blooded
(poikilothermic)
Lay eggs
(external
fertilization)
Live in water
and land, have
moisted skin to
supply
capillaries

Cold Blooded
(poikilothermic)
Lay eggs
(internal
fertilization)
Dry skin to resist
water loss
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Their
feathers insulate
their body

MAMMALS
Fur/Hair
4 limbs

Young feeds on
mothers milk

INVERTEBRATES
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Arthropods:
CLASS
BODY DIVISION
EYES/ ANTENNA
WINGS/LEGS

EXTRA INFO

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4

INSECTA
Head, Thorax,
Abdomen
Compound eyes,
pair of antenna
Wings present/ 3
pairs of legs

ARACHNIDS
Cephalothorax,
abdomen
Simple eyes, no
antenna
No wings/ 4 pairs
of legs

CRUSTACEAN
Cephalothorax,
abdomen
Simple eyes, two
pair of antenna
More than 4 pairs
of legs/ No wings

Wings not present
in all of them

Spiders and
scorpions, they
contain poison

Live in water,
respire through
gills

MYRIAPODS
Many body
segments
Simple eyes, pair
of antenna
No wings/ one pair
of legs in each
segment
Millipedes and
centipedes

Mollusks;
They have a soft body and many have a hard shell, muscular foot and breath by lungs or gills
Annelids;
Some have heads and antenna
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Their
body is divided into many segments
Nematodes;
They are worms like Annelids
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No obvious head or legs
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Some are parasites that live in the digestive system

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