Characteristics of Living Organisms
• Movement: an action by an organism or part of an organism causing a
change of position or place
• Respiration: the chemical reactions that break down nutrient molecules in
living cells to release energy for metabolism
• Sensitivity: the ability to detect or sense stimuli in the internal or external
environment and to make appropriate responses
• Growth: a permanent increase in size and dry mass by an increase in cell
number or cell size or both
• Reproduction: the processes that make more of the same kind of organism
• Excretion: the removal from organisms of toxic materials, the waste
products of metabolism (chemical reactions in cells including respiration)
and substances in excess of requirements
• Nutrition: the taking in of materials for energy, growth and development;
plants require light, carbon dioxide, water and ions; animals need organic
compounds, ions and usually need water
How Organisms are Classified
There are millions of species of organisms on Earth. A species is defined as a
group of organisms that can reproduce to produce fertile offspring. These species
can be classified into groups by the features that they share e.g. all mammals
have bodies covered in hair, feed young from mammary glands and have external
ears (pinnas).
Organisms were first classified by a Swedish naturalist called Linnaeus in a way
that allows the subdivision of living organisms into smaller and more specialised
groups. The species in these groups have more and more features in common the
more subdivided they get. He named organisms in Latin using the binomial
system where the scientific name of an organism is made up of two parts starting
with the genus (always given a capital letter) and followed by
the species (starting with a lower case letter). When typed binomial names are
always in italics (which indicates they are Latin) e.g. Homo sapiens
The sequence of classification is:
Kingdom Phylum Class Order Family Genus Species
King Philip Came Over For Gran’s Spaghetti
Organisms share features because they originally descend from a common
ancestor. Originally, organisms were classified using morphology (the overall
,form and shape of the organism, e.g. whether it had wings or legs)
and anatomy (the detailed body structure as determined by dissection)
As technology advanced, microscopes, knowledge of biochemistry and
eventually DNA sequencing allowed us to classify organisms using a more
scientific approach. Studies of DNA sequences of different species show that
the more similar the base sequences in the DNA of two species, the more closely
related those two species are (and the more recent in time their common ancestor
is). The similarities in amino acid sequences in proteins can also be used to
determine how closely related organisms are
Common Cell Structures
The cells of all living organisms contain the following:
• Cytoplasm
• Cell membrane
• DNA as genetic material (either found in the nucleus or free in the
cytoplasm)
• Ribosomes for protein synthesis
• Enzymes for anaerobic respiration (in many, but not all types of cells,
found in mitochondria)
The Five Kingdoms
The first division of living things in the classification system is to put them into
one of five kingdoms. They are:
• Animals
o they are multicellular
o their cells contain a nucleus but no cell walls or chloroplasts
o they feed on organic substances made by other living things
,• Plants
o they are multicellular
o their cells contain a nucleus, chloroplasts and cellulose cell walls
o they all feed by photosynthesis
• Fungi
o usually multicellular
o cells have nuclei and cell walls not made from cellulose
o do not photosynthesize but feed by saprophytic (on dead or decaying
material) or parasitic (on live material) nutrition
, • Protoctists
o most are unicellular but some are multicellular
o all have a nucleus, some may have cell walls and chloroplasts
o meaning some protoctists photosynthesise and some feed on organic
substances made by other living things
• Prokaryotes
o often unicellular
o cells have cell walls (not made of cellulose) and cytoplasm but no
nucleus or mitochondria
• Movement: an action by an organism or part of an organism causing a
change of position or place
• Respiration: the chemical reactions that break down nutrient molecules in
living cells to release energy for metabolism
• Sensitivity: the ability to detect or sense stimuli in the internal or external
environment and to make appropriate responses
• Growth: a permanent increase in size and dry mass by an increase in cell
number or cell size or both
• Reproduction: the processes that make more of the same kind of organism
• Excretion: the removal from organisms of toxic materials, the waste
products of metabolism (chemical reactions in cells including respiration)
and substances in excess of requirements
• Nutrition: the taking in of materials for energy, growth and development;
plants require light, carbon dioxide, water and ions; animals need organic
compounds, ions and usually need water
How Organisms are Classified
There are millions of species of organisms on Earth. A species is defined as a
group of organisms that can reproduce to produce fertile offspring. These species
can be classified into groups by the features that they share e.g. all mammals
have bodies covered in hair, feed young from mammary glands and have external
ears (pinnas).
Organisms were first classified by a Swedish naturalist called Linnaeus in a way
that allows the subdivision of living organisms into smaller and more specialised
groups. The species in these groups have more and more features in common the
more subdivided they get. He named organisms in Latin using the binomial
system where the scientific name of an organism is made up of two parts starting
with the genus (always given a capital letter) and followed by
the species (starting with a lower case letter). When typed binomial names are
always in italics (which indicates they are Latin) e.g. Homo sapiens
The sequence of classification is:
Kingdom Phylum Class Order Family Genus Species
King Philip Came Over For Gran’s Spaghetti
Organisms share features because they originally descend from a common
ancestor. Originally, organisms were classified using morphology (the overall
,form and shape of the organism, e.g. whether it had wings or legs)
and anatomy (the detailed body structure as determined by dissection)
As technology advanced, microscopes, knowledge of biochemistry and
eventually DNA sequencing allowed us to classify organisms using a more
scientific approach. Studies of DNA sequences of different species show that
the more similar the base sequences in the DNA of two species, the more closely
related those two species are (and the more recent in time their common ancestor
is). The similarities in amino acid sequences in proteins can also be used to
determine how closely related organisms are
Common Cell Structures
The cells of all living organisms contain the following:
• Cytoplasm
• Cell membrane
• DNA as genetic material (either found in the nucleus or free in the
cytoplasm)
• Ribosomes for protein synthesis
• Enzymes for anaerobic respiration (in many, but not all types of cells,
found in mitochondria)
The Five Kingdoms
The first division of living things in the classification system is to put them into
one of five kingdoms. They are:
• Animals
o they are multicellular
o their cells contain a nucleus but no cell walls or chloroplasts
o they feed on organic substances made by other living things
,• Plants
o they are multicellular
o their cells contain a nucleus, chloroplasts and cellulose cell walls
o they all feed by photosynthesis
• Fungi
o usually multicellular
o cells have nuclei and cell walls not made from cellulose
o do not photosynthesize but feed by saprophytic (on dead or decaying
material) or parasitic (on live material) nutrition
, • Protoctists
o most are unicellular but some are multicellular
o all have a nucleus, some may have cell walls and chloroplasts
o meaning some protoctists photosynthesise and some feed on organic
substances made by other living things
• Prokaryotes
o often unicellular
o cells have cell walls (not made of cellulose) and cytoplasm but no
nucleus or mitochondria
