CHARACTERISTICS AND
CLASSIFICATION OF LIVING
ORGANISMS
1.1 Characteristics of living organisms(LO)
Describe the characteristics of living organisms by describing :
a)– movement as an action by an organism causing a change of position or place
b)– respiration as the chemical reactions in cells that break down nutrient molecules and
release energy
c)– sensitivity as the ability to detect and respond to changes in the environment
d)– growth as a permanent increase in size
e)– reproduction as the processes that make more of the same kind of organism
f)– excretion as removal from organisms of toxic materials and substances in excess of
requirements
g)– nutrition as taking in of materials for energy, growth and development
Pg 1-5 text book.
1.1 CHARACTERISTICS OF LIVING ORGANISMS
• MERRING
• M- Movement –an action by an organism causing a change of
position or place
• E- Excretion – removal of waste products of metabolism,toxic
materials and substances in excess of requirements
• R- Respiration – chemical reactions in the cells that break down
nutrient molecules and release energy for metabolism
• R-Reproduction – processes that make more of the same kind of
organism
• I- Irritability/Sensitivity –the ability to detect or sense stimuli in the
internal or external environment and to make appropriate responses.
• N- Nutrition – taking in of materials for energy, growth and
development
• G – Growth – a permanent increase in size and dry mass by an
increase in cell number or cell size or both.
1.2 Concept and uses of classification
systems(LO)
1 State that organisms can be classified into groups by the features that they share
2 Describe a species as a group of organisms that can reproduce to produce fertile
offspring
3 Describe the binomial system of naming species as an internationally agreed
system in which the scientific name of an organism is made up of two parts showing
the genus and species
4 Construct and use dichotomous keys based on identifiable features
5 Explain that classification systems aim to reflect evolutionary relationships
6 Explain that the sequences of bases in DNA are used as a means of classification
7 Explain that groups of organisms which share a more recent ancestor (are more
closely related have base sequences in DNA that are more similar than those that
share only a distant ancestor
Pg 6-9 text book.
Need to classify
• Observing characteristics allows scientists to put all living organisms
into categories. – classification
• Classification is important in –
1. Conservation – to identify organisms in managed habitats, to
control which organisms to be used in breeding programmes
2. Understanding evolutionary relationships- the more features shared
by different organisms the more recently they separated from one
another during evolution.
• Biologists try to classify organisms according to how closely they
think they are related.
• Scientists believe that all mammals descended from a species that
lived more than 200 million years ago. This species was the common
ancestor of mammals. All mammals are related because they all
share a relatively recent common ancestor.
• https://www.youtube.com/watch?v=lnvlMlopu2A
Species
• A species is a group of organisms that can reproduce with each other
to produce offspring that can also reproduce. The offspring are fertile.
• Members of the same species have same morphology, anatomy and
can mate amongst each other and produce fertile offspring.
• Horses are a species, Donkeys are a species. Donkeys and horses can
mate and reproduce but their offspring the Mule is infertile.
Binomial Naming system
• Scientific names of organisms always have two words.
• The naming system is therefore called the binomial system.
• ‘Bi’ means two, and ‘nomial’ means to do with names
• Carolus Linnaeus gave every organism a two part name –binomial
nomenclature
• First word is genus (spp that are related to each other)
• Eg. horses Equus caballus: donkeys Equus asinus.
• Panthera leo – lion ( in italics) –underlined
• Members of the same species have same morphology, anatomy and
can mate amongst each other and produce fertile offspring.
• https://www.youtube.com/watch?v=HLnaIJm5wM4
Classification Keys-to help identify organisms
• When we classify organisms, we look for features that they share with
others, which suggest that they are related to one another
• Series of questions is a classification key
• Based on morphology and anatomy
• Eg. Dichotomous key – key with only 2 answers to each question.
• ‘Dichotomous’ means branching (dividing) into two.
• A dichotomous key is a way of leading you through to the name of
your organism by giving you two descriptions at a time and asking you
to choose between them.
Dichotomous key(branching form)
New species and new basis of classification
• Protein structure - organisms which are closely related(more recent
ancestor) have very similar amino acid sequences in proteins such as
hemoglobin
• DNA structure – closely related organisms have very similar base
sequence in DNA because less evolutionary time for mutations to
change base sequences.(eg humans and chimps share 98.6% genes)
(explain base sequences)
Hierarchy of classification
1.3 Features of organisms(LO)
1.State the main features used to place animals and plants into the appropriate
kingdoms
2.State the main features used to place organisms into groups within the animal
kingdom, limited to:
–– the main groups of vertebrates: mammals, birds, reptiles, amphibians, fish
–– the main groups of arthropods: myriapods, insects, arachnids, crustaceans
3. Classify organisms using features identified in 1.3.1 & 1.3.2
4. State the main features used to place all organisms into one of the five
kingdoms: Animal, Plant, Fungus, Prokaryote, Protoctist
5.State the main features used to place organisms into groups within the plant
kingdom, limited to ferns and flowering plants (dicotyledons and monocotyledons)
6. Classify organisms using the features identified in 1.3.4 & 1.3.5
7. State the features of viruses, limited to protein coat and genetic material
Pg 10-24 textbook.
Kingdoms
• Smallest classification group is species, largest is Kingdoms.
• Living organisms fall into 5 main groups
• Distinguished by morphology and anatomy
1. Animals
2. Plants
3. Fungi
4. Protoctistans
5. Prokaryotes
Main differences between kingdoms
KINGDOM
Cell type
nucleus
Cell wall
Mode of nutrition
Uni or multi
cellular
Animal
Eukaryote
present
absent
Heterotroph
multicellular
Plant
Eukaryote
present
Present(cellulose) Autotroph
(photosynthetic)
multicellular
Fungi
Eukaryote
present
Present (chitin)
Heterotroph
(absorption)
Uni or
multicellular
Protoctist/Protist Eukaryote
a
Present
Present in most
forms
Photosynthetic
Heterotrophic
Most
unicellular,some
multicellular
Prokaryote
Absent
Present
(non cellulose)
Photosynthetic
Heterotroph
unicellular
Prokaryote
Humans
• Mammals
• Able to modify their environment
• Widest range of habitat
• Advanced development of brain
• Extremely sensitive to changes in temperature-fine regulation of
temp
• Upright posture
Invertebrate groups
• Nematodes
• Annelids
• Molluscs
• Arthropods
Arthropods
• No backbone
• Several pairs of jointed legs
• Waterproof exoskeleton- allows them to live on land without drying
out and gives support.
• Skeleton made of chitin
Classes of arthropods
Plant Kingdom
• Plants with flowers and plants without flowers
• Autotrophs-photosynthesis
• Have chloroplasts
• Contain light absorbing pigment-chlorophyll
• Definite cellulose cell wall
Ferns are well adapted to live on land whereas mosses & algae grow near water
Angiosperms /flowering plants live in a wide variety of environments,
almost all available habitat. More than 80% of plants are angiosperms
Angiosperms are divided into 2 subgroups
Features to adapt angiosperms for life on dry
land
• Flowers- color, pattern, shape, scent and nectar to attract animals
• Large leaf surface- high rate of photosynthesis
• Ovary protects the ovules and developing embryo
• Fruits – specialized shapes to aid dispersal of seeds
• Stomata-and guard cells regulate exchange of gases and loss of water
• Vascular system- transport
• Extensive root systems- anchor shoot systems and absorb nutrients.
(saprophytes)
Fungi
• Useful –to make ethanol and bread(yeast), antibiotic penicillin
• Harmful – cause food decay and diseases (ringworm and athlete’s
foot)
Can be animal like or plant like
• Animal like (unicellular)
Plant like(unicellular)
Videos on paramecium and amoeba
movement.
• Paramecium movement
• https://www.youtube.com/watch?v=RyQfvxH425Q
• Amoeba movement
• https://www.youtube.com/watch?v=7pR7TNzJ_pA
• Chlamydomonas movement
• https://www.youtube.com/watch?v=EMNFZnDt75c
Prokaryotes
• Most abundant organisms on earth
• Metabolically diverse
• Microscopic ( cannot be seen without microscope)
• Do not have a nucleus or any other membrane bound organelle like
mitochondria
• Bacteria have a single loop of DNA, free in the cytoplasm
• Often have plasmids
• Reproduce by binary fission
Viruses
• Do not show living features- respiration, nutrition, reproduction
unless within a living organism
• All viruses are parasites
• Has genetic material and a protein coat
• No cytoplasm
• Viruses are disease causing- infect humans, domestic animals and
plants
• Video of bacteriophage attacking bacteria
• https://www.youtube.com/watch?v=V73nEGXUeBY
• 2014 s p 21 Q 1
• 2014 s p 22 Q 1
• 2014 s p 23 Q 1