Classification:
Objectives:
Characteristics and classification of living organisms
1. Describe the characteristics of living organisms by describing:
(a) movement as an action by an organism or part of 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 for
metabolism
(c) sensitivity as the ability to detect and respond to changes in the internal or external environment
(d) growth as a permanent increase in size and dry mass
(e) reproduction as the processes that make more of the same kind of organism
(f) excretion as the removal of the waste products of metabolism and substances in excess of requirements
(g) nutrition as the taking in of materials for energy, growth and development
Concept and uses of classification systems
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 Supplement
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
Features of organisms
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:
(a) the main groups of vertebrates: mammals, birds, reptiles, amphibians, fish
(b) the main groups of arthropods: myriapods, insects, arachnids, crustaceans
3. Classify organisms using the features identified in 1.3.1 and 1.3.2 Supplement
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 and 1.3.5 7 State the features of viruses, limited to a
protein coat and genetic material
Reproduction as the processes that make more of the same kind of organism.
Classification means putting into groups.
Easier to study
Mammals, Features common (having hair), common ancestors
Using DNA to classify:
In past…..1. Morphology or 2. Anatomy
Now…using DNA
DNA is a chemical form which our chromosomes are made
It is a genetic material which passes from generation to generation.
DNA is made up of string of small molecules called bases.
Compare sequence of base pairs in organisms of 2 different species.
More similarity, more common ancestors.
The classification system:
Flowers from monocotyledons contain petals in multiples of 3
Flowers from dicotyledons contain petals in multiples of 4 or 5
Leaves from monocotyledons have parallel leaf veins
Leaves from dicotyledons have reticulated leaf veins (meaning that they are all
interconnected and form a web-like network throughout the leaf)
