Watch Videos
Characteristics of Living Organisms
Movement: an action 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: Ability to detect or sense stimuli in the internal or external environment and to make appropriate responses
Growth: Permanent increase in size and dry mass by an increase in cell number or cell size or both.
Reproduction: processes that make more of the same kind of organism.
Excretion: removal from organisms of the waste products of metabolism, toxic materials and substances in excess of requirements.
Nutrition: taking in of materials for energy, growth and development
Concept and use of a classification system
● Organisms can be classified into groups by the features that they share
Due to being a descendant from a common ancestor
Originally classified using morphology (form and shape of the organism) and anatomy (detailed body structure as determined by dissection)
● Species are a group of organisms that can reproduce to produce fertile offspring
● Organisms which share a more recent ancestor (closely related) have base sequences in DNA that are more similar than those that share only a distant ancestor.
● The sequence of bases in DNA and amino acids in proteins are used as a more accurate means of classification.
DNA base sequences are used to code for amino acids sequences in proteins.
Binomial naming system
Internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and the species
The first word (first part): Genus
The first letter is always capital
The second word: Species
All letters are lowercase
● The sequence of Classification (becoming more specific downwards)
Kingdom
Phylum
Class
Order
Family
Genus
Species
Features of Organisms
● All living Organisms contain:
Cytoplasm
Cell membrane
DNA as genetic material
Ribosomes for protein synthesis
Enzymes for respiration
Five Kingdoms
Viruses are not a part of any classification as they are considered non-living
■ Contain only genetic material and a protein contain
1.Animals
Multicellular, contain a nucleus
Feed on organic substances
2.Plants
Multicellular, contain a nucleus
Have a cell wall made of cellulose and chloroplast
3.Fungi
Multicellular, have a nucleus
Have a cell wall
Feed on dead or decaying material, saprophytic or parasitic nutrition
4.Protoctists
Unicellular, have a nucleus
Some have cell walls and chloroplasts
5.Prokaryotes
Often unicellular
Have cell walls and cytoplasm but no nucleus or mitochondria
Classification of plants
There are 3 main types
○ Ferns ■ Have leaves called fronds ■ Do not produce flowers reproduce by spores
○ Flowering Plants
■ Monocotyledons and Dicotyledons ● Reproduce by sexually means of flowers and seeds ● Seeds are produced inside ovary found at the base of the flower
■ Distinguish monocotyledons and Dicotyledons
● Flowers
○ Flowers from monocotyledons contain petals in multiples of 3
○ Flowers from dicotyledons contain petals in multiples of 4 or 5 ● Leaves
○ Leaves from monocotyledons have parallel leaf veins ○ Leaves from dicotyledons have reticulated leaf veins