Characteristics and Classification of Living Organisms
Characteristics of Living Organisms
Mnemonic: MRS GREN (Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition)
7 Characteristics of All Living organisms
Nutrition: Taking in organic substances and mineral ions for growth and tissue repair. Plants make their own food through photosynthesis.
Excretion: Removal of waste products of metabolism and substances in excess.
Respiration: Breaking down food in cells to release energy.
Sensitivity: Sensing changes in the environment (stimuli) and responding.
Reproduction: Producing offspring to prevent extinction.
Growth: Increase in size and mass by increasing cell number and/or cell size.
Movement: Changing position or place.
Classification System
Organisms are classified into groups based on shared features.
Classification is dividing organisms into groups based on similarities.
7 levels: Kingdom (largest) to Species (smallest).
Each organism belongs to only one group at each level.
Classification reflects evolutionary relationships
Binomial System
Internationally agreed system for naming species, with two parts: Genus and species.
Genus is capitalized, species is lowercase, and both are written in italics.
Example: Homo sapiens (Human)
Dichotomous Keys
Tool for identifying organisms using a series of choices between two statements.
'Dichotomous' means 'branching into two'.
DNA in Classification
DNA base sequences are used for classification.
More similar base sequences indicate a more recent common ancestor.
DNA molecules are made of strings containing four bases: A, C, G, and T.
Kingdoms
Five kingdoms: Animal, Plant, Fungus, Protoctist, Prokaryote.
Animal Kingdom Groups
Vertebrates:
Mammals, Birds, Reptiles, Amphibians, Fish
Arthropods:
Myriapods, Insects, Arachnids, Crustaceans
Plant Kingdom Groups
Ferns and Flowering Plants (Dicotyledons and Monocotyledons)
Dicotyledons
Viruses
Composed of a protein coat and genetic material.