Biology: Characteristics of Living Organisms

Characteristics of Living Organisms

• MRS GREN is an acronym that represents the characteristics of living organisms: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.
• Movement refers to an action by an organism or part of an organism causing a change of position or place.
• Respiration is the process of breaking down nutrient molecules to release energy for metabolism.
• Sensitivity is the ability to detect and respond to changes in the internal or external environment.
• Growth is a permanent increase in size and dry mass.
• Reproduction involves the processes that make more of the same kind of organism.
• Excretion is the removal of waste products of metabolism and substances in excess of requirements.
• Nutrition is the taking in of materials for energy, growth, and development.

Classification of Living Organisms

• Classification is a system that helps show the evolutionary relationships between organisms.
• Scientists use the DNA base sequence to classify organisms, as the similarity in DNA chains shows how closely two organisms are related.
• Dichotomous Keys are used to classify organisms based on visible features, providing a choice of two features at each step until the organism is narrowed down to its genus and species.

Features of Organisms

• The Five Kingdoms of organisms are classified based on shared features.
• Animals are multicellular, ingestive, and heterotrophic (eat living organisms).
• The sequence of classification is: Kingdom → Phylum → Classes → Orders → Families → Genus → Species.
• The acronym "King Philip, Come Over For Good Soup" is used to remember the sequence of classification.
• The Binomial Nomenclature is an internationally agreed system where an organism's scientific name consists of two parts: genus and species.