Characteristics of Living Organisms and Classification

Characteristics of Living Organisms

• All living organisms exhibit movement, either of the whole organism or parts.
• Respiration involves chemical reactions releasing energy from nutrients.
• Organisms exhibit sensitivity, responding to internal or external changes.
• Growth involves a permanent increase in size (dry mass, cell size, or number).
• Reproduction creates new organisms of the same kind.
• Excretion removes waste products (toxic materials, excess substances, carbon dioxide).
• Organisms need nutrition to develop and repair. Needs differ between animals and plants/

Classification Systems

• Classification groups species based on shared features.
• Species can reproduce and produce fertile offspring.
• Organisms are named using the binomial system (genus and species).
• Organisms are classified by evolutionary relationships, determined by physical characteristics or DNA sequences.
• Traditional classification used morphology and anatomy. Modern methods include DNA sequencing.

Features of Organisms

• Organisms are categorized into five kingdoms: Animalia, Plantae, Fungi, Prokaryota, and Protoctista.
• Cell features (e.g., cell wall, chlorophyll) differentiate kingdoms.
• Animal cells lack cell walls and chlorophyll.
• Plant cells do contain cell walls and chlorophyll.
• Eukaryotic cells have a membrane-bound nucleus, whereas prokaryotic cells do not.

Classification of Animals

• Vertebrates possess a backbone (mammals, birds, reptiles, amphibians, fish).
• Arthropods lack a backbone. Identified by exoskeletons and segmented bodies (myriapods, insects, arachnids, crustaceans).

Plant Classification

• Plants are divided into flowering and non-flowering groups.
• Flowering plants are further categorized into dicots and monocots.
• Dicots and monocots are identified by their leaves.
• Non-flowering plants (like ferns) reproduce via spores.

Viruses

• Viruses are not considered living organisms.
• They lack the ability to carry out the life processes of living things.
• Viruses consist of genetic material enclosed in a protein coat.