Biology Unit 1: Characteristics & Classification

Characteristics of Living Organisms

• Movement: Living organisms exhibit movement; animals move to seek food, shelter, or mates, while plants grow towards light.
• Respiration: Involves chemical reactions in cells that break down nutrients to release energy, requiring oxygen.
• Sensitivity: The ability to detect and respond to environmental changes; animals use sense organs, while plants respond to gravity and light.
• Growth: A permanent increase in size; animals grow until they reach adulthood, whereas plants continue to grow throughout their lifespan.
• Reproduction: The process of producing more organisms of the same kind, including animals reproducing through eggs or live birth and plants propagating from seeds.
• Excretion: The removal of waste products from organisms, including metabolic waste; animals use lungs, kidneys, and skin, while plants shed leaves.
• Nutrition: The intake of materials necessary for energy and growth; animals consume food, while plants produce their own through photosynthesis.

Concept and Uses of Classification Systems

• Organisms can be grouped based on shared characteristics, aiding identification and understanding of relationships.
• A species comprises organisms capable of producing fertile offspring.
• The binomial naming system assigns each species a two-part name indicating its genus and species, ensuring universal recognition.
• Dichotomous keys help in identifying species based on distinct features.
• Classification reflects evolutionary relationships; DNA base sequences reveal genetic closeness among organisms sharing recent common ancestors.

Features of Organisms in Classification

• Animal Kingdom: Classified into main groups based on features; vertebrates include mammals, birds, reptiles, amphibians, and fish.
• Arthropod Groups: Includes myriapods, insects, arachnids, and crustaceans; each has distinct physical traits.
• Plant Kingdom: Comprises various groups, with important types being ferns and flowering plants (monocots and dicots).
• Five Kingdoms: Organisms are categorized into fungi, prokaryotes, and protoctists based on structural and functional characteristics.
• Viruses: Defined by having a protein coat and genetic material, distinguishing them from other life forms.

Organisms Overview

• Biology: The study of living organisms and what differentiates them from non-living entities.
• Prokaryotes (bacteria) and eukaryotic cells (found in multicellular organisms) highlight cellular differences.
• Bacteria Classification: Based on shape; includes coccus (spherical), bacillus (rod-shaped), and spirilla (spiral).

Plant Kingdom Characteristics

• Plants are multicellular eukaryotes with a cellulose cell wall and chloroplasts for photosynthesis.
• Coniferophyta: Non-flowering plants like fir and pine.
• Angiospermophyta: Flowering plants with roots, stems, and leaves, producing seeds within fruits; includes monocots (e.g., rice, corn) and dicots (e.g., hibiscus).

Animal Kingdom Characteristics

• Composed of multicellular, heterotrophic organisms that do not have cell walls and do not photosynthesize.
• Phylum Overview: Major phyla include Annelida (segmented worms), Nematoda (roundworms), Mollusca (soft-bodied, often shelled), Arthropoda (invertebrates with exoskeletons), and Chordata (vertebrate animals).
• Insect Characteristics: Three pairs of legs, a segmented body into head, thorax, and abdomen, with two pairs of wings and one pair of antennae.
• Arachnids: Four pairs of legs, chelicerae for feeding, and a body divided into two main regions.
• Crustaceans: Typically possess five or more pairs of legs and two pairs of antennae, with a hard exoskeleton.
• Phylum Chordata: Vertebrates possess a vertebral column; includes various classes of vertebrate animals.

Dive into the essentials of Biology with this quiz on Unit 1, which covers the characteristics of living organisms, including movement, respiration, and reproduction. Additionally, explore the concept of classification systems and the significance of species. Test your understanding and enhance your knowledge of fundamental biological concepts.