Characteristics, Classification & Features of Organisms

Characteristics of Living Organisms

• Movement: Change of position.

• Respiration: Chemical reactions releasing energy.

• Sensitivity: Detecting stimuli and responding.

• Growth: Permanent increase in size and dry mass.

• Reproduction: Producing more organisms of the same kind.

• Excretion: Removal of toxic waste.

• Nutrition: Taking in materials for energy and growth.

• Mnemonic: MRS. GREN

Classification Systems

• Species: Organisms that can reproduce fertile offspring.

• Classification: Grouping organisms by shared features.

• Binomial System: Two-part Latin name (Genus species).

  • Genus: Capitalized.

  • Species: Lowercase.

  • Italicized when typed (e.g., Homo sapiens).

• Classification Sequence: Kingdom, Phylum, Class, Order, Family, Genus, Species.

• Mnemonic: KING PHILIP CAME OVER FOR GRAN’S SPAGHETTI

Dichotomous Keys

• Used to identify organisms based on features.

• Dichotomous: Branching into two.

• Process: Follow statements, choose descriptions, identify organism.

Evolutionary Relationships & DNA

• Classification aims to reflect evolutionary relationships.

• Traditional systems grouped organisms by shared features.

• DNA sequencing: More similar DNA base sequences indicate closer relation.

• Similarities in amino acid sequences also determine relatedness.

Five Kingdoms

• Animals: Multicellular, nucleus, no cell walls/chloroplasts, feed on organic substances.

• Plants: Multicellular, nucleus, chloroplasts, cellulose cell walls, photosynthesis.

• Fungi: Usually multicellular, nucleus, cell walls (not cellulose), saprophytic/parasitic nutrition.

• Protoctists: Mostly unicellular, nucleus, some have cell walls/chloroplasts, some photosynthesize.

• Prokaryotes: Often unicellular, cell walls (not cellulose), cytoplasm, no nucleus/mitochondria.

Animal Kingdom - Vertebrates

• Vertebrates: Have a backbone.

  • Mammals: Fur/hair, placenta, mammary glands, external ears, endothermic.

  • Birds: Feathers, 2 legs/2 wings, lay hard-shelled eggs, beak, endothermic.

  • Reptiles: Dry, fixed scales, lay rubbery-shelled eggs.

  • Amphibians: Smooth, moist skin, adults on land (lungs), larvae in water (gills), lay shell-less eggs in water.

  • Fish: Loose, wet scales, gills, lay shell-less eggs in water.

Animal Kingdom - Invertebrates

• Invertebrates: Do not have a backbone.

• Arthropods: Invertebrates with jointed legs.

Plant Kingdom

• Ferns: Leaves (fronds), reproduce by spores.

• Flowering Plants: Reproduce by flowers and seeds.

  • Monocotyledons: Petals in multiples of 3, parallel leaf veins.

  • Dicotyledons: Petals in multiples of 4 or 5, reticulated leaf veins.

Viruses

• Not considered living things.

• Do not carry out life processes; take over host cells.

• Structure: Genetic material (RNA or DNA) in a protein coat.

• Invertebrates: Do not have a backbone.

  • Arthropods: Invertebrates with jointed legs.

  • Insects:

  • Body: Head, thorax, abdomen.

  • Legs: Six legs.

  • Wings: Usually two pairs of wings.

  • Characteristics: Have antennae, compound eyes, and change form as they grow.

  • Examples: Butterflies, beetles, ants, bees.

  • Arachnids:

  • Legs: Eight legs.

  • Body: Two segments (cephalothorax & abdomen).

  • Characteristics: Often have fangs and make silk.

  • Examples: Spiders, scorpions.

  • Crustaceans:

  • Habitat: Mostly aquatic.

  • Limbs: Many pairs of limbs.

  • Antennae: Two pairs of antennae.

  • Characteristics: Have a hard shell that they shed and breathe through gills.

  • Examples: Crabs, lobsters, shrimp.

  • Myriapods:

  • Body: Segmented with many legs.

  • Characteristics: Many segments with legs.

  • Examples: Millipedes, centipedes.