Characteristics of Life, Biology Fundamentals, and Evolutionary Relationships

Characteristics of Life

• Properties of Life (8 characteristics):

  1. Order: Living things exhibit highly organized structures.
     • Atoms → molecules → organelles → cells
  2. Sensitivity/Response to Stimuli: Organisms detect and respond to environmental changes.
  3. Reproduction: Organisms produce offspring and pass on genetic material (DNA).
     • Asexual reproduction: 1 parent → identical offspring (e.g., bacteria)
     • Sexual reproduction: 2 parents → genetically unique offspring
  4. Adaptation: Inherited traits aid survival and reproduction in specific environments.
     • Occurs over generations, not lifetimes.
  5. Growth and Development: Organisms increase in size and undergo cell specialization.
     • Example: Tadpole developing into a frog.
     • Growth = increase in mass/size
     • Development = cells change and specialize
  6. Regulation/Homeostasis: Maintaining stable internal conditions despite external changes.
     • Example: Sweating to cool body temperature, insulin regulating blood sugar.
  7. Energy Processing: Organisms use energy for life processes.
     • Autotrophs: Make their own food (e.g., plants via photosynthesis).
     • Heterotrophs: Consume other organisms for energy (e.g., animals, fungi).
  8. Evolution: Populations change over time due to natural selection.
     • Evolution explains diversity and similarity among organisms.
     • Example: Antibiotic resistance in bacteria

• Mnemonic: Smart Rabbits Are Greatly Responsible Energy Experts

Fundamental Concepts of Biology

• Biology is the study of life.
• Prokaryotic cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria and archaea).
• Eukaryotic cells: Contain a nucleus and membrane-bound organelles (e.g., animal and plant cells).

Evolutionary Relationships

• Phylogenetic Tree: A diagram showing evolutionary relationships based on genetic and physical similarities.
  • Nodes: Represent common ancestors and points of divergence.
  • Branch length: May indicate time or degree of evolutionary change.
• Carl Woese: Proposed the three-domain system (Bacteria, Archaea, Eukarya) based on RNA evidence.

Phylogenetic Tree Example

• Vertebrae: Ray-finned fish, Amphibians, Primates, Rodents & Rabbits, Dinosaurs, Crocodiles & Birds, Sharks
• Four limbs: Amphibians, Primates, Rodents & Rabbits, Dinosaurs, Crocodiles & Birds
• Bony skeleton: Ray-finned fish, Amphibians, Primates, Rodents & Rabbits, Dinosaurs, Crocodiles & Birds, Sharks
• Amniotic egg: Primates, Rodents & Rabbits, Dinosaurs, Crocodiles & Birds
• Two post-orbital fenestrae: Dinosaurs, Crocodiles & Birds
• Hair: Primates, Rodents & Rabbits