Classification

• How many species of organisms are estimated to exist?

  1 million species
• Why is the classification of organisms into groups convenient?

  It makes the study of them more manageable and easier to see relationships between species
• What are the three domains of life in the current classification system?

  • Eubacteria
  • Archaea
  • Eukaryota
• What are the five kingdoms of life?

  1. Plantae
  2. Animalia
  3. Fungi
  4. Protista
  5. Prokaryota
• What is the purpose of the phylum in biological classification?

  It contains all organisms with the same major characteristics
• What does the class in biological classification represent?

  It groups organisms with the same general traits, such as body plan
• What is the order in biological classification?

  It is a subdivision of class that provides more information, such as diet
• What does the family in biological classification refer to?

  A group of closely related genera
• What is the genus in biological classification?

  A group of closely related species
• What is the species in biological classification?

  The basic unit of classification, representing organisms that can interbreed to form fertile offspring
• What is the significance of Carl Linnaeus in biological classification?

  He developed the binomial naming system for species
• Why is the binomial naming system important?

  It is in Latin, making it universally understood by scientists
• What is the biological definition of a species?

  A group of organisms that interbreed to form fertile offspring
• What is the phylogenetic definition of a species?

  A group of individuals that are similar in appearance, anatomy, physiology, biochemistry, and genetics
• What was the basis of classification before microscopes were invented?

  It relied on observable features
• What was the early two-kingdom classification system based on?

  It categorized organisms based on whether they were plant or animal
• What led to the formation of the five kingdoms?

  Advancements in microscopy highlighted differences among organisms
• What are the characteristics of prokaryotes?


  • No nucleus
  • Looped and naked DNA
  • No membrane-bound organelles
  • Smaller ribosomes
  • Smaller cells
  • May be free-living or parasitic
• What are the characteristics of protists?

  • Eukaryotic
  • Mostly single-celled
  • Wide infrakingdom variety
  • Mostly free-living
  • Autotrophic and heterotrophic
  • Have plant and animal features
• What are the characteristics of fungi?

  • Eukaryotic
  • Walls of chitin
  • Multinucleate cytoplasm
  • Saprophytic
• What are the characteristics of plantae?

  • Eukaryotic
  • Multicellular
  • Cellulose cell wall
  • Autotrophic
  • Contains chlorophyll
• What are the characteristics of animalia?

  • Eukaryotic
  • Multicellular
  • Heterotrophic
  • Usually able to move around
• Why can two species look and act very similarly?

  Because they have adapted to their environment
• How can biological chemistry evidence help in classification?

  It shows how closely related two species are based on similar biological molecules
• What does the sequence of amino acids in cytochrome C indicate?

  The more differences found, the less closely related the two species are
• What is the significance of DNA in classification?

  The DNA code is universal, meaning it codes for the same amino acids across different species
• What do mutations in DNA base sequences indicate?

  Many differences suggest that species have evolved separately for a long time
• What did Carl Woese contribute to classification in 1990?


  He used ribosomal RNA to divide prokaryotes into Archaea and Bacteria
• What are the fundamental differences between Bacteria and Archaea?

  They have different cell membrane structures and internal structures
• Why is the three-domain system of classification widely accepted?

  It reflects the fundamental differences between Bacteria, Archaea, and Eukaryotes
• What are the two types of classification?

  • Artificial classification:
  • For convenience (e.g., by color or purpose)
  • Based on only a few characteristics
  • Does not reflect evolutionary relationships
  • Provides limited information

  
  

  • Natural classification:
  • Involves detailed study of individuals
  • Uses many characteristics
  • Reflects evolutionary relationships
  • Provides useful information
  • May change with advancing knowledge
• How can natural classification be used in conservation?

  It helps avoid harming endangered species by understanding their relationships with more populous species
• What is phylogeny?

  • The study of evolutionary relationships between species
  • Represented by an evolutionary/phylogenetic tree
  • Indicates closeness of certain species
• What do common ancestors indicate in evolutionary relationships?

  They show that species have evolved from a shared ancestor
• What did Darwin contribute to the theory of evolution?

  He proposed the theory of natural selection
• What were Darwin's four observations during his trip to the Galapagos Islands?


  1. Offspring generally resemble their parents. 2. No two individuals are identical. 3. Organisms can produce large numbers of offspring. 4. Populations tend to remain stable in size.
• What conclusions did Darwin draw from his observations?

  1. There is a struggle to survive.
  2. Better-adapted individuals survive and pass on their adaptations.
  3. Over time, changes occur that can lead to the rise of new species.
• Why is fossil evidence important for the theory of evolution?

  Fossils show that past species varied from those today and that new species often resemble old ones
• What are the limitations of fossil records?

  They are incomplete due to lack of discovery, natural disasters, and lack of correct conditions for fossilization
• How do biological molecules provide evidence for evolution?

  Closely related species will have very similar biological molecules, indicating a common ancestor