11.1.1 Animal Classification

• What is the main purpose of classification systems in biology?

  To explain evolutionary relationships among organisms
• How were organisms traditionally classified?

  According to similarities and differences in their morphological and anatomical characteristics
• What modern methods are used for classifying organisms?

  By genetics and the sequence of bases in DNA
• What does it indicate if two organisms have similar DNA base sequences?

  They are more closely related
• What is the significance of amino acid sequences in classification?

  They can also be used to classify organisms
• What defines a species in biological terms?

  A group of organisms that can reproduce to produce fertile offspring
• What is the binomial naming system?

  An organism is named using two parts: the genus and the species
• How is the genus name formatted in the binomial naming system?

  The genus name starts with a capital letter
• Give an example of a species using the binomial naming system.

  Homo sapiens (humans)
• How is the animal kingdom divided?

  Into vertebrates and invertebrates
• What are the two main groups of vertebrates?

  Bony fish and invertebrates
• What are the characteristics of bony fish?

  They absorb oxygen through gills and have wet scales
• How do bony fish reproduce?

  By external fertilization and laying eggs
• What is a defining feature of amphibians?

  They can live on land and water
• How do amphibians absorb oxygen?

  Through their lungs and moist skin
• How do amphibians reproduce?

  By external fertilization and laying eggs
• What are the characteristics of reptiles?

  They have lungs and dry scales
• How do reptiles reproduce?

  By internal fertilization and laying eggs
• What are the characteristics of birds?

  They have lungs, feathers, and beaks
• How do birds maintain their body temperature?

  They are warm-blooded
• How do birds reproduce?

  By internal fertilization and laying eggs
• What are the characteristics of mammals?

  They have lungs and fur
• How do mammals reproduce?

  By internal fertilization and giving birth to live young
• What are the main characteristics of vertebrates?

  • Have a backbone and an internal skeleton
  • Include bony fish, amphibians, reptiles, birds, and mammals

  
• What are the main characteristics of invertebrates?

  • Do not have a backbone
  • Include arthropods
• What does the term "dichotomous" mean in the context of dichotomous keys?

  It means 'branching into two'
• How does a dichotomous key function?

  It leads the user through to the name of the organism by giving two descriptions at a time
• What is the process for using a dichotomous key?

  Pick a single organism and follow the statements until you find the name
• What are cladograms used for?

  • To illustrate evolutionary relationships
  • To show how different species are related through common ancestors