Biology grade 9 unit 5 and 6

• Species


  A group of organisms that can breed successfully with one another to produce fertile offspring
• Pentadactyl


  Having five fingers or toes
• Reasons biologists classify living things

  • To simplify their study
  • To bring order out of chaos or confusion
  • To try to understand how life originated
• Species


  The most important unit of classification, defined as a group of organisms that can breed successfully with one another to produce fertile offspring
• In the 21st century scientists make decisions about which organisms belong in the same species in a number of ways
• How living things are classified

  • According to similarities on or in their bodies
  • One example is animals that have limbs built on the same basic plan
  • Limbs have the pentadactyl pattern and this is useful for classifying and tracing ancestors
• Morphology


  Appearance of an organism
• Taxonomy


  The process of classifying living organisms
• Taxa


  Categories in the classification system
• Main taxonomic categories


  • Kingdom
  • Phylum (or division for plants)
  • Class
  • Order
  • Family
  • Genus
  • Species
• The species is the smallest unit of classification
• Binomial


  Having two names
• The two names of an organism are in Latin
• Rules for writing scientific names

  • The first name is the genus, written with a capital letter
  • The second name is the species, written with a small letter
  • The two names are underlined when handwritten or in italics when printed
• Living things are classified and named to create an internationally accepted way of referring to them, to avoid confusion created by different languages, and to help simplify classification and study
• Hierarchy of groups


  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Dichotomous key


  A type of key based on making choices between two statements or alternatives
• Dichotomous keys are used to identify unknown specimens
• Kingdom Plantae

  The kingdom of plants, which range from tiny mosses to giant trees
• Major divisions of Kingdom Plantae

  • Bryophyta (mosses and liverworts)
  • Pteridophyta (ferns)
  • Gymnospermae (conifers)
  • Angiospermae (flowering plants)
• Bryophyta (mosses and liverworts)


  • Simplest land plants, non-vascular, cannot transport food or water, small in size, found in damp places
• Bryophyta


  • Etodon concinnus (moss)
  • Funaria spp. (moss)
• Pteridophyta (ferns)


  • Have true leaves, stems and roots, contain vascular tissue, reproduce via spores, prefer damp shady places
• Pteridophyta


  • Pteridium spp. (bracken)
  • Dryopteris spp. (fern)
• Gymnospermae (conifers)


  • Seeds not enclosed in fruits, have needle-shaped leaves with thick waxy cuticle, evergreen, reproductive structures in cones
• Gymnospermae


  • Pinus sylvestris
  • Pinus resinosa
  • Pinus radiata
• Angiospermae (flowering plants)


  • Most successful land plants, have well-developed roots, stems and leaves, well-developed vascular tissues, male gametes in pollen, female gamete in embryo sac, produce seeds enclosed in fruits
• There are around 300,000 living plant species, with over 80% being flowering plants
• Plants are enormously important, providing food, oxygen, fossil fuels, building materials, clothing, medicines and more
• Viruses are not classified in any of the five kingdoms, as they do not have all the seven characteristics of life
• Five kingdoms in modern classification

  • Monera (bacteria)
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Monera


  Single-celled prokaryotic organisms including bacteria and blue-green algae
• Monera


  • Mycobacterium tuberculosis
  • Haemophilus ducreyi
• Protista


  Microscopic single-celled eukaryotic organisms, can be plant-like or animal-like
• Fungi

  Eukaryotic, usually multicellular, heterotrophic organisms that feed by absorption, play vital roles as decomposers and parasites
• Fungi were previously classified as plants but are now recognised as a separate kingdom due to key differences
• There are around 80,000 species of fungi, ranging from single-celled yeasts to large puffballs
• Yeast is one of the few single-celled fungi, used to make injera rise and produce alcohol
• Conifers

  • Evergreen so they can photosynthesize all year long
  • Reproductive structures are found in cones
• Conifer reproduction

  1. Male cone forms huge numbers of pollen grains that are blown by wind to a female cone

  2. Fertilisation results in a small winged seed