Core Biology Week 1

• Week 1 Core Biology

  Lecture Zoology
• Animal classification


  • Over 1 million species known
  • Traditionally categorised according to morphology
  • DNA and RNA can help clarify phylogenies
  • The animal kingdom is monophyletic- all taxa evolved from a single common ancestor
• Characteristics of animals


  • Absence or presence of different tissues
  • Parazoa and eumetazoa
  • Radial or bilateral symmetry
  • Radiata and bilateria
  • Number of germ layers
  • Diploblastic and triploblastic
  • Absence or presence of a body cavity
  • Acoelomates, pseudocoelomates and coelomates
  • Spiral or radial cleavage in embryonic development
  • Protostomes and deuterostomes
  • Absence or presence of segmentation
  • Common ancestor of all animals
• Invertebrates


  • 95% of all animal species
  • No backbone
  • Categorised into 10 divisions
  • Porifera (sponges)
  • Cnidaria and ctenophore (hydra, anemones and jellyfish)
  • Platyhelminthes (flatworms)
  • Rotifera (rotifers)
  • Lophophorata
  • Mollusca (snails, clams and squid)
  • Annelida (segmented worms)
  • Nematoda (roundworms)
  • Arthropoda (insects, arachnids and crustaceans)
  • Echinodermata (sea stars and sea urchins)
  • Malaria is transmitted by the insect Anopheles mosquito
  • Elephantiasis a disease caused by the nematode parasite Wuchereria bancrofti
• Vertebrates


  • Craniates with a backbone
  • Vertebral column
  • Endoskeleton of bone or cartilage
  • Internal organs
  • 5 out of 11 vertebrate classes are classes of fish
• Major vertebrate innovations


  • Jaws
  • Four limbs
  • Amniote eggs- no longer dependent on water (includes mammals)
  • Milk production
• Evolution of the eye

  1. Photoreceptor proteins in single celled organisms

  2. Photoreceptor cell

  3. Clusters of photoreceptor cells grouped together to form eyespots

  4. Clusters of these cells formed into a depressed region to form eyecup

  5. In creatures with no brain, (jellyfish) messages are directed from the eye directly to muscles
• Oxygen Supply


  • Oxygen supply to fishes
  • Oxygen supply to insects
  • Oxygen supply to humans (detail in HAP)
  • Oxygen supply to birds
• Circulatory systems


  • Circulatory systems in invertebrates
  • Circulatory systems in fish amphibians and mammals
• Molecular methods for categorising animals

  DNA is sequenced and the sequences are compared. Most closely related species have the most similar sequences.
• Marine plants produce between 70 and 80 percent of the oxygen in the atmosphere
• Chemicals produced by plants


  • vitamin A
  • vitamin C
  • vanillin
  • caffeine
  • morphine
  • CO2
  • H2O
  • NO3-
  • PO42-
• Origin of plants


  • Arise from green algae
  • Began to evolve 500 million years ago
  • Water based origin
  • Prior to this high ultraviolet radiation prevented land colonization
  • Protective ozone layer formed enabled movement to land
• Cycads


  Found across much of the subtropical and tropical parts of the world, sometimes confused with and mistaken for palms or ferns, Very common in the Jurassic period, but much less so today
• Ginkgo


  Fossils recognisably related to the modern Ginkgo Biloba, from the Permian, dating back 270 million years
• Characteristics of gymnosperms


  • 630 species
  • Needle-like or scale-like leaves
  • Thick cuticle
  • More resistant to drought & cold than flowering plants
  • High latitude
  • Northern hemisphere
  • Evergreen
  • Two types of cones
  • Small, soft pollen contains pollen sac
  • Large woody, ovulate
• Conifers


  Conifers produce the largest Plants, Sequoiadendron giganteum
• Significance of gymnosperms


  • Ecological importance: Food and habitat for wildlife, Forests prevent soil erosion, Reduce greenhouse gasses
  • Economic & commercial importance: Lumber for wood, paper, Resins and oils for wood and furniture, Ornamental plants e.g. landscaping, Food & drink – pine nuts, juniper berries, oils, Medicines
• Angiosperms: flowering plants


  • Dominate modern landscape
  • Approx 260,000 species
  • Success due to efficient water transport system & evolution of flower
  • Many different forms, ecologically diverse
• Principal differences between Gymnosperms and Angiosperms

  • Angiosperm leaves have finely divided venation
  • Angiosperm xylem contains vessels as well as tracheids
  • Angiosperm ovules protected within an enclosed structure
  • Angiosperms have a Double Fertilization to produce diploid zygote and triploid endosperm nucleus
• The cell wall is not the permeability barrier
• Sepals


  Protect flower when in bud
• Petals


  Attract insects
• Stamens


  Anther: male gamete= pollen, Filament - stalk
• Carpals


  Stigma, Style, Ovary – female gamete
• Flower


  Specialised reproductive shoot
• Fruit


  Mature ovary e.g. pod, Protects seed, e.g. pea containing seeds
• Seed


  From ovules, Increases seed dispersal: Wind, animal, birds
• Why are angiosperms successful?

  • Efficient transport of water & nutrients via xylem and phloem
  • Photosynthesis
• Photosynthesis


  The process by which plants and some other organisms use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar
• Photosynthesis is found in plants, bacteria, and algae
• Photosynthesis has been around for a long time and is very important to understand
• Chloroplasts


  • The site of photosynthesis in eukaryotic cells
• Thylakoid membrane


  Where the light reaction of photosynthesis takes place
• Granum


  A stack of thylakoids
• Stroma


  The liquid-filled space in a chloroplast where the Calvin cycle takes place
• Leaves contain multiple pigments that work together in photosynthesis, including chlorophyll A, chlorophyll B, carotene, and xanthophylls
• Absorption spectrum


  The range of light wavelengths that a pigment can absorb
• Chlorophyll absorbs a lot of blue and red light but reflects green light, which is why plants appear green
• The reason plants appear green is that they reflect green light and absorb other wavelengths