fuel for life

• Modes of nutrition

  • Autotrophic - Photosynthesis and Chemosynthesis
  • Mixotrophs
  • Heterotrophic
  • Parasitic - Endoparasites and Ectoparasites
  • Saprophytic
  • Holozoic
• Photosynthetic organisms

  • Photosynthetic bacteria
  • Plants
  • Protoctists
• Methods of photosynthesis

  • Crussalic acid metabolism
  • C4
  • C3
  • CAM pathway
• C3 photosynthesis

  Uses Rubisco to fix CO2 to Ribulose bisphosphate, Allows production carbohydrates, lipids and proteins
• C4 photosynthesis


  Plants uses PEP - phosphenolpyruvate carboxylase, Plants can partially close their stomata, No Rubisco in mesophyll cells, Chloroplasts in mesophyll form malate which goes into bundle sheath cell and is decarboxylated to give CO2 for the Calvin cycle
• Crussalic Acid Metabolism

  CO2 is taken up at night through the open stomata, Converted into malate by phosphoenolpyruvate carboxylase (PEPC), and stored in the vacuole, During the day, CO2 is produced by a decarboxylation reaction and used by RuBisCO, By utilizing the CO2 stored in the vacuole, stomata can be kept closed during the day to reduce water loss by transpiration
• Autotroph chemosynthetic

  A type of autotrophic nutrition in which organisms (called chemoautotrophs) synthesize organic materials using energy derived from the oxidation of inorganic chemicals, rather than from sunlight
• Autotroph chemosynthetic examples

  • Hot spring chemosynthetic sulphur bacteria
  • Methanogenic bacteria in the rumen of ruminant herbivores
• Mixotrophic

  Organisms that combine autotrophy (self-sustaining food production from a carbon source and inorganic nitrogen) and heterotrophy (ingesting other organisms to acquire carbon)
• Types of mixotrophy

  • Obligate mixotrophy
  • Obligate autotrophy with facultative heterotrophy
  • Facultative autotrophy with obligate heterotrophy
  • Facultative mixotrophy
• heterotroph - parasitic

  • Feeds off a host without benefit to the host
  • Shouldn't kill the host
  • A form of symbiosis
  • example: endoparasites/ectoparasites (mosquitoes)
• Ectoparasite

  Parasite that lives on the outside of the host
• Tapeworm

  • Attaches to host by hooks and suckers via Scolex
  • The body is covered by a tegument- a layer which stops digestion of the worm by its host
  • No gut- gets its nutrients by absorption from the host through segments and some absorption may be through scolex
  • Respiration anaerobic
  • Excretion via excretory canals and nephridial complex in scolex and flame cells
  • Nervous system cerebral ganglion and nerve fibres throughout the body, sensory receptors in each proglottid
  • Tapeworms are hermaphrodites with male and female reproductive organs in each proglottid
• Ectoparasitic flea

  • Adult flea mouthparts are specialized for piercing and sucking, Lack mandibles and have an unpaired labral stylet and two elongate serrate, stylets that together lie within a maxillary sheath to pierce the skin, A salivary pump injects saliva into the wound, and cibbarial and pharyngeal pumps suck up the blood meal
• Heterotroph- semi-parasite

  Mistletoe - Grows on more than 200 tree and shrub species, Hemi-parasitic, bearing evergreen leaves that photosynthesis, Gains mainly water and minerals from host
• Mistletoe haustorium development

  1. Formation of the holdfast

  2. Development of the intrusive organ

  3. Connection of the haustorium to the host
• Heterotroph - saprophytic

  Extracellular nutrition - A process of chemoheterotrophic extracellular digestion involved in the processing of digesting, dead or non-living matter
• Saprophytic species

  • Fungi, bacteria, plants
• Eating of ergot contaminated rye caused the Salem witch trials
• Symptoms of ergot poisoning

  Convulsions, spasms, mania and psychosis, gangrene, lameness
• Types of carnivores

  • Hypercarnivores (obligate carnivores) - more than 70% meat
  • Mesocarnivores - 50-70% meat diet
  • Hypocarnivores - less than 30% meat
• Carnivore features

  • Heavy skulls with strong facial musculature
  • Sharp angled mandible and tight TMJ temporomandibular joint
  • Enlarged canines
  • Carnassial teeth
  • Don't produce salivary amylase in the gut
  • One stomach which is a relatively large part of the gut
  • Large volumes of hydrochloric acid in the stomach
  • Longer small intestine
  • Shorter large intestine
• Digestion of carbohydrates and protein in ruminants

  1. Carbohydrates

  2. Proteins
• Non ruminant herbivores- hind gut fermenters

  Horses

  • The large intestine accounts for 60% of the total volume of the digestive tract
  • The caecum and large colon contains active bacteria similar to the microbes of the rumen
  • Bacterial breakdown of cellulose and other carbohydrates result in the production of volatile fatty acids (VFAs)
  • The small colon is the primary site of water absorption and the rectum is where manure is expelled
• Coprophages

  Have a long caecum containing fermentation bacteria and mucus, Produce caecotrophs - have twice the protein and half of the fibre of the typical hard faecal pellet, They also contain high levels of vitamin K and the B vitamins, Produced at night, Digested the second time through
• Coprophages

  • Rabbits, guinea pigs
• Heterotrophic – Holozoic   

  Ruminants:

  • No  upper incisors or canines 
  • Diastema 
  • Four chambered stomach 
  • Rumen – fermentation vat 
  • The reticulum allows food to be passed back up to the mouth or onto  the omasum 
  • Omasum absorbs water and products of microbial digestion
  • Abomasum similar to non-ruminant stomach