Biology

• All living things are made up of CELLS. Thus, there are two types of organisms: UNICELLULAR and MULTICELLULAR
• Unicellular organisms


  Only made of one cell, usually have simple structures and do not rely on a transport system for their nutrients, instead move dissolved gases and nutrients around by diffusion, do not rely on sexual reproduction to continue their species, instead reproducing by splitting in two
• Multicellular organisms


  Require a more complex structure and specialized systems may be necessary to enable the organism to digest and transport food, escape predators, seek shelter and find a sexual mate to continue the species
• Characteristics of living organisms

  • Growth
  • Respiration
  • Irritability
  • Movement
  • Nutrition
  • Excretion
  • Reproduction
• Metabolism


  The chemical processes that occur in the body
• Locomotion


  The ability of an organism to move from one location to another
• Species


  Members have very similar physical and biological characteristics and are able to interbreed and produce viable, fertile offspring
• Artificial classification involves categorising by certain features of anatomy
• Anatomical/physical features to differentiate ant and termite

  • Antennae shape
  • Body shape
  • Wing segments
• Anatomical/physical features to differentiate A-E

  • Number of dorsal fins
  • Presence of whiskers
  • Tailfin shape
  • Tailfin striping
• Using artificial classification can be problematic for identifying organisms of the same species due to inherited genetic traits, changes during maturity, and differences between genders
• Natural/modern classification


  Based on an organism's DNA base sequences and evolutionary descent, structured as a hierarchy with each level called a taxon

  
• Binomial name


  Genus and species
• Examples of genus names

  • Canis
  • Equus
  • Citrus
  • Homo
• Five kingdoms


  • Plantae
  • Animalia
  • Fungi
  • Prokaryota/Monera
  • Protista
• Viruses are not classed under any kingdom because they are not considered living organisms
• Eukaryotic cells


  Can be unicellular or multicellular, DNA is found in a nucleus in chromosomes

  
• Prokaryotic cells


  Only unicellular, no nucleus, DNA is in loose threads
• An ecosystem is a system of living and non-living factors that interact with each other
• Components of an ecosystem

  • Biotic (organisms)
  • Abiotic (physical features)
• Population


  A group of one species within a particular habitat
• Community


  All the populations of different species in a particular habitat
• Niche


  An organism's role in its environment, including its behaviour, interactions, how it meets its needs, and how it reproduces
• Habitat


  The place where an organism lives, can be classified as terrestrial or aquatic
• Categories of organisms in a food chain

  • Autotrophs (producers)
  • Heterotrophs (consumers)
  • Decomposers
• Decomposers are not to be confused with carrion feeders or detritivores
• Energy moves from organism to organism in a food chain in a unidirectional flow, as it cannot be directly returned to an organism or the Sun

  
• Trophic level


  Each stage in the food chain, where energy decreases through each successive level
• Most food chains are limited to four to six trophic level links because there would be too little energy available to sustain life on higher trophic levels
• A food web is a combination of several food chains within a habitat or ecosystem
• Components of a food web

  • Autotroph (algae)
  • Herbivore (tadpole)
  • Carnivore (frog)
  • Omnivore (small fish)
  • Tertiary consumer (kingfisher)
  • Predator/prey (frog and snail)
• Types of ecological pyramids

  • Pyramid of numbers
  • Pyramid of biomass
  • Pyramid of energy

  
• Predator-prey relationship


  The predator hunts and eats the prey, the number of predators is usually less than the number of prey
• Advantages of biological controls

  • Targets a specific pest
  • Does not result in air and land pollution
  • Is a long-term solution and less manual labour is required

  
• Disadvantages of biological controls

  • Can result in disruptions in the food web
  • Takes a long time to work properly
  • Research is expensive
• Types of symbiotic relationships

  • Parasitism (one organism is harmed while the other benefits)
  • Commensalism (one or both organisms benefit, but neither is harmed)
  • Mutualism (both organisms benefit)
• Advantages of Biological Controls

  • Targets a specific pest
  • Does not result in air and land pollution, such as pesticides
  • Is a long-term solution and less manual labour is required in the long run
• Disadvantages of Biological Controls

  • Can result in disruptions in the food web if the control becomes a predator
  • Takes a long time to work properly, unlike using chemical control
  • Research is expensive
• Section


  1. Predator pop. high because prey pop. is high

  2. Prey pop. decreases because predator pop. is too high; food is depleted

  3. Prey is allowed to reproduce since predator pop. is low. Predator pop. then increases once again
• Symbiosis


  Relationships where at least one organism benefits