Biology

• Ecology


  The study of the interrelationships of living organisms with each other and with their environment
• Environment


  The combination of factors that surround and act upon an organism
• Factors in the environment

  • Biotic factors (all the other living organisms that are present such as predators, prey, competitors, parasites and pathogens)
  • Abiotic factors (all the non-living chemical and physical factors)
• Habitat


  The place where a particular organism lives
• Species


  A group of organisms of common ancestry that closely resemble each other and are normally capable of interbreeding to produce fertile offspring
• Population


  All the members of a particular species living together in a particular habitat
• Community


  All the populations of different, interacting species living together in a particular habitat
• Ecosystem


  A community of living organisms interacting with each other and with their abiotic environment
• Niche


  The position or role of an organism within an ecosystem
• Studying an ecosystem


  1. Observe and record common species of plants and animals

  2. Note any adaptations that enable the organisms to survive

  3. Note any interrelationships between the organisms

  4. Use quadrats to study distribution and abundance

  5. Use line transects to record species along a line

  6. Use belt transects to record species in a strip
• Quadrats


  • A square frame of known area used to sample an ecosystem
• Line transects


  • A measuring tape or string placed in a straight line across an ecosystem, with species recorded at regular intervals
• Belt transects


  • A strip of field with parallel lines, where species found between the lines are recorded
• Sweep nets


  • Used to sample insects, especially flying insects, by sweeping through vegetation a fixed number of times
• Abiotic factors


  The non-living chemical and physical factors in the environment
• Abiotic factors


  • Edaphic factors (connected with the soil)
  • Climatic factors
  • Aquatic factors
• Edaphic factors


  Factors connected with the soil, such as texture, pH, air, mineral nutrients, humus, and organic matter
• Food chain


  A series of organisms each dependent on the next as a source of food, starting with a primary producer
• Consumers in a food chain

  • Herbivores (consume plants)
  • Carnivores (consume animals)
  • Omnivores (consume both plants and animals)
• Trophic level


  The feeding level within a food chain, e.g. primary producer, primary consumer, secondary consumer
• Food chains are interrelated to form food webs
• Detritivores


  Animals that feed on pieces of decomposing organic matter, breaking them down
• Decomposers


  Micro-organisms, such as bacteria and fungi, that feed saprophytically on dead and waste organic matter, causing it to decompose
• Symbiosis


  Any close relationship between two organisms of different species
• Types of symbiosis


  • Parasitism
  • Commensalism
  • Mutualism
• Parasitism


  A relationship where one organism, the parasite, gains benefits while the other organism, the host, is harmed
• Commensalism


  A relationship where one organism, the commensal, gains benefits while the other organism neither gains nor is harmed
• Mutualism


  A relationship where both organisms gain benefit, and in many cases, they cannot survive without each other
• Examples of symbiotic relationships

  • Lichens (mutualism between algae and fungi)
  • Nitrogen-fixing bacteria in legume roots (mutualism with plants)
  • Coral polyps and algae (mutualism)
• Materials are constantly being recycled in nature, with different chemical elements making up the bodies of living organisms
• Root nodules


  Swellings on their roots
• Nitrogen fixation


  1. Bacteria use nitrogen in the air in the soil to produce organic nitrogenous compounds

  2. Plants manufacture proteins from the organic nitrogenous compounds
• Coral polyps


  • Have green algae within their tissues helping their digestive abilities
  • Gain food and oxygen from the algae photosynthesis
  • Algae gain carbon dioxide and nitrogenous compounds recycled by the polyps
• Termites


  • Have protozoa living in their intestines
  • Protozoa are able to digest the cellulose in the wood that termites eat
  • Termites gain food from the protozoa
• Materials are constantly being recycled in nature
• Chemical elements that make up the bodies of living organisms

  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Sulfur
  • Calcium
• Recycling of materials in nature

  Decomposers are essential to the recycling of most of these elements
• Water cycle


  1. Plants have a continuous supply of water to manufacture organic food by photosynthesis

  2. Living organisms have a continuous supply of water to keep their cells hydrated and for various physiological processes

  3. Provides a constant environment for organisms to live in
• Carbon cycle


  1. Carbon atoms are cycled by being converted into different compounds containing carbon, e.g. carbon dioxide and all organic compounds

  2. Plants have a continuous supply of carbon dioxide to manufacture organic food by photosynthesis

  3. Animals and decomposers have a continuous supply of organic food
• Nitrogen cycle


  1. Nitrogen atoms are cycled by being converted into different compounds containing nitrogen, e.g. nitrates and proteins

  2. Plants have a continuous supply of nitrates to manufacture proteins

  3. Animals and decomposers have a continuous supply of proteins