Biology Y9 B1

• Nucleus

  Control centre
• Cell membrane

  Controls what goes what goes in and out
• Mitochondria

  Power house - energy production
• Cytoplasm

  Where reactions occur
• Cell wall

  Provides support
• Chloroplast

  Contains Chlorophyll
• Vacuole

  Contains cell sap
• Chloroplasts in the upper epidermis
• All of the energy that flows through food chains comes originally from the sun
• Arrows in food chains show what eats what
• The arrows show the flow of energy through the system
• What the arrows represent in a food chain


  The flow of energy from one organism to another
• Trophic level


  Each feeding level in a food chain
• Trophic levels


  • Producer
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
• Keywords


  • Plants
  • Animals
  • Fungi/Bacteria
  • Decomposers
• Producers


  They produce their own food using carbon dioxide and water
• Consumers


  Things that eat other living things (can be herbivores, omnivores or carnivores)
• Herbivore


  An animal that feeds on plants
• Carnivore


  An animal that feeds on other animals
• Omnivore


  An animal that eats both plants and animals
• Ecologists have calculated only 10% of energy available in a trophic level is taken up by the level after
• Energy flow in a food chain

  1. Sun

  2. Producer

  3. Primary consumer

  4. Secondary consumer

  5. Tertiary consumer
• • 98% energy lost from sun to producer
  • 90% energy lost from producer to primary consumer
  • 90% energy lost from primary consumer to secondary consumer
  • 90% energy lost from secondary consumer to tertiary consumer
• Why only THREE consumers in the chain?
• Biomass


  The total mass of an organism
• How is the energy from food used by organisms?

  • Movement
  • Nutrition
  • Excretion
  • Reproduction
  • Growth
  • Sensitivity
  • Respiration
  • Maintenance of body temperature
• Energy from cellular respiration is transferred by heating the surroundings
• Food pyramid


  Each trophic level is represented by a horizontal bar, with the base representing the producer
• Pyramid of energy


  The width of the bar represents the amount of energy available at each level in the food chain, measured over a period of time
• Most food chains only have a few links because energy is lost at each level, for example as heat, for movement, and in urine and faeces
• Energy flow through producers

  1. Most of the sunlight that falls on leaves is not absorbed and used

  2. The overall efficiency of energy transfer during photosynthesis is less than 10%

  3. Only about 1 - 5% of sunlight energy reaching the plant is transferred into useful chemical energy in the carbohydrates
• Only about 10% of energy is transferred to the next trophic level
• How energy is lost along the food chain


  • Escapes as heat in respiration to the surroundings
  • Some parts of the plant is not eaten e.g. roots
  • Some parts of the organism is not eaten/digested e.g. fur, teeth, bone, claws
  • Some materials are not absorbed and are egested e.g. urine, faeces
  • Organism uses the energy to stay alive
  • When organism die- energy is 'locked up' which transfers to decomposers
• Eating meat is wasteful in terms of food energy
• Food web


  A series of food chains all connected to each other
• Food webs are easily unbalanced if one population of organisms in the web disappears due to over-predation or hunting, disease, pollution, use of pesticides, lack of food, or emigration
• Terrestrial, marine, and freshwater food webs are examples of ecosystems
• Quadrats


  Tools biologists use to estimate the number of plants in an area

  
• Sampling


  Taking small samples to investigate distribution of organisms in a large area
• Distribution


  The way living things are spread out in their habitat