Organisms and Their Environment Mind Map

Organisms and their environment mind map · Cambridge IGCSE Biology · clockitwithsci.com

Organisms and their environment

Energy flow and food chains
- Sun: principal energy source
  - Light energy
  - Photosynthesis
- Energy flows, not cycled
  - Chemical energy in organisms
  - Heat to environment
- Food chain
  - Transfer of energy
  - Starts with producer
  - Arrows: food to feeder
- Food web
  - Interconnected food chains
- Consumers
  - Primary
  - Secondary
  - Tertiary
  - Quaternary
- Herbivore, carnivore, decomposer
  - Eats plants
  - Eats animals
  - Feeds on dead material
- Human impact
  - Overharvesting
  - Introduced species
Trophic levels and pyramids
- Trophic level
  - Position in food chain
  - Producers are level 1
- Pyramid of numbers
  - Number of organisms
  - Can be inverted
- Pyramid of biomass
  - Mass of living material
  - Takes size into account
- Pyramid of energy Supplement
  - kJ per m² per year
  - Always pyramid-shaped
- Energy transfer is inefficient Supplement
  - Parts not eaten
  - Faeces and urine
  - Respiration: heat
- Food chains are short Supplement
  - Fewer than five levels
  - Too little energy left
- Plants versus livestock Supplement
  - Fewer trophic levels
  - Less energy lost
Nutrient cycles
- Carbon cycle
  - Photosynthesis removes CO₂
  - Respiration adds CO₂
  - Feeding passes carbon on
  - Fossil fuels and combustion
- Decomposition
  - Bacteria and fungi
  - Release CO₂ by respiration
- Nitrogen cycle Supplement
  - Nitrate absorbed by plants
  - Amino acids and proteins
  - Feeding and digestion
  - Deamination forms urea
- Bacteria and nitrogen Supplement
  - Decomposition: ammonium ions
  - Nitrification: nitrates
  - Nitrogen fixation
  - Denitrification: nitrogen gas
- Fixation by lightning Supplement
  - Air nitrogen to nitrates
Populations
- Population
  - One species
  - Same area
  - Same time
- Community
  - All populations
  - Different species
- Ecosystem
  - Community plus environment
  - Interacting together
- Growth factors
  - Food supply
  - Competition
  - Predation
  - Disease
- Sigmoid curve phases
  - Lag
  - Exponential (log)
  - Stationary
  - Death
- Explaining the phases Supplement
  - Limiting factors
  - Birth rate and death rate