Ecosystem

• Source of energy in all ecosystems

  The sun
• How green plants convert light energy from the sun

  1. Into chemical energy (food) through photosynthesis

  2. Chemical energy transferred to primary consumers

  3. Transferred to secondary and tertiary consumers in the food chain and food web
• Organisms in an ecosystem

  • Producers
  • Consumers
  • Decomposers
• Producers


  Green plants that produce their own food through photosynthesis
• Types of consumers

  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
• Primary consumers


  Eat producers (herbivores and omnivores)
• Secondary consumers


  Eat primary consumers (omnivores and carnivores)
• Tertiary consumers


  Eat secondary consumers (mostly carnivores)
• Decomposers


  Break down dead animals and plants into simpler materials or nutrients (e.g. mushrooms, bacteria)
• The interaction between decomposers and dead organisms is called saprophytism
• Decomposers


  • Mushrooms
  • Bacteria
• Food chain


  1. Shows feeding relationships between organisms

  2. Energy flows from one organism to the next
• The arrow in a food chain represents the flow of energy
• In a food chain, the producer is the green plant and the consumers are the primary, secondary and tertiary consumers
• Food web


  Formed by combining multiple food chains
• Energy is not completely transferred from one organism to the next in a food chain/web, some energy is lost through movement, respiration, undigested food/faeces
• Nutrient cycle


  Nutrients can be obtained from a balanced ecosystem. Living things use these nutrients and then return them back to the environment, creating a cycle.
• Nutrient cycle

  1. Take nutrients

  2. Use nutrients

  3. Return nutrients to environment

  4. Take nutrients again

  5. Return nutrients again
• Role of plants in water cycle

  1. Water absorbed by roots

  2. Water returned to environment through transpiration

  3. Fallen leaves slow down evaporation

  4. Roots hold soil and prevent erosion
• Role of animals in water cycle

  1. Respiration

  2. Defecation

  3. Excretion

  4. Increase water content in atmosphere
• Respiration by plants and animals

  Use oxygen, release carbon dioxide
• Photosynthesis by green plants


  Take in carbon dioxide, release oxygen
• Green plants are important for the nutrient cycle
• Human activities that disrupt the nutrient cycle

  • Unrestricted logging
  • Burning of fossil fuels
  • Overconsumption of water resources
• Ways to solve interference to the nutrient cycle

  • Create planned agricultural systems
  • Use public transport to reduce car use and fossil fuel burning
  • Collect rainwater for daily use
  • Replant trees after logging
  • Use natural resources responsibly
• Habitat


  The natural home of an organism, where a living thing lives
• Species


  A group of organisms that have common characteristics and can reproduce to breed offspring
• Population


  A group of organisms of the same species that live in the same habitat
• Community


  Different populations of organisms that live together in the same habitat and have mutual interactions
• Ecosystem


  A community of living organisms and their non-living environment, all interacting as a system
• In a balanced ecosystem, living things are interdependent on each other and on the non-living components, existing in harmony
• Living things need to adapt to different environments, such as tropical, desert, or tundra
• Factors that can influence population size


  • Disease
  • Presence of predators
  • Source of food
  • Changes in weather
• Increase in crow population in Malaysia


  Caused by abundance of food scraps
• Migration


  1. Animals move from one place to another due to changes in season

  2. Can bring changes to the ecosystem, e.g. decrease in insect population
• Limited water supply


  Can upset the balance of the ecosystem, e.g. decrease in paddy plant population
• Changes in population size

  Can change the size of other populations, e.g. increase in pest population decreases plant population
• Forest logging


  • Extinction of flora and fauna species
  • Soil erosion
  • Greenhouse effect
• Industrialization


  • Pollution (air, water, soil)
  • Acid rain
  • Greenhouse effect
• Agriculture


  • Overuse of pesticides and fertilizers
  • Pollution of water
  • Soil losing minerals