B4

Carbon Cycle and Water Cycle

The Water Cycle: Stages

  1. Water from lakes, rivers, oceans, and the soil, evaporates into water vapour, and rises into the atmosphere.

  2. Water can also evaporate from plants in a process called transpiration.

  3. As the water vapour accumulates it can condense to form clouds.

  4. Later, the water will fall as rain, which we call precipitation.

  5. The water will then seep into the soil, flow into rivers or lakes, and be taken up by plants. 

  6. The whole cycle then repeats over and over. 

The Carbon Cycle: Stages

  1. Photosynthesis: Plants absorb CO₂ from the air and convert it into glucose and oxygen, storing carbon in plant tissues and releasing oxygen.

  2. Consumption and Respiration: Animals consume plants, obtaining carbon and energy. Through respiration, they release CO₂ back into the air.

  3. Decomposition: When plants and animals die, microbes break down their bodies, releasing carbon back into the soil or atmosphere.

  4. Fossil Fuel Formation: In anaerobic conditions (like swamps), dead organisms can be buried and slowly convert into fossil fuels over millions of years.

  5. Combustion: Burning fossil fuels (like coal, oil, and gas) releases stored carbon back into the atmosphere, adding to atmospheric CO₂ levels.

Ecosystem Relationships and Dynamics

Overview

  • Ecosystem Interdependence: All organisms in an ecosystem rely on each other. A change in one population, like a decline in mice, can affect other species and the ecosystem’s overall balance.

Key Components of Ecosystems

  1. Living Organisms (Biotic): Includes plants, animals, and microbes, all interacting and forming complex relationships.

  2. Non-living Environment (Abiotic): Factors like water, sunlight, and soil that support life.

Interactions within Ecosystems

  1. Habitat and Population: A habitat is where an organism lives; a population is a group of the same species living in a habitat.

  2. Interdependence: Organisms depend on each other for survival—plants, animals, and microbes form a web of connections.

  3. Food Webs: Visualize feeding relationships, showing who eats whom and illustrating how energy flows through the ecosystem.

  4. Competition: Occurs over limited resources, both within (intraspecific) and between species (interspecific), impacting population sizes.

Biotic and Abiotic Factors in Ecosystems

Overview

  • Definition: Ecosystems are influenced by biotic factors (living components) and abiotic factors (non-living components) that shape organism interactions and environmental conditions.

Key Components and Examples

Biotic Factors (Living)

  1. Competition: Species often compete for resources like food and habitat.

  2. Predation: Predators impact the population and behaviour of prey species.

  3. Disease: Illness among species can control population sizes, affecting ecosystem stability.

Abiotic Factors (Non-living)

  1. Temperature: Influences growth rates, such as increasing photosynthesis in plants.

  2. Light Intensity: Impacts energy availability for plants, affecting food chains.

  3. Moisture Levels: Essential for plants and animals, influencing survival and habitat suitability.

Key Insights and Examples

  1. Biotic and Abiotic Interactions: The clownfish, for example, relies on anemones for shelter (biotic) and is affected by water temperature and light levels (abiotic).

  2. Indirect Effects: Abiotic changes, like temperature shifts, can affect entire food webs, impacting both plant and animal species.

  3. Importance of Disease: Disease among animals highlights the role of biotic factors in regulating populations.

  4. Ecosystem Dynamics: Understanding these factors helps predict species interactions and ecosystem stability, essential knowledge for ecological studies.

Energy Flow Through Ecosystems

Overview

  • Energy Transfer: Energy flows through ecosystems via food chains, starting with producers and moving through various consumer levels. Each step in the chain sees a loss of energy, impacting the efficiency of the transfer.

Stages of the Food Chain

  1. Producers:

    • Role: Organisms like grass that convert sunlight into energy through photosynthesis.

    • Significance: Forms the base of the food chain by creating glucose and biomass.

  2. Primary Consumers:

    • Role: Herbivores, such as mice, that eat producers.

    • Significance: Represent the first level of consumption and energy transfer.

  3. Secondary Consumers:

    • Role: Carnivores like owls that feed on primary consumers.

    • Significance: Illustrate predator-prey dynamics essential for ecosystem stability.

  4. Tertiary Consumers:

    • Role: Higher-level predators that consume secondary consumers.

    • Significance: Show the complexity of food chains and energy pathways.

Key Insights

  1. Energy Loss:

    • Energy decreases significantly at each trophic level (e.g., from 1,000 joules to 20 joules), highlighting the inefficiency of energy transfer.

  2. Illustrating Energy Flow:

    • Arrows in food chains indicate the direction of energy flow from one organism to another, serving as a visual representation of ecological relationships.

  3. Simplification of Ecosystems:

    • Food chains provide a simplified overview of complex interactions found in food webs, making it easier to understand energy transfer fundamentals.

  4. Ecosystem Health:

    • Analysing food chains helps assess ecosystem health and understand the effects of environmental changes, aiding conservation efforts.