1. Understand the basic concepts of ecology (Trophic Levels and Energy Flow)

2. Define and differentiate biotic and abiotic factors

3. Describe the interaction between each trophic levels/organisms

Biotic Components

Biotic components refer to all living components in an ecosystem.  Based on nutrition, biotic components can be categorised into autotrophs, heterotrophs and saprotrophs (or decomposers).

Abiotic Components

Abiotic components are the non-living component of an ecosystem.  It includes air, water, soil, minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc. 

While most autotrophs rely on photosynthesis, some, particularly in extreme environments, employ chemosynthesis. This process involves utilizing energy from chemical reactions, often involving substances like hydrogen sulfide or methane, to produce food. Examples of such environments include active volcanoes, hot springs in Yellowstone National Park, and deep-sea hydrothermal vents. Bacteria thriving in these locations oxidize specific chemicals to synthesize their own food, showcasing the diverse strategies autotrophs employ to sustain themselves.

4 Types:

1. Herbivores – Organisms that eat only producers (plants); also called a primary or first-level consumer; Examples are the ruminants – cows, goats, carabaws.

2. Carnivores – Organisms that eat only other animals; can be a secondary / tertiary / quarternary consumer; Examples are members of Order Carnivora – Dogs, cats, bears, wolves.

3. Omnivores –Organisms that eat both plant and animal material; Example – Humans

4. Scavengers– Organisms that eat only other animals after they are already killed; Example - vultures, hyenas

The significance of decomposers lies in their ability to convert complex organic substances into simpler compounds, including water and carbon dioxide, along with essential nutrients like nitrogen, phosphorus, and calcium. This process replenishes the soil or water with vital nutrients, benefiting primary producers like plants and algae. Without decomposers, the world would be overwhelmed by dead leaves, insects, and animals.

• Mutualism

• Commensalism

• Parasitism

  
  

Symbiosis – Types

1. In mutualism, both the involved organisms benefit from each other. Example – Coral reefs are nothing but a mutualistic association between coral organisms and various types of algae residing inside them.

2. In commensalism, only one organism benefits, while the other is neither benefited nor harmed. Example – Hermit crabs use gastropod shells to protect their bodies.

3. In parasitism, one organism is benefited while the other organism is harmed. Example – Liver fluke attaches itself to the liver and makes its way to the tissue and bile.

The food chain consists of four major parts, namely:

1. The Sun: The sun is the initial source of energy, which provides energy for everything on the planet.

2. Producers include all autotrophs such as plants. They are called autotrophs as they can produce food through the process of photosynthesis. Consequently, all other organisms higher up on the food chain rely on producers for food.

3. Consumers or heterotrophs are organisms that depend on other organisms for food. Consumers are further classified into primary consumers, secondary consumers and tertiary consumers.

   a. Primary consumers are always herbivores as they rely on producers for food.

   b. Secondary consumers depend on primary consumers for energy. They can either be carnivores or omnivores.

   c. Tertiary consumers are organisms that depend on secondary consumers for food.  Tertiary consumers can also be carnivores or omnivores.

   d. Quaternary consumers are present in some food chains. These organisms' prey on tertiary consumers for energy. Furthermore, they are usually at the top of a food chain as they have no natural predators.

4. Decomposers include saprophytes such as fungi and bacteria. They directly thrive on the dead and decaying organic matter.  Decomposers are essential for the ecosystem as they help in recycling nutrients to be reused by plants.