II) FOOD CHAIN: –
A food chain refers to the order of events in an ecosystem, where one living organism eats another organism, and later that organism is consumed by another larger organism. The flow of nutrients and energy from one organism to another at different trophic levels forms a food chain.
The food chain also explains the feeding pattern or relationship between living organisms. Trophic level refers to the sequential stages in a food chain, starting with producers at the bottom, followed by primary, secondary and tertiary consumers. Every level in a food chain is known as a trophic level.
The food chain consists of four major parts, namely:
- The Sun: The sun is the initial source of energy, which provides energy for everything on the planet.
- Producers: The producers in a food chain include all autotrophs such as phytoplankton, cyanobacteria, algae, and green plants. This is the first stage in a food chain. The producers make up the first level of a food chain. Producers are also known as autotrophs as they make their own food. Producers are any plant or other organisms that produce their own nutrients through photosynthesis.
- Consumers: Consumers are all organisms that are dependent on plants or other organisms for food. This is the largest part of a food web, as it contains almost all living organisms. It includes herbivores, which are animals that eat plants, carnivores which are animals that eat other animals, parasites that live on other organisms by harming them and lastly the scavengers, which are animals that eat dead animals.
Here, herbivores are known as primary consumers and carnivores are secondary consumers. The second trophic level includes organisms that eat producers. Therefore, primary consumers or herbivores are organisms in the second trophic level.
Decomposers: Decomposers are organisms that get energy from dead or waste organic material. This is the last stage in the food chain. Decomposers are an integral part of a food chain, as they convert organic waste materials into inorganic materials, which enriches the soil or land with nutrients.
8) Describe about the tropic levels and explain the energy pyramids.
Trophic Levels :
Trophic levels represent the different levels in a food chain or food web, where organisms obtain energy by consuming other organisms. These levels are organized based on the position of an organism within the food chain and its source of energy. There are typically four main trophic levels:
- Producers (Autotrophs): These are organisms that produce their own energy through photosynthesis or chemosynthesis. They are usually plants or certain bacteria that convert sunlight or chemicals into energy-rich organic molecules. Producers are at the base of the food chain and serve as the primary source of energy for all other trophic levels.
- Primary Consumers (Herbivores): These organisms are herbivores that consume producers (plants) for their energy needs. They directly depend on plants and are the second trophic level. Examples include animals like rabbits, deer, and insects that feed on plants.
- Secondary Consumers (Carnivores and Omnivores): These organisms are carnivores and omnivores that feed on primary consumers. They are the third trophic level and include animals like lions, wolves, and humans. Carnivores exclusively consume other animals, while omnivores have a diet that includes both plants and animals.
- Tertiary Consumers (Top Carnivores): These are carnivores at the top of the food chain that feed on secondary consumers. They occupy the fourth trophic level and are often apex predators. Examples include top predators like eagles, sharks, and large carnivorous mammals.
Energy Pyramids :
An energy pyramid is a graphical representation of the energy flow through different trophic levels in an ecosystem. It illustrates the diminishing energy available as you move up the food chain. Energy is lost at each trophic level due to metabolic processes, heat production, and inefficient energy transfer. As a result, there is less energy available to support higher trophic levels.
The energy pyramid is divided into several horizontal layers or levels, each representing a trophic level. The width of each level corresponds to the amount of energy available at that level. Here’s how the energy pyramid is structured:
- The base of the pyramid represents the producers (plants), which have the highest energy content since they directly capture energy from the sun.
- The succeeding levels represent the primary, secondary, and tertiary consumers, with each level having progressively less energy available.
- As you move up the pyramid, the width of each level narrows, symbolizing the decreasing energy transfer efficiency between trophic levels.
- At the top of the pyramid, you find the tertiary consumers (top predators), which have the least amount of energy available, as most of the energy has been lost through the lower levels.
In summary, energy pyramids visually demonstrate the principles of energy transfer and efficiency within an ecosystem’s food chain, showcasing the interdependence of different trophic levels and their reliance on energy derived from the lower levels.