Definitions [7]
A series of organisms where one is eaten by the next and energy flows from producers to consumers is called a food chain.
A network of interconnected food chains showing how various organisms are related through feeding relationships is called a food web.
Define the term predation.
A predator is any consumer that kills and eats another living organism in order to obtain energy. The organism being eaten is called the prey.
Define the food chain and give two examples.
Food chain, in ecology, the sequence of transfers of matter and energy in the form of food from organism to organism. Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant. Plants, which convert solar energy to food by photosynthesis, are the primary food source. In a predator chain, a plant-eating animal is eaten by a flesh-eating animal. In a parasite chain, a smaller organism consumes part of a larger host and may itself be parasitized by even smaller organisms. In a saprophytic chain, microorganisms live on dead organic matter.
Define the following term and give two examples:
Symbiosis
It refers to relationships between organisms of different species that show on intimate association with each other. Symbiotic relationships provide atleast one of the participating species with a nutritional advantage.
Examples of Symbiosis Relationships are of Fungus and photosynthestic alga and Microbes and cattle.
The circular movement of nutrients between living organisms and the physical environment of an ecosystem is called biogeochemical cycle.
Define chemoautotrophs.
Chemoautotrophs are those who make their own food by deriving the energy from chemical reactions. e.g., Nitrifying bacteria, Iron bacteria etc.
Key Points
| Trophic Level | Meaning | Examples | Role in Energy Flow |
| Producers (Autotrophs) | Organisms that synthesise their own food using sunlight through photosynthesis. | Green plants, algae, phytoplankton | Convert solar energy into chemical energy, forming the base of the food chain. |
| Primary Consumers (Herbivores) | Organisms that directly depend on producers for their food. | Grasshopper, squirrel, elephant, deer | Consume plant material, store energy for the next trophic level, and act as a link to higher consumers. |
| Secondary Consumers (Carnivores) | Carnivores that feed on herbivores to obtain energy. | Frog, owl, fox, snake | Transfer energy from herbivores to higher levels and help control herbivore populations. |
| Apex or Top Consumers (Carnivores) | Predators at the highest level of the food chain, feeding on herbivores and carnivores. | Tiger, lion, eagle, crocodile | Regulate populations of secondary consumers, maintain ecosystem stability, and have no natural predators. |
| Omnivores (Mixed Consumers) | Organisms that consume both plants (producers) and animals (herbivores and carnivores). | Humans, bears, raccoons | Diversify energy flow by feeding across multiple levels and connecting various parts of the food chain. |
- A food chain is a linear sequence of organisms in which food energy is transferred from producers to consumers.
- Every food chain begins with producers (green plants) and usually ends with top consumers that are not preyed upon.
- Energy decreases at each trophic level, so food chains are usually short (not more than five levels).
- Shorter food chains are more stable and efficient, as less energy is lost at each step.
- A food web is a network of interconnected food chains operating within an ecosystem.
- It shows multiple feeding relationships, as organisms may have more than one food source.
- Food webs represent the flow of energy and nutrients among producers and consumers.
- The complexity of a food web depends on the diversity of organisms and the number of alternative food choices.
- Carbon is an essential element of all organic compounds, and atmospheric carbon dioxide is the main source of carbon for living organisms.
- Photosynthesis fixes carbon dioxide into organic compounds, which pass through food chains from producers to consumers.
- Respiration, decomposition, combustion of fossil fuels, and volcanic activity return carbon dioxide back to the atmosphere.
- Some carbon is stored long-term in fossil fuels and carbonate rocks, and is released slowly through burning, weathering, or acid rain.
- Human activities increase atmospheric CO₂, enhancing the greenhouse effect and leading to global warming and climate change.
