The correct option is 1, 2 and 3
Explanation
Organisms within an ecosystem are classified into specific groups based on their mode of nutrition. This classification defines their trophic level and role in the flow of energy and cycling of nutrients.
Statement-wise Analysis:
- Pair 1 is correctly matched: Autotrophs (producers) are organisms capable of synthesizing their own organic food from inorganic raw materials such as carbon dioxide and water. They typically utilize sunlight for photosynthesis. Green plants, algae, and certain bacteria are the primary examples of autotrophs.
- Pair 2 is correctly matched: Heterotrophs (consumers) are organisms that cannot synthesize their own food. They depend on autotrophs or other heterotrophs for their nutritional requirements. All animals, including herbivores, carnivores, and omnivores, are heterotrophs.
- Pair 3 is correctly matched: Saprotrophs (decomposers) are organisms that obtain nutrients by feeding on dead and decaying organic matter. They secrete digestive enzymes onto the dead matter to break it down extracellularly and then absorb the resulting nutrients. Fungi and many bacteria are saprotrophs.
Key Takeaway: The functional stability of an ecosystem depends on the interaction between Autotrophs (energy producers), Heterotrophs (consumers), and Saprotrophs (nutrient recyclers).