Ecosystems — Important Questions

Tertiary consumer

Step 1: Let us map each organism in the food chain to its consumer level. Step 2: Grass = Producer (Trophic Level I). Step 3: Grasshopper eats grass = Primary Consumer (Trophic Level II). Step 4: Frog eats grasshopper = Secondary Consumer (Trophic Level III). Step 5: Snake eats frog = Tertiary Consumer (Trophic Level IV). The peacock that eats the snake would be the Quaternary consumer.

Bacteria and fungi

Step 1: After death, organisms are broken down in stages. Step 2: Scavengers like vultures and kites eat the dead flesh – they are NOT decomposers. Step 3: Detritivores like earthworms and millipedes feed on decomposing plant and animal parts (detritus) – but they ingest material directly. Step 4: Decomposers are organisms that break down dead organic matter by absorbing nutrients – they cannot ingest matter directly. Step 5: Bacteria, fungi, and protists are true decomposers because they secrete enzymes and absorb the broken-down nutrients.

Sunlight

Step 1: Green plants produce food through the process of photosynthesis. Step 2: Photosynthesis requires sunlight as the energy source to convert carbon dioxide and water into glucose. Step 3: Wind helps in dispersal of seeds and pollen but does not directly help in food production. Step 4: Humidity refers to water vapour in the air – it influences climate but is not the direct energy source for photosynthesis. Step 5: Soil provides minerals and support but is not the energy source for food production. Hence, sunlight is the correct answer.

A network of interconnecting food chains in a community

Step 1: A food chain is a single, straight sequence – e.g., Grass → Rabbit → Fox. Step 2: In reality, animals eat more than one type of food, so many food chains overlap and connect. Step 3: This complex network of interconnected food chains is called a food web. Step 4: Option C is wrong – a food web includes all organisms, not just producers. Step 5: Option D describes a pyramid of numbers, not a food web. Food webs provide more stability to an ecosystem than a simple food chain.