Life Sciences - Term 4 - Week 2

Ecosystems are composed of various organisms that play specific roles. Producers, such as plants, convert sunlight into energy through photosynthesis, forming the base of the food chain. Consumers, including herbivores and carnivores, rely on producers and other consumers for energy. Decomposers, like fungi and bacteria, break down dead organic matter, returning essential nutrients to the soil, which supports plant growth. This interconnectedness is vital for maintaining ecological balance.

Energy flows through an ecosystem in a one-way stream, from producers to various levels of consumers. This flow is represented in food chains and food webs. Nutrient cycling, on the other hand, is a closed loop where nutrients are reused and recycled. For example, when plants die, decomposers break them down, releasing nutrients back into the soil, which are then taken up by new plants. Understanding these processes is crucial for appreciating how ecosystems function.

Consider a simple food chain: Grass → Grasshopper → Frog → Snake. In this chain, grass (the producer) captures sunlight and converts it into energy. The grasshopper (primary consumer) eats the grass, gaining energy. The frog (secondary consumer) eats the grasshopper, and the snake (tertiary consumer) preys on the frog. Each step in this chain illustrates how energy is transferred from one organism to another, highlighting the importance of each role.

In groups, students will be provided with a diagram of a local food web. They will identify and label the producers, primary consumers, secondary consumers, and decomposers. After labeling, each group will present their findings, discussing how energy flows through their specific food web and the importance of each organism's role in maintaining ecosystem health.

Students will choose an ecosystem (e.g., forest, ocean, grassland) and research how human activities have impacted its dynamics. They will write a report detailing the changes observed, the effects on producers, consumers, and decomposers, and propose solutions to mitigate negative impacts. This project will help students connect theoretical knowledge with real-world applications.

• To decompose organic matter
• To convert sunlight into energy
• To consume other organisms
• To compete for resources

Answer: To convert sunlight into energy

Producers, such as plants, use photosynthesis to convert sunlight into chemical energy, forming the foundation of the food chain.

• Grass
• Frog
• Snake
• Grasshopper

Answer: Grasshopper

A primary consumer is an organism that eats producers; in this case, the grasshopper feeds on grass.

Answer: Decomposers break down dead organic matter, returning nutrients to the soil, which supports plant growth.

Decomposers are essential for recycling nutrients, ensuring the sustainability of ecosystems.

• A linear sequence of energy transfer
• A complex network of feeding relationships
• A diagram showing only producers
• A type of ecosystem

Answer: A complex network of feeding relationships

A food web illustrates how various organisms are interconnected through multiple feeding relationships.

Answer: Energy flows from producers to consumers in a one-way direction, with each level transferring energy to the next.

This flow is crucial for understanding how energy is utilized and lost at each trophic level.

• Planting trees
• Pollution
• Conserving wildlife
• Creating parks

Answer: Pollution

Pollution can introduce harmful substances into ecosystems, affecting the health of organisms and disrupting natural processes.