Ecosystems exercise - Free Printable

Problem Analysis:

The task involves analyzing an energy flow diagram in an ecosystem and answering questions related to the food web. The diagram shows a food web with various organisms, including grass, mouse, hawk, snake, and dragonfly. Arrows indicate the direction of energy flow from one organism to another.

#### Key Concepts:
1. Producers: Organisms that produce their own food through photosynthesis (e.g., grass).
2. Consumers:
- Primary Consumers: Organisms that eat producers (e.g., mouse, dragonfly).
- Secondary Consumers: Organisms that eat primary consumers (e.g., snake).
- Tertiary Consumers: Organisms that eat secondary consumers (e.g., hawk).
3. Decomposers: Organisms that break down dead organic matter (not shown in this diagram).

#### Questions to Solve:
1. Which organism in the food web above is a first-level consumer and sustains a second-level consumer?
2. Choose one organism in this food web. Name all the organisms that are in that chain. Start with the producer and end with the top-level consumer.
3. Draw an energy pyramid to show how much food energy is available at each level.

---

Solution:

#### Question 1: Which organism in the food web above is a first-level consumer and sustains a second-level consumer?

- First-Level Consumer: An organism that directly consumes producers (plants). In this food web, the mouse and dragonfly are first-level consumers because they eat grass.
- Second-Level Consumer: An organism that eats first-level consumers. In this food web, the snake eats the mouse, making the mouse a first-level consumer that sustains a second-level consumer (the snake).

Answer: The mouse is a first-level consumer that sustains a second-level consumer (the snake).

---

#### Question 2: Choose one organism in this food web. Name all the organisms that are in that chain. Start with the producer and end with the top-level consumer.

Let's choose the hawk as the top-level consumer and trace the food chain backward:

1. Hawk (top-level consumer) →
2. Snake (secondary consumer) →
3. Mouse (primary consumer) →
4. Grass (producer)

Answer: The food chain starting from the producer and ending with the hawk is: Grass → Mouse → Snake → Hawk.

---

#### Question 3: Draw an energy pyramid to show how much food energy is available at each level.

An energy pyramid illustrates the decrease in available energy as you move up the trophic levels. Typically, only about 10% of the energy at one trophic level is transferred to the next higher level. The rest is lost as heat or used for metabolic processes.

Here’s how to construct the energy pyramid for this food web:

1. Base Level (Producers): Grass. This level has the most energy because it captures sunlight through photosynthesis.
2. Second Level (Primary Consumers): Mouse and Dragonfly. These organisms have less energy than the producers because they consume only a portion of the grass.
3. Third Level (Secondary Consumers): Snake. This level has even less energy because the snake consumes only a portion of the mouse.
4. Fourth Level (Tertiary Consumers): Hawk. This level has the least energy because the hawk consumes only a portion of the snake.

Energy Pyramid Diagram:
```
Hawk (Top-Level Consumer)
|
Snake (Secondary Consumer)
|
Mouse & Dragonfly (Primary Consumers)
|
Grass (Producer)
```

Each level of the pyramid is narrower than the one below it, reflecting the decreasing amount of available energy.

---

Final Answers:

1. The mouse is a first-level consumer that sustains a second-level consumer (the snake).
2. One food chain: Grass → Mouse → Snake → Hawk.
3. Energy Pyramid:
```
Hawk
|
Snake
|
Mouse & Dragonfly
|
Grass
```

Boxed Final Answer:
\[
\boxed{\text{1. Mouse, 2. Grass → Mouse → Snake → Hawk, 3. Energy Pyramid as described}}
\]