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Here are the solutions to the problems on your worksheet.

Part One: Energy Pyramid

In an energy pyramid, energy starts at 100% at the bottom and decreases as it moves up. The general rule is that only about 10% of the energy is passed from one level to the next (the rest is used for life processes or lost as heat).

Left Side (Energy from Sun):
* Bottom Level (Producers): They get their energy directly from the sun. So, this is 100%.
* 2nd Level (Primary Consumers): They eat the producers. They get 10% of the producer's energy. So, this is 10%.
* 3rd Level (Secondary Consumers): They eat the primary consumers. They get 10% of that level's energy. So, this is 1%.
* Top Level (Tertiary Consumers): They eat the secondary consumers. They get 10% of that level's energy. So, this is 0.1%.

Right Side (Energy Transferred / Available Energy):
The problem states the bottom level has 10,000 kCal. We calculate the levels above by taking 10% of the number below it.

* Bottom Level: 10,000 kCal (Given)
* 2nd Level: $10,000 \times 0.10 =$ 1,000 kCal
* 3rd Level: $1,000 \times 0.10 =$ 100 kCal
* Top Level: $100 \times 0.10 =$ 10 kCal

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Part Two: Organizing a Food Web

To organize this, we look at "What it eats" to determine if it is a Producer (makes its own food) or a Consumer (eats others), and what level of consumer it is.

1. Weeds, Grass: These are plants. They do not eat anything listed; they make energy from the sun.
* Role: Autotroph / Producer
2. Desert Tortoise: Eats Weeds/Grass.
* Role: Heterotroph / Primary Consumer
3. Kangaroo Rat: Eats Weeds/Grass.
* Role: Heterotroph / Primary Consumer
4. Cricket: Eats Weeds/Grass.
* Role: Heterotroph / Primary Consumer
5. Lizards: Eat Crickets (which are primary consumers).
* Role: Heterotroph / Secondary Consumer
6. Rattlesnake: Eats Lizards (secondary) and Kangaroo rats (primary). Since it eats a secondary consumer, it acts as a Tertiary consumer here.
* Role: Heterotroph / Tertiary Consumer (also Secondary)
7. Hawk: Eats Lizards, Rattlesnakes, and Kangaroo rats. Since it eats Rattlesnakes (tertiary), the Hawk is at the top.
* Role: Heterotroph / Quaternary Consumer (also Tertiary and Secondary)

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Part Three: Thinking Critically

1. Arrange organisms in the pyramid:
We need to order them by who eats whom:
* Grass is the producer (Bottom).
* Cricket eats grass (2nd level).
* Lizard eats crickets (3rd level).
* Hawk eats lizards (Top level).

a. Which organism has the biggest population?
In an ecosystem, the producers (plants) always have the largest population because they support all the other animals.
* Answer: Grass

b. Which organism has the smallest population?
The animals at the very top of the food chain require the most energy to survive, so there are fewer of them.
* Answer: Hawk

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Final Answer:

Part One: Energy Pyramid Labels

* Left Side (Percentages from Sun):
* Top: 0.1%
* Middle-Top: 1%
* Middle-Bottom: 10%
* Bottom: 100%
* Right Side (Energy Transferred):
* Top: 10 kCal
* Middle-Top: 100 kCal
* Middle-Bottom: 1,000 kCal
* Bottom: 10,000 kCal

Part Two: Organism Roles

* Weeds, Grass: Autotroph, Producer
* Desert Tortoise: Heterotroph, Primary Consumer
* Kangaroo Rat: Heterotroph, Primary Consumer
* Cricket: Heterotroph, Primary Consumer
* Lizards: Heterotroph, Secondary Consumer
* Hawk: Heterotroph, Tertiary/Quaternary Consumer
* Rattlesnake: Heterotroph, Tertiary Consumer

Part Three: Critical Thinking

* Pyramid Order (Bottom to Top): Grass $\rightarrow$ Cricket $\rightarrow$ Lizard $\rightarrow$ Hawk
* a. Biggest Population: Grass
* b. Smallest Population: Hawk