Educational worksheet on symbiotic relationships in ecosystems, featuring mutualism, commensalism, and parasitism with illustrations and a color-coding key.

Problem Overview:

The task involves understanding and defining three types of symbiotic relationships: mutualism, commensalism, and parasitism. Additionally, you need to create a key to color the examples based on whether one party benefits, both parties benefit, or one party is harmed.

Step-by-Step Solution:

#### 1. Define Each Symbiotic Relationship
- Mutualism: A relationship where both organisms benefit from each other.
- Commensalism: A relationship where one organism benefits while the other is neither helped nor harmed.
- Parasitism: A relationship where one organism (the parasite) benefits at the expense of the other (the host), which is harmed.

#### 2. Analyze the Images
- Mutualism Image: The image shows a fish cleaning the mouth of a larger fish. This is an example of mutualism because:
- The smaller fish gets food (cleaning waste).
- The larger fish gets its mouth cleaned, which helps maintain its health.
- Commensalism Image: The image shows a bird nesting in a tree. This is an example of commensalism because:
- The bird benefits by using the tree for nesting and protection.
- The tree is neither helped nor harmed by the bird's presence.
- Parasitism Image: The image shows a mosquito biting a human hand. This is an example of parasitism because:
- The mosquito benefits by feeding on the human's blood.
- The human is harmed by the bite, which can cause irritation or transmit diseases.

#### 3. Create the Key
- Negative Gain (Harmed): Color this effect to indicate when one organism is harmed.
- Positive Gain (Benefits): Color this effect to indicate when one or both organisms benefit.
- Zero Gain (Unaffected): Color this effect to indicate when one organism is neither helped nor harmed.

#### 4. Color the Examples
- Mutualism: Both the fish are benefiting, so color both parts positively (e.g., green for "Positive Gain").
- Commensalism: The bird benefits, but the tree is unaffected, so color the bird positively (e.g., green) and the tree neutrally (e.g., gray).
- Parasitism: The mosquito benefits, but the human is harmed, so color the mosquito positively (e.g., green) and the human negatively (e.g., red).

Final Answer:

- Mutualism Definition: Both organisms benefit.
- Commensalism Definition: One organism benefits, and the other is unaffected.
- Parasitism Definition: One organism benefits, and the other is harmed.

Key for Coloring:
- Negative Gain (Harmed): Red
- Positive Gain (Benefits): Green
- Zero Gain (Unaffected): Gray

Colored Examples:
- Mutualism: Fish (both colored green).
- Commensalism: Bird (green), Tree (gray).
- Parasitism: Mosquito (green), Human (red).

Final Answer Box:
\[
\boxed{
\text{Mutualism: Both benefit; Commensalism: One benefits, one is unaffected; Parasitism: One benefits, one is harmed.}
}
\]