Dichotomous Keys | Cambridge IGCSE Biology - Tutopiya - Free Printable

Problem Description:

The image provided is a dichotomous key used to identify different insect species. A dichotomous key is a tool that helps in identifying organisms by presenting a series of choices between two characteristics at each step. The goal is to use the key to identify an insect based on its physical features.

Solution Approach:

To solve the problem using the dichotomous key, we need to follow the steps systematically by answering the questions presented at each node. Let’s break it down:

#### Step 1: Start with the main category.
The key begins with the category "Insects."

#### Step 2: Choose between "Large Wings" and "Small or no wings."
- If the insect has large wings, it is identified as a Butterfly.
- If the insect has small or no wings, proceed to the next set of options.

#### Step 3: For insects with "Small or no wings," choose between "Very long rear legs" and "Short rear legs."
- If the insect has very long rear legs, proceed to the next set of options.
- If the insect has short rear legs, proceed to the next set of options.

#### Step 4: For insects with "Very long rear legs," choose between "Antennae in front of head" and "Antennae to the rear."
- If the insect has antennae in front of the head, it is identified as a Mosquito.
- If the insect has antennae to the rear, it is identified as a Grass Hopper.

#### Step 5: For insects with "Short rear legs," choose between "Horned head" and "Not horned head."
- If the insect has a horned head, proceed to the next set of options.
- If the insect does not have a horned head, proceed to the next set of options.

#### Step 6: For insects with "Horned head," choose between "Small eyes" and "Large eyes."
- If the insect has small eyes, it is identified as a Termite (soldier).
- If the insect has large eyes, it is identified as a Beetle.

Example Walkthrough:

Let’s identify an insect using this key. Suppose we are given an insect with the following characteristics:
- Small or no wings
- Short rear legs
- Horned head
- Large eyes

#### Step-by-Step Identification:
1. The insect has small or no wings, so we move to the "Small or no wings" branch.
2. The insect has short rear legs, so we move to the "Short rear legs" branch.
3. The insect has a horned head, so we move to the "Horned head" branch.
4. The insect has large eyes, so we identify it as a Beetle.

Final Answer:

Using the dichotomous key, the insect with the given characteristics is identified as a Beetle.

$$
\boxed{\text{Beetle}}
$$

This methodical approach ensures accurate identification by systematically eliminating options based on observable characteristics.