In the absence of an external source of water, the kangaroo rot in North American deserts is capable of meeting all its water requirements through

Options

A. internal carbohydrate oxidation.
B. internal fat oxidatin.
C. internal protein oxidation.
D. Both (B) and (C)

Answer

To solve the question regarding how kangaroo rats in North American deserts meet their water requirements in the absence of an external water source, we can break it down step by step:

### Step 1: Understand the Environment
Kangaroo rats live in arid desert environments where water is scarce. They have adapted to survive without drinking water directly from external sources.

**Hint:** Consider the adaptations of animals living in extreme environments.

### Step 2: Identify the Source of Water
Kangaroo rats can meet their water needs through metabolic processes. Specifically, they rely on the oxidation of stored nutrients in their bodies.

**Hint:** Think about how animals can derive water from the food they consume or from their own body reserves.

### Step 3: Determine the Type of Oxidation
Among the nutrients that can be oxidized, fats, carbohydrates, and proteins can all produce water as a by-product. However, in the case of kangaroo rats, fat oxidation is the primary source.

**Hint:** Recall which macromolecule yields the most water when oxidized.

### Step 4: Conclusion
The oxidation of fat in the kangaroo rat's body leads to the production of water, which helps them meet their hydration needs. This process allows them to concentrate their urine and minimize water loss.

**Final Answer:** The kangaroo rat in North American deserts meets all its water requirements through **internal fat oxidation**.

### Summary of Steps:
1. Understand the desert environment and the need for water.
2. Identify that kangaroo rats derive water from metabolic processes.
3. Recognize that fat oxidation is the key process for water production.
4. Conclude that internal fat oxidation is how they meet their water needs.