National League for Nursing (NLN PAX) Practice Exam

Which adaptation in plants helps prevent water loss?

1. Root system

2. Thick stem

3. Waxy epidermis

4. Deep roots

The correct answer is: Waxy epidermis

The adaptation that helps prevent water loss in plants is the waxy epidermis. The waxy epidermis is a protective outer layer found on the surfaces of leaves and stems. This layer is made of a substance called cutin, which creates a barrier that minimizes water evaporation. The presence of a waxy coating helps to retain moisture inside the plant and is particularly important in environments where water availability may be limited. While options such as a root system, thick stem, and deep roots can contribute to a plant's overall ability to survive in arid conditions, they do not directly limit water loss from the plant's surface to the environment like the waxy epidermis does. The root systems and deep roots primarily serve to absorb water from the soil, and a thick stem can aid in storing water; however, the key feature in preventing evaporation and water loss is the waxy epidermal layer.