Which term describes the protective barriers created by certain plants against pests?

The term that describes the protective barriers created by certain plants against pests is known as physical defenses. These defenses refer to the structural adaptations of plants that deter herbivores and other pests. Examples of physical defenses include thorns, spines, tough leaves, or husks that physically obstruct or harm the pests trying to feed on the plant. These adaptations make it more challenging for pests to access the plant's tissues, thus providing a form of protection without relying on chemicals or behaviors.

In contrast, chemical defenses involve the production of toxic compounds that can deter pests or reduce their ability to feed, while behavioral defenses pertain to actions taken by animals to avoid threats or attack. Biological defenses involve interactions with other organisms, such as recruiting predators or parasites of the pests. While all these strategies can be effective, physical defenses specifically refer to the tangible, structural attributes of the plants that offer direct protection against pest damage.