AP BIOLOGY

Detailed explanation-1: -Constitutive (continuous) defenses include many preformed barriers such as cell walls, waxy epidermal cuticles, and bark. These substances not only protect the plant from invasion, they also give the plant strength and rigidity.

Detailed explanation-2: -The first line of defense in plants is an intact and impenetrable barrier composed of bark and a waxy cuticle. Both protect plants against herbivores. Other adaptations against herbivores include hard shells, thorns (modified branches), and spines (modified leaves).

Detailed explanation-3: -Examples of physical defenses are thorns on roses and spikes on trees like hawthorn. These physical defenses hurt the herbivores and stop them from eating plants’ stems or leaves.

Detailed explanation-4: -Sclerophylly refers to the hardened leaves, and plays an active role in plant defense against herbivores by reducing the palatability and digestibility of the tissues, thereby, reducing the herbivore damage. Spinescence includes plant structures such as spines, thorns and prickles.