The skin is an example of a non-specific defense.
For example, bacteria or diseases have trouble entering a healthy person's skin because it is formed by closely packed cells with multiple layers and a substance called keratin that protects is.
On the other hand, the immune system is a specific defense mechanism.
When bacteria is able to enter the body in cases of fever for example, the immune system is activate and sends out protector cells such as the white blood cells to combat infection.
Answer: C. Black snakes will not prey on cane toads in areas where cane toads have been present for 40–60 years.
Explanation:
Cane toad secret a toxin called bufotoxin which is a defense mechanism against predators. These defense mechanism is capable of killing black snakes if they eat cane toads. Within a period of 40 to 60 years, the black snakes in these area will be aware of the presence of a toxin capable of killing them in cane toads and will not prey on them. This phenomenon is termed learned behavioral adaptation.
