Final answer:
Biological defense mechanisms include mechanical defenses like shells in turtles and thorns in plants, as well as chemical defenses such as toxic compounds produced by foxgloves. Additionally, biological barriers like harmless bacteria in the human body act by occupying space and resources, preventing harmful bacteria from establishing themselves.
Step-by-step explanation:
Biologic Defense Mechanisms in Animals and Plants
Examples of biological defense mechanisms can be observed in both the animal kingdom and in plants. Animals such as the Florida red-bellied turtle (Pseudemys nelsoni) use mechanical defenses like their hard shell to protect against predators. Plants, for instance, use thorns as a mechanical defense to discourage herbivores from consuming them, as is the case with the honey locust tree (Gleditsia triacanthos). Additionally, certain plant species produce secondary plant compounds that are toxic and thus reduce the likelihood of being eaten. A well-known example is the foxglove (Digitalis sp.), which creates compounds such as digitalis that can be harmful when consumed.
Furthermore, there are various types of biological barriers that serve as defense mechanisms within organisms. In humans, a multitude of harmless bacteria occupy the skin and gastrointestinal tract, making the environment unsuitable for pathogenic bacteria by using up essential resources and sometimes altering the pH or releasing toxins.