Final answer:
Secondary compounds in plants are chemicals not essential for basic life processes, serving primarily as a defense against predators. They include alkaloids that can repel or harm herbivores and are used in various ways, including in human medicine. Plants produce them in response to stimuli rather than continuously.
Step-by-step explanation:
Secondary Compounds in Plants
Secondary compounds are chemicals produced by plants that are not directly involved in their growth, development, or reproduction, meaning they are not necessary for the basic metabolic processes such as photosynthesis and respiration.
These compounds often serve as a defense mechanism against predators and can be toxic or lethal if ingested.
Examples of secondary compounds include alkaloids, which can repel predators through unpleasant odors or tastes, and some may even become toxic only after being ingested, such as glycol cyanide in cassava.
Secondary metabolites are produced by plants in response to specific stimuli and are not constantly secreted. They are used in various ways, including plant defense mechanisms against herbivory and parasitism.
For instance, the volatile oils found in mint and sage or the bitterness of quinine deter herbivores, while caffeine can overstimulate and opioids can induce lethargy.
Furthermore, secondary compounds can play a role in human medicine, with many pharmaceutical drugs being derived from plant compounds like digitalis from foxglove or opium from poppies.