Final answer:
Biologically active forms of vitamins are necessary for human health and can be obtained from both animal and plant sources. They are usually inactive until converted by the body into a usable form.
Step-by-step explanation:
Biologically active forms of vitamins are essential for human health and are usually found in both animal and plant sources. They are typically inactive until converted by the body into a usable form. Absorption of vitamins can vary depending on the type of vitamin and the food source. For example, fat-soluble vitamins are absorbed through the intestinal tract with lipids, while water-soluble vitamins are absorbed directly into the bloodstream.