Name the two major gland types and where each secretes.

• A. Endocrine glands secrete hormones into the bloodstream; exocrine glands secrete onto surfaces or into ducts
• B. Endocrine glands secrete onto surfaces; exocrine glands secrete hormones into the bloodstream
• C. Endocrine glands secrete bile; exocrine glands secrete enzymes
• D. Endocrine glands secrete mucus; exocrine glands secrete hormones

Answer: (A)

The key idea is how glands release their products: endocrine glands send hormones into the bloodstream, while exocrine glands release substances onto body surfaces or into ducts. This distinction is exactly what the statement describes.

Endocrine glands secrete hormones directly into the blood, allowing these signals to travel to distant targets. Exocrine glands, on the other hand, release their products onto surfaces such as skin or mucous membranes, or into ducts that lead to a body surface or organ, like the digestive tract. A helpful example is the pancreas, which has both types: islets of Langerhans release hormones into the blood (endocrine), while pancreatic acinar cells secrete digestive enzymes into the pancreatic duct (exocrine).

Options that mix up where secretions go or what is secreted don’t fit this classification. For instance, bile and mucus are not products described by this endocrine vs. exocrine framework in the same way, and hormones are not secreted onto surfaces or into ducts.