Question

In all vertebrate animals, the digestive tract is ventral to the vertebral column and always includes a liver and pancreas as the major digestive glands. This is a feature in support of:

• A. Analogous organs
• B. Homologous organs
• C. Differential organs
• D. Converging organs

Answer 1

Answer: (B)

Homologous organs

Homologous organs are adapted to perform different functions and have different appearance but share common basic structural plan and origin. Evolution of organisms in different directions from a common ancestry is known as divergent evolution. Homologous organs exhibit divergent evolution. The whole digestive tract except mouth, pharynx and rectum are derived from endoderm, the innermost germ layer. Likewise, all digestive glands that open into digestive tract are also derived from endoderm. Thus, digestive tract (digestion), liver (bile secretion and production of plasma proteins) and pancreas (serve as both exocrine and endocrine gland) have common origin but are functionally differentiated to serve in different functions. These are examples of homologous organs.

Therefore, the correct answer is option B.