Chapter 24, Problem 18A

Summary Introduction

Introduction:

Animal body plans with bilateral symmetry include the gut, which is either a sac within the body or a tube flowing through the body, where food is digested. A saclike gut has one opening i.e. a mouth for food intake and waste disposal. A tube-like gut has a mouth and anus opening at both sides, and is a complete digestive organ.

Answer to Problem 18A

Correct answer :

The correct answer is option (C) feeding

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) feeding. In the evolution, the coelom was a central adaptation in developing larger, more specialized body structures. Specialized organs and body systems that created from mesoderm form in the coelom. The organ systems that may evolve are circulatory system, muscular system and become more active by increasing in size. Therefore, feeding cannot be evolved as it neither an organ nor a body system, it is just a process. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) circulation. In the evolution, the coelom was a central adaptation in developing larger, more specialized body structures. Specialized organs and body systems that created from mesoderm form in the coelom. Circulatory system is a body system that can evolve. So, this is an incorrect option.

Option (B) movement. In the evolution, the coelom was a central adaptation in developing larger, more specialized body structures. Specialized organs and body systems that created from mesoderm form in the coelom. Muscular system is a body system that can evolve due to which animals can become more active i.e., in movement. So, this is an incorrect answer.

Option (D) muscular system. In the evolution, the coelom was a central adaptation in developing larger, more specialized body structures. Specialized organs and body systems that created from mesoderm form in the coelom. Muscular system is a body system that can evolve. So, this is an incorrect answer.

Conclusion

The evolution of an internal body cavity had adaptive advantage in all except in feeding. Hence, the correct answer is Option (C) feeding