Chapter 39, Problem 1SQ

Summary Introduction

Introduction: Most animals consume large and complex foods. Large food particles are broken down into smaller monomers in such a form that can be circulated to every cell throughout the body. These functions are carried out by a set of specialized structure present in an organism called as digestive system. Most of the organism undergoes extracellular digestion. Four tasks are mainly carried out by the digestive system: ingestion, digestion, absorption, and elimination.

Answer to Problem 1SQ

Correct answer: A digestive system functions in order to secrete enzymes, absorb compounds, and eliminate wastes.

Hence, the correct answer is option d.

Explanation of Solution

Reason for correct answer: Digestion of food material starts at the point of the food consumption itself. Varied enzymes are released to break down the food to simpler form. The larger and complex macromolecules are converted to simpler absorbable form. Then, the nutrients are absorbed to respective structures and circulated throughout the body of the organism. At the end of the digestive process, the undigested and unabsorbed materials are expelled out of the organism.

Option d. is given as “all of the above”. This is correct because the digestive system performs all the given functions. It secretes enzymes, absorbs compounds, and also helps in excreting toxic compounds out of the body.

Hence, the correct answer is option d.

Reasons for incorrect answer:

Option a. is given as “secreting enzymes”. Digestive system secretes a series of enzymes called as digestive enzymes that help to break down the complex macromolecules into simpler monomers. But this is incorrect because secreting enzyme is only one of the functions performed by the digestive system. Hence, the correct answer is option a.

Option b. is given as “absorbing compounds”. A digestive system functions as absorbing compounds. Digestion of complex molecules gives small monomers. While passing through the walls of the digestive organ, it gets absorbed to the internal environment of the organism. But this is incorrect because they also perform other functions like secreting enzyme and eliminating waste. Hence, option b.  is incorrect.

Option c. is given as “eliminating wastes”. The waste materials that are not digested and absorbed are eliminated by the body. This is incorrect as the digestive system is also involved in other functions. After only digestion and absorption, the elimination step can be carried out. Hence, option c. is incorrect.

Hence, the options a., b., and c. are incorrect.

Conclusion

A digestive system functions in secreting different enzymes to digest the food, absorption of nutrient compounds into the cells, and eliminating wastes out of the body.