Chapter 3, Problem 1TYK

Which functional group has a double bond and forms organic acids?

a. carboxyl

b. amino

c. hydroxyl

d. carbonyl

e. sulfhydryl

Summary Introduction

Introduction:

Biomolecules are the organic compounds that form carbohydrates, lipids, proteins, and nucleic acids. They are called so because these molecules are essential for the survival of living organisms. The common functional groups present in biomolecules are $\text{OH}$ (hydroxyl), $\text{C=O}$ (carbonyl), $\text{C}=\text{O and OH}$ together (carboxylic acids), ${\text{NH}}_2$ (amino), ${\text{PO}}_{\text{4}}{}^{\text{3-}}$ (phosphate) and $\text{SH}$ (sulfhydryl).

Answer to Problem 1TYK

Correct answer:

Carboxyl group contains a double bond and forms organic acid.

Explanation of Solution

Justification for the correct answer:

Option (a) is carboxyl. The group that contains a double bond and forms organic acids is the carboxyl group. The organic acids are carboxylic acids and this functional group contains a double bond between carbon and oxygen. The carboxyl group is present in fatty acids (lipids). Hence, option (a) is correct.

Justification for the incorrect answers:

Option (b) is amino. The amino group is ${\text{NH}}_2$. It neither has a double bond nor does it form acids. It has two hydrogen atoms attached to nitrogen. So, it is an incorrect option.

Option (c) is hydroxyl group. The hydroxyl group is $\text{OH}$. It has one single bond, which is between oxygen and a hydrogen atom. So, it is an incorrect option.

Option (d) is carbonyl. The carbonyl group is $\text{C}=\text{O}$. It has a double bond but it does not form acids, rather it is a part of sugars. So, it is an incorrect option.

Option (e) is sulfhydryl. The sulfhydryl group is $\text{SH}$. It has a single bond present between sulfur and hydrogen. So, it is an incorrect option.

Hence, options, (b), (c), (d) and (e) are incorrect.

Conclusion

Therefore, it can be concluded that a group that contains double bond and forms organic acids is the carboxyl group. The organic acids formed are known as carboxylic acids. It is also present in fatty acids (lipids).