Chapter 9, Problem 7STP

Summary Introduction

Introduction:

In living organisms, chemical energy is stored in organic compounds and this energy is converted to other forms of energy. All living organisms need energy to carry out various biological functions.All the chemical reactions in a cell are together called metabolism. There are two metabolic pathways; anabolic pathway and the catabolic pathway. Photosynthesis is anabolic pathway during which energy is stored in organic molecules. Cellular respiration is the catabolic pathway in which organic molecules are broken down to release energy for use by the cell.

Answer to Problem 7STP

Correct answer :

The correct answer is option B. the conversion of ADP to ATP.

Explanation of Solution

Explanation/justification for the correct answer:

Option B. the conversion of ADP to ATP−In living organisms, chemical energy is stored in organic compounds and this energy is converted to other forms of energy. Adenosine triphosphate or ATP is the most important biological molecule that provides chemical energy.ATP is a multipurpose storehouse of chemical energy that can be used by cells in a variety of reactions. An ATP molecule is made of an adenine base, a ribose sugar and three phosphate groups. Energy is stored in the phosphate bond formed when ADP receives a phosphate group and becomes ATP. The conversion of ADP to ATP stores energy for powering cellular activities in organisms.

Hence this is the correct option.

Explanation for incorrect answer:

Option A. the breaking of lipid chains−When lipid chains are broken down by hydrolysis energy is released from fat. In this case energy is not stored for cellular processes. Hence this is not the correct option.

Option C. the synthesization of proteins from RNA codons- When proteins are synthesized from RNA by using the codon sequence as a template, energy is used for the process and not stored for cellular activities. Hence this is not the correct option.

Option D. the transportation of ions across the membrane- Energy is used for transportation of ions across the plasma membrane against the concentration gradient. It is not stored during this process.Hence this is not the correct option.