Chapter 5, Problem 1TQ

Summary Introduction

Metabolism is the biological process in the living system which constitutes the anabolism and catabolism as its integral part. Construction of energy rich biomolecules from organic source is said to be anabolism. Destruction of organic molecule that result in liberation of heat and energy is said to be catabolism.

Answer to Problem 1TQ

Metabolic pathway is often characterized as a sequence of multiple reactions, like anabolism and catabolism.

Therefore, option (c) is correct.

Explanation of Solution

Justify reasons for the correct statement:

Metabolic pathways include number of chemical reactions that are linked to each other at various stages in a cell. The metabolic reactions are arranged into a multistep sequence of chemical reactions. In this multistep sequence of chemical reactions, product of one metabolic pathway is substrate for other.

Option (c) is given as “are often organized as a multistep sequence of reactions”.

Hence, option (c) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “always break down large molecule into smaller units”.

Catabolism is the reaction in which larger molecules get converted into simpler molecules, or the molecules in their polymer forms are getting converted into their monomeric units. Hence, it is a wrong answer.

Option (b) is given as “only link smaller molecules together to create polymers”.

Anabolism is the reaction in which simpler molecules are linked together to form macromolecules. For example, simple amino acids are linked together to form peptide or larger proteins. Hence, it is a wrong answer.

Option (d) is given as “occur only in mitochondria”.

Metabolic pathways occur in the cell cytoplasm and the energy oxidation process alone takes place inside mitochondria.  Hence, it is a wrong answer.

Hence, options (a), (b), and (d) are incorrect.

Conclusion

Metabolic pathway is an essential process in all living forms for energy production and building machinery. Any life form cannot exist without metabolic pathways.