Question

Catabolic and anabolic pathways are often coupled in the cell because
(a) Both the paths have the same energy.
(b) The free energy released from one pathway is used to drive another.
(c) The intermediates of a catabolic pathway are used in the anabolic pathway.
(d) Their enzymes are controlled by their activators and inhibitors.

Answer 1

These two processes together constitute the entire process of metabolism in which there exists a mutual relationship between both the pathways in such a way that the absence of one process will also disturb another.

Complete answer:
Catabolic and anabolic pathways are often coupled in the cell because the free energy released from one pathway is used to drive another. The catabolic pathway is a pathway through which energy is released by breaking down complex molecules or compounds into simpler ones. The anabolic pathway is the pathway through which large molecules or compounds are synthesized by the use of energy released through the catabolic pathway. So, to maintain the energy balance of the cells both the catabolic and the anabolic pathways are required.
The energy required by the process of anabolism is fulfilled by the energy released by the process of catabolism.
The catabolic pathway releases energy in the form of ATP by the breakdown of complex molecules.
In the anabolic pathway energy in the form of ATP is used for the synthesis of large molecules or compounds.
The catabolic pathway includes glycolysis, the citric acid cycle, the breakdown of muscle protein to use amino acids as substrates for gluconeogenesis, the breakdown of fat in adipose tissue to fatty acids, and oxidative deamination of neurotransmitters by monoamine oxidase.
Cortisol, glucagon, and adrenaline are the classic catabolic hormones known since the early 20th century.

Hence, the correct answer is option (b).

Note:
In catabolism, large molecules such as polysaccharides, lipids, nucleic acids, and proteins break into smaller units such as monosaccharides, fatty acids, nucleotides, and amino acids, respectively.
The catabolic processes are oxidation processes which involve the release of free energy, some of which is lost as heat, but the rest of which is used to drive the synthesis of adenosine triphosphate (ATP).
The synthesis of molecules from the smaller components with a series of biochemical reactions is known as anabolism.