Respiration is
A. Anabolic and exergonic
B. Anabolic and endergonic
C. Catabolic and exergonic
D. Catabolic and endergonic
anabolic and endergonic
C. Catabolic and exergonic
Respiration is a catabolic process because it involves the breakdown of organic molecules, such as glucose, to produce energy. It is also exergonic, which means it releases energy.
To determine which option is correct, we need to understand the terms used in the question.
1. Anabolic: Anabolic processes convert smaller molecules into larger molecules, usually requiring energy.
2. Catabolic: Catabolic processes break down larger molecules into smaller molecules, usually releasing energy.
3. Exergonic: Exergonic reactions release energy.
4. Endergonic: Endergonic reactions require energy.
Respiration refers to the process by which cells break down glucose and produce ATP (adenosine triphosphate), the energy currency of the cell. It involves two main steps: glycolysis and cellular respiration.
Glycolysis is the initial step in respiration, and it is an anaerobic process (meaning it does not require oxygen). During glycolysis, glucose is broken down into pyruvate, which generates a small amount of ATP.
Cellular respiration occurs in the mitochondria and can be either aerobic or anaerobic (depending on the availability of oxygen). If oxygen is present, cellular respiration includes three main stages: the Krebs cycle, the electron transport chain, and chemiosmosis, which ultimately produce ATP.
Now let's analyze the options:
A. Anabolic and exergonic: Respiration is not an anabolic process because it involves the breakdown (catabolism) of glucose molecules. Additionally, respiration releases energy (through the process of cellular respiration), so it is exergonic. Therefore, option A is incorrect.
B. Anabolic and endergonic: Just like option A, respiration is not an anabolic process. Furthermore, respiration is an energy-releasing process, so it is not endergonic. Therefore, option B is incorrect.
C. Catabolic and exergonic: Respiration involves the breakdown (catabolism) of glucose molecules, making it a catabolic process. Moreover, respiration releases energy through ATP synthesis. Therefore, option C is correct.
D. Catabolic and endergonic: Option D is incorrect because respiration is not an endergonic process, as it releases energy.
Therefore, the correct answer is C. Catabolic and exergonic.