Final answer:
The assertion that photosynthesis is the most important metabolic pathway is false since cellular respiration is a metabolic pathway used by both plants and animals, indicating its broader significance across various life forms.
Step-by-step explanation:
The statement regarding photosynthesis being the most important metabolic pathway is FALSE. While photosynthesis is indeed crucial, it is only the primary pathway for photosynthetic organisms such as plants and planktonic algae. These organisms harness solar energy to synthesize carbohydrates, with oxygen being a by-product.
This oxygen is then used by many organisms, including plants and animals, to carry out cellular respiration, a process that breaks down carbon compounds to produce CO2 and ATP.
Hence, cellular respiration is a pathway used by both plants and animals to metabolize carbohydrates, signifying its broad importance across living organisms. Additionally, some organisms rely on anaerobic processes like fermentation to derive energy.
Therefore, while photosynthesis is vital to introducing energy and organic compounds into the biosphere, cellular respiration is equally critical in energy extraction and is used by a wider range of organisms.