Final answer:
Aerobic cellular respiration is essential because it produces a high amount of ATP, a critical energy unit. Alternatives such as anaerobic respiration and fermentation exist but are less efficient. These processes enable survival in low-oxygen environments and are vital for complex life forms.
Step-by-step explanation:
Aerobic cellular respiration is crucial for organisms because it generates a high yield of ATP, which is the primary energy currency of the cell, from glucose and oxygen. Lizards and other organisms have some alternative metabolic strategies if aerobic respiration is impaired, such as anaerobic respiration or fermentation. These alternatives generate ATP without oxygen but are less efficient and produce less energy than aerobic respiration. Nonetheless, they can be crucial for survival in environments where oxygen is scarce.
Coming to the evolution of photosynthesis before aerobic respiration, it is believed that photosynthesis evolved first because it provided the oxygen which was a prerequisite for the evolution of aerobic cellular respiration. Carnivores like lions depend on photosynthesis because it is the starting point of the food chain, producing the biomass that ultimately feeds herbivores, which in turn are prey for the carnivores. Photosynthesis and cellular respiration are interdependent, as photosynthesis releases oxygen and produces glucose required for respiration, while respiration releases carbon dioxide needed for photosynthesis.
The importance of aerobic respiration can also be seen in how it may have driven the evolution of complex multicellular life due to its high energy output. Glycolysis, which evolved earlier, is a common step in both aerobic and anaerobic respiration and enables cells to generate small amounts of ATP without oxygen — an essential function for survival under anaerobic conditions.