Question 15

Anaerobic respiration occurs in bacteria because they inhabit environments with low oxygen levels.

Bacteria are capable of performing anaerobic respiration as they thrive in environments where oxygen is scarce or absent, allowing them to generate energy through alternative metabolic pathways.

A) Animals; they require energy

While animals do require energy, they primarily rely on aerobic respiration, which requires oxygen. Anaerobic respiration can occur in animals, such as during intense exercise, but it is not the primary site of anaerobic respiration as suggested by this option.

B) Plants; they undergo photosynthesis

Plants primarily rely on photosynthesis and aerobic respiration for energy production. Although some plants can undergo anaerobic respiration in waterlogged conditions, this is not their main mode of energy generation, making this option incorrect.

C) Bacteria; they inhabit environments with low oxygen levels

Bacteria are well-known for their ability to perform anaerobic respiration, especially in environments where oxygen levels are low, such as in deep soil or in the intestines of animals. This capability allows them to generate energy without oxygen, making this the correct choice.

D) None of the above

This option is incorrect because bacteria do indeed perform anaerobic respiration in low-oxygen environments, which is a fundamental aspect of their metabolic processes.

Conclusion

The correct answer is C, as it accurately describes the conditions under which anaerobic respiration occurs in bacteria. Options A and B incorrectly attribute anaerobic respiration to animals and plants, respectively, while D dismisses the possibility entirely, which is not accurate. Thus, C stands out as the only correct choice based on the context provided.