Question

Which of the following statements is false?

विकल्प

• First living cells were prokaryotes.

• Cyclic pathway of photosynthesis first appeared in some eubacterial species.

• Oxygen began accumulating in the atmosphere after the noncyclic pathway of photosynthesis evolved.

• In the Proterozoic, increasing levels of atmospheric oxygen enhanced the spontaneous formation of organic molecules.

Answer 1

In the Proterozoic, increasing levels of atmospheric oxygen enhanced the spontaneous formation of organic molecules.

Explanation:

Before the rise of atmospheric oxygen, the Earth’s atmosphere was reducing, which favored the spontaneous formation of complex organic molecules. This reducing environment allowed organic molecules to form and accumulate without being broken down. However, with the evolution of photosynthetic organisms (such as cyanobacteria), oxygen began to accumulate in the atmosphere, turning it oxidizing rather than reducing.