[2026] PTE Academic Reading - Re-order paragraphs

Re-order paragraphs #0091

Re-order paragraphs

The text boxes below are in the wrong order. Arrange them in a correct order by dragging them to the appropriate numbered boxes.

The text boxes in the left panel have been placed in a random order. Restore the original order by dragging the text boxes from the left panel to the right panel. You can also reorder items in the right panel using the ▲▼ buttons.

Source

This composition began to change when early cyanobacteria evolved the ability to perform photosynthesis, releasing oxygen as a metabolic byproduct.

As these oxygen levels rose, the gas reacted with methane and iron before eventually accumulating in the atmosphere and oceans.

Roughly 2.4 billion years ago, Earth's atmosphere underwent a fundamental transformation known as the Great Oxidation Event.

Before this period, the atmosphere was primarily composed of volcanic gases and lacked any significant presence of free oxygen.

This massive geochemical shift ultimately paved the way for the evolution of complex, multicellular life forms that depend on oxygen today.

Target

Drag sentences here →

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Highlights

ID:pt4725175084

Test No:#0091

Difficulty:Hard

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