Questions 1–5.

Questions 6–10. Select the TWO correct answer choices.

Questions 11–15 are based on the passage below.

Peer review of the fossil record has repeatedly confirmed that whales descend from land-dwelling, four-legged mammals, a conclusion that seemed almost absurd when first proposed but is now supported by an unusually complete transitional sequence. Pakicetus, one of the earliest known whale ancestors, resembled a wolf-sized land mammal with functional legs, yet its inner ear already showed specialized structures found only in whales, hinting at an aquatic lifestyle despite its terrestrial build. Later forms such as Ambulocetus retained limbs capable of walking but show clear adaptations for swimming, including a flexible spine suited to an otter-like undulating stroke. By the time of Dorudon, some ten million years after Pakicetus, the hind limbs had shrunk to tiny, functionally useless nubs, fully external evidence of an internal skeleton no longer needed for locomotion but not yet eliminated by natural selection. Modern whales retain these vestigial pelvic bones as a genetic echo of that transition, floating disconnected within their body wall, evolution's incomplete erasure of a body plan its owners no longer require.

Questions 16–20 are based on the passage below.

The peppered moth, long a textbook illustration of natural selection in action, tells a more complicated story than most introductory accounts suggest. During Britain's Industrial Revolution, soot-darkened tree bark is said to have favored a rare dark-colored ("melanic") variant of the moth over the common pale form, since the dark moths were better camouflaged against predatory birds; as pollution controls later cleaned the air, pale moths regained their advantage and the population reverted. This account, while broadly correct, drew renewed scrutiny in the 1990s and 2000s after critics noted that the classic photographs supporting it had been staged, with dead moths pinned to tree trunks rather than photographed in natural resting positions. Skeptics seized on this methodological lapse to question the entire phenomenon, and some popular accounts wrongly concluded that natural selection itself had been undermined. Careful field studies conducted since then, using live moths and rigorous protocols, have in fact reaffirmed the core finding: bird predation does vary with camouflage against different bark colors, and moth populations did shift in the predicted direction as pollution levels changed. The lesson is not that the peppered moth story was false, but that even well-supported findings deserve the same scrutiny of their evidentiary basis as more contested ones — a lapse in illustration does not invalidate an underlying mechanism confirmed by independent methods.