Igcse Model Questions Vol1 2025 Biology Question 25

Practice objective / multiple choice question 25 from the 2025 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2025 Biology Objective / Multiple Choice Hard Difficulty
Question 25 IGCSE_MODEL_QUESTIONS_VOL1 • 2025 • BIOLOGY • objective

Two species of birds differ by 5 % in their mitochondrial DNA sequences. The molecular clock for this gene is 1 % sequence divergence per million years per lineage. (a) Estimate the time since the two species diverged. (b) A third species differs by 7 % from the first species. Has this third species diverged earlier or later than the second species? Justify your answer.

Answer Options

Correct Answer A. a) 2.5 million years; b) earlier (the third species diverged about 3.5 million years ago)
B. a) 5 million years; b) later (the third species diverged about 2.5 million years ago)
C. a) 2.0 million years; b) earlier (the third species diverged about 4.0 million years ago)
D. a) 3.0 million years; b) earlier (the third species diverged about 2.5 million years ago)
Correct Answer
A
Correct Option:
a) 2.5 million years; b) earlier (the third species diverged about 3.5 million years ago)

About This Question

This is Igcse Model Questions Vol1 2025 Biology Question 25. It is one of the objective questions from the 2025 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Hard .

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