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May 2025 Section II

0/34 marks

2025 · 6 questions · 32 parts · 34 marks

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1(A)1(B)(i)1(B)(ii)1(B)(iii)1(C)(i)1(C)(ii)1(C)(iii)1(D)(i)1(D)(ii)2(A)2(B)(i)2(B)(ii)2(C)(i)2(C)(ii)2(D)(i)2(D)(ii)3(A)3(B)3(C)3(D)4(A)4(B)4(C)4(D)5(A)5(B)5(C)5(D)6(A)6(B)6(C)6(D)

Context for question 4

Twenty million years ago the Caribbean Sea and Pacific Ocean were connected, and water flowed freely between the two bodies of water. Many of the same marine species were found in both areas. Over millions of years, the land referred to as the Isthmus of Panama formed, eventually closing off the connection between the Caribbean Sea and Pacific Ocean and creating two separate bodies of water. The ecology of these two marine habitats was dramatically altered by this land formation. The warmer Caribbean water could no longer flow west, so the Pacific water cooled and became more nutrient-rich, while the Caribbean water became warmer.

4(A)Natural Selection, Genetic Drift and Hardy-WeinbergEasy1 mark

Describe the genetic evidence that evolution is occurring in a population.

4(B)Evidence for Evolution, Speciation and ExtinctionEasy1 mark

Explain how the isolation of marine species by the formation of a land barrier can lead to divergent evolution of those species. The formation of the Isthmus of Panama connected two continents, North America and South America. Many North American land animal species migrated to South America after the formation of the isthmus and occupied similar niches as South American species.

4(C)Ecosystems, Populations and SuccessionEasy1 mark

Predict the effect the formation of the isthmus had on resource availability for South American species.

4(D)Ecosystems, Populations and SuccessionMedium1 mark

Justify your prediction in part C.