UPSC Prelims 2014 · Question 73 of 100
UPSC Prelims 2014 question on Continental Drift Evolution
- ExamUPSC CSE
- Year2014
- PaperGeneral Studies Paper I
- SubjectGeography
- TopicGeomorphology
- DifficultyMedium
- TypeStatement
Which of the following phenomena might have influenced the evolution of organisms?
1. Continental drift
2. Glacial cycles
Select the correct answer using the code given below.
Show answer
Answer: C. Both 1 and 2
Verdict
The answer is both 1 and 2. Continental drift and glacial cycles have each shaped the evolution of organisms.
Analysis
Statement 1 is CORRECT. The break up and reassembly of landmasses separated populations, created new oceans and land bridges, and drove allopatric speciation, which is why marsupials dominate Australia and why related fossil groups appear on now distant continents. Statement 2 is CORRECT. Glacial and interglacial cycles repeatedly shifted climate zones, fragmented habitats into refugia and reconnected them, forcing migration, extinction and divergence.
Source
NCERT Class XI Geography, fundamentals of physical geography.
How to crack it
The stem uses might have influenced, which is deliberately permissive, so the bar for a statement to count is low. Both statements describe large scale, long duration changes in the physical environment, and evolution responds to exactly that. When a two statement question offers two mechanisms of the same kind and the stem is phrased permissively, both 1 and 2 is the natural landing point unless one statement contains a factual error. Look for the error first; if there is none, accept the inclusive option.