Passage: Geographers analyzed 175 satellite images of ocean colour, which is an indicator of Phytoplankton…
Passage: Geographers analyzed 175 satellite images of ocean colour, which is an indicator of Phytoplankton productivity at the ocean's surface, and found that giant icebergs are responsible for storing up to 20 percent of carbon in the Southern Ocean. The researchers discovered that melting water from giant icebergs which contains iron and other nutrients, supports hitherto unexpectedly high levels of phytoplankton growth.
Based on the above passage, the following assumptions have been made:
1. Giant icebergs have a bearing on primary productivity and food chains of the Southern Ocean.
2. Melting of giant icebergs can produce climate change effects and impact world fisheries.
Which of the assumptions given above is/ are valid?
1 only
2 only
Both 1 and 2
Neither 1 nor 2
Solution
Assumption 1 is valid: melting water from icebergs supports high phytoplankton growth, and phytoplankton form the base of the marine food chain, so icebergs have a bearing on primary productivity and food chains of the Southern Ocean. Assumption 2 is invalid: the passage does not discuss broader climate change effects or impacts on world fisheries; that connection is not established. Hence only assumption 1 is valid. (Vision IAS marks this with an asterisk; the Insights IAS answer key lists this as A/C, since assumption 1's food-chain link is not explicit. The marked answer A is used here.)