APTI PLUS Academy For Civil Services

Statement 2 is Correct: Article 118(4) provides that the Speaker of the Lok Sabha presides over a joint sitting; in the Speaker's absence, the Deputy Speaker presides, and if the Deputy Speaker is also absent, the Deputy Chairman of the Rajya Sabha presides (the Chairman of the Rajya Sabha / Vice-President never presides because they are not a member of either House).
Statement 3 is Incorrect: The mechanism of joint sitting is applicable only to Ordinary Bills and Financial Bills; it is explicitly not available for Money Bills (where Rajya Sabha has only 14 days' recommendatory power) or Constitutional Amendment Bills under Article 368 (which must be passed separately by each House by a special majority).

Q4. With reference to Ecological Succession and pioneer communities, consider the following statements:
1. Primary ecological succession occurs on newly formed, sterile substrate where no biological community previously existed.
2. Lichens and mosses typically serve as the pioneer species in primary xerarch succession on bare rock surfaces.
3. Secondary ecological succession proceeds much more slowly than primary succession due to the complete lack of organic soil.
Which of the statements given above are correct?
(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2, and 3

Answer: (b)
Explanation:
Statement 1 is Correct: Primary succession takes place on barren, newly exposed terrestrial or aquatic sites where no vegetative cover or organic soil layer previously existed, such as newly cooled lava flows, newly formed sand dunes, or retreat zones of glaciers.
Statement 2 is Correct: In primary succession on bare rock (xerarch succession), crustose lichens act as pioneer species by secreting organic acids that weather the mineral rock face, accumulating organic matter and dust that enable hardy mosses and grasses to take root.
Statement 3 is Incorrect: Secondary succession occurs on areas where an established biological community was disturbed or destroyed (e.g., by forest fires, floods, or abandoned agricultural fields) but where biologically viable soil, organic nutrients, and seeds or underground propagules persist; consequently, secondary succession establishes much FASTER than primary succession.

Q5. Consider the following statements regarding the Continental Drift Theory and Plate Tectonics:
1. Alfred Wegener proposed that all continents were once assembled into a single supercontinent called Pangea, surrounded by the ocean Panthalassa.
2. Wegener cited the presence of identical Glossopteris plant fossils across South America, Africa, India, Australia, and Antarctica as evidence of continental drift.
3. Modern plate tectonics asserts that continental masses move across a static, non-convecting liquid outer core.
Which of the statements given above are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1, 2, and 3

Answer: (c)
Explanation:
Statement 1 is Correct: In 1912, German meteorologist Alfred Wegener postulated the Continental Drift Theory, proposing that during the late Paleozoic era, all landmasses formed a singular supercontinent named Pangea ('all earth'), surrounded by an immense universal ocean called Panthalassa ('all water').
Statement 2 is Correct: Wegener provided paleobiological evidence including the widespread distribution of identical fossils of the seed-fern Glossopteris and the reptile Mesosaurus across fragmented continents of Gondwanaland (South America, Africa, Madagascar, India, Australia, and Antarctica), which could not have crossed open oceanic expanses.
Statement 3 is Incorrect: Plate Tectonics theory demonstrates that rigid lithospheric plates (crust and uppermost solid mantle) float and move horizontally over the ductile, semi-fluid asthenosphere in the upper mantle; their motion is driven by thermal convection currents generated by radioactive decay in the mantle (not movement over the liquid outer core).

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