Question

In which one of the following geological periods did the first land plants appear?
A) Precambrian
B) Permian
C) Silurian
D) Carboniferous

Answer 1

Hint: The geological periods largely represent the natural patterns and changes that have occurred throughout Earth's history. Victorian geologists realised that diverse fossil assemblages characterised successive stratal successions: past biological dynasties, if you will. The geological Periods are classified further into Epochs and Ages. Most day-to-day practical time-slicing is still done using fossils at the highest levels.

Complete answer:
The Precambrian is the oldest of the geologic ages, which are distinguished by sedimentary rock layers. These rock strata, which have been laid down over millions of years, hold a permanent record of the Earth's past, including petrified remnants of plants and animals that were buried when the sediments were produced.

When life began, the Earth had already been around for around 600 million years. The planet had cooled from its molten condition, resulting in a solid crust and oceans formed by water vapour in the atmosphere. Many scientists believe that these primordial seas gave origin to life by acting as catalysts for chemical processes over the surface of small water bubbles, with hot, mineral-rich volcanic vents functioning as catalysts.

Other bubbles, by drawing molecules from their surroundings, are supposed to have generated self-replicating compounds. Over time, the two merged to form living cells that use energy.

Therefore the correct answer is option ‘A’.

Note: Microscopic bacteria were the first living species, appearing in the fossil record as early as 3.4 billion years ago. Bacteria sought an alternative energy source when their numbers grew and stocks of their chemical fuel were depleted.