Question

The following are some major events in the early history of life:
P. First heterotrophic prokaryotes
Q. First genes
R. First eukaryotes
S. First autotrophic prokaryotes
T. First animals
Which option below places these events in the correct order?
A)P, Q, S, R, T
B)Q, S, R, P, T
C)Q, P, S, R, T
D)Q, S, P, R, T

Answer 1

Biologists claim that all living species on Earth would have one last universal ancestor, so it would be nearly impossible for the many intricate biochemical processes common to all living organisms to be independently formed from two or three different lineages.

Complete answer:
The oldest complex land plants date back to about 850 Ma, from carbon isotopes in Precambrian rocks, although multicellular algae-like land plants date back to around 1 billion years ago, while evidence indicates that the earliest terrestrial habitats were created by microorganisms of at least 2.7 Ga. Microorganisms are believed to have paved the way for the formation in the Ordovician of land plants. Land plants have been so successful that they are presumed to have contributed to the case of the Late Devonian extinction. (The inferred long causal chain appears to include the progress of early tree archaeopteris (1) drew down CO2 levels, contributing to global cooling and lower sea levels, (2) archaeopteris roots encouraged soil growth that enhanced rock weathering, and the resultant run-off of nutrients may have triggered algal blooms resulting in anoxic events that caused die-offs of marine life.

Organisms have evolved from simplified shapes to complicated forms. Hence, first genes, then autotrophic prokaryotes, then heterotrophic prokaryotes, then eukaryotes, and then organisms are the sequence of events.

Hence, the correct answer is option (D)

Note: Around 4.54 billion years old was the earliest meteorite fragments discovered on Earth; this, combined mainly with the dating of ancient lead deposits, placed the approximate age of Earth at about that time. The Moon has the same structure as the crust of the Earth but does not have an iron-rich core like that of the Earth.