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(B) Describe the history of life on Earth Explanation: The Geological Time Scale is primarily used to divide Earth's history into distinct intervals and describe the evolution of life forms that have existed on Earth.

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(B) Mesozoic Era Explanation: The Mesozoic Era, which lasted from approximately 252 to 66 million years ago, is often referred to as the "Age of Reptiles" because it witnessed the dominance and diversification of reptiles, including dinosaurs.

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(C) Eocene Epoch Explanation: The Eocene Epoch, which occurred between 56 and 33.9 million years ago, is known for the emergence of early primates, such as the ancestors of lemurs and tarsiers.

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(A) The extinction of the dinosaurs Explanation: The boundary between the Cretaceous and Paleogene periods, known as the K-Pg boundary, is defined by a mass extinction event that led to the extinction of the dinosaurs and many other species.

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(A) Eon Explanation: An eon is the largest division of geological time. It represents a major span of Earth's history and is subdivided into eras, periods, and epochs.

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(B) The appearance of the first multicellular organisms Explanation: The Cambrian Explosion, which occurred around 541 million years ago, refers to a rapid diversification and appearance of various complex multicellular organisms in the fossil record.

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(A) The diversification of mammals Explanation: The Quaternary Period, which began approximately 2.6 million years ago and continues to the present, is characterized by the diversification and success of mammals, including humans.

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(D) The Permian-Triassic mass extinction Explanation: The boundary between the Paleozoic and Mesozoic eras is defined by the Permian-Triassic mass extinction, which was one of the most significant extinction events in Earth's history, resulting in the loss of about 96% of marine species.

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(A) Complex life forms Explanation: The Proterozoic Eon, which spanned from approximately 2.5 billion to 541 million years ago, witnessed the emergence and diversification of complex life forms, including the first multicellular organisms.

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(D) 90% Explanation: The Precambrian Era encompasses the vast majority of Earth's history, representing about 90% of the geological time scale, extending from the formation of Earth around 4.6 billion years ago to the beginning of the Cambrian Period.

Question 1

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Accepted Answer

(B) Describe the history of life on Earth
Explanation: The Geological Time Scale is primarily used to divide Earth's history into distinct intervals and describe the evolution of life forms that have existed on Earth.

Question 2

Answer

Accepted Answer

(B) Mesozoic Era
Explanation: The Mesozoic Era, which lasted from approximately 252 to 66 million years ago, is often referred to as the "Age of Reptiles" because it witnessed the dominance and diversification of reptiles, including dinosaurs.

Question 3

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(C) Eocene Epoch
Explanation: The Eocene Epoch, which occurred between 56 and 33.9 million years ago, is known for the emergence of early primates, such as the ancestors of lemurs and tarsiers.

Question 4

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Accepted Answer

(A) The extinction of the dinosaurs
Explanation: The boundary between the Cretaceous and Paleogene periods, known as the K-Pg boundary, is defined by a mass extinction event that led to the extinction of the dinosaurs and many other species.

Question 5

Answer

Accepted Answer

(A) Eon
Explanation: An eon is the largest division of geological time. It represents a major span of Earth's history and is subdivided into eras, periods, and epochs.

Question 6

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Accepted Answer

(B) The appearance of the first multicellular organisms
Explanation: The Cambrian Explosion, which occurred around 541 million years ago, refers to a rapid diversification and appearance of various complex multicellular organisms in the fossil record.

Question 7

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Accepted Answer

(A) The diversification of mammals
Explanation: The Quaternary Period, which began approximately 2.6 million years ago and continues to the present, is characterized by the diversification and success of mammals, including humans.

Question 8

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Accepted Answer

(D) The Permian-Triassic mass extinction
Explanation: The boundary between the Paleozoic and Mesozoic eras is defined by the Permian-Triassic mass extinction, which was one of the most significant extinction events in Earth's history, resulting in the loss of about 96% of marine species.

Question 9

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Accepted Answer

(A) Complex life forms
Explanation: The Proterozoic Eon, which spanned from approximately 2.5 billion to 541 million years ago, witnessed the emergence and diversification of complex life forms, including the first multicellular organisms.

Question 10

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Accepted Answer

(D) 90%
Explanation: The Precambrian Era encompasses the vast majority of Earth's history, representing about 90% of the geological time scale, extending from the formation of Earth around 4.6 billion years ago to the beginning of the Cambrian Period.

Question 11

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(C) Cenozoic Era
Explanation: The formation of the Himalayan mountain range took place during the Cenozoic Era, specifically in the Tertiary Period.

Question 12

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(A) Paleozoic Era
Explanation: The first appearance of abundant complex life forms, including trilobites, is characteristic of the Paleozoic Era.

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(B) Archean Eon
Explanation: The "Great Oxidation Event" occurred during the Archean Eon, leading to the rise of atmospheric oxygen.

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(B) Cretaceous Period
Explanation: The extinction of the non-avian dinosaurs occurred at the end of the Cretaceous Period, precisely at the Cretaceous-Paleogene (K-Pg) boundary.

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(B) Pleistocene Epoch
Explanation: The "Ice Age" that occurred approximately 2.6 million years ago is part of the Pleistocene Epoch.

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(A) Pleistocene Epoch
Explanation: The first appearance of humans (genus Homo) falls within the Pleistocene Epoch.

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(A) Permian Period
Explanation: The largest mass extinction in Earth's history occurred at the end of the Permian Period and is known as the Permian-Triassic mass extinction.

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(D) The first appearance of mammals
Explanation: The boundary between the Paleogene and Neogene periods is marked by the first appearance of mammals.

Question 19

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(C) Periods of extreme glaciation in the past
Explanation: The "Snowball Earth" hypothesis proposes that Earth experienced prolonged periods of extreme glaciation in the past.

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(D) Holocene and Pleistocene
Explanation: The Quaternary Period is divided into the Pleistocene Epoch and the Holocene Epoch.

Category: Geochronology

Geological Time Scale – Important MCQ

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