Concept explainers
Introduction:
Biodiversity is defined as the richness of the living systems present at all the levels of
Answer to Problem 1TYK
Correct answer:
The greatest extinction in the history of life on the earth might be occurring now.
Explanation of Solution
Justification for the correct answer:
Option (e) states that ‘the greatest extinction on the earth may be occurring now.’ The biodiversity is now declining rapidly. It is occurring much faster than it might have occurred in the history of the earth. The reasons behind the greatest extinction are threats to the biodiversity. There are three major threats to biodiversity, namely deforestation, over-exploitation of fish population, and alteration of freshwater ecosystems. Hence, option (e) is correct.
Justification for the incorrect answers:
Option (a) states that ‘the greatest extinction on the earth occurred at the end of the Permian period.’ The Permian period ended with a Permian–Triassic extinction event, in which nearly 96% of the marine species and 70% of the terrestrial vertebrates became extinct. The present day extinction is going at a faster pace than the Permian period’s extinction. So, it is an incorrect option.
Option (b) states that ‘the greatest extinction on the earth occurred at the end of the Cretaceous period.’ The Cretaceous period ended with the event of Cretaceous–Paleogene extinction, which led to the non-avian dinosaurs, large marine reptiles, and pterosaurs extinction. It is still not the greatest extinction in the history of the earth. So, it is an incorrect option.
Option (c) states that ‘at the end of the Ordovician period, the greatest extinction occurred on the earth.’ The Ordovician period ended with the Ordovician–Silurian extinction event, which led to the extinction of invertebrates including mollusks and arthropods. This did not end with mass extinction. So, it is an incorrect option.
Option (d) states that ‘the greatest extinction took place at the end of the Cambrian era.’ The Cambrian era ended with the Cambrian–Ordovician extinction event, in which many brachiopods and conodonts got extinct. The greatest extinction did not take place at the end of this era. So, it is an incorrect option.
Hence, options (a), (b), (c), and (d) are incorrect.
Thus, it can be concluded that the greatest extinction might be occurring now and did not take place at the end of the Permian, Cretaceous, Ordovician, and Cambrian era. The current extinction is taking place due to human activities.
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Chapter 55 Solutions
Biology: The Dynamic Science
- Which of the following is characteristic of the end of the Paleozoic Era? a There was a mass extinction that eliminated 70% of marine life. b All of Earth's landmasses are joined together in a supercontinent called Pangaea. c Mountains began to form. d The supercontinent Pangaea separated into present-day continents.arrow_forwardWhich of the following statements about the fossil record is true? a. The fossil record is a complete accounting of life on earth b. The fossil record is unbiased in the fossils that are found c. The fossil record is evenly sampled across all of life's history on earth d. There are certain biases in the fossil recordarrow_forwardWe live in the Cenozoic era, and scientists know more about this era and the epochs it’s divided into than any other time period. Why is this? A. We know more about the Cenozoic era because this is the only era that has had a wide diversity of species living on Earth. B. We know more about the Cenozoic era because this is the most recent time period in the history of the Earth, and we have more information available to study. C. We know more about the Cenozoic era because the planet’s poles reversed magnetic fields at the beginning of this era. D. We know more about the Cenozoic era because fossils don’t exist to document previous eras.arrow_forward
- Which of the following do not provide evidence that a meteor strike was a partial cause of the Cretaceous-Paleogene mass extinction? a. A potential meteor crater off the coast of Mexico b. High layers of iridium in soil deposits in the geologic record at that time c. Shocked quartz was formed in large quantities at that time around the potential impact site d. An ozone hole appeared in the atmosphere at the time of the meteor strikearrow_forwardDuring the ____ epoch, there were fewer ____ and more ____, a reversal in the relative representation of these forms during modern times. a. Eocene; omomyids; eosimiids b. Miocene; Old World monkeys; apes C. Miocene; apes; Old World monkeys d. Oligocene; apes; Old World monkeys e. Paleocene; New World monkeys; Old World monkeysarrow_forwardOne hypothesis for the Cambrian explosion was an increase in predator-prey relationships. It is thought that the resulting co-evolution of predator and prey may have been a factor in the rapid speciation of animals seen during this time. What findings in the fossil record would most support this? Group of answer choices a. increased incidence of larger-bodied animals b. increased incidence of sessile animals c. decreased incidence of animals with bilateral symmetry d. increased incidence of animals with radial symmetry e. increased incidence of shells, bony plates, spines, and/or clawsarrow_forward
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- Place these events in the history of life on Earth in the order that they occurred. a. accumulation of O2 in Earth’s atmosphere b. colonization of land by plants and fungi c. diversification of animals (Cambrian explosion) d. origin of eukaryotes e. origin of humans f. origin of multicellular organisms g. origin of prokaryotesarrow_forwardSome epileptic conditions are due to neurons firing too often. This could be due to a lowering of the: Select one: a. threshold. b. set point. c. trigger point. d. cut off. The period of time during which an “explosion” of fossilized animals with bilateral symmetry are first found is the: Select one: a. Devonian. b. Jurassic. c. Cambrian. d. Ediacaran.arrow_forwardPlant life first appeared on land during which of the following periods? a. Cambrian period b. Ordovician period c. Silurian period d. Devonian periodarrow_forward