• NEW! FREE Beat The GMAT Quizzes
Hundreds of Questions Highly Detailed Reporting Expert Explanations
• 7 CATs FREE!
If you earn 100 Forum Points

Engage in the Beat The GMAT forums to earn
100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## An extinction event (also known as a mass extinction ##### This topic has 4 expert replies and 2 member replies ## An extinction event (also known as a mass extinction An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on earth. Such an event is identified by a sharp change in the diversity and abundance of macroscopic life. It occurs when the rate of extinction increases with respect to the rate of speciation. Because the majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life. Over 98% of documented species are now extinct, but extinction occurs at a very uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine invertebrates and vertebrates every million years. Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organism fossils. Since life began on Earth, the five major mass extinctions have significantly exceeded the background extinction rate for animal and plant species. The most recent, the Cretaceous-Paleocene extinction event, which occurred approximately 66 million years ago, was a large-scale mass extinction of animal and plant species in a geologically short period of time. In the past 540 million years, during each of these five major events, over 50% of animal and plant species died. Mass extinctions seem to be a Phanerozoic-era phenomenon, with extinction rates low before large complex organisms arose. Q3: It can be inferred from the passage that the Phanerozoic era was: a) a time period that existed before 540 million years ago. b) a time period during which few new species emerged. c) a time period before the Cretaceous-Paleocene era. d) a time period during which large, complex organisms existed. e) a time period during which fewer than 50% of animal and plant species died. ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 Mechmeera wrote: An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on earth. Such an event is identified by a sharp change in the diversity and abundance of macroscopic life. It occurs when the rate of extinction increases with respect to the rate of speciation. Because the majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life. Over 98% of documented species are now extinct, but extinction occurs at a very uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine invertebrates and vertebrates every million years. Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organism fossils. Since life began on Earth, the five major mass extinctions have significantly exceeded the background extinction rate for animal and plant species. The most recent, the Cretaceous-Paleocene extinction event, which occurred approximately 66 million years ago, was a large-scale mass extinction of animal and plant species in a geologically short period of time. In the past 540 million years, during each of these five major events, over 50% of animal and plant species died. Mass extinctions seem to be a Phanerozoic-era phenomenon, with extinction rates low before large complex organisms arose. Q3: It can be inferred from the passage that the Phanerozoic era was: a) a time period that existed before 540 million years ago. b) a time period during which few new species emerged. c) a time period before the Cretaceous-Paleocene era. d) a time period during which large, complex organisms existed. e) a time period during which fewer than 50% of animal and plant species died. Here's what we're told about the Phanerozoic era: Mass extinctions seem to be a Phanerozoic-era phenomenon, with extinction rates low before large complex organisms arose We know that when a mass extinction happens, extinction rates are relatively high. Well, if they were low before large complex organisms arose, and they were high in the Phanerozoic era, it stands to reason that large complex organisms had to have existed during the Phanerozoic era. So the answer is D _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!
Master | Next Rank: 500 Posts
Joined
05 Jun 2015
Posted:
362 messages
Followed by:
2 members
3
DavidG@VeritasPrep wrote:
Mechmeera wrote:
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on earth. Such an event is identified by a sharp change in the diversity and abundance of macroscopic life. It occurs when the rate of extinction increases with respect to the rate of speciation. Because the majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life.

Over 98% of documented species are now extinct, but extinction occurs at a very uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine invertebrates and vertebrates every million years. Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organism fossils.

Since life began on Earth, the five major mass extinctions have significantly exceeded the background extinction rate for animal and plant species. The most recent, the Cretaceous-Paleocene extinction event, which occurred approximately 66 million years ago, was a large-scale mass extinction of animal and plant species in a geologically short period of time. In the past 540 million years, during each of these five major events, over 50% of animal and plant species died. Mass extinctions seem to be a Phanerozoic-era phenomenon, with extinction rates low before large complex organisms arose.

Q3: It can be inferred from the passage that the Phanerozoic era was:

a) a time period that existed before 540 million years ago.
b) a time period during which few new species emerged.
c) a time period before the Cretaceous-Paleocene era.
d) a time period during which large, complex organisms existed.
e) a time period during which fewer than 50% of animal and plant species died.
Here's what we're told about the Phanerozoic era: Mass extinctions seem to be a Phanerozoic-era phenomenon, with extinction rates low before large complex organisms arose

We know that when a mass extinction happens, extinction rates are relatively high. Well, if they were low before large complex organisms arose, and they were high in the Phanerozoic era, it stands to reason that large complex organisms had to have existed during the Phanerozoic era. So the answer is D
HI Dave,

Could you please explain my below query!!!

The author would most probably agree with which of the following statements?

a) The diversity of microbial life has changed dramatically during mass extinction events.
b) The Cretaceous-Paleocene extinction event was the most significant in the past 540 million years.
c) There were many mass extinction events prior to 540 million years ago.
d) Extinction rates have varied widely over the past 540 million years.
e) Mass extinctions are less likely now than in the past 540 million years.

OA: D

How to find out author would most probably agree with which of the following statements. I often get this kind of question wrong!!!

It can be inferred from the passage that:

a) in an extinction event, there is a dramatic decrease in microbial life on earth.
b) over 90% of easily observed, biologically complex species become extinct during a biotic crisis.
c) the background extinction rate of animal and plant species is well below 50%.
d) marine fossils are easier to find and thus more useful to those studying mass extinction events.
e) new species do not emerge during a mass extinction event.

OA: C

This is very generic question . Do we need to sum up all three para?

The primary purpose of the passage is to:

b ) discuss the causes of a particular scientific phenomenon.
c) present new evidence to support the theory of mass extinction events.
d) describe an important scientific and historical occurrence
e) suggest that mass extinctions are likely to continue in the future.

OA: D

How B is wrong? Historical occurrence doesn't mean that the author should give series of events?

Thanks
Nandish

### GMAT/MBA Expert

Legendary Member
Joined
14 Jan 2015
Posted:
2667 messages
Followed by:
122 members
1153
GMAT Score:
770
Quote:
Could you please explain my below query!!!

The author would most probably agree with which of the following statements?

a) The diversity of microbial life has changed dramatically during mass extinction events.
b) The Cretaceous-Paleocene extinction event was the most significant in the past 540 million years.
c) There were many mass extinction events prior to 540 million years ago.
d) Extinction rates have varied widely over the past 540 million years.
e) Mass extinctions are less likely now than in the past 540 million years.

OA: D

How to find out author would most probably agree with which of the following statements. I often get this kind of question wrong!!!
There will always be textual evidence to support the correct answer for this kind of question. In the first sentence of paragraph 2, we see this clause: extinction occurs at a very uneven rate. This notion is best encapsulated in D.

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 Quote: It can be inferred from the passage that: a) in an extinction event, there is a dramatic decrease in microbial life on earth. b) over 90% of easily observed, biologically complex species become extinct during a biotic crisis. c) the background extinction rate of animal and plant species is well below 50%. d) marine fossils are easier to find and thus more useful to those studying mass extinction events. e) new species do not emerge during a mass extinction event. OA: C This is very generic question . Do we need to sum up all three para? The correct answer doesn't have to capture the gist of the entire passage. Rather, it's best to simply go through the answer choices one by one and find one that has textual support somewhere. In the last paragraph we could these two sentences: 1) Since life began on Earth, the five major mass extinctions have significantly exceeded the background extinction rate for animal and plant species. and 2) In the past 540 million years, during each of these five major events, over 50% of animal and plant species died. If the background extinction rate is far lower than the extinction rate during a major event, and during a major event over 50% of animal and plant species die, it stands to reason that the background extinction rate is far below that 50% threshold. The answer is C _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

### GMAT/MBA Expert

Legendary Member
Joined
14 Jan 2015
Posted:
2667 messages
Followed by:
122 members
1153
GMAT Score:
770
Quote:
The primary purpose of the passage is to:

b ) discuss the causes of a particular scientific phenomenon.
c) present new evidence to support the theory of mass extinction events.
d) describe an important scientific and historical occurrence
e) suggest that mass extinctions are likely to continue in the future.

OA: D

How B is wrong? Historical occurrence doesn't mean that the author should give series of events?
B is wrong because the passage isn't about what's causing the extinctions. (No mentioned of meteorites or climate change, etc.) Rather, it's about how the rate of extinction changes over time and spikes during major events.

'Historical occurrence' simply refers to something that happened in the past.

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! Master | Next Rank: 500 Posts Joined 05 Jun 2015 Posted: 362 messages Followed by: 2 members Upvotes: 3 Thanks a lot Dave • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

Available with Beat the GMAT members only code

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

• Free Trial & Practice Exam
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• 5 Day FREE Trial
Study Smarter, Not Harder

Available with Beat the GMAT members only code

• FREE GMAT Exam
Know how you'd score today for \$0

Available with Beat the GMAT members only code

### Top First Responders*

1 Ian Stewart 50 first replies
2 Brent@GMATPrepNow 37 first replies
3 Jay@ManhattanReview 33 first replies
4 GMATGuruNY 29 first replies
5 ceilidh.erickson 14 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 Scott@TargetTestPrep

Target Test Prep

209 posts
2 Max@Math Revolution

Math Revolution

92 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

79 posts
4 Ian Stewart

GMATiX Teacher

57 posts
5 GMATGuruNY

The Princeton Review Teacher

49 posts
See More Top Beat The GMAT Experts