Question 1

The following questions refer to the description below.
All animals with eyes or eyespots that have been studied so far share a gene in common.When mutated,the gene Pax-6 causes lack of eyes in fruit flies,tiny eyes in mice,and missing irises (and other eye parts)in humans.The sequence of Pax-6 in humans and mice is identical.There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies,even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago.
-Fruit fly eyes are of the compound type,which is structurally very different from the camera-type eyes of mammals.Even the camera-type eyes of molluscs,such as octopi,are structurally quite different from those of mammals.Yet,fruit flies,octopi,and mammals possess very similar versions of Pax-6.The fact that the same gene helps produce very different types of eyes is most likely due to

Accepted Answer

A) the few differences in nucleotide sequence among the Pax-6 genes of these organisms. 
B) variations in the number of Pax-6 genes among these organisms. 
C) the independent evolution of this gene at many different times during animal evolution. 
D) differences in the control of Pax-6 expression among these organisms.

Question 2

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb.This type of change is illustrative of

Accepted Answer

A) the influence of environment on development. 
B) paedomorphosis. 
C) a change in a developmental gene or its regulation that altered the spatial organization of body parts. 
D) heterochrony. 
E) gene duplication.

Question 3

The following questions refer to the description below.
You were asked to give a presentation about fossils to a group of young students.You tell the students that the fossil record shows how organisms can change over time,but unfortunately the fossil record is incomplete.After your talk a student tells you that his pet salamander has died and he wants his salamander to be fossilized.The boy plans to lay his salamander on the grass and cover the salamander's body with leaves and twigs.You had told the class that a critical step in the fossilization process is the burial of an organism.
-Which of the statement(s)below lends support to your claim about the fossilization process?

Accepted Answer

A) Burying hides the body/carcass from scavengers. 
B) Burying protects the carcass from environmental elements such as rain, snow, and wind. 
C) Burying speeds up the process of decay by fungi. 
D) Burying speeds up the process of decay by bacteria. 
E) A and B

Question 4

The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley,with alternating patches of black and white indicating sea floor with reversed magnetic polarities.At the arrow labelled "I" (the rift valley),the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating.At the arrow labeled "III," however,the igneous rock is about 1 million years old,and potassium-40 dating is typically used to date such rocks.Note: The horizontal arrows indicate the direction of sea-floor spreading,away from the rift valley.
 
-Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above,what should be the approximate age of marine fossils found in undisturbed sedimentary rock immediately overlying the igneous rock at the arrow labelled "II"?

Accepted Answer

A) 10 000 years 
B) 250 000 years 
C) 400 000 years 
D) 1 000 000 years

Question 5

The oxygen revolution changed Earth's environment dramatically.Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

Accepted Answer

A) the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules 
B) the persistence of some animal groups in anaerobic habitats 
C) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen 
D) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria 
E) the evolution of multicellular eukaryotic colonies from communities of prokaryotes

Question 6

The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley,with alternating patches of black and white indicating sea floor with reversed magnetic polarities.At the arrow labelled "I" (the rift valley),the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating.At the arrow labeled "III," however,the igneous rock is about 1 million years old,and potassium-40 dating is typically used to date such rocks.Note: The horizontal arrows indicate the direction of sea-floor spreading,away from the rift valley.
 
-Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above,Earth's magnetic field has undergone reversal at an average rate of once every

Accepted Answer

A) 10 000 years. 
B) 25 000 years. 
C) 100 000 years. 
D) 250 000 years. 
E) 1 000 000 years.

Question 7

What does the circled part of the phylogenetic tree above indicate?

Accepted Answer

A) an adaptive radiation 
B) a mass extinction event 
C) rapid speciation 
D) an adaptive radiation and rapid speciation 
E) evolution of eukaryotes

Question 8

What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?

Accepted Answer

A) They had the same proportion of L and D isomers as Earth does today. 
B) Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere. 
C) There were more kinds of amino acids on the chondrites than are found in living organisms today. 
D) They were delivered in the form of polypeptides.

Question 9

Refer to the following information to answer the questions below.
Fossils of Lystrosaurus,a dicynodont therapsid,are most common in parts of modern-day South America,South Africa,Madagascar,India,South Australia,and Antarctica.It apparently lived in arid regions,and was mostly herbivorous.It originated during the mid-Permian period,survived the Permian extinction,and dwindled by the late Triassic,though there is evidence of a relict population in Australia during the Cretaceous period.The dicynodonts had two large tusks,extending down from their upper jaws.The tusks were not used for food gathering,and in some species were limited to males.Food was gathered using an otherwise toothless beak.Judging from the fossil record in sedimentary rocks,these pig-sized organisms were the most common mammal-like reptiles of the Permian period.
-Which of the following is the most likely explanation for the modern-day distribution of dicynodont fossils?

Accepted Answer

A) Two previous supercontinents existed at different times long before the Permian period. 
B) The dicynodonts were evenly distributed throughout all of Pangaea. 
C) The dicynodonts were distributed more abundantly throughout Gondwanaland than throughout any other land mass. 
D) The dicynodonts were amphibious and able to swim long distances. 
E) The dicynodonts could survive for periods of months aboard "rafts" of vegetation, few of which made their way to the northern hemisphere.

Question 10

Which organisms would you expect to be most poorly represented in the fossil record?

Accepted Answer

A) common, soft-bodied slugs 
B) rare, soft-bodied worms 
C) bony fish 
D) marine crabs 
E) flightless birds

Question 11

What is true of the Cambrian explosion?

Accepted Answer

A) There are no fossils in geological strata that are older than the Cambrian explosion. 
B) Only the fossils of microorganisms are found in geological strata older than the Cambrian explosion. 
C) The Cambrian explosion is evidence for the instantaneous creation of life on Earth. 
D) The Cambrian explosion marks the appearance of filter-feeding animals in the fossil record. 
E) Recent evidence supports the contention that the Cambrian explosion may not have been as "explosive" as was once thought.

Question 12

On the basis of their morphologies,how might Linnaeus have classified the Hawaiian silverswords?

Accepted Answer

A) He would have placed them all in the same species. 
B) He would have classified them the same way that modern botanists do. 
C) He would have placed them in more species than modern botanists do. 
D) He would have used evolutionary relatedness as the primary criterion for their classification.

Question 13

Which of the following statements does not apply to Hox genes?

Accepted Answer

A) They are a type of homeotic gene. 
B) They alter the timing of reproductive development. 
C) They provide positional information in animal embryos. 
D) Changes in how two Hox genes in snakes are expressed results in suppression of limb formation.

Question 14

Which event is nearest in time to the end of the period known as snowball Earth?

Accepted Answer

A) oxygenation of Earth's seas and atmosphere 
B) evolution of mitochondria 
C) Cambrian explosion 
D) evolution of true multicellularity 
E) Permian extinction

Question 15

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth.Which graph below,if the results were produced abiotically,would have the greatest promise for revealing important information about the origin of Earth's first genetic system?

Accepted Answer

A)   
B)   
C)   
D)

Question 16

Refer to the following information to answer the questions below.
Fossils of Lystrosaurus,a dicynodont therapsid,are most common in parts of modern-day South America,South Africa,Madagascar,India,South Australia,and Antarctica.It apparently lived in arid regions,and was mostly herbivorous.It originated during the mid-Permian period,survived the Permian extinction,and dwindled by the late Triassic,though there is evidence of a relict population in Australia during the Cretaceous period.The dicynodonts had two large tusks,extending down from their upper jaws.The tusks were not used for food gathering,and in some species were limited to males.Food was gathered using an otherwise toothless beak.Judging from the fossil record in sedimentary rocks,these pig-sized organisms were the most common mammal-like reptiles of the Permian period.
-If an increase in dicynodont species diversity (in other words,number of species)occurred soon after the Permian extinction,and if it occurred for the same general reason usually given for the increase in mammalian diversity following the Cretaceous extinction,then it should be attributed to

Accepted Answer

A) an innovation among the dicynodonts that allowed them to fill brand-new niches. 
B) the availability of previously occupied niches. 
C) the extinction of the dinosaurs (except the birds). 
D) their outcompetition of many other terrestrial organisms.

Question 17

The following questions refer to this hypothetical situation.
A female fly,full of fertilized eggs,is swept by high winds to an island far out to sea.She is the first fly to arrive on this island,and the only fly to arrive in this way.Thousands of years later,her numerous offspring occupy the island,but none of them resembles her.There are,instead,several species,each of which eats only a certain type of food.None of the species can fly,for their flight wings are absent,and their balancing organs (in other words,halteres)are now used in courtship displays.The male members of each species bear modified halteres that are unique in appearance to their species.Females bear vestigial halteres.The ranges of all of the daughter species overlap.
-In each fly species,the entire body segment that gave rise to the original flight wings is missing.The mutation(s)that led to the flightless condition could have

Accepted Answer

A) duplicated all of the Hox genes in these flies' genomes. 
B) altered the nucleotide sequence within a Hox gene. 
C) altered the expression of a Hox gene. 
D) all three of the above responses. 
E) Two of the above answers are correct.

Question 18

Which of the following characteristics should have been possessed by the first animals to colonize land?
1)were probably herbivores (ate photosynthesizers)
2)had four appendages
3)had the ability to resist dehydration
4)had lobe-finned fishes as ancestors
5)were invertebrates

Accepted Answer

A) 3 only 
B) 3 and 5 
C) 1, 3, and 5 
D) 2, 3, and 4 
E) 1, 2, 3, and 4

Question 19

Bagworm moth caterpillars feed on evergreens and carry a silken case or bag around with them in which they eventually pupate.Adult female bagworm moths are larval in appearance; they lack the wings and other structures of the adult male and instead retain the appearance of a caterpillar even though they are sexually mature and can lay eggs within the bag.This is a good example of

Accepted Answer

A) allometric growth. 
B) paedomorphosis. 
C) sympatric speciation. 
D) adaptive radiation. 
E) changes in homeotic genes.

Question 20

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?

Accepted Answer

A) The species have become separated by convergent evolution. 
B) The climates of the two regions are similar. 
C) India is in the process of separating from the rest of Asia. 
D) Life in India was wiped out by ancient volcanic eruptions. 
E) India was a separate continent until 45 million years ago.

Exam 25: The History of Life on Earth