biology 102 exam 1

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Which of the following factors weaken(s) the hypothesis of abiotic synthesis of organic monomers in early Earth’s atmosphere?

i. The relatively short time between intense meteor bombardment and the appearance of the first life-forms

iii. Uncertainty about which gases comprised early Earth’s atmosphere


2 How were conditions on the early Earth of more than 3 billion years ago different from those on today’s Earth?

a. Only early Earth was intensely bombarded by large space debris


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

a. There were more kinds of amino acids on the chondrites than are found in living organisms today


4 Which of the following is the correct sequence of events in the organ of life?

ii. Synthesis of organic monomers

iii. Synthesis of organic polymers

i. Formation of protobionts

iv. Formation of DNA-based genetic systems


5 Which of the following is a defining characteristic that all protobionts had in common?

a. A surrounding membrane or membrane-like structure


6 The first genes on Earth were probably:

a. Auto-catalytic RNA molecules


7 The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On earth, those primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

a. Earlier genetic systems than those based on DNA


8 Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

a. How did RNA sequences come to carry the code for amino acid sequences?


9 If natural selection in a particular environment favored genetic systems that permitted the production of daughter “cell” that were genetically dissimilar from mother “cells” then one should expect selection for which of the following?

ii. Polynucleotide polymerases without proofreading capability

v. Polynucleotide polymerases with high mismatch error rates


10 If the half-life of carbon-14 is about 5,730 years, then a fossil that has one-sixteenth the normal proportion of carbon-14 to carbon-12 should be about how many years old?

a. 22,900


11 Which measurement(s) would help determine absolute dates by radiometric means?

a. Two of the responses above are correct


12 Approximately how far back in time does the fossil record extend?

a. 3.5 billion years


13 What is true of the fossil record of mammalian origins?

a. It includes transitional forms with progressively specialized teeth


14 If a fossil is encased in stratum of sedimentary rock without any strata of igneous rocks nearby then it should be:

a. Difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock


15 An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to

a. Cause iron in ocean water and terrestrial rocks to rust


16 Which of the following statements provides the strongest evidence that prokaryotes evolve before eukaryotes?

a. The oldest fossilized cells resemble prokaryotes


17 What is true of the Cambrian explosion?

a. Recent evidence supports the contention that the Cambrian explosion may not have been as “explosive” as was once though


18 What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?

iv. Origin of cyanobacteria

i. Origin of mitochondria

iii. Origin of chloroplasts

ii. Origin of multicellular eukaryotes

v. Origin of fungal-plant symbioses


19 If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2 billion year old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils?

ii. A nuclear envelope

iv. A nucleolus


20 Recent evidence indicates that the first major diversification of multicellular eukaryotes may have coincided in time with the:

a. Melting that ended the “snowball Earth” period


21 Which of these observations gives the most support to the endosymbiotic theory of the origin of eukaryotic cells?

a. The similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts


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

a. Cambrian explosion


23 The snowball earth hypothesis provides a possible explanation for the:

a. Diversification of animals during the late Proterozoic era


24 Which of the following characteristics should have been possessed by the first animals to colonize land?

i. Were probably herbivores

iii. Had the ability to resist dehydration

v. Were invertebrates


25 The first terrestrial organism probably were considered which of the following?

ii. Photosynthetic

iv. Prokaryotes


26 If two continents converge and are united, then the collision should cause

a. A net loss of intertidal zone and costal habitat


27 The major evolutionary episode corresponding most closely in time with the formation of Pangaea was the:

a. Permian extinctions


28 One the basis of their morphologies, how might Linnaeus have classified the Hawaiian silverwords?

a. He would have placed them in more species than modern botanists do


29 An organism has a relatively large number of Hox genes in its genome. Which of the following is true to this organism?

a. The organism has the genetic potential to have a relatively complex anatomy


30 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 mature and can lay eggs within the bag. This is a good example of:

a. Paedomorphosis


31 The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic effects of Pitx1 gene:

a. Silencing (loss of expression)


32 Larval flies (maggots) express the Ubx gene in all of their segments, and thereby lack appendages. If this same gene continued to be expressed throughout subsequent

developmental stages, except in the head region, and if the result was a fit, sexually mature organisms that still strongly resembled a maggot, this would be an example of

a. Two of the responses above are correct


33 How many of the following statements concerning the loss of hind limbs during whale evolution are true?

i. It is well documented by a series of transitional fossils

ii. It explains why modern whales have vestigial pelvic girdles

iii. It involved changes in the sequence or expression of hox genes

iv. It is an example of macroevolution


34 The existence of the phenomenon of exaptation is most closely associated with which of the following observation that natural selection cannot fashion perfect organism?

a. Evolution is limited by historical constraints


35 One explanation for the evolution of insect wings suggest that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, modern insect wings could best be described as:

a. Exaptation


36 If one organ is an exaptation of another organ, then what must be true of these two organs?

a. They are both homologous organs


37 Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

a. Species selection


38 In the 5-7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis. Both species had large brains and advanced intellects. The fact that these traits were common to both species is most easily explained by which of the following?

a. Species selection


39 The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that:

a. In particular environments, similar adaptations can be beneficial in more than one species


40 Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these father-bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that:

a. Their feathers originally served as insulation, and only later became flight surfaces


41 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 systems?



47 If arrows indicate locations in the column where fossils of a particular type (see key above) first appear, then which core in Figure 25.2 has the most accurate arrangement of fossils?

Core A


48 Which of the following reasons may explain why the sediment core lacks fossils of dragonflies with 3-feet wingspans?

i. This particular sediment core includes the correct stratum, but the part of the stratum captured by the core lacks such fossils.

ii. The sea was not present at this site during the time that 3-feet dragonflies existed.

iv. The sediments containing these fossils at this site may have been eroded away during a time when the sea had receded from this site.


49 In order to properly interpret sediment cores, it is necessary to apply the principle of

a. Superposition


50 Assuming the existence of fossilized markers for each of the following chemicals, what is the sequence in which they should be found in this sediment core, working from ancient sediments to recent sediments?

ii. chlorophyll

iv. cellulose

i. chitin coupled with protein

iii. bone


51 In order to assign absolute dates to fossils in this sediment core, it would be most helpful if

a. Volcanic ash layers were regularly interspersed between the sedimentary strata.


70 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?

a. The evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules


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

a. India was a separate continent until 45 million years ago.


72 Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

a. Genetic drift


73 Which of the following steps has not yet been accomplished by scientists studying the origin of life?

a. formation of protocells that use DNA to direct the polymerization of amino acids


74 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

a. A change in a developmental gene or its regulation that altered the spatial organization of body parts.


75 A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of

a. Exaptation


what year did darwin write about natural selection



the four types of data that document the pattern of evolution

1) direct observations


3)fossil record



3 requirements for national selction

1) individuals vary in their phenotypic traits

2) traits are heritable

3)variation in traits cause some individuals to experience higher fitness in a given environment


what is life?

The phenomenon of life defies a short definition. We recognize and define life, or in other words, the living state of matter by what living things do and by the attributes of cells.


· Four mechanisms cause allele frequency change

1. Genetic drift

2. Gene flow

3. Natural Selection

4. Mutation (variation in nucleotide sequence)


The five conditions for non-evolving populations are rarely met in nature

1. No Mutations

2. Random Mating

3. No Natural Selection

4. Extremely Large Population Size

5. No Gene Flow


· Three major factors alter allele frequencies and bring about most evolutionary change

1. Natural selection

2. Genetic drift

3. Gene flow


genetic drift

describes how allele frequencies fluctuate unpredictably from one to generation to the next


what is the founder effect

occurs when a few individuals become isolated from a larger population


what is bottleneck effect

a sudden reduciton in population size due to a change in the enviroment


effects of genetic drift

1. Genetic drift is significant in small populations

2. Can cause allele frequencies to change at random

3. Lead to a loss of genetic variation within populations

4. Can cause harmful alleles to become fixed


gene flow

consists of the movements of alleles among populations


directions selection

favors individuals at one extreme end of the phenotype range


disruptive selection

favors individuals at both extremes of the phenotypic range


stabilizing selection

intermediate variants and acts against extreme phenotypes


sexual selection

natiural selection for mating success


intrasexual selection

direct competition among individuals of one sex for mates of the opposite sex


intersexual selection

occurs when individuals of one sex are choosy in selecting their mates


heterozygote advantage

occurs when heterozygotes have a higher fitness that do both hmozygotes



the origin of the new species



consist of changes in allele frequency in a population over time



refers to broad patterns of evolutionary change above the species level,


biological species concept

states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring


reproductive isolation

the existence of biological factors ( barriers) that impede two species from producing viable, fertile offspring



offspring of crosses between different species


prezygotic barriers block fertilization from occurring by

o Impeding different species from attempting to mate

o Preventing the successful completion of mating

o Hindering fertilization if mating is successful


· Postzygotic barriers prevent the hybrid zygote from developing into a viable, fertile adult

o Reduced hybrid viability

o Reduced hybrid fertility

o Hybrid breakdown


morphological species concept

defines a species by structural features

- applies to sexual and asexual species but relies on subjective criteria


· The ecological species concept

views a species in terms of it ecological niche

applies to sexual and asexual species and emphasizes the role disruptive selection


· The phylogenetic species concept

defines a species as the smallest group of individuals on a phylogenetic tree

It applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species


Allopatric Speciation

gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations


In sympatric speciation

speciation takes place in geographically overlapping populations



extra set of chromosomes due to accidents during cell division



individual with more than two chromosome sets, derived from single species



species with multiple sets of chromosomes derived from different species


sexual selection

can drive sympatric speciation


· The Phanerozoic is divided into three eras:

the Paleozoic, Mesozoic, and Cenozoic


The oldest known fossils



when did oxygen begin accumulating in the atmosphere

2.7 billion years


how old is the oldest fossil of eukaryptic cells date back to?

1.8 billion years


· The endosymbiont theory

proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells


· Key evidence supporting an endosymbiotic origin of mitochondria and plastids

o Inner membranes are similar to plasma membranes of prokaryotes

o Division and DNA structure is similar in these organelles and some prokaryotes

o These organelles transcribe and translate their own DNA

o Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes

o Chloroplasts are similar to certain cyanobacteria