BIO TEST 4

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1

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?

I. Transform bacteria with a recombinant DNA molecule.

II. Cut the plasmid DNA using restriction enzymes.

III. Extract plasmid DNA from bacterial cells.

IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.

V. Use ligase to seal plasmid DNA to nonplasmid DNA.

A) I, II, IV, III, V

B) II, III, V, IV, I

C) III, II, IV, V, I

D) III, IV, V, I, II

E) IV, V, I, II, III

III, II, IV, V, I

2

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because

A) it allows researchers to use the sequence to build a "better" nematode, which is resistant to disease.

B) it allows research on a group of organisms we do not usually care much about.

C) the nematode is a good animal model for trying out cures for viral illness.

D) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

E) a sequence that is found to have no introns in the nematode genome is likely to have acquired the introns from higher organisms.

a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

3

3) Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?

A) altering the nucleotide sequence of the DNA fragment

B) methylating the cytosine bases within the DNA fragment

C) increasing the length of the DNA fragment

D) decreasing the length of the DNA fragment

E) neutralizing the negative charges within the DNA fragment

altering the nucleotide sequence of the DNA fragment

4

) In 1997, Dolly the sheep was cloned. Which of the following processes was used?

A) use of mitochondrial DNA from adult female cells of another ewe

B) replication and dedifferentiation of adult stem cells from sheep bone marrow

C) separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe

D) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

E) isolation of stem cells from a lamb embryo and production of a zygote equivalent

fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

5

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?

A) Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells.

B) Cloning to produce embryonic stem cells may lead to great medical benefits for many.

C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning.

D) A clone that lives until the blastocyst stage does not yet have human DNA.

E) No embryos would be destroyed in the process of therapeutic cloning.

Cloning to produce embryonic stem cells may lead to great medical benefits for many.

6

Which of the following is true of embryonic stem cells but not of adult stem cells?

A) They can differentiate into many cell types.

B) They make up the majority of cells of the tissue from which they are derived.

C) They can continue to replicate for an indefinite period.

D) They can provide enormous amounts of information about the process of gene regulation.

E) One aim of using them is to provide cells for repair of diseased tissue.

They make up the majority of cells of the tissue from which they are derived.

7

Which of the following is a representation of gene density?

A) Humans have 2,900 Mb per genome.

B) C. elegans has ~20,000 genes.

C) Humans have ~20,000 genes in 2,900 Mb.

D) Humans have 27,000 bp in introns.

E) Fritillaria has a genome 40 times the size of a human.

Humans have ~20,000 genes in 2,900 Mb.

8

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

A) Characteristics acquired during an organism's life are generally not passed on through genes.

B) Spontaneous mutations can result in the appearance of new traits.

C) Only favorable adaptations have survival value.

D) Disuse of an organ may lead to its eventual disappearance.

E) If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation.

Characteristics acquired during an organism's life are generally not passed on through genes.

9

Which of the following must exist in a population before natural selection can act upon that population?

A) genetic variation among individuals

B) variation among individuals caused by environmental factors

C) sexual reproduction

D) Three of the responses are correct.

E) Two of the responses are correct.

genetic variation among individuals

10

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

A) These genes should continue to be maintained in case the antibiotics ever appear.

B) These bacteria should be outcompeted and replaced by bacteria that have lost these genes.

C) The bacteria should try to make the cost worthwhile by locating, and migrating to, microenvironments where traces of antibiotics are present.

D) The bacteria should start making and secreting their own antibiotics.

These bacteria should be outcompeted and replaced by bacteria that have lost these genes.

11

If two modern organisms are distantly related in an evolutionary sense, then one should expect that

A) they live in very different habitats.

B) they should share fewer homologous structures than two more closely related organisms.

C) their chromosomes should be very similar.

D) they shared a common ancestor relatively recently.

E) they should be members of the same genus.

they should share fewer homologous structures than two more closely related organisms.

12

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?

A) All organisms require energy.

B) All organisms use essentially the same genetic code.

C) All organisms reproduce.

D) All organisms show heritable variation.

E) All organisms have undergone evolution.

All organisms use essentially the same genetic code.

13

Members of two different species possess a similar-looking structure that they use in a similar fashion to preform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

A) The two species live at great distance from each other.

B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

C) The sizes of the structures in adult members of both species are similar in size.

D) Both species are well adapted to their particular environments.

The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

14

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

A) homologous.

B) examples of convergent evolution.

C) adaptations to a common environment.

D) Three of the responses above are correct.

E) Two of the responses above are correct.

Two of the responses above are correct.

15

What must be true of any organ that is described as vestigial?

A) It must be analogous to some feature in an ancestor.

B) It must be homologous to some feature in an ancestor.

C) It must be both homologous and analogous to some feature in an ancestor.

D) It need be neither homologous nor analogous to some feature in an ancestor.

It must be homologous to some features in an ancestor

16

What is true of pseudogenes?

A) They are composed of RNA, rather than DNA.

B) They are the same things as introns.

C) They are unrelated genes that code for the same gene product.

D) They are vestigial genes.

They are vestigil genes

17

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that

A) humans and chimpanzees share a relatively recent common ancestor.

B) humans evolved from chimpanzees.

C) chimpanzees evolved from humans.

D) convergent evolution led to the DNA similarities.

E) humans and chimpanzees are not closely related.

humans and chimpanzees share a relatively recent common ancestor

18

During an individual organism's lifetime, which of these is most likely to help the organism respond properly to changes in its environment?

A) microevolution

B) change in allele or gene frequency

C) change in gene expression

D) change in average heterozygosity

change in gene expression

19

In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution?

A) mistakes in translation of structural genes

B) mistakes in protein folding

C) rampant changes to the dictionary of the genetic code

D) binary fission

E) recombination by crossing over in meiosis

recombination by crossing over in meiosis

20

Which of the following statements best summarizes evolution as it is viewed today?

A) It represents the result of selection for acquired characteristics.

B) It is synonymous with the process of gene flow.

C) It is the descent of humans from the present-day great apes.

D) It is the differential survival and reproduction of the most-fit phenotypes.

It is the differential survival and reproduction of the most fit phenotypes

21

In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?

A) disruptive selection

B) directional selection

C) stabilizing selection

D) No selection would operate because the population is in Hardy-Weinberg equilibrium.

directional selection

22

Blue light is that portion of the visible spectrum that penetrates the deepest into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue light. Which of the following graphs best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best?

X shaped graph, blue up UV down

23

In a very large population, a quantitative trait has the following distribution pattern:

What is true of the trait whose frequency distribution in a large population appears in the previous figure? It has probably undergone

A) directional selection.

B) stabilizing selection.

C) disruptive selection.

D) normal selection.

stabilizing selection

24

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

A) the bottleneck effect.

B) disruptive selection.

C) frequency-dependent selection.

D) neutral variation.

E) stabilizing selection.

stabalizing selection

25

What is true of macroevolution?

A) It is the same as microevolution, but includes the origin of new species.

B) It is evolution above the species level.

C) It is defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye.

D) It is defined as a change in allele or gene frequency over the course of many generations.

E) It is the conceptual link between irritability and adaptation.

It is evolution above the species level.

26

26. Which of the following statements about species, as defined by the biological species concept, is (are) correct?

I. Biological species are defined by reproductive isolation.

II. Biological species are the model used for grouping extinct forms of life.

III. The biological species is the largest unit of population in which successful interbreeding is possible.

A) I and II

B) I and III

C) II and III

D) I, II, and III

I and III

27

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?

A) biological

B) phylogenetic

C) ecological

D) morphological

morphological

28

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

A) reduced hybrid fertility

B) hybrid breakdown

C) mechanical isolation

D) habitat isolation

E) gametic isolation

habitat isolation

29

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms is applicable?

A) behavioral isolation

B) mechanical isolation

C) hybrid breakdown

D) reduced hybrid viability

mechanical isolation

30

According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that

A) the species is now extinct.

B) speciation occurred instantaneously.

C) speciation occurred in one generation.

D) speciation occurred rapidly in geologic time.

E) the species will consequently have a relatively short existence, compared with other species.

speciation occurred rapidly in geologic time.

31

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.

Which species is most closely related to species W?

A) V is most closely related to species W.

B) X is most closely related to species W.

C) Y and Z are equally closely related to W.

D) It is not possible to say from this tree.

V is most closely related to species W

32

Which of these five species originated earliest and appeared suddenly in the fossil record?

A) V

B) W

C) X

D) Y

E) Z

W

33

Which of these five species is the extant (i.e., not extinct) species that is most closely related to species X, and why is this so?

A) V; shared a common ancestor with X most recently

B) W; shared a common ancestor with X most recently

C) Y; arose in the same fashion (i.e., at the same tempo) as X

D) Z; shared a common ancestor with X most recently, and arose in the same fashion as X

E) This tree does not provide enough information to answer this question.

V; shared a common ancestor with X most recently

34

The data in the previous graphs indicate that

A) a hybrid zone was established after the completion of the bridge.

B) no interspersal of the two types of squirrel occurred after the completion of the bridge.

C) gene flow occurred from one type of squirrel into the gene pool of the other type of squirrel.

D) two-way migration of squirrels occurred across the bridge, but without hybridization.

E) some northern squirrels migrated south, but no southern squirrels migrated north across the bridge.

two-way migration of squirrels occurred across the bridge, but without hybridization

35

Which of the following reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids?

A) hybrid breakdown

B) hybrid inviability

C) hybrid sterility

D) temporal isolation

E) a geographic barrier

hybrid sterility

36

. In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?

A) They have been geographically isolated from each other for a longer time.

B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.

C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.

D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

Answer: A

hey have been geographically isolated from each other for a longer time.

37

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

A) 3.5 million years

B) 5.0 million years

C) 3.5 billion years

D) 5.0 billion years

3.5 billion years

38

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

A) Prokaryotic cells lack nuclei.

B) The meteorites that have struck Earth contain fossils only of prokaryotes.

C) Laboratory experiments have produced liposomes abiotically.

D) Liposomes closely resemble prokaryotic cells.

E) The oldest fossilized cells resemble prokaryotes.

The oldest fossilized cells resemble prokaryotes.