Biology 101 Test 3 (Ch 10, 13, and 14)

In eukaryotic cells, a terminator in mRNA synthesis is

a specific nucleotide sequence in DNA that signals the RNA polymerase to stop

________ marks the end of a gene and causes transcription to stop.

a terminator

polyploid speciation

accidents in cell division result in extra sets of chromosomes forming new plant species

how are adaptations beneficial to organisms?

adaptations help organisms survive and reproduce in a particular environment

Mass extinctions create conditions that promote _____.

adaptive radiation

_____ is rapid speciation under conditions in which there is little competition

adaptive radiation

Darwin was the first person to draw an evolutionary tree, a diagram that represents

evidence-based hypotheses regarding our understanding of patterns of evolutionary descent.

When a T2 bacteriophage infects an Escherichia coli cell, which part of the phage enters the bacterial cytoplasm?

only the DNA

In artificial selection, humans provide the selective pressure for species to change and shape the evolution of various breeds. What provides the selective pressure in natural selection?

the environment

A promoter is a specific binding site for _____.

the enzyme RNA polymerase

The "one gene-one enzyme" hypothesis states that

the function of an individual gene is to dictate the production of a specific polypeptide.

In an important experiment, radioactively labeled bacteriophages were allowed to infect bacteria. In the first trial, the phages contained radioactive DNA, and radioactivity was detected in the bacteria. Next, other phages containing radioactive protein were allowed to infect bacteria, and radioactivity was not detected in the bacteria. These experiments led to the conclusion that:

the genes of this phage were made of DNA

Which genotype relative to the sickle-cell allele has the greatest reproductive success in regions where malaria is a common disease?

the heterozygous genotype

A gene is usually _____.

the information for making a polypeptide

The information carried by a DNA molecule is in _____.

the order of the nucleotides in the molecule

Which of the following lists of assumptions was part of Charles Darwin's theory of natural selection?

1. Organisms vary in heritable ways. 2. Some traits improve the survival and reproduction of individuals who possess them. 3. Populations produce more offspring than their environment can support, so individual organisms must compete for limited resources. 4. Earth and its life are very old.

Events of Transcription

1. RNA polymerase binds to a promoter on DNA, initiating transcription 2. RNA polymerase peels open the double helix of DNA, with one strand serving as a template for the formation of RNA 3. The RNA transcript is processed to remove segments that do not encode for amino acids and to splice together those that do 4. mRNA leaves the nucleus through a nuclear pore and enters the cytoplasm

Events of RNA processing

1. a modified guanine nucleotide is added to the beginning of the RNA strand as a cap 2. Segments of the RNA strand that do not actually code for the protein are removed 3. Segments of the RNA that do code for the protein are reconnected 4. Extra adenine nucleotides are added to the end of the RNA strand, forming a tail 5. The completed messenger RNA leaves the nucleus

examples of allopatric speciation

1. pine forest separated by a mountain range, a canyon, or body of water contain isolated populations of organims 2. two species of squirrels that share common ancestry no longer interbreed because they are separated by the Grand Canyon 3. a population of ants are separated by new, large housing development that prohibits gene flow

ex of sympatric speciation

1. small fish called chichlids live in the same lake but at different depths which cues differential reproduction 2. medium size ground finches living on the same island develop different bill sizes, which alters their mating signals 3. self-fertilization in plants allows a new species to arise amidst the ancestral population

Hershey and Chase used _____ to radioactively label the T2 phage's proteins:

35^S

According to a recent survey of many studies, an average plant or animal lineage might produce a new species approximately once every _____.

5 million years

When one DNA molecule is copied to make two new DNA molecules, the resulting DNA molecules contain

50% of the parent DNA

Mutation plays a large role in the microevolution of bacterial populations. Why?

Bacteria multiply very rapidly, and they are haploid so a mutant allele will immediately have a full effect on the phenotype

microevolution

Change in allele frequencies in a population over generations.

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

DNA polymerase can assemble DNA only in the 5' to 3' direction

The radioactive isotope 32^P labels the T2 phage's:

DNA

What enzyme joins DNA fragments?

DNA ligase

Two new strands of DNA molecules grow as bases are added by the enzyme _____.

DNA polymerase

Which enzyme catalyzes the elongation of a new DNA strand?

DNA polymerase

Which of the following occurs during DNA replication?

DNA polymerase elongates the daughter strand, adding new nucleotides to the 3' end. The molecule grows 5' to 3' but the template strand is read 3' to 5'

Which option best describes the concept of an evolutionary tree diagram?

Evolutionary trees relate species to each other by ancestry. An ancestor common to all of the species is placed at the root of the tree. Branch points are defined by homologous features that are shared by the descendant species along a particular branch

Who demonstrated that DNA is that genetic material of the T2 phage?

Hershey and Chase

Which statement reflects a possible weakness of the fossil record?

Many species probably did not die in the right place at the right time to be captured in fossils, and many fossils will never by found by paleontologists.

Which of the following catalyzes the linkage between nucleotides to form RNA?

RNA polymerase

What do Dodd's experiments with fruit flies indicate?

Reproductive barriers will arise more quickly if isolated populations experience and become adapted to differing environments.

Which of the following statements about reproductive barriers and speciation is true?

Speciation can occur with even a single gene mutation if that mutation involves reproductive barriers.

Hershey and Chase's experiment allowed them to discern whether DNA or proteins contain genetic information because:

T2 viruses consist only of proteins and DNA and only the DNA was injected into the host cells

Which statement regarding a DNA double helix is true, regarding the ratios of the 4 bases?

The amount of adenine is equal to the amount of thymine and the amount of guanine is equal to the amount of cytosine

Which of the following thinkers argued that much of human suffering was the result of human populations increasing faster than food supply, an argument that later influenced Charles Darwin's ideas of natural selection?

Thomas Malthus

Which best describes the fossil record?

The fossil record is the highly ordered sequence in which fossils are found in layers of sedimentary rock.

A single base mutation occurs in a gene that codes for a protein due to an error in DNA replication. Which of the following outcomes is not possible?

The mutation results in mRNA being made from the protein.

What was significant to Darwin about the fauna and flora of the Galápagos Islands?

The species were similar to South American species, indicating common descent, but they had been extensively modified and were well-adapted to island life.

A diploid cell in a plant undergoes chromosome duplication but fails to divide properly, initiating a tetraploid (4n) branch. This branch produces a 4n flower. What can happen next?

The tetraploid (4n) flower produces 2n gametes and may then be able to self-pollinate to produce fertile 4n offspring.

Which of the following is true of homologous structures?

They are structurally similar due to inheritance from a common ancestor.

Why is the morphological species concept still used to define and describe species?

This is the most convenient way of identifying species, and it is one of the few ways to identify fossil or asexual species.

Who developed a theory of evolution almost identical to Darwin's?

Wallace

The way that genetic material of a bacteriophage enters a bacterium is most like the way that

a drug is injected with a hypodermic needle.

Which of the following would most quickly be eliminated by natural selection? 1. a harmful recessive allele in a sexual, diploid population 2. a harmful recessive allele in a sexual, polyploid population 3. a harmful allele in an asexual, haploid population 4. any harmful allele, regardless of the system of inheritance

a harmful allele in an asexual haploid population

sympatric speciation

a new species may arise as mating and gene flow are reduced between populations that share the same area

allopatric speciation

a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift

Which of the following statements about evolutionary adaptation is true?

a population that has an increase in frequency of alleles for thicker fur has become adapted to the cold

an anticodon is

a set of triplet bases on a tRNA that is complementary to a codon triplet on mRNA

All known organisms use genetic information to produce protein molecules via the same genetic code. This finding strongly supports the hypothesis that ________

all organisms are descended from one or a few common ancestors

Which of the following is found in RNA but not in DNA?

an additional hydroxyl group

Broccoli, cabbages, and Brussels sprouts all descend from the same wild mustard and can still interbreed. These varieties were produced by

artificial selection

When a horse and a donkey mate, they produce infertile hybrids called mules. According to the _____ species concept, horses and donkeys are _____.

biological; different species

The main focus of Charles Darwin's studies was on the gradual process of adaptation within populations. In other words, microevolution occurs by means of natural selection. Although critical to evolution this form of change _______ 1. occurs mainly in small, isolated populations 2. explains all important forms of evolutionary change 3. cannot account by itself for the increase in species diversity over time 4. is the main means by which new species arise

cannot account by itself for the increase in species diversity over time

Which of the following options most accurately lists the sequence of events in translation?

codon recognition → peptide bond formation → translocation → termination

DNA is transferred through a sex pilus from a living donor to a living recipient in which of the following forms of bacterial gene transfer?

conjugation

Bacteria can quickly acquire new genes in a single generation through __________.

conjugation, transformation, and transduction

In natural selection, _____ determines which phenotypes are successful?

current conditions in the local environment

the function of tRNA during protein synthesis is to

deliver amino acids to their proper site during protein synthesis

sexual dimorphism

differences between the sexes in size, appearance and behavior; this is a result of individuals with certain inherited characteristics being more likely to obtain mates than others

Which of the following statements about eukaryotic RNA is true? 1. a small cap of extra nucleotides is added to both ends of the RNA 2. exons are spliced together 3. introns are not transcribed from DNA to RNA 4. the modified RNA molecule is transported into the nucleus

exons are spliced together

Experiments and observations indicate that natural selection acts

fairly quickly in some circumstances (within a few generations), and often temporarily in response to changes in the immediate environment

Stabilizing selection

favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation

Directional selection

favors pehnotypes at one end of range and is common in period of environmental change

Disruptive selection

favors phenotypes at both ends of a range over intermediate phenotypes. This type of selection may occur when the habitat is varied

Genetic differences between populations tend to be reduced by

gene flow

The first step in the replication of DNA is catalyzed by _____.

helicase

Most polyploid plants arise as a result of _____.

hybridization

The bonds that hold tRNA molecules in the correct three-dimensional shape are __________.

hydrogen bonds

The two strands of a DNA molecule are held together by

hydrogen bonds between nucleotide bases

A new species can arise in a single generation _____.

if a change in chromosome number creates a reproductive barrier

Where do transcription and translation occur in prokaryotic cells?

in the cytoplasm

In eukaryotic cells, the RNA is processed before it leaves the nucleus. This processing

includes the addition of a cap and tail, which protect the mRNA molecule from enzymatic attack, and the removal of introns

mate choice

individuals of one sex are choosy in selecting their mates based on showy appearance of behavior

intrasexual selection

individuals of one sex compete directly for mates; this may involve ritualized displays or physical combat

If a population is in Hardy-Weinberg equilibrium which of the following will be true? 1. the relative frequencies of three genotypes will gradually become stabilized at 1:1:1 2. the population organisms will evolve 3. the dominant allele will take over 4. individuals survive and reproduce equally well regardless of their genotype

individuals survive and reproduce equally well regardless of their genotype

Which of the following is not true about the genetic code? 1. the genetic code is almost universal 2. the nucleotides making up the codons occur in a linear order along the DNA and RNA with no gaps or punctuation separating codons 3. the genetic code is redundant 4. the genetic code is ambiguous

it is ambiguous

How does RNA polymerase know where to start?

it starts at a certain nucleotide sequence called a promoter

Which of the following is true about double-stranded DNA? 1. shaped like a double helix 2. adenine and uracil are present in equal amounts 3. strands have sugar-phosphate backbones 4. the two strands are identical

its strands have sugar-phosphate backbones

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material

labeled DNA .... DNA

Which condition would tend to make the Hardy-Weinberg equation more accurate for predicting the genotype frequencies of future generations in a population of a sexually reproducing species? 1. a small population size 2. mutations that alter the gene pool 3. little gene flow with surrounding populations 4. a tendency on the part of females to mate with the healthiest males

little gene flow with surrounding populatiosn

Genetic drift is 1. the mechanism by which new alleles originate 2. adaptive 3. more likely to have an impact on to small populations 4. an important microevolutionary mechanism in large population

more likely to have an impact on small populations

The ____ species concept is the most applicable to classifying species from the fossil record. ecological, biological, phylogenetic, morphological

morphological

Of the choices listed, which contributes the most to genetic variation among individuals in most prokaryote species? independent assortment of homologous chromosomes, genetic drift, crossing over, or mutation

mutation

The original source of all genetic variation is

mutation

What is the relation between natural selection and evolution?

natural selection is one of several mechanisms of evolution

The monomers of DNA and RNA are

nucleotides

Transcription takes place in the

nucleus

For which of the following groups would the biological definition of species be useful? 1. asexually reproducing plant and animal species that live in the present 2. oaks and other sexually reproducing currently living trees 3. fossil bacteria, which are known to have reproduced asexually 4. fossil dinosaurs, which are known to have reproduced sexually

oaks and other sexually reproducing, currently living trees

adaptive radiation

occurs when a species gives rise to many new species after colonized a region with diverse habits

A uracil nucleotide is a __________ nitrogenous base attached to the __________, with the 5′ carbon of the sugar attached to a phosphate group.

one-ringed : carbon of a sugar that has an OH group at the 2′ carbon

Which type of organism is most likely to undergo sympatric speciation by polyploidy?

plant species that are capable of self-pollination and some degree of asexual reproduction

According to the __________ model, evolution occurs in spurts; species evolve relatively rapidly and then remain unchanged for long periods.

punctuated equilibrium

Which of the following statements about reinforcement is true? 1. reinforcement decreases the morphological difference between two new species 2. reinforcement is a type of natural selection 3. reinforcement increases the number of intermediate phenotypes 4. reinforcement is also called dispersive selection

reinforcement is a type of natural selection in which extreme phenotypes are favored over intermediate phenotypes

The action of helicase creates _____.

replication forks and replication bubbles

both allopatric speciation and sympatric speciation depend on the establishment of

reproductive barriers, which prevents gene flow between a new species and its parent species

Which statement best expresses the concept of natural selection?

reproductive success influenced by inherited characteristics

Which statement regarding the structure of DNA is false? 1. Watson and Crick received Nobel Prize for their description of the structure of DNA 2. DNA molecule have uniform diameter 3. Adenine bonds to thymine and guanine to cytosine 4. sequence of nucleotides along length of single DNA strand is restricted by base-pairing rules

sequence of nucleotides along the length of a single DNA strand is restricted by the base-pairing rules

During replication, the original parent DNA

serves as the template for the create of two complete sets of DNA

Which condition would disturb the Hardy-Weinberg equilibrium and cause the gene pool to change? 1. several homozygous recessive individuals to leave the population 2. mating occurs at random 3. no mutations occur 4. all genotypes on average produce an equal number of fertile adult offspring

several homozygous recessive individuals to leave the population

Multiple origins of replication on the DNA molecules of eukaryotic cells serve to

shorten the time necessary for DNA replication

In which of the following situations is adaptive radiation least likely to occur? 1. species has flexible morphological structures that lend themselves to specialization 2. dominant organisms in an area become extinct 3. new island chain forms far from shore and is reached by a few groups of long-distance colonists 4. species with inflexible morphological traits finds itself in a species-rich, highly competitive environment

species with inflexible morphological traits finds itself in a species-rich, highly competitive environment

At the start of translation, where does the initiator tRNA bind?

start codon on the mRNA molecule

Hershey and Chase were able to differentiate between proteins and nucleic acids using radioactive atoms of elements found only in those macromolecules. Which of the following would be found only in proteins?

sulfur

Modern bread wheat is the product of multiple instances of hybridization of wheat species, including wheat found in Middle Eastern farms 10,000 years ago. This is an example of __________.

sympatric speciation

A subset of a population of birds leaves its habitat and colonizes a nearby island. After many generations, the island sinks and the population of birds living on the island returns to its original habitat. Which of the following statements mostaccurately describes the two bird populations?

the birds were separated by dispersal; one population migrated to an isolated location

Genetic drift resulting from a disaster that drastically reduces population size is called

the bottleneck effect

Which of the following takes place during translation?

the conversion of genetic information from the language of nucleic acids to the language of proteins

If protein production were an assembly line, a ribosome would be

the worker who puts all of the pieces together

A friend accidentally sends an email to you that contains a computer virus from his computer. Without knowing it, you infect your computer with the virus when you open the email. This process of spreading the computer virus via email is most like

transduction

During translation, _____ matches an mRNA codon with the proper amino acid

transfer RNA

If whales evolved from land-dwelling mammals, one would expect the fossil record to include intermediate forms, creatures more whale-like than land-dwelling mammals yet still possessing hind limbs and a pelvis lacking in modern whales. Such intermediates are termed __________.

transitional forms

Which of the following processes takes place in the cytoplasm of eukaryotic cells?

translation

Conjugation is a very effective process for spreading antibiotic resistance among diverse bacterial populations such as those found in the mammalian gut. Which statement best explains this observation?

two different species of bacteria can share DNA, including antibiotic-resistance genes, during conjugation

Life on Mars is finally discovered and a new organism that has six different nucleotides that encode 30 different amino acids is found on this planet. Which of the following nucleotide combinations would encode the minimum number of amino acids needed in this organism?

two-nucleotide sequence (6^3 combos)

Which of the following is only associated with RNA?

uracil

Whereas some modern whales possess a small and useless __________ pelvis, __________ linking modern whales to their four-legged evolutionary ancestors possess a larger and even functional pelvis.

vestigial; transitional forms