Quiz 12

Question 1

The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical classification system differ from each other on the basis of

a) how widely the organisms assigned to each are distributed throughout the environment.
b) their inclusiveness.
c) the relative genome sizes of the organisms assigned to each.
d) morphological characters that are applicable to all organisms.

Answer 1

b) their inclusiveness.

Question 2

The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are best described as

a) structural homologies
b) molecular homologies
c) homoplasies
d) the result of shared ancestry.

Answer 2

c) homoplasies

Question 3

One morphological feature of modern cetaceans is a vestigial pelvic girdle. If it is determined that cetacean lineage diverged from the artiodactyls’ lineage after the divergence of pigs and other artiodactyla, then what should be true of the vestigial pelvic girdle of cetaceans?

a) It should be considered a shared ancestral character of the cetartiodactyls.
b) It should be considered a shared derived character of the cetartiodactyls.
c) It should be considered a shared ancestral character of the cetaceans.
d) It should be considered a shared derived character of the cetaceans.

Answer 3

d) It should be considered a shared derived character of the cetaceans.

Question 4

The reason that paralogous genes can diverge from each other within the same gene pool, whereas orthologous genes diverge only after gene pools are isolated from each other, is that

a) having multiple copies of genes is essential for the occurrence of sympatric speciation in the wild.
b) paralogous genes can occur only in diploid species; thus, they are absent from most prokaryotes.
c) polyploidy is a necessary precondition for the occurrence of sympatric speciation in the wild.
d) having an extra copy of a gene permits modifications to the copy without loss of the original gene product.

Answer 4

d) having an extra copy of a gene permits modifications to the copy without loss of the original gene product.

Question 5

A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?

a) Among themselves, they should share relatively few ancestral traits, especially those that enabled ancestral forms to adapt to extreme conditions.
b) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.
c) They should contain genes that originated in eukaryotes that are the hosts for numerous species of bacteria.
d) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic archaeans.

Answer 5

b) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.

Question 6

The predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering, what is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey’s cytoplasm?

1. membrane composed mostly of lipopolysaccharide
2. membrane composed mostly of phospholipids
3. peptidoglycan
4. capsule

Answer 6

4, 1, 3, 2

Question 7

Match the numbered terms to the description that follows. Choose all appropriate terms.

1. autotroph
2. heterotroph
3. phototroph
4. chemotroph

an organism that obtains both carbon and energy by ingesting prey

Answer 7

2 & 4

Question 8

A fish that has been salt-cured subsequently develops a reddish color. You suspect that the fish has been contaminated by the extreme halophile, Halobacterium. Which of these features of cells removed from the surface of the fish, if confirmed, would support your suspicion?

1. the presence of the same photosynthetic pigments found in cyanobacteria
2. cell walls that lack peptidoglycan
3. cells that are isotonic to conditions on the surface of the fish
4. cells containing bacteriorhodopsin
5. the presence of very large numbers of ion pumps in its plasma membrane

Answer 8

2, 3, 4 and 5

Question 9

In general, what is the primary ecological role of prokaryotes?

a) parasitizing eukaryotes, thus causing diseases
b) breaking down organic matter
c) metabolizing materials in extreme environments
d) serving as primary producers in terrestrial environments

Answer 9

b) breaking down organic matter

Question 10

Biologists have long been aware that the defunct kingdom Protista is polyphyletic. Which of these statements is most consistent with this conclusion?

a) Many species within this kingdom were once classified as monerans.
b) Animals, plants, and fungi arose from different protist ancestors.
c) The eukaryotic condition has evolved more than once among the protists.
d) Chloroplasts among various protists are similar to those found in prokaryotes.

Answer 10

c) The eukaryotic condition has evolved more than once among the protists.

Question 11

Members of which kingdom have cell walls and are all heterotrophic?

a) Plantae
b) Fungi
c) Animalia
d) Protista
e) Moner

Answer 11

b) Fungi

Question 12

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

a) A and B
b) A and C
c) B and D
d) C and F
e) D and F

Answer 12

e) D and F

Question 13

Traditionally, zoologists have placed birds in their own class, Aves. More recently, molecular evidence has shown that birds are more closely related to reptiles than their anatomy reveals. Genetically, birds are more closely related to crocodiles than crocodiles are to turtles. Bird anatomy has become highly modified as birds have adapted to flight, without their genes having undergone nearly as much change.

Taxonomically, what should be done with the birds?

a) The birds should be reclassified, and their new taxon should be the subclass Aves. Genetic similarity trumps morphological dissimilarity.
b) The rest of the reptiles should be reclassified as a subclass within the class Aves.
c) Science is consensual. Taxonomy is a science. Variant classification schemes involving the birds should be tolerated until consensus is reached.
d) The traditional stance is correct. Such dramatic morphological change as undergone by birds merits that the birds be placed in their own order, separate from the reptiles.

Answer 13

c) Science is consensual. Taxonomy is a science. Variant classification schemes involving the birds should be tolerated until consensus is reached.

Question 14

Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?

a) nitrogen-fixing bacteria that live in root nodules
b) extreme halophiles
c) methanogens
d) cyanobacteria
e) extreme thermophiles

Answer 14

b) extreme halophiles

Question 15

Mycoplasmas are bacteria that lack cell walls. On the basis of this structural feature, which statement concerning mycoplasmas should be true?

a) They possess typical prokaryotic flagella.
b) They are gram-negative.
c) They are subject to lysis in hypotonic conditions.
d) They should contain less cellulose than do bacteria that possess cell walls.
e) They lack a cell membrane as well.

Answer 15

c) They are subject to lysis in hypotonic conditions.

Question 16

A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.

This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Thus, this bacterium should be an

a) anaerobic chemoautotroph.
b) aerobic chemoautotroph.
c) anaerobic chemoheterotroph.
d) aerobic chemoheterotroph.

Answer 16

c) anaerobic chemoheterotroph.

Question 17

An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?

a) It has an endospore.
b) It relies on photosystems that float freely in its cytosol.
c) It must have gained extra mitochondria when it lost its plastids.
d) It engulfs organic material by phagocytosis or by absorption.
e) It is protected by a case made of silica.

Answer 17

d) It engulfs organic material by phagocytosis or by absorption.

Question 18

Giardia lamblia is an intestinal parasite of humans and other mammals that causes intestinal ailments in most people who ingest the cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites. These attach to the small intestine’s lining via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the host’s intestinal contents to produce ATP. Reproduction is completely asexual, occurring by longitudinal binary fission of trophozoites, with each daughter cell receiving two haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large intestine by secreting around itself a case that is resistant to cold, heat, and dehydration. Infection usually occurs by drinking untreated water that contains cysts.

The mitosome of Giardia has no DNA within it. If it did contain DNA, then what predictions should we be able to make about its DNA?

1. It is linear.
2. It is circular.
3. It has many introns.
4. It has few introns.
5. It is not associated with histone proteins.
6. It is complexed with histone proteins.

Answer 18

2, 4 and 5

Question 19

According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?

a) from engulfed, originally free-living proteobacteria
b) by secondary endosymbiosis
c) when a protoeukaryote engaged in a symbiotic relationship with a protocell
d) from the nuclear envelope folding outward and forming mitochondrial membranes
e) from infoldings of the plasma membrane, coupled with mutations of genes for proteins in energy-transfer reactions

Answer 19

a) from engulfed, originally free-living proteobacteria

Question 20

Nucleic acid sequences that undergo few changes over the course of evolutionary time are said to be conserved. Conserved sequences of nucleic acids

a) comprise a larger proportion of pre-mRNA (immature Mrna) than of mature mRNA.
b) are abundant in ribosomes.
c) are proportionately more common in eukaryotic introns than in eukaryotic exons.
d) include all mitochondrial DNA.
e) are found in the most crucial portions of proteins.

Answer 20

b) are abundant in ribosomes.

Question 21

We have overwhelming evidence that Bacteria and Archaea are masters of adaptation. Which key characteristic enables these prokaryotes to occupy almost every habitat on earth?

a) metabolic diversity
b) fast reproductive rate
c) high mutation rate
d) presence of a protective cell wall
e) small size

Answer 21

a) metabolic diversity

Question 22

Extreme halophiles

a) live in extremely cold environments.
b) live in highly saline environments.
c) live in extremely hot environments.
d) require methane for energy.

Answer 22

b) live in highly saline environments.

Question 23

The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?

a) cyanobacteria → green algae → fungi → land plants
b) cyanobacteria → green algae → land plants
c) red algae → brown algae → green algae → land plants
d) cyanobacteria → red algae → green algae → land plants

Answer 23

b) cyanobacteria → green algae → land plants

Question 24

Which of the following was derived from an ancestral cyanobacterium?

a) mitochondrion
b) chloroplast
c) mitosome
d) hydrogenosome
e) Two of the responses above are correct.

Answer 24

b) chloroplast

Question 25

What is true of the Cambrian explosion?

a) The Cambrian explosion is evidence for the instantaneous creation of life on Earth.
b) There are no fossils in geological strata that are older than the Cambrian explosion.
c) Recent evidence supports the contention that the Cambrian explosion may not have been as “explosive” as was once thought.
d) Only the fossils of microorganisms are found in geological strata older than the Cambrian explosion.
e) The Cambrian explosion marks the appearance of filter-feeding animals in the fossil record.

Answer 25

c) Recent evidence supports the contention that the Cambrian explosion may not have been as “explosive” as was once thought.

Question 26

Genetic variation in bacterial populations cannot result from

a) transduction.
b) conjugation.
c) mutation.
d) meiosis.

Answer 26

d) meiosis.

Question 27

Photoautotrophs use..?

a) light as an energy source and CO2 as a carbon source.
b) light as an energy source and methane as a carbon source.
c) N2 as an energy source and CO2 as a carbon source.
d) CO2 as both an energy source and a carbon source

Answer 27

a) light as an energy source and CO2 as a carbon source.

Question 28

Which of the following statements is not true?

a) Archaea and bacteria have different membrane lipids.
b) The cell walls of archaea lack peptidoglycan.
c) Only bacteria have histones associated with DNA.
d) Only some archaea use CO2 to oxidize H2, releasing methane.

Answer 28

c) Only bacteria have histones associated with DNA.

Question 29

Which of the following involves metabolic cooperation among prokaryotic cells?

a) binary fission
b) endospore formation
c) biofilms
d) photoautotrophy

Answer 29

c) biofilms

Question 30

Plant-like photosynthesis that releases O2 occurs in..?

a) cyanobacteria.
b) gram-positive bacteria.
c) archaea.
d) chemoautotrophic bacteria.

Answer 30

a) cyanobacteria.

Question 31

In a comparison of birds and mammals, having four limbs is

a) a shared ancestral character.
b) a shared derived character.
c) a character useful for distinguishing birds from mammals.
e) an example of analogy rather than homology.

Answer 31

a) a shared ancestral character.

Question 32

To apply parsimony to constructing a phylogenetic tree,

a) choose the tree that assumes all evolutionary changes are equally probable.
b) choose the tree in which the branch points are based on as many shared derived characters as possible.
c) choose the tree that represents the fewest evolutionary changes, in either DNA sequences or morphology.
d) choose the tree with the fewest branch points.

Answer 32

c) choose the tree that represents the fewest evolutionary changes, in either DNA sequences or morphology.

Question 33

Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V. A grouping that consists of species T, X, Y, and Z (but not U or V) makes up…?

a) a monophyletic clade.
b) an ingroup, with species U as the outgroup.
c) a paraphyletic group.
d) a polyphyletic group.

Answer 33

c) a paraphyletic group.

Question 34

Which of the following provides some evidence that RNA probably evolved before DNA?

a) RNA polymerase uses DNA as a template.
b) DNA polymerase uses primer, usually made of RNA.
c) DNA polymerase has proofreading function.
d) RNA polymerase makes a single-stranded molecule.
e) RNA polymerase does not require localized unwinding of the DNA.

Answer 34

b) DNA polymerase uses primer, usually made of RNA.

Question 35

Which of the following pairs is incorrectly matched?

a) orthologous and paralogous genes — both lead to speciation
b) orthologous genes — speciation with divergence of genes
c) paralogous genes — gene duplication and divergence
d) paralogous genes — divergence within a species

Answer 35

a) orthologous and paralogous genes — both lead to speciation

Question 36

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

a) behavioural
b) ecological
c) nutritional
d) molecular
e) anatomical

Answer 36

d) molecular

Question 37

You are taking an art class and your instructor asks you to draw several animals, including a shark, a dolphin, and a penguin. As you draw these animals you notice that they all have a fusiform shape; in other words, they are tapered at both ends. Despite their similar shape, you are well aware that the shark is a fish, the dolphin is a mammal, and the penguin is a bird.

What is the best explanation for the similarities and differences in these three species?

a) There is some homology and some analogy in all living organisms.
b) You are seeing an example of homology: the evolution of similar function in distantly related organisms due to adaptations to similar environments.
c) You are seeing an example of convergent evolution: the evolution of similar traits in distantly related organisms due to adaptations to similar environments.
d) You are seeing an example of analogy: the evolution of modified traits in related organisms.
e) The animals all share a very distant common ancestor.

Answer 37

c) You are seeing an example of convergent evolution: the evolution of similar traits in distantly related organisms due to adaptations to similar environments.

Question 38

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform 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 share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.
b) Both species are well adapted to their particular environments.
c) The sizes of the structures in adult members of both species are similar in size.
d) The two species live at great distance from each other.

Answer 38

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

Question 39

You have read that soapberry bugs, Jadera haematoloma, adapt to available food sources. For example, in southern Florida, soapberry bugs feed on seeds of a native plant, the balloon vine. In central Florida, the balloon vine is rare and soapberry bugs have switched to eating seeds of an introduced species, the goldenrain tree. The seeds of the goldenrain tree fruits are much closer to the fruit surface than the seeds of the native balloon vine fruit. As a result, natural selection results in beaks that are shorter in soapberry bugs that utilize goldenrain tree fruits than those that feed on balloon vine fruit seeds.

A conservation organization has been trying to eliminate introduced species and encourage the growth/spread of native species. After several years, the balloon vine has almost totally replaced the goldenrain tree in the experimental plot. Based on your knowledge of evolution, which of the following outcomes would appear to be the most logical?

a) Intermediate beak length will be favoured just in case the introduced goldenrain tree makes a comeback.
b) Half of the soapberry bugs will die.
c) Variation in beak size will remain present in the soapberry bug population, but natural selection will favour beak lengths that are best adapted to the current food source.
d) The genes for short beaks will be lost.
e) To save soapberry bugs with short beaks, the researchers must relocate them to a different plot.

Answer 39

c) Variation in beak size will remain present in the soapberry bug population, but natural selection will favour beak lengths that are best adapted to the current food source.

Question 40

Which of the following is true of all horizontally oriented phylogenetic trees, where time advances to the right?

a) The more branch points there are, the fewer taxa are likely to be represented.
b) The common ancestor represented by the rightmost branch point existed more recently in time than the common ancestors represented at branch points located to the left.
c) The fewer branch points that occur between two taxa, the more divergent their DNA sequences should be.
d) Organisms represented at the base of such trees are descendants of those represented at higher levels.
e) Each branch point represents a point in absolute time.

Answer 40

b) The common ancestor represented by the rightmost branch point existed more recently in time than the common ancestors represented at branch points located to the left.

Question 41

When using a cladistic approach to systematics, which of the following is considered most important for classification?

a) analogous primitive characters
b) the number of homoplasies
c) shared derived characters
d) overall phenotypic similarity
e) shared primitive characters

Answer 41

c) shared derived characters

Question 42

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species?
1. It is a bacterium.
2. It is an archaean.
3. The optimal pH of its enzymes will lie above pH 7.
4. The optimal pH of its enzymes will lie below pH 7.
5. It could inhabit certain hydrothermal springs.
6. It could inhabit alkaline hot springs.

Answer 42

2, 4, and 5

Question 43

Which of the following obtain energy by oxidizing inorganic substances—energy that is used, in part, to fix CO2?

a) parasitic chemoheterotrophs
b) photoautotrophs
c) photoheterotrophs
d) chemoheterotrophs that perform decomposition
e) chemoautotrophs

Answer 43

e) chemoautotrophs

Question 44

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient proteobacterium and an ancient cyanobacterium?

a) Plantae
b) Fungi
c) Animalia
d) Protista
e) Monera

Answer 44

a) Plantae

Question 45

A researcher wants to determine the genetic relatedness of several breeds of dog (Canis lupus familiaris). The researcher should compare homologous sequences of this type of biochemical—________—which can be described as ________.

a) nucleic acids, poorly conserved
b) fatty acids; highly conserved
c) proteins; highly conserved
d) amino acids; highly conserved
e) lipids; poorly conserved

Answer 45

a) nucleic acids, poorly conserved

Question 46

Since all organisms share a common ancestor, it comes as no surprise that some characteristics are shared while others are not. If we consider the backbone and feathers, respectively, of birds, we can say that the former is a ________ while the latter are a ________.

a) shared ancestral character, shared derived character
b) ingroup, outgroup
c) shared derived character, shared ancestral character
d) monophyletic characteristic, polyphyletic characteristic
e) monophyletic characteristic, paraphyletic characteristic

Answer 46

a) shared ancestral character, shared derived character

Question 47

Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?

a) Some have cell walls only to control osmotic balance.
b) Some closely resemble animals, which lack cell walls.
c) Some have cell walls only for protection from herbivores.
d) Their cell walls are composed of very different biochemicals.
e) Some have cell walls only for support.

Answer 47

d) Their cell walls are composed of very different biochemicals.

Question 48

Which statement about bacterial cell walls is false?

a) Bacterial cell walls are similar in function to the cell walls of many protists, fungi, and plants.
d) Cell walls prevent cells from bursting in hypotonic environments.
c) Cell walls provide the cell with a degree of physical protection from the environment.
d) Cell walls prevent cells from dying in hypertonic conditions.
e) Bacterial cell walls differ in molecular composition from plant cell walls.

Answer 48

d) Cell walls prevent cells from dying in hypertonic conditions.

Question 49

A high degree of endemism is most likely in environments that are

a) easily reached and homogeneous.
b) isolated and extremely cold.
c) isolated and heterogeneous.
d) easily reached and heterogeneous.
e) isolated and homogeneous.

Answer 49

c) isolated and heterogeneous.

Question 50

Match the numbered terms to the description that follows. Choose all appropriate terms.
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
Description: a prokaryote that obtains both energy and carbon as it decomposes dead organisms

Answer 50

2 & 4

Question 51

Which of the following traits do archaeans and bacteria share?
1. composition of the cell wall
2. presence of plasma membrane
3. lack of a nuclear envelope
4. identical rRNA sequences

Answer 51

2 & 3

Question 52

Which kingdom has been replaced with two domains?

a) Plantae
b) Fungi
c) Animalia
d) Protista
e) Monera

Answer 52

e) Monera