Handout 3

Question 1

a catabolic pathway in which inorganic molecules other than oxygen accept electrons at the ‘downhill’ end of electron transport chain

Answer 1

anaerobic respiration

Question 2

one of the five supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes; this monophyletic group, which includes red algae, green algae, and land plants, descended from and ancient protist ancestor that engulfed a cyanobacterium

Answer 2

archaeplastida

Question 3

an organism that obtains organic food molecules without eating other organisms or substances derived from other organisms. Autotrophs use energy from the sun or from oxidation of inorganic substances to make organic molecules from inroganic ones

Answer 3

autotroph

Question 4

a method of asexual reproduction by “division in half”; in prokaryotes it
does not involve mitosis; where relevant in single-celled eukaryotes,
mitosis is part of the process.

Answer 4

binary fission

Question 5

A surface-coating colony of one or more species of prokaryotes that
engage in metabolic co-operation.

Answer 5

biofilm

Question 6

The use of organisms to detoxify and restore polluted and degraded
ecosystems.

Answer 6

bioremediation

Question 7

(1) A leaf-like structure of a seaweed that provides most of the surface
area for photosynthesis. (2) The flattened portion of a typical leaf.

Answer 7

blade

Question 8

A multicellular, photosynthetic protist with a characteristic colour that
results from carotenoids in its plastids; most are marine, and some have
a plant-like body (thallus)

Answer 8

brown alga

Question 9

(1) In many prokaryotes, a dense and well-defined layer of
polysaccharide or protein that surrounds the cell wall and is sticky,
protecting the cell and enabling it to adhere to substrates or other cells.
(2) The sporangium of a bryophyte (moss, liverwort, or hornwort)

Answer 9

capsule

Question 10

A protective layer external to the plasma membrane in the cells of
plants, prokaryotes, fungi, and some protists; polysaccharides such as
cellulose (in plants and some protists), chitin (in fungi), and
peptidoglycan (in bacteria) are important structural components.

Answer 10

cell wall

Question 11

One of five supergroups of eukaryotes proposed in a current hypothesis
of the evolutionary history of eukaryotes; may have originated by
secondary endosymbiosis and include two large protist clades, the
alveolates and the stramenopiles.

Answer 11

chromalveolata

Question 12

A short appendage containing microtubules in eukaryotic cells; a motile
version is specialized for locomotion or moving fluid past the cell; it is
formed from a core of nine outer doublet microtubules and two inner
single microtubules (the “9 + 2” arrangement) ensheathed in an
extension of the plasma membrane; a primary version is usually non-
motile and plays a sensory and signalling role; it lacks the two inner
microtubules (the “9 + 0” arrangement).

Answer 12

cilium

Question 13

A symbiotic relationship in which one organism benefits but the other is
neither helped nor harmed.

Answer 13

commensalism

Question 14

An organism that absorbs nutrients from non-living organic material
such as corpses, fallen plant material, and the wastes of living
organisms and converts them to inorganic forms

Answer 14

decomposer

Question 15

A cell containing two sets of chromosomes (2n), one set inherited from
each parent

Answer 15

diploid cell

Question 16

A protist that has modified mitochondria, two equal-sized nuclei, and
multiple flagella.

Answer 16

diplomonad

Question 17

A thick-coated, resistant cell produced by some bacterial cells when
they are exposed to harsh conditions.

Answer 17

endospore

Question 18

A toxic component of the outer membrane of certain gram-negative
bacteria that is released only when the bacteria die.

Answer 18

endotoxin

Question 19

Member of a diverse clade of flagellated protists that includes
predatory heterotrophs, photosynthetic autotrophs, and pathogenic
parasites

Answer 19

euglenozoan

Question 20

One of five supergroups of eukaryotes proposed in a current hypothesis
of the evolutionary history of eukaryotes; have unique cytoskeletal
features, and some species have an “excavated” feeding groove on one
side of the cell body.

Answer 20

excavata

Question 21

A toxic protein that is secreted by a prokaryote or other pathogen and
that produces specific symptoms, even if the pathogen is no longer
present

Answer 21

exotoxin

Question 22

An organism that lives in a highly saline environment, such as the Great
Salt Lake or the Dead Sea.

Answer 22

extreme halophile

Question 23

An organism that thrives in hot environments (often 60-80°C or hotter).

Answer 23

extreme thermophile

Question 24

An organism that lives in environmental conditions so extreme that few
other species can survive there; include “salt lovers” and “heat lovers”

Answer 24

extremophile

Question 25

An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present.

Answer 25

facultative anaerobe

Question 26

A short, hair-like appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells

Answer 26

fimbria

Question 27

A long cellular appendage specialized for locomotion; eukaryotic forms have a core with nine outer doublet microtubules and two inner single microtubules (the “9 + 2” arrangement) ensheathed in an extension of the plasma membrane; prokaryotic forms have a different structure

Answer 27

flagellum

Question 28

A bi-flagellated, photosynthetic protist named for its colour, which results from its yellow and brown carotenoids

Answer 28

golden alga

Question 29

Describing the group of bacteria that have a cell wall structurally more complex and contains less peptidoglycan than the cell wall of (and are often more toxic than) the other major type of gram-staining bacteria.

Answer 29

gram-negative

Question 30

Describing the group of bacteria that have a cell wall structurally less complex and contains more peptidoglycan than the cell wall of (and are usually less toxic than) the other type of major gram-staining bacteria

Answer 30

gram-positive

Question 31

A method that distinguishes between two different kinds of bacterial cell walls; may be used to help determine medical response to an infection.

Answer 31

gram stain

Question 32

A photosynthetic protist, named for green chloroplasts that are similar in structure and pigment composition to those of land plants; they are a paraphyletic group, some of whose members are more closely related to land plants than they are to other members.

Answer 32

green alga

Question 33

A cell containing only one set of chromosomes (n).

Answer 33

haploid cell

Question 34

A specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; also called a heterocyte.

Answer 34

heterocyst

Question 35

A root-like structure that anchors a seaweed.

Answer 35

holdfast

Question 36

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms

Answer 36

horizontal gene transfer

Question 37

The larger participant in a symbiotic relationship, often providing a home and food source for the smaller participant.

Answer 37

host

Question 38

Referring to a solution that, when surrounding a cell, will cause the cell to lose water

Answer 38

hypertonic

Question 39

Referring to a solution that, when surrounding a cell, will cause the cell to take up water.

Answer 39

hypotonic

Question 40

The collection and sequencing of DNA from a group of species, usually an environmental sample of microorganisms. Computer software sorts partial sequences and assembles them into genome sequences of individual species making up the sample.

Answer 40

metagenomics

Question 41

An organism that produces methane as a waste product of the way it obtains energy; all known are in domain Archaea

Answer 41

methanogen

Question 42

An organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP

Answer 42

mitochondrion

Question 43

An organism that is capable of both photosynthesis and heterotrophy.

Answer 43

mixotroph

Question 44

A symbiotic relationship in which both participants benefit.

Answer 44

mutualism

Question 45

The conversion of atmospheric nitrogen (N2) to ammonia (NH3); carried out by certain prokaryotes, some of which have mutualistic relationships with plants.

Answer 45

nitrogen fixation

Question 46

A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated.

Answer 46

nucleoid

Question 47

An organism that requires oxygen for cellular respiration and cannot live without it.

Answer 47

obligate aerobe

Question 48

An organism that only carries out fermentation or anaerobic respiration. Such organisms cannot use oxygen and in fact may be poisoned by it

Answer 48

obligate anaerobe

Question 49

Protist with flagellated cells, such as a water mould, white rust, or downy mildew, that acquires nutrition mainly as a decomposer or plant parasite.

Answer 49

oomycete

Question 50

Regulation of solute concentrations and water balance by a cell or organism.

Answer 50

osmoregulation

Question 51

The diffusion of free water across a selectively permeable membrane.

Answer 51

osmosis

Question 52

A protist, such as a trichomonad, with modified mitochondria.

Answer 52

parabasalid

Question 53

A symbiotic relationship in which one organism benefits at the expense of another by living either within or on it.

Answer 53

parasitism

Question 54

An organism, virus, viroid, or prion that causes disease.

Answer 54

pathogen

Question 55

A type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides.

Answer 55

peptidoglycan

Question 56

in bacteria, a structure that links one cell to another at the start of conjugation

Answer 56

pilus

Question 57

A small, circular, double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome; in DNA cloning, used as vectors carrying up to about 10,000 base pairs (10 kb) of DNA; are also found in some eukaryotes, such as yeasts

Answer 57

plasmid

Question 58

An organism that produces organic compounds from CO2 by harnessing light energy (in photosynthesis) or by oxidizing inorganic chemicals (in chemosynthetic reactions carried out by some prokaryotes)

Answer 58

producer

Question 59

A cellular extension of amoeboid cells used in moving and feeding.

Answer 59

pseudopodium

Question 60

One of five supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes; a morphologically diverse protist clade that is defined by DNA similarities

Answer 60

rhizaria

Question 61

A stem-like structure of a seaweed.

Answer 61

stipe

Question 62

A protist in which a “hairy” flagellum (one covered with fine, hair-like projections) is paired with a shorter, smooth flagellum

Answer 62

stramenophile

Question 63

The smaller participant in a symbiotic relationship, living in or on the other participant

Answer 63

symbiont

Question 64

An oriented movement toward or away from a stimulus.

Answer 64

taxis

Question 65

A seaweed body that is plant-like, consisting of a holdfast, stipe, and blades, yet lacks true roots, stems, and leaves

Answer 65

thallus

Question 66

One of five supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes; this clade, which is supported by studies of myosin proteins and DNA, consists of amoebozoans and opisthokonts.

Answer 66

unikonta

Question 67

concept 5.1

Answer 67

structural and functional adaptations contribute to prokaryotic success

Question 68

concept 5.2

Answer 68

diverse nutritional and metabolic adaptations have evolved in prokaryotes

Question 69

concept 5.3

Answer 69

molecular systematics is illuminating prokaryotic phylogeny

Question 70

concept 5.4

Answer 70

prokaryotes play crucial roles in the biosphere

Question 71

concept 5.5

Answer 71

prokaryotes have both beneficial and harmful impacts on humans

Question 72

concept 6.1

Answer 72

most eukaryotes are single-celled organisms

Question 73

concept 6.2

Answer 73

excavates includes protists with modified mitochondria and protists with unique flagella

Question 74

concept 6.3

Answer 74

chromalveolates may have originated by secondary endosymbiosis

Question 75

concept 6.4

Answer 75

rhizarians are a diverse group of protists defined by DNA similarities

Question 76

concept 6.5

Answer 76

red algae and green algae are the closest relatives of land plants

Question 77

concept 6.6

Answer 77

unikonts include protists that are closely related to fungi and animals

Question 78

concept 6.7

Answer 78

protists play key roles in ecological communities

Question 79

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?

Answer 79

B. their cell walls are composed of very different biochemicals

Question 80

Which of these is the most common compound in the cell walls of gram-positive bacteria?

Answer 80

D. peptidoglycan

Question 81

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 which can inhibit phagocytosis, 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 81

D. 4 → 1 → 3 → 2.

Question 82

Jams, jellies, preserves, honey, and other foodstuffs with a high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment

Answer 82

A. undergo death by plasmolysis.

Question 83

The typical prokaryotic flagellum features

Answer 83

C. a complex ʺmotorʺ embedded in the cell wall and plasma membrane.

Question 84

Which statement about the genomes of prokaryotes is correct?

Answer 84

D. The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.

Question 85

Referring to structures found in a gram-positive prokaryotic cell: Not present in all bacteria, this cell covering enables cells that possess it to resist the defences of host organisms:

Answer 85

E. capsule.

Question 86

Referring to structures found in a gram-positive prokaryotic cell: Not present in all bacteria, this structure enables those that possess it to germinate after exposure to harsh conditions, such as boiling:

Answer 86

A. endospore

Question 87

Referring to structures found in a gram-positive prokaryotic cell: If this structure connects the cytoplasm of two bacteria, one of these cells may gain new genetic material:

Answer 87

B. sex pilus

Question 88

Match the numbered terms to the descriptions that follow. For each item, choose all appropriate terms, but only appropriate terms. 1. Autotroph; 2. Heterotroph; 3. Phototroph; 4. Chemotroph: An organism that obtains its energy from chemicals

Answer 88

D. 4 only.

Question 89

Match the numbered terms to the descriptions that follow. For each item, choose all appropriate terms, but only appropriate terms. 1. Autotroph; 2. Heterotroph; 3. Phototroph; 4. Chemotroph: A prokaryote that obtains both energy and carbon as it decomposes dead organisms

Answer 89

D. 2 and 4.

Question 90

Match the numbered terms to the descriptions that follow. For each item, choose all appropriate terms, but only appropriate terms. 1. Autotroph; 2. Heterotroph; 3. Phototroph; 4. Chemotroph: An organism that obtains both carbon and energy by ingesting prey

Answer 90

D. 2 and 4.

Question 91

Which of the following are responsible for high levels of O2 in Earth’s atmosphere?

Answer 91

A. photoautotrophs

Question 92

Which statement about the domain Archaea is false?

Answer 92

C. The genomes of archaeans are unique, containing no genes that originated within bacteria.

Question 93

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

Answer 93

A. extreme halophiles.

Question 94

The thermoacidophile, Sulfolobus acidocaldarius lacks peptidoglycan. 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 94

C. 2, 4, and 5

Question 95

What is the primary ecological role of prokaryotes?

Answer 95

B. breaking down organic matter

Question 96

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf’s non-living, waxy covering, while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply. 1. Nutrient recycler; 2. Mutualist; 3. Commensal; 4. Parasite; 5. Primary producer.

Answer 96

C. 2, 4, 1

Question 97

How can prokaryotes be considered to be more successful on Earth than humans?

Answer 97

A. Prokaryotes are much more numerous and have more biomass. B. Prokaryotes occupy more diverse habitats. C. Prokaryotes are more diverse in metabolism. ANSWER; E. A, B, and C are correct

Question 98

Which statement about gram-negative bacteria is correct?

Answer 98

B. They often possess an outer membrane containing toxic lipopolysaccharides.

Question 99

Protists are alike in that all are

Answer 99

B. eukaryotic.

Question 100

Biologists have long been aware that the defunct kingdom Protista is paraphyletic. Which of these statements is both true and consistent with this conclusion?

Answer 100

E. Some protists, all animals, and all fungi share a protist common ancestor, but these protists, animals, and fungi are currently assigned to three different kingdoms

Question 101

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

Answer 101

B. from engulfed, originally free-living prokaryotes.

Question 102

A biologist discovers a new unicellullar organism that possesses more than two flagella and two small, but equal-sized, nuclei. The organism has reduced mitochondria (mitosomes), no chloroplasts, and is anaerobic. To which clade does this organism probably belong?

Answer 102

B. the diplomonads

Question 103

Which of these taxa contains species that produce potent toxins that can cause extensive fish kills, contaminate shellfish, and poison humans?

Answer 103

B. dinoflagellates

Question 104

You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile, using many short extensions of the cytoplasm, each featuring the 9+2 filament pattern. It has well-developed organelles and three nuclei, one large and two small. This organism is most likely to be a member of which group?

Answer 104

C. ciliates.

Question 105

The Irish potato famine was caused by an organism that belongs to which group?

Answer 105

B. oomycetes

Question 106

Thread-like pseudopods that can perform phagocytosis are generally characteristic of which group?

Answer 106

A. radiolarians and forams

Question 107

Diatoms are mostly asexual members of the phytoplankton. Diatoms lack any organelles that might have the 9+2 pattern. They obtain their nutrition from functional chloroplasts, and each diatom is encased within two porous, glasslike valves. Which question would be most important for one interested in the day-to-day survival of individual diatoms?

Answer 107

C. How do diatoms with their glasslike valves keep from sinking into poorly lit waters?

Question 108

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?

Answer 108

B. foraminiferans

Question 109

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

Answer 109

A. cyanobacteria → green algae → land plants

Question 110

The chloroplasts of all of the following are derived from ancestral red algae, except those of

Answer 110

D. green algae

Question 111

A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. This alga probably belongs to which group?

Answer 111

A. red algae

Question 112

Which taxon of eukaryotic organisms is thought to be directly ancestral to the plant kingdom?

Answer 112

E. green algae.

Question 113

Which pair of alternatives is highlighted by the life cycle of the cellular slime moulds, such as Dictyostelium?

Answer 113

C. unicellular or multicellular.

Question 114

Which of the following correctly pairs a protist with one of its characteristics?

Answer 114

C. apicomplexans – parasitic

Question 115

You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (e.g. 250 m deep), and can also crawl about and engulf small particles. With which two of these structures would you provide your protist? 1. Hydrogenosome; 2. Apicoplast; 3. Pseudopods; 4. Chloroplast from red alga; 5. Chloroplast from green alga

Answer 115

D. 3 and 4

Question 116

You are designing an artificial drug-delivery ʺcellʺ that can penetrate animal cells. Which of these protist structures should provide the most likely avenue for research along these lines?

Answer 116

B. apical complex

Question 117

A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably what type of alga?

Answer 117

C. brown

Question 118

Which of the following statements concerning living phytoplanktonic organisms are true? 1. They are important members of communities surrounding deep-sea hydrothermal vents; 2. They are important primary producers in most aquatic food webs; 3. They are important in maintaining oxygen in Earth’s seas and atmosphere; 4. They are most often found growing in the sediments of seas and oceans; 5. They can be so concentrated that they affect the colour of seawater

Answer 118

D. 2, 3, and 5.