Handout 3 Flashcards
a catabolic pathway in which inorganic molecules other than oxygen accept electrons at the ‘downhill’ end of electron transport chain
anaerobic respiration
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
archaeplastida
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
autotroph
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.
binary fission
A surface-coating colony of one or more species of prokaryotes that
engage in metabolic co-operation.
biofilm
The use of organisms to detoxify and restore polluted and degraded
ecosystems.
bioremediation
(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.
blade
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)
brown alga
(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)
capsule
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.
cell wall
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.
chromalveolata
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).
cilium
A symbiotic relationship in which one organism benefits but the other is
neither helped nor harmed.
commensalism
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
decomposer
A cell containing two sets of chromosomes (2n), one set inherited from
each parent
diploid cell
A protist that has modified mitochondria, two equal-sized nuclei, and
multiple flagella.
diplomonad
A thick-coated, resistant cell produced by some bacterial cells when
they are exposed to harsh conditions.
endospore
A toxic component of the outer membrane of certain gram-negative
bacteria that is released only when the bacteria die.
endotoxin
Member of a diverse clade of flagellated protists that includes
predatory heterotrophs, photosynthetic autotrophs, and pathogenic
parasites
euglenozoan
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.
excavata
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
exotoxin
An organism that lives in a highly saline environment, such as the Great
Salt Lake or the Dead Sea.
extreme halophile
An organism that thrives in hot environments (often 60-80°C or hotter).
extreme thermophile
An organism that lives in environmental conditions so extreme that few
other species can survive there; include “salt lovers” and “heat lovers”
extremophile
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.
facultative anaerobe
A short, hair-like appendage of a prokaryotic cell that helps it adhere to
the substrate or to other cells
fimbria
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
flagellum
A bi-flagellated, photosynthetic protist named for its colour, which
results from its yellow and brown carotenoids
golden alga
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.
gram-negative
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
gram-positive
A method that distinguishes between two different kinds of bacterial
cell walls; may be used to help determine medical response to an
infection.
gram stain
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.
green alga
A cell containing only one set of chromosomes (n).
haploid cell
A specialized cell that engages in nitrogen fixation in some filamentous
cyanobacteria; also called a heterocyte.
heterocyst
A root-like structure that anchors a seaweed.
holdfast
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
horizontal gene transfer
The larger participant in a symbiotic relationship, often providing a
home and food source for the smaller participant.
host
Referring to a solution that, when surrounding a cell, will cause the cell
to lose water
hypertonic
Referring to a solution that, when surrounding a cell, will cause the cell
to take up water.
hypotonic
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.
metagenomics
An organism that produces methane as a waste product of the way it
obtains energy; all known are in domain Archaea
methanogen
An organelle in eukaryotic cells that serves as the site of cellular
respiration; uses oxygen to break down organic molecules and
synthesize ATP
mitochondrion
An organism that is capable of both photosynthesis and heterotrophy.
mixotroph
A symbiotic relationship in which both participants benefit.
mutualism
The conversion of atmospheric nitrogen (N2) to ammonia (NH3); carried
out by certain prokaryotes, some of which have mutualistic
relationships with plants.
nitrogen fixation
A non-membrane-bounded region in a prokaryotic cell where the DNA
is concentrated.
nucleoid
An organism that requires oxygen for cellular respiration and cannot
live without it.
obligate aerobe
An organism that only carries out fermentation or anaerobic
respiration. Such organisms cannot use oxygen and in fact may be
poisoned by it
obligate anaerobe
Protist with flagellated cells, such as a water mould, white rust, or
downy mildew, that acquires nutrition mainly as a decomposer or plant
parasite.
oomycete
Regulation of solute concentrations and water balance by a cell or
organism.
osmoregulation
The diffusion of free water across a selectively permeable membrane.
osmosis
A protist, such as a trichomonad, with modified mitochondria.
parabasalid
A symbiotic relationship in which one organism benefits at the expense
of another by living either within or on it.
parasitism
An organism, virus, viroid, or prion that causes disease.
pathogen
A type of polymer in bacterial cell walls consisting of modified sugars
cross-linked by short polypeptides.
peptidoglycan
in bacteria, a structure that links one cell to another at the start of
conjugation
pilus
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
plasmid
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)
producer
A cellular extension of amoeboid cells used in moving and feeding.
pseudopodium
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
rhizaria
A stem-like structure of a seaweed.
stipe
A protist in which a “hairy” flagellum (one covered with fine, hair-like
projections) is paired with a shorter, smooth flagellum
stramenophile
The smaller participant in a symbiotic relationship, living in or on the
other participant
symbiont
An oriented movement toward or away from a stimulus.
taxis
A seaweed body that is plant-like, consisting of a holdfast, stipe, and
blades, yet lacks true roots, stems, and leaves
thallus
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.
unikonta
concept 5.1
structural and functional adaptations contribute to prokaryotic success
concept 5.2
diverse nutritional and metabolic adaptations have evolved in prokaryotes
concept 5.3
molecular systematics is illuminating prokaryotic phylogeny
concept 5.4
prokaryotes play crucial roles in the biosphere
concept 5.5
prokaryotes have both beneficial and harmful impacts on humans
concept 6.1
most eukaryotes are single-celled organisms
concept 6.2
excavates includes protists with modified mitochondria and protists with unique flagella
concept 6.3
chromalveolates may have originated by secondary endosymbiosis
concept 6.4
rhizarians are a diverse group of protists defined by DNA similarities
concept 6.5
red algae and green algae are the closest relatives of land plants
concept 6.6
unikonts include protists that are closely related to fungi and animals
concept 6.7
protists play key roles in ecological communities
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?
B. their cell walls are composed of very different biochemicals
Which of these is the most common compound in the cell walls of gram-positive
bacteria?
D. peptidoglycan
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
D. 4 → 1 → 3 → 2.
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
A. undergo death by plasmolysis.
The typical prokaryotic flagellum features
C. a complex ʺmotorʺ embedded in the cell wall and plasma membrane.
Which statement about the genomes of prokaryotes is correct?
D. The prokaryotic chromosome is not contained within a nucleus but, rather,
is found at the nucleoid region.
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:
E. capsule.
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:
A. endospore
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:
B. sex pilus
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
D. 4 only.
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
D. 2 and 4.
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
D. 2 and 4.
Which of the following are responsible for high levels of O2 in Earth’s atmosphere?
A. photoautotrophs
Which statement about the domain Archaea is false?
C. The genomes of archaeans are unique, containing no genes that originated
within bacteria.
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. extreme halophiles.
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
C. 2, 4, and 5
What is the primary ecological role of prokaryotes?
B. breaking down organic matter
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.
C. 2, 4, 1
How can prokaryotes be considered to be more successful on Earth than humans?
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
Which statement about gram-negative bacteria is correct?
B. They often possess an outer membrane containing toxic
lipopolysaccharides.
Protists are alike in that all are
B. eukaryotic.
Biologists have long been aware that the defunct kingdom Protista is paraphyletic.
Which of these statements is both true and consistent with this conclusion?
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
According to the endosymbiotic theory of the origin of eukaryotic cells, how did
mitochondria originate?
B. from engulfed, originally free-living prokaryotes.
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?
B. the diplomonads
Which of these taxa contains species that produce potent toxins that can cause
extensive fish kills, contaminate shellfish, and poison humans?
B. dinoflagellates
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?
C. ciliates.
The Irish potato famine was caused by an organism that belongs to which group?
B. oomycetes
Thread-like pseudopods that can perform phagocytosis are generally characteristic
of which group?
A. radiolarians and forams
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?
C. How do diatoms with their glasslike valves keep from sinking into poorly lit
waters?
A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which
group?
B. foraminiferans
The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
A. cyanobacteria → green algae → land plants
The chloroplasts of all of the following are derived from ancestral red algae, except those of
D. green algae
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?
A. red algae
Which taxon of eukaryotic organisms is thought to be directly ancestral to the plant
kingdom?
E. green algae.
Which pair of alternatives is highlighted by the life cycle of the cellular slime moulds, such as Dictyostelium?
C. unicellular or multicellular.
Which of the following correctly pairs a protist with one of its characteristics?
C. apicomplexans – parasitic
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
D. 3 and 4
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?
B. apical complex
A gelatinous seaweed that grows in shallow, cold water and undergoes
heteromorphic alternation of generations is most probably what type of alga?
C. brown
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
D. 2, 3, and 5.
