Chapter 28- Protists TEST

A large seaweed that floats freely on the surface of deep bodies of water would be expected to lack which of the following?

holdfasts

Ulva (Sea lettuce)

(Chlorophyll, Archaeolastida) Edible seaweed Multicellular thallus split into leaflike blades & rodlike holdfast that anchors the alga against turbulent waves

Caulerpa

(Chlorophyll, Archaeolastida) Intertidal chlorophyte Branched ailments lack cods-walls and thus, are multi-nucleate. Looks like one huge "supercell"

Part G - Interpreting the comparison matrix Which bacterial species has an rRNA gene that is most similar to that of the wheat mitochondrion?

A. tumefaciens

Which species interaction applies to bees that harvest nectar and pollen from flowers?

Mutualism.

Are the functions of pseudopodia limited to movement?

No

Which description best suits the term meiosis?

Non-indentical haploid cells

Unikonta: Opisthonkontas

Nucleariids, fungi, choanoflagellates, animals

Protista have diverse

Nutritional modes & habitats

Secondary endosymbiosis

Occurs when a living cell (host) engulfs another eukaryote cell that has already undergone primary endosymbiosis

Part E - Understanding the methodology Why did the researchers choose only one plant (wheat) to include in the comparison matrix?

Only one source of mitochondrial rRNA was needed to represent all mitochondria.

The members of _____ are characterized by cells with small membrane-bounded cavities under their cell membranes.

Alveolata

Which of these groups includes both aquatic decomposers and the parasites responsible for late potato blight?

oomycetes

Golden algae, brown algae, red algae, chlorophytes, and charophyceans are some examples of protists that are _____.

photosynthetic

Reinforced, threadlike pseudopods that can perform phagocytosis are generally characteristic of which group?

radiolarians and forams

Which of these algal groups possess a photosynthetic pigment that allows them to live in deep water?

red algae

Which group is incorrectly paired with its description?

red algae-acquired plastids by secondary endosymbiosis

Rhizaria

Chlorarachniophytes, forams, radiolarians

Which of the following have a wall of hydrated silica?

Diatoms

Part G Which of these groups is characterized by glasslike walls containing silica?

Diatoms Correct Diatoms are characterized by glasslike walls containing silica.

Chromalveolata: Stramenopiles include

Diatoms, golden algae, brown algae, oomycetes

Entamoeba Histolytica

Entamoeba Hosts in humans Pathogenic Causes amebic dysentery 3rd leading parasitic death

Kinetoplastids

Euglenozoa, Excavata 1 large mitochondrion that contains organized DNA mass (kinetoplast) Include free-living consumers of bacteria in freshwater, marine, and moist terrestrial ecosystems, and parasites of other eukarya Includes Trypanosoma brucei and Trypanosome cruzi

Euglenids

Euglenozoa, Excavata 1 or 2 flagella that emerge from a pocket at one end of the cell Store glucose polymer paramylon (energy) Autotrophic (photosynthetic) Heterotrophic (fungal/phagocytosis)

Stentora

Freshwater cilliate; unicellular protozoan

Which plant form would you find after meiosis takes place:

Gametophyte

Which term describes the multicellular haploid form of a protist that shows alternation of generations?

Gametophyte

Part C Which term describes the multicellular haploid form of a protist that shows alternation of generations?

Gametophyte Correct A gametophyte is the multicellular haploid form of a protist that shows alternation of generations.

How does the haploid form of Ulva "switch" to its diploid form?

Gametophytes produce cells that undergo mitosis to produce gametes that fuse to form a zygote.

Part F How does the haploid form of Ulva "switch" to its diploid form?

Gametophytes produce cells that undergo mitosis to produce gametes that fuse to form a zygote. Correct Gametophytes are haploid adults that produce cells that undergo mitosis and form gametes that fuse to form a diploid zygote.

Heteromorphic

Generations are structurally different

Isomorphic

Generations look similar

What color is the accessroy pigment, phycoerythrin, found in red algae?

Red

Archaeplastida

Red Algae & green algae are the closest relatives of land plants Over a billion years ago, a heterotrophic protists acquired a cyanokbactrical ensymbiont: descendants evolved into red and green algae 475 may, green algae lineage produced land plants in secondary endosymbiosis

Which group is characterized by cells with fine hairlike projections on their flagella?

Stramenopila

Part L Which group is characterized by cells with fine hairlike projections on their flagella?

Stramenopila Correct Stramenopiles are characterized by cells that bear fine hairlike projections on their flagella.

Diatoms, Golden and Brown algae, Oomycetes

Stramenopiles

Which term describes the fusion of two gametes to form a diploid zygote?

Syngamy

Part B Which term describes the fusion of two gametes to form a diploid zygote?

Syngamy Correct Syngamy is the fusion of two gametes to form a diploid zygote.

Alternation of generations

The alternation of multicellular haploid and multicellular diploid forms

What advantage do organisms that reproduce sexually have over organisms that reproduce asexually?

Their offspring may be more adaptable to changes in the environment.

Part A What advantage do organisms that reproduce sexually have over organisms that reproduce asexually?

Their offspring may be more adaptable to changes in the environment. Correct Offspring produced by sexual reproduction are genetically different from their parents and may be better able to thrive if the environment changes.

Which of the following is characteristic of ciliates?

They are often multinucleate.

Amoebozoans

Unikonta Lobe-shaped pseudopodia Includes gymnamoebas, entamoebas, and slime molds

Plastids that are surrounded by more than two membranes are evidence of

secondary endosymbiosis.

Many types of foraminiferans form a symbiotic relationship with _____.

algae

Which of the following are actual mutualistic partnerships that involve a protist and a host organism?

all except that involving humans

Plasmodium, the parasitic organism that causes malaria, is a _____.

apicomplexan

Part H Plasmodium, the parasitic organism that causes malaria, is a _____.

apicomplexan Correct Plasmodium, is an apicomplexan.

Human Use of Seaweeds

Mostly red algae of Poryphora genus Harvest for food Agar & Carrageenan are extracted from red algae Dried and used in sushi Antibodies used in biotechnology

Ceratium tripos

Unicellular marine dinoflagella

The largest seaweeds are _____.

brown algae

Which three groups contain large algae known as seaweeds?

brown algae, red algae, and green algae

Part E Which three groups contain large algae known as seaweeds?

brown algae, red algae, and green algae Correct All three of these are seaweeds.

Protists can reproduce:

Both asexually and sexually

A paramecium is a(n) _____.

ciliate

All of the organisms classified as _____ move and feed using cilia.

ciliates

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?

ciliates

Which of the following pairs of protists and their characteristics is mismatched?

ciliates-red tide organisms

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

foraminiferans

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

from engulfed, originally free-living proteobacteria

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

green algae.

Slime molds (Mycetozoans)

(Amoebozoans, Unikonta) Once thought to be funds Multicellular aggregate that forms asexual fruiting bodies (like fungi) Two groups distinguished by life cycle: Plasmodial & cellular Bright yellow or orange

Entamoebas

(Amoebozoans, Unikonta) Parasites that infect veterbrates & some invertebrates Humans host 6 species Includes E. histolytica

Select the four statements about Plasmodium that are true.

(1) Plasmodium cells infect two specific types of cells in humans. (2) Plasmodium cells infect two specific types of cells in humans. (3) Plasmodium cells are transferred to humans through mosquito saliva. (4 )Inside an infected mosquito, haploid gametes fuse, forming a diploid zygote that develops into an oocyst.

Name one example of a (1) beneficial protist and a (2) harmful protist. Format your answer: (1) ______________ and (2)_________________

(1) trypanosoma and (2) postelisia

Dinoflagellates

(Alveolata, Chromalveolata) Aquatic photoautotrophs & heterotrophs Abundant components of marine and freshwater plankton 2 flagella that make then spin as they move through the water ("dino-") Internal cellulose plate "armor" B/C of rapid growth, responsible for "red tides" which are toxic to humans Kills invertebrates & fish or humans that eat infected fish

Apicomplexans

(Alveolata, Chromalveolata) Parasites of animals and cause human disease Named because one end (apex) contains a complex of organelles specialized for penetrating host cells and tissues Non photosynthetic plastids (apicoplast) Reproduce sexually and sexually which req. 2 or more different host species of completion Causes malaria (attacks RBC) & carried in mosquito saliva

Ciliata

(Alveolata, Chromalveolata) Use Cilia to move and feed Have micronuclei (have duplicate genes to regulate daily cell activities like feeding, water balance, and waste removal) and micronuclei (conjugation, sexual process producing genetic variation) Red algae for secondary endosymbiosis

Gymnamoebas

(Amoebozoans, Unikonta) Common unicellular amoebozoans Live in soil, freshwater, or marine environments Most are heterotrophic & actively seek to consume bacteria and other protists

Plasmodial Slime molds

(Amoebozoans, Unikonta) Forms a mass at one point in life called plasmodium to produce fruiting bodies in sexual reproduction Plasmodium: undivided by membranes, contains many diploid nuclei, extends pseudopodia through decomposing material, engulfs food by phagocytosis, & cytoplasmic streams spread nutrients & O2 through out cytoplasm Includes Physarum polycephalum

Cellular Slime molds

(Amoebozoans, Unikonta) Multicellular aggregate that forms asexual fruiting bodies Cells remain separated by their membranes Solitary cells Low food levels cause aggregation Haploid with diploid zygotes Includes Dictyosetlium discoideum

Volvox

(Chlorophyll, Archaeolastida) Multicellular olonial freshwater chlorophyte Colony is a hallow ball whose wall is composed of thousands of biflagellate cells embedded in gelatinous matrix. Cells are usually connected by strands of cytoplasm & if isolated, the cells can't produce. Large colonies eventually produce small "daughter" cells within them.

Diatoms

(Stramenopiles, Chromalveolata) Close to brown and gold algae b/c stramenopila Shaped like shoe box Unicellular photosynthetic algae Has 2-part glass-like strong walls of hydrate silica (frustules) that survives fossilization (diatomaceous earth) 90% asexual via amitosis (each gets half of wall) 10% sexual via ameboid or flagellated sperm Stores food with Laminarin (glucose polymer)

Oomycetes

(Stramenopiles, Chromalveolata) Include water molds, white rusts, and downy mildew Most are decomposers or parasites Have filaments (hyphae) that absorb nutrients Phytophthora ingestans causes late blight of potatoes

Brown Algae (Phaeophytes, Seaweed)

(Stramenopiles, Chromalveolata) Largest & most complex algae Multicellular & localized to temperate coasts Brown b/c carotenoid pigments in plastids Mostly marine Analogous to plants No true roots, stems, or leaves Leaflike: blade, Stemlike: stipe, Rootlike: holdfast Cell walls have cellulose and gel forming polysaccharides called Agarose Adaptions to strong waves to protect thalli Used in soup, biotechnology, and Algin is used Include an alternation of generations Include Lminaria, Macrocystis, and Postelsia

Golden Algae (Chrysophytes)

(Stramenopiles, Chromalveolata) Named for yellow/brown carotenoids Biflagellated with both flagella attached near 1 cell end of the cell Live in vase shaped lorica Major component in phytoplankton Most are photosynthetic, some are mixotrophic Unicellular, Synura except Dinobryon

When did secondary endosymbiosis occur

1.7 billion years ago

How many species of protists are there

115000

When did protists come about

2.1 billion years ago

Part A - Understanding the comparison matrix Find the cell that represents the comparison of Comamonas testosteroni and Escherichia coli. What value is given in that cell?

61

Describe endosymbiosis (3pts) and name two organelles that evolved through this process (1pt).

A relationship between two organisms in which one organism lives inside the cell or cells of another organism. Mitchondria and plastids are involved in this process

Heterotroph

Absorb organic molecules or ingest larger food particles (fungal/animal, protozoans)

Diatomaceous Earth

Accumulations of fossilized diatom cell walls A soft, crumbly, porous sedimentary deposit formed from the fossil remains of diatoms.

Protists are mostly unicellular except

Algae

Part A Many types of foraminiferans form a symbiotic relationship with _____.

Algae Correct Forams derive nourishment from photosynthetic algae living within their shells.

Which of the following statements concerning protists is true?

All protists have mitochondria, though in some species they are much reduced and known by different names.

Dinoflagellates, Apicomplexans, Ciliates

Alveolata

Part B The members of _____ are characterized by cells with small membrane-bounded cavities under their cell membranes.

Alveolata Correct Dinoflagellates, apicomplexans and ciliates are classified in Alveolata, a group characterized by cells with small membrane-bounded cavities under their cell membranes.

Slime molds, Gymnamoebas, Entamoebas

Amoebozoans

Which of the following have lobe or tube-shaped pseudopodia:

Amoebozoans

Which of the following is true of secondary endosymbiosis?

An organism containing an endosymbiont is engulfed by another organism and becomes an endosymbiont.

Green Algae

Archaeolastida Name b/c chloroplasts Resemble plant chloroplasts Viridiplantae (subkingdom of plants) Consists of two groups: Chlorophytes & Charophytes

Chlorophytes

Archaeolastida Type of green algae Most live in freshwater & some marine Some live in damp spoil as symbionts in lichens (fungal) or in snow (Chlamydomonas nivalis) 7000 species Simplest are biflagellate Unicellular, colonial, & multicellular Sexual & Asexual Includes Volvox

Red Algae (Rhodophyta)

Archaeplastida Color b/c pigment (phycoerythrin) which masks green chlorophyll 6,000 species Usually multicellular & largest are seaweeds Most abundant large algae in tropics Most are autotrophic, some are heterotrophic parasites of other red algae Alteration of generation- no flagellated cells Includes Bonnemaisonia hamifera and Dulse (Palmaria palmata)

Delesseria sanguinea

Multicellular

Which of the following is often called seaweed?

Brown algae

Part J The largest seaweeds are _____.

Brown algae Correct Brown algae are the largest of the seaweeds.

Trichonomonas Vaginalis

Caused by parabasalids Epithelial Pathogen Alters vaginal pH (acidity) Males can get from sex

Part F Stramenopiles include all of the following groups EXCEPT ______.

Cellular slime molds Correct Cellular slime molds are amoebozoans

Which of the following is a correct statement about slime molds?

Cellular slime molds form masses when food is scarce, but their cells remain separated.

Part A Which of the following is a correct statement about slime molds?

Cellular slime molds form masses when food is scarce, but their cells remain separated. Correct Cellular slime molds function almost like multicellular organisms when food is depleted. They form a multicellular mass that forms fruiting bodies.

Photoautotroph

Contain chloroplasts (plant, algae)

Part O Which algal group has chloroplasts much like those of green plants in structure and pigment makeup?

Chlorophytes Correct Chlorophytes (green algae), like green plants, contain both chlorophylls a and b.

Stramenopiles

Chromalveolata Hairy and smooth flagella Includes heterotrophs and some algae

Alveolata

Chromalveolaya Membrane-bounded sacs (alveoli) under the plasma membrane

Part I A paramecium is a(n) _____.

Ciliate Correct A paramecium makes use of its cilia to move and feed.

Part K All of the organisms classified as _____ move and feed using cilia.

Ciliates Correct Ciliates move and feed using cilia.

Mixotrophs

Combine photosynthesis and heterotrophic nutrition

Which process is not an example of consumption?

Commensalism.

Part A Archaeplastids, which include red and green algae and land plants, are thought to have descended from a heterotrophic protist that engulfed a(n) _____.

Cyanobacterium Correct Structural and molecular biological evidence supports the idea that endosymbiotic cyanobacteria gave rise to the chloroplasts found in red and green algae and land plants.

How do humans combat infection by the Plasmodium parasite?

Cytotoxic T cells destroy infected liver cells by recognizing a Plasmodium protein bound to an HLA protein on the surface of those cells.

Which of the following have two flagella, spin through the water, and are the cause of toxic red tides?

Dinoflagellates

Part A A sign on the beach states, "Beach Closed. Red Tide." The organisms interfering with your use of this beach are probably _____.

Dinoflagellates Correct Dinoflagellate blooms, episodes of explosive population growth, cause red tides in coastal waters.

Part A Coral bleaching, which causes high coral mortality, has been occurring widely in coral reefs. Coral bleaching actually refers to the death of symbiotic dinoflagellates living within the corals. Why does coral bleaching cause the corals to die?

Dinoflagellates provide nutrients from the products of photosynthesis to the corals in exchange for a safe place to live. Correct Without the extra nutrients provided by symbiotic protists, the corals cannot compete with other organisms for resources.

Red Algae is a common ancestor of

Dinoflagellates, Apicomplexans, Ciliatae, and Stramenopiles

Chromalveolata: Alveolates include

Dinoflagellates, apcomplexans, & ciliates

Secondary endosymbiosis created

Dinucleation in some (2 nuclei)

Giadia Intenstinalis

Diplomonad Mammalian Pathogen Cysts (killed with boing) ingested via feces and drinking water and cause severe diarrhea

Excavata include

Diplomonads, parabasalids, & euglenozoans

Protists fit into which domain?

Eukaryotes

Euglenozoa

Excavata Includes predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites presence of a spiral or Flagella have crystalline rod of unknown function inside their flagella Mitochondrion have disk shaped cristae Has two groups: Kinetoplastids & Euglenids

Diplomonads

Excavata No plastids Two nuclei and multiple flagella Causes Giadia Intenstinalis

Parabasalids

Excavata No plastids Move with flagella and an undulating part of the plasma membrane Causes Trichomonas Vaginalis

True or false? Organisms that exhibit alternation of generations reproduce sexually in the diploid stage

False

Part G True or false? Organisms that exhibit alternation of generations reproduce sexually in the diploid stage.

False Correct Organisms that exhibit alternation of generations reproduce asexually in the diploid stage by producing haploid cells that form spores, which then germinate into haploid adults. The haploid adults produce haploid gametes that can then participate in sexual reproduction.

Chlorophytes, Charophyceans

Green Algae

Which chromosomal form would you find after meiosis takes place:

Haploid

Which of the following statements about Ulva's haploid stage is true?

Haploid cells are produced by meiosis of diploid cells.

Part E Which of the following statements about Ulva's haploid stage is true?

Haploid cells are produced by meiosis of diploid cells. Correct This statement is true; the diploid sporophyte produces haploid spores through meiosis.

All protists come from a

Heterotrophic, Archean cyanobactrium

Which structure mediates the attachment of spores to a surface on which to grow?

Holdfast

Part D Which structure mediates the attachment of spores to a surface on which to grow?

Holdfast Correct A holdfast attaches spores to surfaces on which they can grow.

Plasmodium, which causes malaria, is an apicomplexan that requires both the mosquito and what other organism to complete its life cycle?

Human

Trypanosome cruz (Chagas' disease)

Kinetoplastid (Euglenozoa, Excavata) Carried by Triatomine bugs (kissing bugs) In South America Causes fatigue, fever, swollen lymph glands, and heart failure Nifurtimox and Benznidazole

Trypanosome Brucei

Kinetoplastid (Euglenozoa, Excavata) Causes African Sleeping Sickness carried by African tsetse fly Causes fever, skin lesions, rash, & slurred speech Cured wth Suramin or Melarsoprol

Part D Which of these groups consist of parasitic flagellated cells, such as Trypanosoma, the organism that causes sleeping sickness?

Kinetoplastids Correct Parasitic flagellated cells, such as Trypanosoma, are classified as kinetoplastids

Kintoplastids, Euglenids

Kintoplastids, Euglenids

Dipomonads and parabasalids

Lack plastids No mitochondria with DNA Anaerobic

Diplomonad and Parabasalids share all the following characteristic except:

Live in aerobic environments

Which of the following statements about the Plasmodium parasite is true?

Merozoites live off the hemoglobin and nutrients in red blood cells and divide to produce more merozoites, destroying red blood cells in the process.

Which form of Plasmodium is the immediate cause of anemia in humans?

Merozoites.

Primary Endosymbiosis

Mitochondria evolved by endosymbiosis of an aerobic prokaryote. Plastids evolved by endosymbiosis of a photosynthetic cyanobacterium.

Primary endosymbiosis

Mitochondria evolved by endosymbiosis of an aerobic prokaryote. Plastids evolved by endosymbiosis of a photosynthetic cyanobacterium.

If an organism is both photosynthetic and heterotrophic, how would you categorize the organism?

Mixotroph

Part N Which of these groups includes both aquatic decomposers and the parasites responsible for late potato blight?

Oomycetes Correct Correct. Oomycetes (water molds and their relatives) include both decomposers and the parasites responsible for late potato blight.

Part C Golden algae, brown algae, red algae, chlorophytes, and charophyceans are some examples of protists that are _____.

Photosynthetic Correct All of the listed groups are photosynthetic.

Part A _____ are eukaryotic autotrophs that float near the surface of water and are the basis of the food chain.

Phytoplankton Correct These photosynthetic organisms serve as the basis of the food chain.

Green algae is a common ancestor of

Plastids and euglenids

Protists originate from

Primary and secondary endosymbiosis

How would you classify golden and brown algae?

Protist

Part M Which of these algal groups possess a photosynthetic pigment that allows them to live in deep water?

Red algae Correct The phycobilins and other accessory pigments of red algae allow them to absorb the wavelengths of light that penetrate deep water and to use them in photosynthesis.

Archaeplastida

Red algae, chorophytes, charophyters, (green algae), land plants

From primary endosymbiosis, protists separated into

Red and green algae

Radiolaria

Rhizaria Marine Tests are fused into 1 delicate piece made of silica Phagocytose microorganisms with pseudopodia Axopodia (pseudopodia) radiate from central body and facilitate in movement and feeding

Cercozoa

Rhizaria Mostly heterotrophs, some mixotrophic chlorachniophytes Marine freshwater and soil Includes Paulinella chrmoatophora Chromatophore-peptidoglycan present, alternate cyanobacterium species symbiont

Foramnifera

Rhizaria Unicellular Named for porous multi chambered shells (tests) Calcium carbonate hardened organic matter Pseudopodia extend through the pores in the test, used for swimming feeding test formation Members of plankton communities Sand/rock/algeae attachment Found in marine or freshwater Excellent index fossils Heterotrophic but form symbiotic relationships with photosynthesis algae in phytoplankton

Unikonta: Amoebozoans

Slime molds, gymnamoebas, entamoebas

If an organism's life cycle includes 'alternation of generation', what is it alternative between?

Sporophyte and Gametophyte generations

Part F Why did the researchers include five bacterial species in the comparison matrix?

They wanted to identify which bacterium is most closely related to the ancestor of mitochondria.

Part C Why do some cells have a dash rather than a value?

Those cells would compare one species to itself.

Part D Why are some cells shaded gray, with no value?

Those cells would duplicate comparisons shown elsewhere in the matrix.

Rhizaria

Threadlike pseudopodia Like amoebas

True or false? One example of a coevolutionary arms race is when faster deer evolve and favor wolves and cougars that have stronger eyesight and senses of smell.

True

Unikonta

Two groups: Amoebozoans & Oposthokonts

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

brown

Stramenopiles include all of the following groups EXCEPT ______.

cellular slime molds

Which algal group has chloroplasts much like those of green plants in structure and pigment makeup?

chlorophytes

Which process results in genetic recombination, but is separate from the process by which the population size of Paramecium increases?

conjugation

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

cyanobacteria → green algae → land plants

Which of these groups is characterized by glasslike walls containing silica?

diatoms

A sign on the beach states, "Beach Closed. Red Tide." The organisms interfering with your use of this beach are probably _____.

dinoflagellates

The cells of _____ and _____ have modified mitochondria.

diplomonads ...parabasalids

Part A The cells of _____ and _____ have modified mitochondria.

diplomonads ...parabasalids Correct Correct. The cells of diplomonads and parabasalids have modified or reduced mitochondria.

Which of the following are two groups that are adapted to anaerobic conditions and contain modified mitochondria that lack DNA?

diplomonads and parabasalids

Part A Which of the following are two groups that are adapted to anaerobic conditions and contain modified mitochondria that lack DNA?

diplomonads and parabasalids Correct These groups are known for their modified mitochondria.

All protists are

eukaryotic.

Which of these groups consist of parasitic flagellated cells, such as Trypanosoma, the organism that causes sleeping sickness?

kinetoplastids

In life cycles with an alternation of generations, multicellular haploid forms alternate with

multicellular diploid forms.

Part B What does the value 61 signify about the comparable rRNA gene sequences in Comamonas testosteroni and Escherichia coli?

that 61% of the 617 nucleotide positions are the same in both species

Part H The rRNA gene of A. tumefaciens is most similar to the wheat mitochondrial rRNA gene. What does that suggest?

that the alpha proteobacteria are more closely related to the ancestor of mitochondria than the other bacterial taxa Correct Many alpha proteobacterial species are intimately associated with eukaryotic hosts, establishing intracellular associations with their hosts. For example, Rhizobium species live in nodules in the roots of legumes and fix atmospheric N2 into ammonia. Agrobacterium species live within plant tissues, where they grow as tumors. This feature of alpha proteobacteria is likely relevant to the origin of mitochondria, which arose as mutualistic endosymbionts and evolved into essential eukaryotic organelles.