protists (mylab and mastering)
Based on this tree, hypothesize whether it would be most difficult to develop drugs to combat human pathogens that are prokaryotes, protists, animals, or fungi. (You do not need to consider the evolution of drug resistance by the pathogen.) Rank the pathogens from most to least difficult to develop drugs against.
Most difficult - animals - fungi - protists - prokaryotes Least difficult
A protist with a shell made of silica is most likely a(n) ________.
diatom
All of the species in the list below are seaweeds. Which is the EXCEPTION?
diatoms
Which of these groups is characterized by glasslike walls containing silica?
diatoms Diatoms are characterized by glasslike walls containing silica.
Which of the following are two groups that are adapted to anaerobic conditions and contain modified mitochondria that lack DNA?
diplomonads and parabasalids These groups are known for their modified mitochondria.
Which group is correctly paired with its description?
diplomonads−−protists with modified mitochondria
Which group of organisms is most closely related to plants?
green algae
Complete the phylogenetic tree that includes an ancestral prokaryote and other groups of organisms.
https://media.cheggcdn.com/coop/257/257ad9e6-67ab-485a-ad67-f92a2687d3c2/1606982271000_55DFDB3C-B427-4538-991B-5B33A8704329.png 1. Ancestral prokaryote 2. Archeaplastids 3. Excavata 4. SAR Clade 5. Amoebozoans 6. Animals 7. Choanoflagellates 8. Fungi 9. Nucleariids 10. Unikonta
Which of these groups consist of parasitic flagellated cells, such as Trypanosoma, the organism that causes sleeping sickness?
kinetoplastids Parasitic flagellated cells, such as Trypanosoma, are classified as kinetoplastids.
A paramecium is a(n) _____.
ciliate A paramecium makes use of its cilia to move and feed.
All of the organisms classified as _____ move and feed using cilia.
ciliates Ciliates move and feed using cilia.
What accounts for the similarity between seaweeds and plants?
convergent evolution
Archaeplastids, which include land plants and red and green algae, are thought to have descended from a heterotrophic protist that engulfed a(n) __________.
cyanobacterium Structural and molecular biological evidence supports the idea that endosymbiotic cyanobacteria gave rise to the chloroplasts found in land plants and red and green algae.
According to the hypothesis of serial endosymbiosis, which of the following was a key initial step in the origin of mitochondria?
A prokaryotic host cell engulfed an aerobic, heterotrophic bacterium. If you had trouble with this question, review the following material: Evidence indicates that the eukaryotes originated by endosymbiosis when a prokaryotic cell engulfed a small aerobic, heterotrophic bacterium whose descendants evolved into an organelle found in all eukaryotes, the mitochondrion. The prokaryotic ancestor of the mitochondrion probably entered the host cell as undigested prey or an internal parasite. Later, a eukaryotic host cell engulfed a photosynthetic bacterium, leading to the evolution of plastids.
The members of _____ are characterized by cells with small membrane-bounded cavities under their cell membranes.
Alveolata Dinoflagellates, apicomplexans and ciliates are classified in Alveolata, a group characterized by cells with small membrane-bounded cavities under their cell membranes.
Which of the following statements is true of secondary endosymbiosis?
An organism containing an endosymbiont is engulfed by another organism and becomes an endosymbiont. This is a description of secondary endosymbiosis. In many cases, secondary endosymbionts are surrounded by four membranes.
Can you identify the supergroups to which these protists belong?
Archaeplastida - green algae Excavata - Trichomonas vaginalis - Giardia intestinalis SAR (Stramenopila, Alveolata, and Rhizaria) - diatoms - brown algae - foraminiferans - dinoflagellates Unikonta - plasmodial slime molds
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. Cellular slime molds function almost like multicellular organisms when food is depleted. They form a multicellular mass that forms fruiting bodies.
Which group of organisms (ciliates, animals, or plants) has the most complex cells?
Ciliates Single-celled protists are justifiably considered the simplest eukaryotes, but at the cellular level, many protists are very complex. For example, the single cell of a ciliate such as Paramecium is much more complex than any one cell in your body. Read about structural and functional diversity in protists.
Are these ciliates more closely related to all other protists than they are to plants, fungi, or animals?
Ciliates are as closely related to plants as they are to protistan members of the Archaeplastida. Ciliates are as closely related to fungi and animals as they are to protistan members of the eukaryotic supergroup Unikonta.
This figure shows the life cycle of the ciliate Paramecium caudatum. In this figure, what does the green arrow represent? https://session.masteringbiology.com/problemAsset/1311115/7/Chap28_Q5.jpg
Conjugation Conjugation in ciliates is sexual, resulting in the production of two genetically novel individuals combining the genes of two parents. It is not reproduction, because no additional individuals are produced, although it is followed by reproduction. Read about ciliates.
What is the role of endosymbiosis in the evolutionary history of SAR?
Current evidence indicates that _mitochondria_ are descended from a(n) _bacterium_ that was engulfed by a(n) _archaea (or closely related to the archaea)_ cell - a primary endosymbiosis event that led to the origin of the eukaryotes. Current evidence also suggests that two of the major subgroups within SAR, the _alveolates_ (to which ciliates belong) and the _stramenopiles_, arose when the common ancestor of these two groups engulfed a unicellular photosynthetic _red alga_.
________ are responsible for toxic red tides.
Dinoflagellates
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. Without the extra nutrients provided by symbiotic protists, the corals cannot compete with other organisms for resources.
A diploid (2n) cell divides by meiosis, producing four daughter cells. Next, each daughter cell divides by mitosis, producing a total of eight granddaughter cells. Which of the following statements about the granddaughter cells is true?
Each granddaughter cell is haploid (n). If you had trouble with this question, review the following material: In meiosis, a parent cell produces four daughter cells, each of which has half the chromosome number of the parent cell; in this case, the diploid (2n) parent cell produces four daughter cells, each of which is haploid (n). In mitosis, a parent cell produces two daughter cells that are genetically identical to the parent cell; in this case, the four haploid daughter cells produce a total of eight granddaughter cells, each of which is haploid (n).
Which of the following statements supports the hypothesis of an endosymbiotic origin of mitochondria?
Each mitochondrion has its own DNA molecule. The fact that mitochondria have their own DNA provides strong support for the hypothesis of an endosymbiotic origin of mitochondria.
Which of the following domains consists of all the organisms whose cells have true nuclei?
Eukarya If you had trouble with this question, review the following material: The three domains—Bacteria, Archaea, and Eukarya—are a taxonomic level higher than the kingdom level. The domain Bacteria includes most of the currently known prokaryotes, while the domain Archaea consists of a diverse group of prokaryotic organisms that inhabit a wide variety of environments. The domain Eukarya consists of all the organisms that have cells containing true nuclei, including many groups of single-celled organisms as well as plants, fungi, and animals.
Identify the eukaryotic supergroup to which ciliates belong. This micrograph shows a single-celled eukaryote, the ciliate Didinium (left), about to engulf its Paramecium prey, which is also a ciliate. https://session.masteringbiology.com/problemAsset/3066855/6/28_10.jpg
SAR
Which group is characterized by cells with fine hairlike projections on their flagella?
Stramenopila Stramenopiles are characterized by cells that bear fine hairlike projections on their flagella.
Which of the following statements correctly explains why the kingdom Protista has been abandoned?
The kingdom Protista is polyphyletic.Some protists are more closely related to plants, animals, or fungi than they are to other protists. ANSWER: The second and third answers are correct. Recognizing that the kingdom Protista (as originally defined) was polyphyletic and some protists are more closely related to other eukaryotes than to each other, scientists have abandoned the kingdom Protista and reorganized the entire domain Eukarya.
You discover a unicellular organism that moves by what appear to be pseudopodia. You conclude that this organism could be ________.
a type of amoeba, foram, or slime mold
How did endosymbiosis give rise to protist diversity?
a. heterotrophic b. chloroplasts c. chloroplasts d. chloroplasts e. autotrophic f. heterotrophic g. chloroplasts h. mixotrophic https://d2vlcm61l7u1fs.cloudfront.net/media%2Fd0b%2Fd0b33501-1eb4-4f2c-85fc-8a14cd975d88%2FphpSDVuQj.png
Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because
all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
Plasmodium, the parasitic organism that causes malaria, is a _____.
apicomplexan Plasmodium, is an apicomplexan.
All organisms that photosynthesize fit into which nutritional category?
autotrophs
The largest seaweeds are _____.
brown algae Brown algae are the largest of the seaweeds.
Which three groups contain large algae known as seaweeds?
brown algae, red algae, and green algae All three of these are seaweeds.
________ include cells that can function either independently or as a single unit.
cellular slime molds
Stramenopiles include all of the following groups EXCEPT ______.
cellular slime molds Cellular slime molds are amoebozoans
Which algal group has chloroplasts much like those of green plants in structure and pigment makeup?
chlorophytes Chlorophytes (green algae), like green plants, contain both chlorophylls a and b.
After a long period of coevolution, the photosynthetic bacterium consumed by the predatory cell became the cellular organelle known as the:
chloroplast The chloroplast carries out photosynthesis.
Which of these human diseases is caused by an apicomplexan protozoan?
malaria malaria is caused by an apicomplexan in the genus Plasmodium
Which of the features below are found in all protist lineages?
mitichondria Scientists used to think that some groups of protists lacked mitochondria, but they have since discovered that many of these protists have at least modified mitochondria. Read about the diplomonads and parabasalids.
After a long period of coevolution, the aerobic bacterium consumed by the predatory cell became the cellular organelle known as the:
mitochondrion Mitochondria carry out aerobic respiration.
Trichomonas vaginalis is a protozoan that feeds on white blood cells and bacteria living on the cells lining the female human vagina, thereby creating a common sexually transmitted disease often known as "trich." The feeding mechanism of this protozoan makes it a ________.
parasite
Golden algae, brown algae, red algae, chlorophytes, and charophyceans are some examples of protists that are _____.
photosynthetic All of the listed groups are photosynthetic.
What kind of protist is shown in the figure? https://session.masteringbiology.com/problemAsset/2803914/2/unfig_15_03.jpg
plasmodial slime mold
Eukaryotes that are not fungi, animals, or plants are classified in a "catch-all" category called ________.
protists
Flagellates, amoebas, apicomplexans, and ciliates are all what type of protist?
protozoans
Which of these algal groups possess a photosynthetic pigment that allows them to live in deep water?
red algae 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.
Plastids that are surrounded by more than two membranes are evidence of
secondary endosymbiosis.
The bacteria initially persist in the predatory cell because:
the predatory cell is unable to digest the bacteria. This effect has been demonstrated in amoebas.
The plasmodium of a plasmodial slime mold can grow in order to enlarge the organism's surface area and therefore potentially obtain more nutrients. This is an example of ________.
the relationship between structure and function
The cells of _____ and _____ have modified mitochondria.
trichomonads ... diplomonads The cells of trichomonads and diplomonads lack mitochondria.
While peering through the microscope, a classmate of yours says, "I know that this thing is a ciliate, a flagellate, or an amoeba, but I can't figure out which." You reply, "That's easy. In order to figure it out, __________."
watch how it moves Those organisms can be differentiated on the basis of how they move. Ciliates are propelled by cilia, flagellates by flagella, and amoeba by extension of pseudopodia.
Which of these groups includes both aquatic decomposers and the parasites responsible for the powdery mildew of grapes and late potato blight?
water molds Water molds include both decomposers and the parasites responsible for the powdery mildew of grapes and late potato blight.
