Chapter 28 - Protists

Question 1

Protist -

Answer 1

eukaryotes that are not plants, animals, or fungi.

Question 2

Protists are __________

Answer 2

Unicellular

Question 3

Contractile vacuoles -

Answer 3

pump excess water from the protistan cell

Question 4

Ocelloid -

Answer 4

eye-like organelle with components resembling the lens and retina in the eyes of vertebrates and some other animals

Question 5

Mixotrophs -

Answer 5

combine photosynthesis and heterotrophic nutrition

Question 6

Gram-negative bacteria -

Answer 6

have two cell membranes, an inner plasma membrane and an outer membrane that is part of the cell wall

Question 7

Secondary endosymbiosis -

Answer 7

organism is ingested in the food vacuoles of heterotrophic eukaryotes and becomes an endosymbiont itself

Question 8

Excavata (the excavates) -

Answer 8

one of the four main groups of protists: a clade that was originally proposed based on morphological studies of the cytoskeleton, members of this diverse group have an “excavated” feeding groove on one side of the cell body.

Question 9

Diplomonads -

Answer 9

one of the four main groups of protists: have reduced mitochondria called mitosomes so they get the energy they need from anaerobic biochemical pathways. Many are parasites

Question 10

Mitosomes -

Answer 10

organelles lack functional electron transport chains and hence cannot use oxygen to help extract energy from carbohydrates and other organic molecules

Question 11

Parabasalids -

Answer 11

one of the four main groups of protists: also have reduced mitochondria; called hydrogenosomes

Question 12

Hydrogenosomes -

Answer 12

these organelles generate some energy anaerobically, releasing hydrogen gas as a by-product

Question 13

Euglenozoans -

Answer 13

one of the four main groups of protists: a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites. The main morphological feature that distinguishes protists in this clade is the presence of a rod with either a spiral or a crystalline structure inside each of their flagella

Question 14

kinetoplastids -

Answer 14

have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast. These protists include species that feed on prokaryotes in freshwater, marine, and moist terrestrial ecosystems, as well as species that parasitize animals, plants, and other protists

Question 15

“bait-and-switch” defense -

Answer 15

the urface of a trypanosome is coated with millions of copies of a single protein. However, before the host’s immune system can recognize the protein and mount an attack, new generations of the parasite switch to another surface protein with a different molecular structure

Question 16

A euglenid -

Answer 16

has a pocket at one end of the cell from which one or two flagella emerge

Question 17

SAR

Answer 17

supergroup, also just SAR or Harosa, is a clade of eukaryotic organisms that includes stramenopiles, alveolates, and Rhizaria. The name is an acronym derived from the first letters of each of these clades

Question 18

The stramenopiles -

Answer 18

one major subgroup of SAR that includes some of the most important photosynthetic organisms on the planet and is grouped due to their flagellums

Question 19

In most stramenopiles, this “______” flagellum is paired with a shorter “_______” (nonhairy) flagellum

Answer 19

hairy; smooth

Question 20

The three groups of stramenopiles:

Answer 20

diatoms, oomycetes, and brown algae

Question 21

Diatoms -

Answer 21

unicellular algae that have a unique glass-like wall made of silicon dioxide embedded in an organic matrix

Question 22

estimated ________ living species, _______ are a highly diverse group of protists

Answer 22

100,000; diatoms

Question 23

Brown algae -

Answer 23

the largest and most complex algae, all are multicellular, and most are marine. Especially common along temperate coasts that have cold-water currents. They owe their characteristic brown or olive color to the carotenoids in their plastids

Question 24

Holdfast -

Answer 24

a rootlike specialized structure which anchors the alga

Question 25

Stipe -

Answer 25

specialized structure that provides support

Question 26

Blades -

Answer 26

specialized structure that are leaflike

Question 27

Gas-filled, bubble-shaped floats -

Answer 27

adaptations that enable their main photosynthetic surfaces (the leaflike blades) to be near the water surface

Question 28

Alternation of generations -

Answer 28

the alternation of multicellular haploid and diploid forms, applies only to life cycles in which both haploid and diploid stages are multicellular

Question 29

Zoospores -

Answer 29

haploid spores that move by means of flagella

Question 30

Sporophyte -

Answer 30

the diploid individual that produces spores

Question 31

Zoospores -

Answer 31

the spores that are haploid and move by means of flagella

Question 32

Heteromorphic generations -

Answer 32

the sporophytes and gametophytes are structurally different

Question 33

isomorphic generations -

Answer 33

in which the sporophytes and gametophytes look similar to each other, although they differ in chromosome number

Question 34

Oomycetes -

Answer 34

include the water molds, the white rusts, and the downy mildews. Based on their morphology, these organisms were previously classified as fungi oomycetes typically have cell walls made of cellulose, don't have plastids, no photosynthesis, typically decomposers or parasites

Question 35

Alveolates -

Answer 35

subgroup of SAR; have membrane-enclosed sacs (alveoli) just under the plasma membrane

Question 36

Three alveolate clades:

Answer 36

the dinoflagellates, the apicomplexans, and the ciliates

Question 37

The dinoflagellates -

Answer 37

group of flagellates; The cells of many are reinforced by cellulose plates that house two flagella, one of which causes them to spin as they move through the waters of their marine and freshwater communities

Question 38

The apicomplexans

Answer 38

a group of parasites; nearly all are parasites of animals—and virtually all animal species examined so far are attacked by these parasites

Question 39

The ciliates

Answer 39

a group of protists that move using cilia; a large and varied group of protists named for their use of cilia to move and feed, most are predators, typically of bacteria or of other protists.

Question 40

Conjugation -

Answer 40

genetic variation resulting from a sexual process in which two individuals exchange haploid micronuclei but do not reproduce

Question 41

Rhizarians -

Answer 41

subgroup of SAR, many species in this group are amoebas

Question 42

Amoebas -

Answer 42

protists that move and feed by means of pseudopodia, extensions that may bulge from almost anywhere on the cell surface

Question 43

Pseudopodia -

Answer 43

extensions that may bulge from almost anywhere on the cell surface

Question 44

Three groups of rhizarians:

Answer 44

radiolarians, forams, and cercozoans

Question 45

Radiolarians -

Answer 45

protists that have delicate, intricately symmetrical internal skeletons that are generally made of silica, and the pseudopodia of these mostly marine protists radiate from the central body reinforced by bundles of microtubules

Question 46

Foraminiferans or forams -

Answer 46

protists named for their porous shells called tests that consist of a single piece of organic material that typically is hardened with calcium carbonate, found in both the ocean and freshwater

Question 47

Cercozoans -

Answer 47

a large group of amoeboid and flagellated protists that feed using threadlike pseudopodia, common inhabitants of marine, freshwater, and soil ecosystems.

Question 48

Archaeplastida -

Answer 48

together, red algae, green algae, and plants make up our third eukaryotic supergroup which is a monophyletic group that descended from the ancient protist that engulfed a cyanobacterium

Question 49

Red algae -

Answer 49

reddish, reproduce sexually, and are mostly multicellular, owing to the photosynthetic pigment phycoerythrin, which masks the green of chlorophyll

Question 50

Green algae -

Answer 50

containing green chloroplasts similar in structure and pigment composition to those chloroplasts of plants. Molecular systematics and cellular morphology leave little doubt that plants are closely related

Question 51

Green algae two main groups:

Answer 51

the charophytes and the chlorophytes

Question 52

Unikonta -

Answer 52

an extremely diverse supergroup of eukaryotes that includes animals, fungi, and some protists

Question 53

The two major clades of unikonts:

Answer 53

the amoebozoans (tubulinids and close protist relatives) and the opisthokonts (animals, fungi, and closely related protist groups)

Question 54

Amoebozoan clade -

Answer 54

includes many species of amoebas that have lobe- or tube-shaped pseudopodia rather than the threadlike pseudopodia found in rhizarians. Includes tubulinids, slime molds, and entamoebas

Question 55

Tubulinids -

Answer 55

constitute a large and varied group of amoebozoans that have lobe- or tube-shaped pseudopodia. These unicellular protists are ubiquitous in soil as well as freshwater and marine environments.

Question 56

Slime molds, or mycetozoans -

Answer 56

produce fruiting bodies that aid in spore dispersal, evolutionary convergence based similarity to fungi

Question 57

Slime molds two main branches:

Answer 57

plasmodial slime molds and cellular slime molds.

Question 58

Plasmodium -

Answer 58

not multicellular; it is a single mass of cytoplasm that is undivided by plasma membranes and that contains many nuclei. This “supercell” is the product of mitotic nuclear divisions that are not followed by cytokinesis

Question 59

Cellular slime molds

Answer 59

feeding stage of these organisms consists of solitary cells that function individually, but when food is depleted, the cells form a slug-like aggregate that functions as a unit

Question 60

Entamoeba -

Answer 60

symbiotic parasites, infecting all classes of vertebrate animals as well as some invertebrates

Question 61

Producers -

Answer 61

organisms that use energy from light (or in some prokaryotes, inorganic chemicals) to convert to organic compounds