ch 28 and 31

Chapter 28

1. How far back in time do eukaryotes go? 2.7 billion years (no fossils support this)

2. Describe the endosymbiotic theory. Mitochondria probably evolved from aerobic bacteria that were engulfed by a larger cell

3. What does it mean that “Kingdom Protista is paraphyletic and not a kingdom at all?” Kingdom Protista is not a kingdom because it lumps a bunch of different things together there could be 3-20 different kingdoms made out of just kingdom Protista

4. By what means do protists move? flagella or cilia, pseudopodia, and propulsion

5. What is the range of nutritional strategies among protists? phototrophs, heterotrophs, osmotrophs, phagotrophs, and mixotrophs

6. Campbell’s text identifies four supergroups of eukaryotes. What are they? (pp. 594-595) Supergroup Excavata, SAR clade, Supergroup archaeplastida and Supergroup unikonta

7. What are the basic characteristics of the diplomonads? Give an example of a diplomonad.

two nuclei
unicellular
move with multiple flagella
modified mitochondria called mitosomes

Ex. Giardia intestinalis: this parasite is found in contaminated water and can pass from human to human. they cause diarrhea

8. What are the basic characteristics of the parabasalids? Give an example or two of a parabasalid.

have undulating membranes
move with flagella
reduced mitochondria called hydrogenosomes

Ex. Trichonympha species: lives in the gut of termites and digests cellulose

Ex. Trichomonas vaginalis: STD in humans

9. What are the basic characteristics of the euglenoids? Give an example of a euglenoid.

free-living eukaryotes
pocket at one end with one or two flagella
have mitochondria
flexible pellicle can change shape
one-third of euglenoids have chloroplasts and are fully autotrophic (may become heterotrophic in the dark)
others lack chloroplasts and are heterotrophic
reproduction by mitosis
no sexual reproduction is known

Ex. Euglena: photosynthetic

10. What are the basic characteristics of the kinetoplastids? Give some examples of kinetoplastids and the diseases they cause.

Second major group in Euglenozoa
Kinetoplastid refers to unique, single mitochondrion in each cell
evade immune response with a “bait-and-switch” defense; surface proteins are changed frequently

Trypanosomes: are disease-causing kinetoplastids

African sleeping sickness: transmitted by tsetse fly

Leishmaniasis: transmitted by sand flies

Chagas disease: caused by trypanosoma cruzi (small wild mammals carry the parasite)

11. What are the basic characteristics of the dinoflagellates? What is a “red tide?” What problems do they cause?

photosynthetic unicells
have two flagella located into grooves in the cellulose plates
both marine and freshwater

“red tide”: result from “blooms” of dinoflagellates and are detrimental to fishing industry

12. What are the basic characteristics of the apicomplexans? Give an example of an apicomplexan.

spore-forming parasites of mammals
have apical complex of organelles, vacuoles, fibrils, microtubules at one end of cell

Ex. Plasmodium: causes malaria (the annopheles mosquito is what transmits pathogens for the plasmodium)

13. Describe the life cycle of Plasmodium.

14. What are the basic characteristics of ciliates?

have large numbers of cilia arranged in longitudinal rows or spirals
some cilia may be fused into sheets, spikes, or rods that function as mouths, paddles, teeth or feet
have a pellicle
unicellular heterotrophs
micronucleus may only be needed for sexual reproduction
macronucleus divides by mitosis and is involved with physiological function
vacuoles for ingesting food and maintaining water balance
conjugation involves the exchange of micronuclei

15. Describe conjugation in Paramecia.

16. Name and describe four types of stramenopila (brown algae, golden algae, diatoms, oomycetes).

Brown Algae:

most conspicuous seaweeds in northern regions (kelps)
thallus = blade, stipe, holdfast
algin = gel-forming substance used to thicken puddings or salad dressings
undergoes alternation of generations

Sporophyte: (diploid) goes through meiosis to produce spores

Gametophyte: are smaller, filamentous individuals

Golden Algae:

biflagellated
freshwater or marine (plankton)
all are photosynthetic; some mixotrophic
most are unicellular; some colonial
many species can form protective cysts if environmental conditions deteriorate

Diatoms:

unicellular, photosynthetic organsisms
phytoplackton
double shells (look like a box with lid)
made of opaline silica
live diatoms can withstand pressures as great as 1.4 million kg/m^2 (equal to the pressure under each leg of a table supporting an elephant)
Vibrating fibrils line grooves
diatomaceous earth -filtering medium

Oomycetes: (water molds)

all are parasites or sabrobes
used to be categorized as fungi
have motile spores (zoospores) with two unequal flagella
sexual reproduction via male and female gametes
most oomycetes live in water, but terrestrial forms are plant pathogens

17. What is Phytophthora infestans ? What is Saprolegnia ?

phytophthora infestans: cause late blight of potatoes (Irish potato famine)

Saprolegnia: fish pathogen; can infect amphibians and kill amphibian eggs

18. What are the basic characteristics of the radiolarians? For what are they noted?

Radiolarians:

glassy exoskeleton of silica
bilateral or radial symmetry pseudopodia extend outward through small openings in exoskeleton
forms most of the ooze on seafloor

19. What are the basic characteristics of the foraminiferans? For what are they noted?

Foraminiferans:

heterotrophic freshwater and marine protists
many can derive nourishment from photosynthesis of symbiotic algae living within their tests
fossils created limestone deposits (White Cliffs of Dover)
have tests (shells) of organic substances with grains of calcium carbonate, sand, bits of echinoderm shells or sponge spicules
have podia (cytoplasmic projections) for gathering food and materials for their tests, and for swimming

20. What are the basic characteristics of the cercozoans?

Cercozoans:

contains most of the amoeboid and flagellated protists that feed with threadlike pseudopodia
found in marine and freshwater and in soil
most are parasites or predators

21. What are the basic characteristics of the red algae (rhodophyta)?

Red algae (Rhodophytes):

no centrioles; no flagellaa
reproduce by alternation of generations
produce pigments that give them a red color

Porphyra = Japanese “nori” used to wrap sushi

22. What are the basic characteristics of the green algae? Compare Chlamydomonas, Volvox, Ulva, and Caulerpa.

Green Algae:

divided into two groups - the charophytes and the chlorophytes
charophytes most related to land plants

unicellular cholophytes

chlorophytes includes 7,000+ species
most are freshwater, but also marine and terrestrial forms

Chlamydomonas: simple, unicellular, resemble gametes or zoospores of more complex chlorophytes

Habitats of unicellular chlorophytes include: water (phytoplankton), damp soil, symbiosis inside eukaryotes, and even snow

Colonial and multicellular chlorophytes:

volvox: colonial as are filamentous forms of algae that form pond scum
Ulva: forms true multicellular bodies by cell division and differentiation
Caulerpa: shows repeated division of nuclei with no cytoplasmic division so it is like on big “supercell”

23. Distinguish among the following types of amoeboid organisms: plasmodial slime molds, cellular slime molds, tubulinids (gymnamoebas), entamoebas. Be sure to list any unique features of each group.

Plasmodial slime molds:

multinucleate, moving mass of cytoplasm
usually yellow or orange color
feed on bacteria, yeast, other organic matter
undergoes synchronous mitosis
form sporangium under adverse conditions

Cellular slime molds:

individuals act like amoebas
eat bacteria
if food is scarce, they aggregate to form a moving “slug”

Tubulinids (used to be Gymnamoebas)

large and varied group of amoebas
free-living
found in soil, freshwater, saltwater
heterotrophs that feed on bacteria, other protists, and detritus

Entamoebas:

parasites of vertebrates and some invertebrates

Ex. E. histolytica: causes amebic dysentery and is spread via contaminated food, water, or eating utensils

E. histolytica may sometimes get to brain and cause abscesses

24. Describe the choanoflagellida. They may be the common ancestor of what organism?

Chanoflagellida:

most like the common ancestor of the sponges
have single flagellum surrounded by collar of shorter filaments
feed by straining bacteria from water with their collar

\ Chapter 31

25. Fungi are most related to which other kingdom?

Fungi are more closely related to animals than to plants.

26. What substance is found in the cell walls of fungi? This material is found in which other organisms?

Cell walls of fungi contain chitin
the same material found in the exoskeletons of arthropods

27. Define: hyphae, mycelium, monokaryotic (septate), dikaryotic, heterokaryotic, homokaryotic, coenocytic.

Hyphae: the feathery filaments that make up multicellular fungi

Mycelium: a mass of connected hyphae

Monokaryotic: hypha with one nucleus

Dikaryotic: hypha with two nuclei

Heterokaryotic: nuclei from two genetically distinct individuals

Homokaryotic: nuclei from genetically similar individuals

Coenocytic: hypha made up of a continuous cytoplasmic mass with hundreds or thousands of nuclei

28. What is the relevant unit of reproduction in fungi?

the nucleus

29. How do fungi take in nutrients?

they are heterotrophic, they excrete enzymes for external digestion and then absorb the digested products

30. Briefly, how does sexual reproduction occur in fungi?

Sexual reproduction: involves fusion of hyphae from two compatible mating types or hyphae from same fungus
compatibility is determined by pheromones released by hyphae

31. Define: plasmogamy, karyogamy.

Plasmogamy: union of the cytoplasms of two parent mycelia

Karyogamy: fusion of haploid nuclei from the parent mycelia (produces diploid nucleus)

32. How do fungi reproduce asexually?

Spores can form asexually or sexually and are most often dispersed by the wind which help fungi reproduce asexually

33. What are the features of the chytridiomycota?

Chytridiomycota: Fungi with flagellated zoospores

34. Chytrids have been implicated in the die-off of what organisms around the world?

amphibians

35. What are the key characteristics of the Zygomycota?

Zygomycota: fungi that produce zygotes

36. Describe the reproductive cycle of Rhizopus (bread mold), a member of the Zygomycota.

Rhizopus is commonly found growing on moist bread or fruit
Rhizopus feeds on simple sugars
They are named for the diploid zygote nuclei that they produce

37. Describe the characteristics of the Glomeromycota. Where might they be found?

cannot survive without a host plant.
Mutualism is involved where the fungus proides minerals (especially phosphorus) to the plant, and the plant provides carbohydrates to the fungus
Glomeromycete hyphae grow within the root cells of most trees and herbaceous plants.
These hyphae are called arbuscular mycorrhizae.

38. Describe the characteristics of the Ascomycota. What are some examples?

Ascomycetes make up about 75% of known fungi

Ex. bread yeasts, common molds, morels, cup fungi, and truffles.

Ex. Genus Penicillium is also found in phylum Ascomycota

Sexual reproduction occurs within the ascus.
Asexual reproduction occurs within conidiophores.
Conidia form at the end of modified hyphae.
Some ascomycetes have yeast morphology.

39. How do yeasts reproduce?

They can reproduce asexually by budding or cell fission

40. Describe the characteristics of the Basidiomycota. Give examples. Describe their means of reproduction.

Basidiomycota: the club (basidium) fungi

Basidiocarp: visible reproductive structure

Ex. Mushrooms, toadstools, puffballs, shelf fungi

Basidiomycetes sexually reproduce within basidia
gills on the undersurface of the mushroom cap produce tremendous number of spores

What is biggest in this cycle? basidiocarp

What is the next biggest? basidium

What is smaller? basidiospores

41. What two substances are fungi able to break down? What is the importance of this?

Fungi can break down cellulose and lignin
Breaking down cellulose and lignin releases carbon, nitrogen, and phosphorus making these elements available to other organisms

42. Define: obligate symbiosis, facultative symbiosis, pathogen, parasite, commensal, mutualist.

Obligate symbiosis: essential to survive

Facultative symbiosis: fungus can survive without the host

Pathogens: cause disease

Parasites: do not cause disease unless it is an extreme case

commensal: one partner benefits, but no harm comes to the other

Mutualistic: both the fungus and the host benefits from the relationship

43. What are endophytes? How are they important?

Endophytes live inside plants
they protect plants from parasites

44. What are lichens? Where do they live? How are they important?

A lichen is composed of a fungus, along with cyanobacteria, green algae, or both
Lichens live in very harsh habitats, they are usually the first to colonize an area
Lichens break down rocks and help prepare for invasion of other organisms
Lichens produce very bright pigments some of which are used as dyes
lichens are used to indicate air quality since they can absorb substances dissolved in rain and dew
as pollution decreases, lichen populations increase

45. What are mycorrhizae? How are they important? Distinguish between arbuscular mycorrhizae and ectomycorrhizae.

Mychorrhizae: fungi associated with roots of plants

fungal hyphae increase amount of contact with soil and increase surface area for absorption

Haustoria: specialized hyphae used to extract nutrients from, or exchange nutrients with their plant hosts

Mycorrhizae aid in direct transfer of phosphorus, zinc, copper and other minerals from soil into plant roots

Arbuscular mycorrhizae: grow within the outer cells of the plant root

Ectomycorrhizae: surround root cells but do not penetrate them

46. Give some examples of symbioses between fungi and animals.

Fungi form mutual symbioses with animals

Ex. 1, Ruminant animals have neocallimastigomycete fungi in their gut

Ex. 2, Leaf-cutter ants have domesiticaled a specific fungus that they maintain in an underground garden. Ants provide leaves for the fungi to eat. Ants eat the fungi

47. Briefly identify the following fungal parasites and pathogens: Fusarium, Aspergillus flavus, corn smut, ergot.

Fusarium: grows on spoiled food; produces vomitoxin that can cause brain damage in humans and animals in SW United States

Aspergilus flavus: Produce aflatoxins that are very carcinogenic

corn smut: Damages corn, but is not harmful to animals that consume it

Ergot: fungus associated with rye and other cereal grains

An alkaloid toxin is produced and if eaten can cause hallucinations, gangrene, nervous spasms, burning sensations

48. Fungal infections are difficult to treat. Explain. difficult to treat in humans and other animals owing to the similarities between the two kingdoms

49. Give some examples of fungal diseases that affect humans.

• ringworm

• athlete’s foot

• nail fungus

• thrush

• oral or vaginal infections caused by Candida

• Pneumocystis jiroveci invades lungs

• mold allergies

• Stachybotris causes “sick” buildings

• chytridiomycosis affects amphibians

\ REVIEW QUIZ:

gameotophyte:

Algin:

saphrolegina: