Ch 28

1. List the characteristics of protists.

They are the earliest eukaryotes showed up a billion years before the othersAge 2.1 billion yearsThere are 60,000 living speciesExist as unicellular, colonial, and multicellularAerobic, cilia & flagella, asexual or sexualBottom line: a VERY diverse group

2. Explain why some biologists prefer to use the term undulipodia for eukaryotic flagella and cilia.

Because they appear to “undulate” or wave while acting like feet or “podia”

3. Briefly summarize and compare the two major models of eukaryotic origins, the autogenous hypothesis and the endosymbiotic hypothesis.

• Specialization of the plasma membrane invagination gave rise to the nuclear envelope, the ER, the Golgi apparatus, etc…

3. Endosymbiotic associations may have resulted in organelles mitochondria, chloroplasts, etc…

4. Provide three major lines of evidence for the endosymbiotic hypothesis.

Similarities between organelles and prokaryotesMolecular systematics lends support rRNA of chloroplasts is more similar in base sequence to RNA from certain eubacteria than rRNA in eukaryotic cytoplasm9 + 2 flagella and cilia are analogous to prokaryotes

5. Explain why modern biologists recommend expanding the original boundaries of the Kingdom Protista.

Observation that the Kingdom Protista is polyphyleticCurrent research groups protists into FIVE candidate Kingdoms

6. Explain what is meant by the statement that the Kingdom Protista is a polyphyletic group.

Polyphyletic = ancestry from several possible sources or directionsExample:Protists are animal-like

plant-like fungus-like

7. List five candidate kingdoms of protists and describe a major feature of each.

Archaezoa lack mitochondriaEuglenozoa are both autotrophic and heterotrophic flagellatesAlveolata have subsurface cavities (alveoli)Stramenopila diatoms, golden brown algae, and water moldsRhodophyta red algae; lack flagella

8. Describe amoeboid movement.

Amoebas move in a characteristic motion use “pseudopodia” form as cellular extensions and function in feeding and movementThe cytoskeleton of microtubules and microfilaments functions in this amoeboid movement

9. Outline the life cycle of Plasmodium.

It is the protist that causes malariaThe Anopheles mosquitos serve as the intermediate host and humans are the final hostThe Plasmodium spends most of its life in blood or liver cells

10. Indicate the organism that causes African sleeping sickness and explain how it spread and why it is difficult to control.

It is a species of Trypanosoma that causes the disease and are spread by the bite of the tsetse flyIt belongs in the candidate Kingdom Euglenozoa, in the group Kinetoplastids

11. Describe the function of contractile vacuoles in freshwater climates.

Contractile vacuoles allow freshwater protists to:1. Maintain water balance and homeostasis2. Expel accumulated water from osmosis3. Sometimes helps propel protists

12. Distinguish between macronuclei and micronuclei.

Macronuclei large, over 50 copies of genome- controls everyday functions of the cell by synthesizing RNA- necessary for asexual reproduction during binary fissionMicronuclei small, about 1 – 80 of these- no function in growth, maintenance, or asexual reproduction- functions only in conjugation (sexual genetic variation)

13. Using diagrams, describe conjugation in Paramecium caudatum.

Page 530 in your book• Two paramecium have diploid micronuclei which

go through meiosis to create haploid micronucleiThrough syngamy, the two paramecium exchange a couple haploid micronuclei, and these fuse to become a new, varied, diploid micronucleusThe new diploid micronuclei may also then follow the cycle and exchange with another paramecium throughout it’s life cycle

14. Explain how accessory pigments can be used to classify algae and determine phylogenetic relationships among divisions.

Diatoms brown plastids cause brown/yellow colorGolden algae yellow and brown carotenoids and xanthophyllBrown algae chlorophyll a, c and the carotenoid fucoxanthinRed algae chlorophyll a, carotenoids, phycobilins, and chlorophyll d- color is due to accessory pigment phycoerythrin

15. In a chart, distinguish among the following algal groups based on their pigments, cell wall components, storage products, reproduction, number and position of flagella, and habitat:a. Dinoflagellata b. Bacillariophytac. Chrysophyta d. Phaeophyta

16. Describe three possible evolutionary trends that led to multicellularity in the Chlorophyta.

• Formation of colonies of individual cellsex: Volvox

3. Repeated division of nuclei with no cytoplasmic division (mitosis without cytokinesis ex: Caulerpa

5. Formation of true multicellular formsex: Ulva

Life Cycle overview

Sporophyte generally the adult form of an organism; exists as a diploid (2n); makes spores (ex: humans)

Gametophyte generally an intermediate step before fertilization; exists as a haploid (n); makes gametes (ex: sperm & eggs)

17. Outline the life cycles of Chlamydomonas, Ulva, and Laminaria and indicate whether the stages are haploid or diploid.

Chlamydomonas at maturity it is a single haploid cell- asexual at first, then sexual only if stressed, creating a diploid zygote

2. Ulva diploid sporophyte and haploid gametophyte

3. Laminaria sporophyte (2n) with sporangia makes zoospores (n) which make gametes (n) and then fertilization to get diploid sporophyte again

18. Distinguish between isogamy and oogamy; sporophyte and gametophyte; and isomorphic and heteromorphic generations.

Isogamy when gametes are morphologically indistinguishableOogamy flagellated sperm fertilize the nonmotile eggSporophyte 2n (diploid) generationGametophyte n (haploid) generationIsomorphic gametophytes and sporophytes look alikeHeteromorphic gametophytes and sporophytes are structurally different

19. Compare the life cycles of plasmodial and cellular slime molds and describe the major differences between them.

Plasmodial Slime MoldMultinucleated massDiploid nucleiWhen stressed will form sexual reproductive structures called sporangia

Cellular Slime MoldSolitary haploid cellsCells will aggregate when food supply is lowFruiting bodies (sporangia) function in asexual reproduction

20. Provide evidence that the oomycetes are not closely related to true fungi.

Have coenocytic (multinucleated) hyphae (branching filaments) that are analogous to fungal hyphaeCell walls are made of cellulose rather than the chitin in true fungiHave biflagellated cells fungi lack flagellated cells

21. Give examples of oomycetes and describe their economic importance.

Water molds grow on injured tissue but also will grow on the skin and gills of fishWhite rusts Downy mildews- both of these are parasitic on terrestrial plants – act as pathogens

22. Explain the most widely accepted hypothesis for the evolution of multicellularity.

Multicellularity arose from unicellular ancestors as colonies or loose aggregates of interconnected cellsThis involved cellular specialization and division of labor among the cells

The End