Botany Project

gUidE:

2007-12-13T09:19:00.000+08:00

Nov. 29 - Concept check 28.1

Dec. 1 - Concept check 28.2 - 28.8 & Concept check 27.1 - 27.5

Dec. 8 - Concept check 29.1 - 29.4 & Concept check 30.1 - 30.4

Dec. 9 - Concept check 31.1 - 31.5

Dec. 10 - Concept check 24.1 - 24.3 & Concept check 26.1 - 26.6

Concept 26.6

2007-12-10T20:17:00.000+08:00

Q1: Which kingdoms in Whittaker’s five- kingdom system include organisms now in the domain Eukarya?

A1: Protista, Plantae, Fungi, Animalia

Q2: Based on Figure 26.22, explain why the kingdom Monera is no longer considered a valid taxon?

A2: Monera included both bacteria and archaea, but archaea are more closely related to eukaryotes than to bacteria.

Concept 26.5

2007-12-10T20:13:00.000+08:00

Q1: How does the division of function differ for single-celled and multicellular organisms?

A1: A single-celled organism must carry out all of the functions required to stay alive. Most multicellular organisms have many types of specialized cells, and life functions are divided among specific cell types.

Q2: In what way is “Cambrian explosion” a good description of the early part of the fossil record of animal history? What is meant by the metaphor of a “long fuse” for the Cambrian explosion?

A2: Fossils of most major animal phyla appear suddenly in the first 20 million years of the Cambrian period. Molecular clocks suggest that many animal phyla originated much earlier.

Concept 26.4

2007-12-10T20:06:00.000+08:00

Q1: What evidence supports the hypothesis that mitochondria preceded plastids in the evolution of eukaryotic cells?

A1: All eukaryotes have mitochondria or genetic remnants of these organelles, but not all eukaryotes have plastids.

Q2: How is a eukaryotic cell like a chimera?

A2: The chimera of Greek mythology contained parts from different animals. Similarly, a eukaryotic cell contains parts form various prokaryotes; mitochondria from one type, and bacterium, plastids from another type, and a nuclear genome from parts of the genomes of these endosymbionts and at least one other cell.

Concept 26.3

2007-12-10T20:03:00.000+08:00

Q1: What do fossilized stromatolites suggest about the evolution of prokaryotes?

A1: Prokaryotes must have existed at least 3.5 b.y.a, when the oldest fossilized stromatolites were formed.

Q2: The first appearance of free oxygen in the atmosphere must have triggered a massive wave of extinctions among the prokaryotes of the time. Why?

A2: Free oxygen attacks chemical bonds and can inhibit enzymes and damage cells. Some organisms were able to survive in anaerobic habitats, however.

Concept 26.2

2007-12-10T19:59:00.000+08:00

Q1: Your measurements indicate that a fossilized skull you unearthed has a carbon-14/ carbon-12 ratio about ¼ that of the skulls of present-day animals. What is the approximate age of the fossilized skull?

A1: 22,920 years (four half-life reductions)

Q2: Based on Table 26.1, how long did prokaryotes inhabit Earth before eukaryotes evolved?

A2: About 1,300 million years, or 1.3 billion years.

Concept 26.1

2007-12-10T19:49:00.000+08:00

Q1: What hypothesis did Miller and Urey test in their experiment?

A1: The hypothesis that conditions on the early Earth could have permitted the synthesis of organic molecules from inorganic ingredients.

Q2: Why was the appearance of protobionts surrounded by membranes likely a key step in the origin of life?

A2: In contrast to random mingling of molecules in an open solution, segregation of molecular systems by membranes could concentrate organic molecules, and electrical charge gradients across the membrane could assist biochemical reactions.

Q3: What is ribozyme?

A3: A ribozyme is an RNA molecule that catalyzes a chemical reaction

Concept 24.3

2007-12-10T19:41:00.000+08:00

Q1: How can the Darwinian concept of descent with modification explain the evolution of such complex structures as the vertebrate eye or heart?

A1: Such complex structures do not evolve all at once, but in increments, with natural selection selecting for adaptive variants of the earlier versions.

Q2: Explain why the concept of exaptation does not mean that a structure evolves in anticipation of some future environmental change.

A2: Although an exaption is co-opted for new or additional functions in a new environment, it existed in the first place because it worked as an adaptation to the original environment.

Q3: How can heterochrony cause the evolution of different body forms?

A3: The timing of different development pathways in organisms can change in different ways (heterochrony). This can result in differential growth patterns, such as those producing different patterns of webbing in salamander feet.

Concept 24.2

2007-12-10T19:35:00.000+08:00

Q1: Explain why allopatric speciation would be less likely to occur on an island close to a mainland than on a more isolated island of the same size.

A1: Continued gene flow between mainland populations and those on a nearby island reduces the chance that enough genetic divergence will take place for allopatric speciation to occur.

Q2: Normal watermelon plants are diploid (2n=22) but breeders have produce tetraploid (4n=44) watermelons. If tetraploid plants are hybridized with their diploid relatives, they produce triploid (3n=33) seeds. These offspring can produce triploid seedless watermelons and can be further propagated by cuttings. Are the diploid and tetraploid watermelon plants different species? Explain.

A2: The diploid and tetraploid watermelons are separate species. Their hybrids are triploid and as a result are sterile because of problems carrying out meiosis.

Q3: In the fossil record, transitional fossils linking newer species to older ones are relatively rare. Suggest an explanation for his observation.

A3: According to the model of punctuated equilibrium, in most cases the time during which speciation occurs is relatively short compared with the overall duration of the species' existence. Thus, on the vast geologic time scale of the fossil record, the transition of one species to another seems abrupt, and instances of gradual change in the fossil record are rare. Furthermore, some of the changes that transitional species underwent may not be apparent in fossils.

Concept 24.1

2007-12-10T19:27:00.000+08:00

Q1: Two bird species in a forest are not known to interbreed. One species feeds and mates in the treetops and the other on the ground. But in captivity, the two species can interbreed and produce viable, fertile offspring. What type of reproductive barrier most likely keeps these species separate? Explain.

A1: Since the birds are known to breed successfully in captivity, the reproductive barrier in nature must be prezygotic. Given the species differences in habitat preference, the reproductive barrier is most likely to be habitat isolation.

Q2: a. Which species concept can be used for both asexual and sexual species?
b. Which can only be applied to sexual species?
c. Which would be most useful for identifying species in the field?

A2: a. All species concepts except the biological species concept can be applied to both asexual and sexual species because they define species on the basis of characteristics other than abitlity to reproduce.
b. The biological species concept can be applied only to extant sexual species.
c. The easiest species concept to apply in the field would be the morphological species concept because it is based only on the appearance of the organism. Additional information about its ecological habits, evolutionary history, and reproduction are not required.

Concept 31.5

2007-12-09T00:27:00.000+08:00

Q1: What are some of the benefits that algae in lichens can derive from their relationship with fungi?

A1: A suitable environment for growth, retention of water and minerals, protection from sunlight, and protection form being eaten.

Q2: What characteristics of pathogenic fungi result in their being efficiently transmitted?

A2: A hardy spore stage enables dispersal to host organisms through a variety of mechanisms; their ability to grow rapidly in a favorable new environment enables them to capitalize on the host's resources.

Concept 31.4

2007-12-09T00:19:00.000+08:00

Q1: What feature of chytrids supports the hypothesis that they represent the most primitive fungal lineage?

A1: Flagellated spores.

Q2: Why are glomeromycetes so ecologically significant?
Q3: Give different examples of how form fits function in zygomycetes, ascomycetes, and basidiomycetes.

A2: Most plants form arbuscular mycorrhizae with glomeromycetes; without the fungi, the plants would be poorly nourished.

Q3: Give different examples of how form fits function in zygomycetes, ascomycetes, and basidiomycetes.

A3: Zygomycetes - sturdy, thick-walled zygosporangium can withstand harsh conditions and then undergo karyogamy and meiosis when the environment is favorable for reproduction. Ascomycetes - the asexual spores (conidia) are produced in chains or clusters at the tips of conidiophores, where they are easily dispersed by wind. Basidiomycetes - basidiocarp supports and protects a large surface area of basidia, from which spores are dispersed.

Concept 31.3

2007-12-09T00:14:00.000+08:00

Q1: Why are fungi classified as opisthokonts when most fungi lack flagella?

A1: The fungal lineage thought to be the most primitive, the chytrids, have posterior flagella, as do most other ophisthokonts. This suggests that other fungal lineages lost their flagella after diverging from the chytrid lineage.

Q2: Explain the evolutionary significance of the presence of mycorrhizae in the earliest vascular plants.

A2: This indicates that fungi had already established symbiotic relationships with plants by the time the first vascular plants evolved.

Concept 31.2

2007-12-09T00:11:00.000+08:00

Q1: In terms of haploidy versus diploidy, how do the life cycles of humans and fungi differ?

A1: Majority of human life cycles are dominated by dipoid stages while in fungi, majority consists of haploid stages.

Q2: Suppose that you sample the DNA of two mushrooms on opposite sides of your yard and find that they are identical. What are two hypotheses that could reasonably account for this result?

A2: The 2 mushrooms might be reporoductive structures of the same mycelium. Or they might be parts of 2 separate organisms that have arised from a single organism through asexual reproduction and thus carry the same genetic information.

Concept 31.1

2007-12-09T00:06:00.000+08:00

Q1: Compare and contrast the nutritional mode of a fungus with your own nutritional mode.

A1: Humans and fungus are heterotrophs. In humans, we ingest relatively large pieces of food and digest the food within our bodies. While in fungus, it digests its food externally and then absorbing the small molecules that result form digestion.

Q2: Describe how the structure of a fungus is adapted to its nutritional mode.

A2: The extensive network of hyphae puts a large surface area in contact with the food source, and rapid growth of the mycelium extends hyphae into new territory.

Concept 30.4

2007-12-08T23:57:00.000+08:00

Q1: Explain why it is accurate to consider plant diversity to be a nonrenewable resource.

A1: Because extinction is irreversible, it decreases the total diversity of plants, many of which may have brought important benefits to humans. Such as in the field of medicine and agriculture.

Concept 30.3

2007-12-08T23:46:00.000+08:00

Q1: It has been said that an oak tree is an acorn’s way of making more acorns. Write an explanation that includes these terms:
sporophyte
gametophyte
ovule
seed
ovaryfruit

A1: In the oak's life cycel, the tree (the sporophyte) produces flowers, which contain gametophytes in pollen grains and ovules; the eggs in ovules are fertilized; the mature ovaries develop into dry fruits called acorns; and the acorn seeds germinate, resulting in embryos giving rise to seedlings and finally to mature trees, which produce flowers then acorns.

Q2: Compare and contrast a pine cone and a flower in terms of structure and function.

A2: Pine cones and flowers both have sporophylls , modified leaves that produce spores. Pine trees have separate pollen cones (with pollen grains) and ovulate cones (with ovules inside cone scales). In flowers, pollen grains are produced by the anthers of stamens, and ovules are within the ovaries of carpels. Unlike pine cones, many flowers produce both the pollen and the ovules.

Q3: Explain the use of the terms monocot, dicot and eudicot.

A3: Recent molecular evidence pointed out that while monocots are a clade, dicots are not. Based on phylogenetic relationships, most dicots form a clade, now known as eudicots.

Concept 30.2

2007-12-08T23:38:00.001+08:00

Q1: Based on Figure 30.4, explain why the various types of gymnosperms can be described as being similar yet distinctive.

A1: Although gymnosperms are similar in having "naked" seeds, their seed bearing structure vary greatly. For instance, Cycads have larger cones compared to Ginkgo and Gnetum. Leaf shape also varies greatly, from the needles of many conifers to the palmlike leaves of cycads to Gnetum leaves that look like those of flowering plants.

Q2: Explain how the pine life cycle (see Figure 30.6) reflects basic characteristics of seed plant.

A2: The life cycle illustrates heterospory, as ovulate cones produce megaspores and pollen cones produce microspores. The reduced gametophytes are evident in the formof the microscopic pollen grains and the microscopic female gametophyte within the megaspore. The egg is shown developing within an ovule, and the pollen tube is shown conveying the sperm. The figure also shows the protective and nutritive features of a seed.

Concept 30.1

2007-12-08T23:28:00.000+08:00

Q1: Contrast sperm delivery in seedless vascular plants with sperm deliver in seed plants.

A1: To have any chance of reaching the eggs, the flagellated sperm of seedless vascular plants must rely on swimming through a film of water, usually limited to a range of less than a few centimeters. In contrast, the sperm of seed plants are produced within durable pollen grains that can be carried long distances by wind or by animal pollinators. Although flagellated in some species, the sperm of most seed plants do not require water because pollen tubes convey them directly to the eggs.

Q2: What additional features of seed plants, not present in seedless plants, contributed to the enormous success of seed plants on land?

A2: The reduced gametophytes of seed plants are nurtured by sporophytes and protected from stress, such as drought conditions and UV radiation. Pollen grains have tough protective coats and can be carried long distances, facilitating widespread sperm transfer without reliance on water. Seeds are more resilient than spores, enabling better resistance to environmental stresses and wider distribution.

Concept 29.4

2007-12-08T23:23:00.000+08:00

Question:
I. What are a few key differences between seedless vascular plants and bryophytes?

Answers:
a) Bryophytes: have dominant gametophytes; are non-vascular plants. Seedless vascular plants: have dominant sporophyte; are vascular plants, and the evolution of true plants.

Question:
II. What is the major difference between most lycophytes and most ferns and their relatives?

Answer:
a) Most lycophytes have microphylls, whereas ferns and most fern relatives have megaphylls.

Concept 29.3

2007-12-08T23:11:00.000+08:00

Question:
I. How do bryophytes differ from other plants?

Answer:
a) Bryophytes are described as non-vascular plants, meaning they do not have phloem or xylem. Another difference is that their life cycles is dominated by a gametophyte rather than sporophytes.

Question:
II. Give three examples how structure fits function in bryophytes.

Answer:
a) protonema - large surface area enhances absorption of water and minerals; shape of archegonia - protects eggs during fertilization and transport nutrients to the embryos via placental transfer cells; seta - conducts nutrients form the gametophyte to the capsule where spores are produced.

Concept 29.2

2007-12-08T23:03:00.000+08:00

Question:
I. Identify three derived traits that distinguish plants from charophyceans and facilitate life on land. Explain.

Answer:
a) They have walled spores that are toughened by sporopollenin. They have multicellular, dependent embryos. And they have cuticle. All of which prevents land plants from drying out.

Question:
II. Identify each structure as either haploid or diploid:

sporophyte - diploid (2n)
spore - haploid (n)
gametophyte - haploid (n)
zygote - diploid (2n)
sperm - haploid (n)
egg - haploid (n)

Concept 29.1

2007-12-08T22:57:00.000+08:00

Question:
I. Describe the evidence linking plants to a charophycean ancestry.

Answer:
a) They share rosette cellulose-synthesizing complexes. They both have peroxisomes which minimize loss to photorespiration. They have similar structure of flagellated sperm.

Concept 27.5

2007-12-01T16:43:00.000+08:00

Question:
I. Contrast exotoxins and endotoxins.

Answer:
a) Exotoxins: can produce disease even if the prokaryotes that manufacture them are not present. Endotoxins: released only when the bacteria die and ther cell walls break down.
b) Exotoxins: proteins secreted by prokaryotes. Endotoxins: lipopolysaccharides released from the outer membrane of gramnegative bacteria that have died.

Question:
II. What features of prokaryotes make them a potential bioterrorism threat?

Answer:
a) Pathogenic prokaryotes pose a potential threat as weapons of bioterrorism. For example, Bacillus anthracis, the bacterium that causes anthrax, were found in envelopes mailed to members of news media and the U.S. Senate. Another candidate of prokaryote that could be used as weapons is the C. botulinum & Yersinia pestis, which causes plague.
b) Their quick reproduction can make it difficult to combat them with antibiotics, particularly as they may evolve resistance to the drugs. Some also have the ability to form endospores and withstand harsh environments, surviving until conditions become more favorable.

Question:
III. Identify at least 2 ways that prokaryotes have affected you positively today.

Answers:
a) eating fermented foods such as yogurt and cheese; having clean water and prokaryote-produced medicines

Concept 27.4

2007-12-01T16:35:00.000+08:00

Question:
I. Although individual prokaryotes may be tiny, they are giants in their collective impact on Earth and its life. Explain.

Answer:
a) Although prokaryotes are small, mostly unicellular organisms, they play key roles in ecosystems by decomposing wastes, recycling chemicals, and providing nutrients to other organisms.

Question:
II. Explain how the relationship between humans and B. thetaiotaomicron is an example of mutualism.

Answer:
a) This bacteria, B. thetaiotaomicron, includes a large array of genes involved in synthesizing carbohydrates, vitamins, and other nutrients needed by humans. Signals form the bacterium activate human genes that build the network of intestinal blood vessels necessary to absorb food. Other signal induce human cells to produce antimicrobial compounds to which B. thetaiotaomicron is not susceptible. Keeping other competing bacteria out of the intestines benefits B. thetaiotaomicron as well as its human host.
b)Bacteroides thetaiotatomicron, which lives inside the human intestine, benefits by obtaining nutrients from the digestive system and by receiving protection from competing bacteria from host-produced antimicrobial compounds to which it is not sensitive. The human host benefits because the manufactures carbohydrates, vitamins and other nutrients.

Concept 27.3

2007-12-01T16:25:00.000+08:00

Question:
I. Explain how molecular systematics has greatly increased our understanding of prokaryotic phylogeny.

Answers:
a) Before molecular systematics, taxonomists classified prokaryotes according to phenotypic characters that did not clarigy evolutionary relationships. Molecular comparisons indicated key divergences in prokaryotic lineages.

Question:
II. What do syphilis and Lyme disease have in common?

Answer:
a) The two pathogenic spirochetes unexpectedly share an ATP synthase. The organism that causes Lyme disease is a bacterium, Borrelia burgdorferi, which was cultured from the midgut of Ixodes ticks in the mid-1980s. One of the most infamous relatives of this bacterium, Borrelia burgdorferi, is Treponema pallidum, the bacterium that causes syphilis. In contrast to Lyme disease, syphilis is not a modern affliction; it was first recognized in the 15th century in Europe. It is similar to B. burgdorferi in that it is a spirochete with a relatively small genome and requires a host to survive; however, at the genomic level, the two organisms are not very closely related to each other at all.
b) both diseases are caused by spirochetes.

Question:
I. What characteristics enable some species of Archaea to live in extreme environments?

Answers:
a) The ability of various archaea to use hydrogen, sulfur, and other chemicals as energy sources and to survive or even thrive without oxygen enables them to live in environments where more commonly needed resources are not present.

Concept 27.2

2007-12-01T16:12:00.000+08:00

Question:
I. A bacterium requires only the amino acid methionine as an organic nutrient and lives in lightless caves. What mode of nutrition does it employ? Explain.

Answer:
a)Chemoheterotrophic mode of nutrition - a nutritional classification where the microbe gets its energy from chemicals and its electrons and carbon from organic compounds.
b) Chemoheterotrophy; the bacterium must rely on chemical sources of energy, since it is not exposed to light, and it must be a heterotroph if it requires and organic source of carbon rather than CO2.

Question:
II. What are the sources of carbon and nitrogen for the cyanobacterium Anabaena?

Answers:
a) Anabaena is a photoautotroph that obtains its carbon from CO2. As a nitrogen-fixing prokaryote, Anabaena obtains its nitrogen from N2.

Concept 27.1

2007-12-01T15:52:00.000+08:00

Question:
I. Identify and explain at least 2 examples of adaptations that enable prokaryotes to survive in environments too harsh for other organisms.

Answer:
a) Adaptations include the capsule, plasmids, and the formation of endospores.

Question:
II. Contrast the cellular and genomic organization of prokaryotes and eukaryotes.

Answer:
a) Prokaryotes vs Eukaryotes: prokaryotes lack a nucleus enclosed by membranes, lack other internal compartments bounded by a membrane so instead they use the infolded regions of the plasma membrane to perform many metabolic functions including cellular respiration and photosynthesis, while eukaryotes have internal compartments bounded by a membrane, have smaller and simpler genomes than eukaryotes, may also have smaller rings of DNA, plasmids, that consist of only a few genes unlike in eukaryotes; prokaryotes can survive in most environments without their plasmids because essential functions are programmed by the chromosomes.
b) Prokaryotic cells generally lack the internal compartmentalization of eukaryotic cells. Prokaryotic genomes have much less DNA than eukaryotic genomes, and most of this DNA is contained in a single ring-shaped chromosome located in a nucleoid region rather than within a true membrane-bounded nucleus. In addition, many prokaryotes also have plasmids, small ring-shaped DNA molecules, containing a few genes.

Question:
III. Explain how rapid reproduction allows prokaryotes to adapt to changing environments.

Answer:
a) Prokaryotes can adapt quickly to changes in their environment through evolution by natural selection. Because of prokaryotes' rapid reproduction, mutations that confer greater fitness can swiftly become more common in a population. Horizontal gene transfer also facilitates rapid evolution in prokaryotes.
b) Rapid reproduction enables a favorable mutation to spread quickly through a prokaryotic population by natural selection.

Concept 28.8

2007-12-01T14:53:00.000+08:00

Question:
I. Identify 2 ways in which red algae are different from brown algae.

Answer:
a) Brown Algae: color results from the carotenoid FUCOXANTHIN; carbohydrate storage product: LAMINARIN
Red Algae: color results from PHYCOERYTHRIN; carbohydrate storage product: FLORIDEAN STARCH
b) many red algae contain an accessory pigment called phycoerythrin, which gives them a reddish color and allows them to carry out photosynthesis in relatively deep coastal water. Also unlike brown algae, red algae have no flagellated stages in their life cycle and must depend on water currents to bring gametes together for fertilization.

Question:
II. Why is it accurate to say that Ulva has true multicellularity but Caulerpa does not?

Answer:
a) Ulva's thallus contains many cells and is differentiated into leaflike blades and a rootlike holdfast. Caulerpa's thallus is composed of multinucleate filaments without cross-walls, so it is essentially one large cell.

Concept 28.7

2007-12-01T14:50:00.000+08:00

Question:
I. Contrast the pseudopodia of amoebozoans and forams.

Answer:
a) Amoebozoans have lobe-shaped pseudopodia, whereas forams have threadlike pseudopodia.

Question:
II. In what sense is 'fungus animal' a fitting description of a slime mold? In what sense is it not a fitting description?

Answer:
a) Slime molds are fungus-like in that they produce fruiting bodies that aid in the dispersal of spores, and they are animal-like in that they are motile and ingest food. However, slime molds are more closely related to gymnamoebas and entamoebas that to fungi or animals.

Question:
III. Does cooperation between cells exist in amoebozoans? Explain.

Answer:
a) Yes, in the life cycle of a cellular slime mold, individual amoebas may congregate in response to a chemical signal, forming a slug-like aggregate from that can move. Then some of the cells from a stalk that supports an asexual fruiting body.

Concept 28.6

2007-12-01T14:48:00.000+08:00

Question:
I. Why do forams have such a well-preserved fossil record?

Answer:
a) Because foram tests are hardened with calcium carbonate, they form long-lasting fossils in marine sediments and sedimentary rocks.

Question:
II. Compare feeding forams and radiolarians.

Answer:
a) Forams feed by extending their pseudopodia through pores in therir tests. Radiolarians ingest smaller microorganisms by phagocytosis using their pseudopodia; cytoplasmic streaming carries the engulfed prey to the main part of the cell.

Concept 28.5

2007-12-01T14:31:00.001+08:00

Question:
I. What unique cellular feature is common to all stramenopiles?

Answer:
a) Stramenopiles have "hairy" and smooth flagella. In some stramenopile groups, the only flagellated cells are motile reproductive cells.
b) A pair of flagella, one hairy and one smooth.

Question:
II. Compare the nutrition of oomycetes with that of golden algae.

Answer:
a) Golden Algae: all are photosynthetic, some are mixotrophic, & can also absorb dissolved organic compounds or ingest food particles and prokaryotes by phagocytosis. While, Oomycetes: do not carry out photosynthesis, instead they acuire nutrients as decomposers or parasites.
b) Oomycetes acquire nutrition mainly as decomposers or parasites; golden algae are photosynthetic, but some also absob dissolved organic compounds or ingest food particles and prokaryotes by phagocytosis.

Question:
III. How is the structure of a borwn alga such as Laminaria well suited to its intertidal zone habitat?

Answer:
a) They have unique adaptations that enable them to withstand the waves & the intense heat of the sun. For example, their cell walls are composed of cellulose and gel-forming polysaccharides that help cushion the thalli from waves and reduce drying when the algae are exposed.
b) The holdfast anchors tha alga to the rocks, while the wide, flat blades provide photosynthesis surfaces. The cellulose and algin in the alga's cell walls cushion the thallus from waves and protect it from drying out.

Concept 28.4

2007-12-01T14:25:00.000+08:00

Question:
I. What morphological feature supports molecular data that suggest dinoflagellates, apicomplexans, and ciliates are members of a single clade?

Answer:
a) Membrane-bounded sacs under the plasma membrane

Question:
II. Why is a 'red tide' a cause for concern to people who eat locally caught seafood?

Answer:
a) Red Tide is a microorganism containing a concentrated toxin and occasionally washes onshore. Though not all people are susceptible to the effects of red tide, it can be absorbed by humans directly, as well as be absorbed in shellfish. Red tide can also affect humans if they consume contaminated molluscan shellfish. During a red tide, bivalve shellfish, including clams and oysters, concentrate the toxin. This concentrated toxin can cause neurotoxic shellfish poisoning (NSP) in humans who eat bivalve shellfish. Both mild gastrointestinal and neurological symptoms occur in NSP.
b) A red tide is a bloom of dinoflagellates, some of which produce deadly toxins that accumulate in molluscs and can affect people who eat molluscs.

Question:
III. Why is it incorrect to refer to conjugation in ciliates as a form of reproduction?

Answer:
a) During conjugation, two ciliates exchange micronuclei, but no new individuals are produced.

Concept 28.3

2007-12-01T14:20:00.000+08:00

Question:
I. How is Trypanosoma's ability to produce an array of cell-surface proteins advantageous to its survival?

Answers:
a) The surface of a trypanosome is coated with millions and millions of copies of a single protein. Before, a host's immune system could mount an attack, new generations of the parasite switch to another surface protein with a slightly different molecular structure. Frequent changes in the structure of the surface of the protein prevent the host from developing immunity, thus contributing to its (Trypanosoma) survival.
b) The proteins have slightly different structures, but only one protein at a time is expressed. Frequent changes in expression prevent the host from developing immunity.

Question:
II. Is Euglena an alga? Explain your answer.

Answer:
a) Euglena could be considered an alga because it is a photosynthetic autotroph; however, it could also be considered a fungus-like protist because it can absorb organic nutrients from its environment.

Concept 28.2

2007-12-01T14:05:00.000+08:00

Question:
I. Why do some biologists describe the mitochondria of diplomonads and parabasalids as "highly reduced"?

Anwers:
a) Diplomonads and parabasalids are adapted to anaerobic environments. They lack plastids, and their mitochondria do not contain DNA, an electron transport chain, or citric-acid cycle enzymes.
b) Their mitochondria do not have DNA, an electron transport chain, or citric-acid cycle enzymes.

Question:
II. How is the structure of Trichomonas vaginalis well suited to its parasitic lifestyle inside its host's reproductive and urinary tracts?

Answer:
a) Diplomonads have multiple flagella and 2 nuclei. Parabasalids, include trichomonads, which move by means of flagella and an undulating part of the plasma membrane.
b) Its flagella and undulating membrane enable it to move along the mucus-coated lining of these tracts inside its host.

Concept 28.1

2007-11-29T19:05:00.000+08:00

Question:
I. Cite at least 4 examples of structural & functional diversity among protists

Answer:
a) Protists are more diverse than all other eukaryotes and are no longer classified in a single Kingdom. Most protists are unicellular, some are colonial or multicellular. Protists include photoautotrophs, heterotrophs, & mixotrophs. Most species are aquatic, but others are found in moist terrestrial habitats. Some species are exclusively asexual; others reproduce asexually.

Question:
II. Immediately after a eukaryotic cell ingests a gramnegative cyanobacterum dirung primary endosymboisis, how many membranes separate the cytoplasm of the bacterium from the fluid outside the eukaryotic cell? Identify each membrane.

Answer:
a) Some biologists hypothesize that mitochondria and plastids are descendans of alpha proteobacteria and cyanobacteria, respectively, that were engulfed bt itger cekks abd became endosymbionts. The plastid-bearing lineage enventually evolved into red algae and green algae. Other protist groups evolved form secondary endosymbiotic events in which red algae or green algae were themselves engulfed.