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| Inquiry Questions None for this chapter. Self Test 1). The mitochondria of eukaryotic cells most likely arose as a result of endosymbiosis between a eukaryotic cell and a a). blue-green alga. b). nonsulfur purple bacterium. c). red alga. d). cyanobacterium. Answer: b 2). The protists are a paraphyletic group that have traditionally been grouped together because a). they are all genetically similar to each other. b). they all have very similar morphological characters. c). they are not fungi, animals, or plants. d). they all have similar nutritional modes and live in similar environments. Answer: c 3). Many protists are able to resist harsh environmental conditions by a). forming a cyst and slowing metabolism during times of stress. b). utilizing a wide variety of nutritional modes. c). reproducing asexually through the process of budding. d). moving away from a harsh environment by using pseudopodia. Answer: a 4). The light-sensing organ in the Euglena is a a). flagellum. b). contractile vacuole. c). pellicle. d). stigma. Answer: d 5). The parasitic kinetoplast that causes leishmaniasis must spend part of its life cycle in a nonhuman host. What organism(s) serve(s) as the vector for this life cycle? a). small mammals b). a sand fly c). a mosquito d). a tse-tse fly Answer: b 6). You are examining cells from an unknown organism under the microscope. You note that the cells have a membrane-bounded nucleus and that there are small cavities in the membranes along the internal cell surface. Based upon this information alone, you conclude that these most likely are ___________ cells. a). bacterial b). diatom c). dinoflagellate d). kinetoplastid Answer: c 7). The parasitic protist that causes malaria, Plasmodium, must spend part of its life cycle in a nonhuman host. What organism(s) serve(s) as the vector for this life cycle? a). small mammals b). a sand fly c). a mosquito d). a tse-tse fly Answer: c 8). Phytopthora infestans is the oomycete that causes a). Chagas disease. b). potato blight. c). red tides. d). African sleeping sickness. Answer: b 9). A biologist discovers an alga that is marine, multicellular, lacks flagella and centrioles, and contains phycobilisomes. It probably belongs to which group? a). Rhodophyta b). Brown algae c). Chlorophyta d). Foraminifera Answer: a 10). The green algae gave rise to which modern group of organisms? a). photosynthetic bacteria b). plants c). photosynthetic euglenoids d). animals Answer: b Test Your Visual Understanding 1). This image shows several different types of protists that are characterized by a rigid double wall of silica. To what group do these organisms belong? Answer: These are diatoms in the kingdom Stramenopila. Apply Your Knowledge 1). Protists typically reproduce asexually. However, some protists undergo sexual reproduction during times of environmental stress. What advantage does sexual reproduction give a protist during these times? Answer: Sexual reproduction provides greater genetic variability in the next generation. New gene combinations that are adaptive under the specific environmental stress may enhance the survival and reproduction of offspring with the favorable genotype. 2). Scientists are working to develop a vaccine against African sleeping sickness. Use what you know about the trypanosome responsible for this disease to determine why it is so difficult to develop a vaccine. Answer: The African sleeping sickness trypanosome has a glycoprotein coat that can trigger an immune response. Vaccines are designed to mimic the antigenic part of the glycoprotein coat and to trigger immunity without causing disease. The problem with trypanosomes is that they have a complex genetic mechanism that continually changes the structure of the glycoprotein coat. One vaccine cannot provide immunity against the constantly changing antigens. |