Practice Midterm
Practice Midterm SECTION 1: MULTIPLE CHOICE (Red answers are correct) Chapter 26 1. The snake family Typhlopidae consists of small, burrowing species with vestigial eyes. They are found in Australia, sub-Saharan Africa, India and some adjacent areas, and South America. What is the most likely explanation for this distribution? A) Convergent evolution of these homoplastic traits in the different regions B) Rafting to the different continents from the point of origin on one of these continents C) Origin on Gondwana followed by continental drift and some range expansion D) Several geographically isolated populations experiencing the same chance mutation events and the same selective pressures to increase the frequency of alleles resulting from the mutations. 2. Which of the following could most rapidly result in speciation (under the Biological Species Concept)? A) Natural selection for greater speed in rabbits where marginally greater speed gives a slightly higher chance of survival to reproductive age B) The sudden change in a river path due to a flooding event that divides a large population of ground squirrels into two separate populations C) The chance event that in a single generation of guinea pigs, brown furred guinea pigs had slightly greater average reproductive success than white furred guinea pigs (assume a fairly small population). D) A non-disjunction event in meiosis results in a diploid gametes in a self-pollinating plant. 3. Which of the following acts to prevent speciation in geographically separated populations? A) Gene flow between the populations B) Natural selection C) The founder effect D) Polyploidy 4. Which of the following statements explains why animals are less likely than plants to form new species by polyploidy? A) Animals are more mobile, so populations get separated far less often. B) Animals rarely self-fertilize, so diploid gametes are much less likely to fuse and polyploidy tends to be more disruptive of physiology in animals than plants. C) Animals have better mechanisms for repairing chromosomes than plants have. D) Animals are better at recognizing appropriate mates. 5. You find two different populations of worms. In one population, all worms have 27 annuli (rings) on their skin. In the other population, all worms have 29 annuli. You have no idea if they are able to interbreed. Based on what you have seen, what would you consider these two worms to be? A) Two different species, based on the phylogenetic species concept B) Two different species, based on the biological species concept C) Two different species, based on the morphospecies concept D) Two different species, based on the ecological species concept 6. The common edible frog of Europe is a hybrid between two frog species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer about the hybrids from this information? A) These two species are likely in the process of fusing back into one species. B) The hybrids form a separate species under the biological species concept. C) The hybrids must have adaptive advantages to be so widespread and persistent.
D) Low reproductive success of the hybrids reinforces the separation between Rana lessonae and Rana ridibunda. 7. Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of pairs of closely related tree frogs in South America. If reinforcement of prezygotic isolation is occurring, what would you expect if you compare the calls of two species that have diverged sympatrically versus two species that had diverged allopatrically? A) Two sympatric species would have more similar calls, and two allopatric species would have less similar calls. B) Two allopatric species would have more similar calls, and two sympatric species would have less similar calls. C) Calls would likely be very similar between two species, regardless of whether they were sympatric species or allopatric species. D) Calls would likely be very different between two species, regardless of whether they were sympatric species or allopatric species 8. Male bower birds put on elaborate displays to attract mates. One main component of this is construction of bowers that are decorated with brightly coloured objects. Another component of this is the males puff out their chests and make croaking calls while dancing. Imagine that within a population there are females innately attracted to the calls and the dancing. Imagine that there are other females that are more attracted to colourful bower. Based on this, two primary phenotypes of male emerge, one phenotype of male that invests heavily in construction and decoration of his bower, and a second phenotype of male that invests heavily in croaking and dancing. This is an example of what type of selection? A) Stabilizing B) Directional C) Disruptive D) Female-female competition 9. Suppose that the bower birds in Question 8 rarely interbreed. In other words, females that typically select mates on the basis of call and dance rarely select mates on the basis of bower. Likewise females that typically select mates on the basis of bower rarely select mates on the basis of dance. The result is two populations that become isolated sympatrically, and may diverge over time. These two divergent populations would be an example of: A) Separate Biological Species B) Separate Ecological Species C) Separate Morphological Species D) Separate Phylogenetic Species 10. Based on Question 9, you might now be saying, “but what about the male that invests heavily in both his call and dance and in his bower be more attractive to all females?”. And you would have a point. This principle should result in selection for a hybrid phenotype that has a beautiful bower and a fancy dance. Yet, we do not see this male phenotype. What is a possible explanation? A) Fitness trade-off, the energy invested in both strategies (bower decoration, elaborate dance) might marginally increase attraction of mates, but at too great a cost, as less energy goes into feeding himself, maintaining health, producing sperm, etc. The overall effect is a decrease in fitness. B) Reproductive output reaches ceiling. The male might attract more females than he could possibly mate with, so extra energy spent in attracting both groups of females is wasted energy. C) Discriminating females, a female attracted to an elaborate dance and call would likely be put-off by the decorated bower. Likewise a female attracted to the fancy bower might find the dancing display unattractive. The net outcome is the male has fewer potential mates.
D) Random chance, there is no possible explanation based on natural selection or sexual selection theory. Therefore the lack of such a male phenotype must be a random event. Chapter 27 11. Below is a phylogenetic tree. The letters A – E correspond to the organisms yeast, ferns, penguins, bread mould, and oak trees. Using what you know about the relationships among these organisms, and what you know about constructing phylogenetic trees, match the letters with the organisms above. Which of the options below best matches the letter (A-E) with the correct organism?
A) A – Penguins; B – Oak Trees; C – Yeasts; D – Bread Moulds; E – Ferns B) A – Bread Mould; B – Yeast; C- Ferms; D – Oak Trees; E – Penguins C) A – Ferns; B – Oak Trees; C- Yeast; D – Bread Mould; E – Penguins D) A – Yeast; B – Ferns; C- Penguins; D – Bread Mould; E – Oak Trees E) A – Oak Trees; B – Bread Moulds; C – Yeasts; D – Penguins; E - Ferns 12. Based on your phylogenetic tree, Ferns and Oak trees share a more recent common ancestor than do penguins and bread moulds A) True B) False 13. Based only on your phylogenetic tree above, photosynthesis is a: A) Monophyletic trait B) Polyphyletic trait C) Paraphyletic trait D) Polyphyletic and paraphyletic trait Chapter 28 14. Which of the following are part of a monophyletic group? A. Bacteria and Archaea B. Bacteria and Eukarya C) Archaea and Eukarya
D) Bacteria, Archaea and Eukarya are all part of the same monophyletic group 15. Bacteria and Archaea differ in which of the following ways? A) Shape of the chromosome (bacteria have circular chromosomes, archaea have linear chromosomes B) Composition of the cell wall C) Gene structure, bacteria lack introns, archaea have introns D) All of the above E) B and C only 16. A bacterial cell that lives in lake sediment is capable of using a variety of terminal electron acceptors. This bacterium can use oxygen, nitrate, or an organic molecule such as pyruvate (fermentation). When all three of these potential electron acceptors are abundant, which will the bacterium preferentially use? A) Nitrate B) Oxygen C) Pyruvate D) The bacterium will use each of them equally 17. Which of the following best explains your answer to the previous question? A) Use of oxygen as a terminal electron acceptor yields more energy than the use of nitrate or pyruvate B) Use of nitrate as a terminal electron acceptor yields more energy than the use of oxygen or pyruvate C) Use of pyruvate as a terminal electron acceptor yields more energy than the use of oxygen or nitrate D) Oxygen is most easily transported across the plasma membrane E) The bacterium uses any electron acceptor that is available and does not show any selection for one over the others 18. Nostoc (a genus of bacteria) includes species that use sunlight to fix carbon dioxide. The carbon fixed provides the source of energy for cellular respiration. These bacteria would be characterized as: A) Heterotrophs B) Photoautotrophs C) Chemoautotrophs D) Photoheterotrophs Chapter 29 - Protists Use the following information to answer questions 9 – 11. In class we talked about the endosymbiosis theory for the origin of eukaryotic cells. In the endosymbiosis theory, one cell engulfed another cell (phagocytosis) and retained it. Retaining the smaller cell improved the efficiency of energy production for the larger cell. Over a long period of time, the smaller cell evolved into the mitochondrion. 19. In this theory, the smaller cell was: A) A proteobacterium B) A protist C) A fungal cell D) A plant cell E) An archaea
20. The evidence for this origin of the mitochondrion is: A) The mitochondrion has its own circular chromosome B) The mitochondrial DNA sequence is highly similar to DNA from _______ (your answer from previous question) than to eukaryotic nuclear DNA. C) The mitochondrion has two membrane layers D) All of the above E) Endosymbiosis theory is conjecture, not supported by any scientific evidence 21. For this relationship to have been advantageous to the larger cell, the smaller cell must have carried out what type of metabolism? A) Photosynthesis B) Anaerobic respiration C) Aerobic respiration D) Chemoautotrophy 22. In class we talked about secondary endosymbiotic events. Some of these secondary endosymbiotic events likely explain the origin of chloroplasts in certain groups of protists, making photosynthesis a paraphyletic trait. Some support for the origin comes from how commonly we still see protists engaged in symbiotic relationships. Members of this group of protists are commonly found in modern endosymbiotic relationships, and were likely ancestral to chloroplasts in other protists. A) Cyanobacteria B) Green algae C) Amoebae D) Ciliates 23. All members of this group swim by using their flagella. All members have anaerobic metabolism (fermentation) since they lack mitochondria. Some members of the group (the parabasilids) are obligate parasites. A) Discicristata B) Alveolata C) Excavata D) Amoebozoa E) Stremenopila Chapter 30 – Green Plants 24. Terrestrial plants have a life-cycle that includes alternation of generations. In all plants, one adult form (the gametophyte or the sporophyte) is dominant (larger and more apparent). In the evolution of land plants, the trend has been toward which adult form being dominant? A) Gametophyte B) Sporophyte 25. The selective pressure that has likely driven this evolutionary pattern (from question 14) is: A) The need to withstand ionizing radiation such as UV that can damage DNA B) The need to retain water and prevent dehydration C) The need to grow taller to compete for light D) The need to reproduce in dry climates
26. Not all plant cells produce a secondary cell wall. However, in cells that do contain a secondary cell wall, this wall is made of: A) Cellulose B) Peptidoglycan C) Silica dioxide D) Lignin E) Chitin 27. Construction of a secondary cell wall provides a plant cell with greater strength, but eventually kills the cell leaving behind an empty tube. This would seem a maladaptive trait for the individual cell, but is an adaptive trait for the plant as an organism. How does this formation of secondary cell walls benefit the plant? A) The hollow tube allows for efficient transport of water through the plant B) The rigid secondary cell walls allow the plant to grow tall, without investing energy in maintaining those cells C) The dead cells are able to transport reduced organic compounds such as sugars D) A and B only E) B and C only 28. You go for a walk through a meadow and discover a plant with unusual flower. The petals are not symmetrical, like a rose, but are curled together into a tube. The tube is long, with a small diameter, and most insects would not be able to crawl inside to get nectar. The flower has 6 sepals, and the leaves have parallel veins. What can you tell about this flower? A) It is a monocot, pollinated by a few specific species of animals B) It is a monocot, pollinated by many different species of animal C) It is a dicot, pollinated by a few specific species of animals D) It is a dicot, pollinated by many different species of animal 29. When plants first colonized land, this new habitat posed a number of significant challenges and advantages. The primary challenge that plants had to overcome to make this transition to land was: A) Increased exposure to predation by insects B) Loss of buoyancy, with gravity limiting plant height C) Transport of water from roots to leaves D) Increased risk of drying Chapter 31 - Fungi 30. Fungi play a particularly important ecological role as decomposers. What ability do fungi have that no other organisms have (except a very few species of bacteria)? A) Fungi can decompose cellulose B) Fungi can decompose proteins C) Fungi can decompose chitin D) Fungi can decompose lignin 31. Most plant roots have fungal symbionts. Often, these are mutualistic relationships in which fungi and plants both benefit. How does the plant benefit from this relationship? A) The plant obtains nutrients such as phosphorus from the fungus B) The plant obtains organic molecules such as sugars from the fungus C) The plant obtains water from the fungus D) The plant obtains carbon dioxide from the fungus
32. In most fungi, hyphae are: A) diploid B) haploid C) dikaryotic D) tetraploid 33. The reproductive structures of this group of fungi include many of the mushrooms that we commonly eat. A) Chytridiomycota B) Zygomycota C) Basidiomycota D) Ascomycota E) Glomeromycota 34. In animals, why would you think fungal infections (such as athlete's foot) are so much harder to cure than bacterial infections? A) Fungi and animals are more closely related than bacteria and animals B) Fungi are more highly evolved than bacteria C) Fungi are part of a younger evolutionary lineage than bacteria D) Fungi are a source of many antibiotics that work against bacteria 35. Often, fungi will infect plant leaves, but this symbiotic relationship may benefit both the plant and the fungus. What is the benefit to the plant of a fungal symbiont in the leaf tissue? A) The fungus provides nitrogen and phosphorus to the plant B) The fungus provides sugars to the plant C) The fungus preys upon nematodes, preventing nematode infections of the plant D) The fungus produces compounds that deter herbivores from eating the leaves Chapter 35 - Viruses 36. Which of the following comparisons between viruses and organisms is NOT true? A) Viruses cannot self-replicate, organisms self-replicate B) Viruses all have RNA genomes, organisms all have DNA genomes C) Viruses have no metabolic activity, organisms do D) Viruses are not cellular, organisms are all composed of cells 37. You isolate a new virus and find that the virus has an envelope. This virus is most likely to infect which of the following organisms? A) Bacterium B) Plant C) Fungus D) Diatom E) Jellyfish 38. Viruses evolve more rapidly than most organisms. This, in large part, is why it is so difficult to produce effective vaccines against viruses. What characteristics of viruses allow them to evolve so rapidly? A) Viruses lack repair mechanism to correct mistakes following genome replication B) Viruses are reproduced very rapidly (high rate of genome repliction) C) Viral genome is protected by protein capsule D) A and B E) All of the above
39. The source of most viruses in humans appears to be animals. Viruses in animals evolve and a mutation within an animal virus may allow it to jump to humans. Over time, the virus co-evolves with the human host, and may become relatively common (such as the rhinovirus). Typically, as viruses co-evolve with humans, they: A) Become more virulent (more likely to cause severe disease or death) B) Become less virulent (become less likely to cause severe disease or death) C) Become capable of invading more tissue types within the human host D) None of the above 40. A retrovirus possesses: A) A DNA genome and Reverse Transcriptase B) A DNA genome and DNA Polymerase C) An RNA genome and Reverse Transcriptase D) An RNA genome and RNA Polymerase
SECTION 2: SHORT ANSWER QUESTIONS Short-Answer Questions: 1. Two populations of birds look very similar, but the males have territorial songs that sound different. What function would this difference in song likely serve if the two populations came in contact? [2 points total] Songs are markers of identity. The difference in territorial songs may mean that males of the different populations do not recognize each other’s territorial calls. 1) This could lead to overlapping among the populations (males with overlapping territories). 2) It may also lead to increased confrontation between males of the different populations. 3) Or it may lead to reinforcement of separation between the populations, as the females may recognize males of their own population but not males of the other population. The result would be less frequent selection of mates from the other population. I will accept any of these answers for two points. If the student says something kind of relevant, but not fully on point for any of these three outcomes, I will award 1 point. 2. Archaea differ from both eukaryotes and bacteria in the nature of their cell membrane phospholipids. In archaea, the fatty acid chains are highly branched, while they are not branched in bacteria or eukaryotes. What does this suggest about the ancestor to all three domains (Did it most likely have branched or nonbranched fatty acids)? What is the adaptive advantage to these fatty acids in archaea? Given the advantage for archaea, why do we not also see these branched fatty acids in eukaryotes? (3 points)
A. Suggests that straight chain fatty acids was the ancestral trait, found in the common ancestor to all three domains.
B. The branched chains increase the extent of hydrophobic interactions, permitting these membranes to remain intact even at high temperature (high temperatures reduce strength of van der Waals’ interactions, so having more hydrophobic side chains compensates for this effect). C. This same trait (more hydrophobic interactions) would make a membrane less fluid (more rigid) at lower temperatures. This would make cross membrane transport less efficient in eukaryotic cells that grow at lower temperatures.
3. Why is it likely that an archaeal species lacking a cell wall was ancestral to eukaryotic cells? Provide at least two clear lines of evidence that the ancestor was archael rather than bacterial. Provide one reason the ancestor would likely have lacked a cell wall. (3 points) Two lines of evidence that archaea are ancestral to eukaryotes could include: A) both have introns in their genomic structure, B) both have histones associated with their genomes, C) Archaea and eukaryotes have very similar ribosomal subunit size and structure, D) similar RNA polymerases, and both have multiple RNA Polymerases, E) Both archaea and eukaryotes have translation beginning with methionine. Likely lacked a cell wall because: A) Not all archaea and not all eukaryotes have cell walls, and the compositions of cell walls vary among cells that do have walls. For example, plant cells have cellulose walls, diatoms have silica walls, some archaea have protein walls, some protists have chitin walls. This suggests that cell walls evolved independently in various different lineages. B) A cell possessing a cell wall would not have been able to engulf a proteobacterium. Had the ancestor to eukaryotes had a cell wall, it would not have been possible for it to establish an endosymbiotic relationship with a proteobacterium. 4. Fungi and the roots of plants often form symbiotic associations. One advantage that plants gain from this association is access to phosphorus. Why are fungi more effective in extracting phosphorus from soils than are plant roots (1 point) Fungi secrete extracellular digestive enzymes that can digest organic matter liberating phosphorus (converting organic P into biologically available inorganic P). Also, fungi secrete acids that cause desorption of inorganic P from soil particles, making it available for uptake by plant roots. 5. Fungi have high surface area to volume. Given the mode of nutrition for fungi, why is this body plan (high surface area to volume) an advantage? (1 point) They obtain nutrients by direct absoption of soluble nutrients from the environment. A high surface area to volume allows them to more efficiently gain nutrients by absorption. It reduces the kinetic barrier to nutrient delivery.
6. In protists, photosynthesis is a polyphyletic trait. It is found in all members of the green algae, but only in a few members of other phyla, for example among the stremenopila, diatoms are photosynthetic, but other groups are not. The biochemical pathways of photosynthesis are nearly identical in green algae and in the diatoms. What does this suggest about the origins of photosynthesis in the stremenopila? Does it suggest that photosynthesis was an ancestral trait to both green algae and stremenopila? Or does it suggest independent evolution of photosynthesis in both lineages? Or does it suggest lateral transfer of the trait to stremenopila by secondary endosymbiosis? Explain your answer (2 points) This suggests lateral transfer by secondary endosymbiosis. That the trait is found in all green algae suggests it is ancestral to that lineage. That it is found only in the diatoms within the stremenoplia lineage suggests it is not ancestral to that lineage. That the biochemistry of the photosynthetic process is highly conserved between green algae and diatoms (and for that matter, cyanobacteria) suggests a single origin of the process rather than multiple independent origins. So, the most likely explanation is transfer of the trait from one lineage (green algae) to another group of protists (diatoms) via secondary endosymbiosis
D) Low reproductive success of the hybrids reinforces the separation between Rana lessonae and Rana ridibunda. 7. Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of pairs of closely related tree frogs in South America. If reinforcement of prezygotic isolation is occurring, what would you expect if you compare the calls of two species that have diverged sympatrically versus two species that had diverged allopatrically? A) Two sympatric species would have more similar calls, and two allopatric species would have less similar calls. B) Two allopatric species would have more similar calls, and two sympatric species would have less similar calls. C) Calls would likely be very similar between two species, regardless of whether they were sympatric species or allopatric species. D) Calls would likely be very different between two species, regardless of whether they were sympatric species or allopatric species 8. Male bower birds put on elaborate displays to attract mates. One main component of this is construction of bowers that are decorated with brightly coloured objects. Another component of this is the males puff out their chests and make croaking calls while dancing. Imagine that within a population there are females innately attracted to the calls and the dancing. Imagine that there are other females that are more attracted to colourful bower. Based on this, two primary phenotypes of male emerge, one phenotype of male that invests heavily in construction and decoration of his bower, and a second phenotype of male that invests heavily in croaking and dancing. This is an example of what type of selection? A) Stabilizing B) Directional C) Disruptive D) Female-female competition 9. Suppose that the bower birds in Question 8 rarely interbreed. In other words, females that typically select mates on the basis of call and dance rarely select mates on the basis of bower. Likewise females that typically select mates on the basis of bower rarely select mates on the basis of dance. The result is two populations that become isolated sympatrically, and may diverge over time. These two divergent populations would be an example of: A) Separate Biological Species B) Separate Ecological Species C) Separate Morphological Species D) Separate Phylogenetic Species 10. Based on Question 9, you might now be saying, “but what about the male that invests heavily in both his call and dance and in his bower be more attractive to all females?”. And you would have a point. This principle should result in selection for a hybrid phenotype that has a beautiful bower and a fancy dance. Yet, we do not see this male phenotype. What is a possible explanation? A) Fitness trade-off, the energy invested in both strategies (bower decoration, elaborate dance) might marginally increase attraction of mates, but at too great a cost, as less energy goes into feeding himself, maintaining health, producing sperm, etc. The overall effect is a decrease in fitness. B) Reproductive output reaches ceiling. The male might attract more females than he could possibly mate with, so extra energy spent in attracting both groups of females is wasted energy. C) Discriminating females, a female attracted to an elaborate dance and call would likely be put-off by the decorated bower. Likewise a female attracted to the fancy bower might find the dancing display unattractive. The net outcome is the male has fewer potential mates.
D) Random chance, there is no possible explanation based on natural selection or sexual selection theory. Therefore the lack of such a male phenotype must be a random event. Chapter 27 11. Below is a phylogenetic tree. The letters A – E correspond to the organisms yeast, ferns, penguins, bread mould, and oak trees. Using what you know about the relationships among these organisms, and what you know about constructing phylogenetic trees, match the letters with the organisms above. Which of the options below best matches the letter (A-E) with the correct organism?
A) A – Penguins; B – Oak Trees; C – Yeasts; D – Bread Moulds; E – Ferns B) A – Bread Mould; B – Yeast; C- Ferms; D – Oak Trees; E – Penguins C) A – Ferns; B – Oak Trees; C- Yeast; D – Bread Mould; E – Penguins D) A – Yeast; B – Ferns; C- Penguins; D – Bread Mould; E – Oak Trees E) A – Oak Trees; B – Bread Moulds; C – Yeasts; D – Penguins; E - Ferns 12. Based on your phylogenetic tree, Ferns and Oak trees share a more recent common ancestor than do penguins and bread moulds A) True B) False 13. Based only on your phylogenetic tree above, photosynthesis is a: A) Monophyletic trait B) Polyphyletic trait C) Paraphyletic trait D) Polyphyletic and paraphyletic trait Chapter 28 14. Which of the following are part of a monophyletic group? A. Bacteria and Archaea B. Bacteria and Eukarya C) Archaea and Eukarya
D) Bacteria, Archaea and Eukarya are all part of the same monophyletic group 15. Bacteria and Archaea differ in which of the following ways? A) Shape of the chromosome (bacteria have circular chromosomes, archaea have linear chromosomes B) Composition of the cell wall C) Gene structure, bacteria lack introns, archaea have introns D) All of the above E) B and C only 16. A bacterial cell that lives in lake sediment is capable of using a variety of terminal electron acceptors. This bacterium can use oxygen, nitrate, or an organic molecule such as pyruvate (fermentation). When all three of these potential electron acceptors are abundant, which will the bacterium preferentially use? A) Nitrate B) Oxygen C) Pyruvate D) The bacterium will use each of them equally 17. Which of the following best explains your answer to the previous question? A) Use of oxygen as a terminal electron acceptor yields more energy than the use of nitrate or pyruvate B) Use of nitrate as a terminal electron acceptor yields more energy than the use of oxygen or pyruvate C) Use of pyruvate as a terminal electron acceptor yields more energy than the use of oxygen or nitrate D) Oxygen is most easily transported across the plasma membrane E) The bacterium uses any electron acceptor that is available and does not show any selection for one over the others 18. Nostoc (a genus of bacteria) includes species that use sunlight to fix carbon dioxide. The carbon fixed provides the source of energy for cellular respiration. These bacteria would be characterized as: A) Heterotrophs B) Photoautotrophs C) Chemoautotrophs D) Photoheterotrophs Chapter 29 - Protists Use the following information to answer questions 9 – 11. In class we talked about the endosymbiosis theory for the origin of eukaryotic cells. In the endosymbiosis theory, one cell engulfed another cell (phagocytosis) and retained it. Retaining the smaller cell improved the efficiency of energy production for the larger cell. Over a long period of time, the smaller cell evolved into the mitochondrion. 19. In this theory, the smaller cell was: A) A proteobacterium B) A protist C) A fungal cell D) A plant cell E) An archaea
20. The evidence for this origin of the mitochondrion is: A) The mitochondrion has its own circular chromosome B) The mitochondrial DNA sequence is highly similar to DNA from _______ (your answer from previous question) than to eukaryotic nuclear DNA. C) The mitochondrion has two membrane layers D) All of the above E) Endosymbiosis theory is conjecture, not supported by any scientific evidence 21. For this relationship to have been advantageous to the larger cell, the smaller cell must have carried out what type of metabolism? A) Photosynthesis B) Anaerobic respiration C) Aerobic respiration D) Chemoautotrophy 22. In class we talked about secondary endosymbiotic events. Some of these secondary endosymbiotic events likely explain the origin of chloroplasts in certain groups of protists, making photosynthesis a paraphyletic trait. Some support for the origin comes from how commonly we still see protists engaged in symbiotic relationships. Members of this group of protists are commonly found in modern endosymbiotic relationships, and were likely ancestral to chloroplasts in other protists. A) Cyanobacteria B) Green algae C) Amoebae D) Ciliates 23. All members of this group swim by using their flagella. All members have anaerobic metabolism (fermentation) since they lack mitochondria. Some members of the group (the parabasilids) are obligate parasites. A) Discicristata B) Alveolata C) Excavata D) Amoebozoa E) Stremenopila Chapter 30 – Green Plants 24. Terrestrial plants have a life-cycle that includes alternation of generations. In all plants, one adult form (the gametophyte or the sporophyte) is dominant (larger and more apparent). In the evolution of land plants, the trend has been toward which adult form being dominant? A) Gametophyte B) Sporophyte 25. The selective pressure that has likely driven this evolutionary pattern (from question 14) is: A) The need to withstand ionizing radiation such as UV that can damage DNA B) The need to retain water and prevent dehydration C) The need to grow taller to compete for light D) The need to reproduce in dry climates
26. Not all plant cells produce a secondary cell wall. However, in cells that do contain a secondary cell wall, this wall is made of: A) Cellulose B) Peptidoglycan C) Silica dioxide D) Lignin E) Chitin 27. Construction of a secondary cell wall provides a plant cell with greater strength, but eventually kills the cell leaving behind an empty tube. This would seem a maladaptive trait for the individual cell, but is an adaptive trait for the plant as an organism. How does this formation of secondary cell walls benefit the plant? A) The hollow tube allows for efficient transport of water through the plant B) The rigid secondary cell walls allow the plant to grow tall, without investing energy in maintaining those cells C) The dead cells are able to transport reduced organic compounds such as sugars D) A and B only E) B and C only 28. You go for a walk through a meadow and discover a plant with unusual flower. The petals are not symmetrical, like a rose, but are curled together into a tube. The tube is long, with a small diameter, and most insects would not be able to crawl inside to get nectar. The flower has 6 sepals, and the leaves have parallel veins. What can you tell about this flower? A) It is a monocot, pollinated by a few specific species of animals B) It is a monocot, pollinated by many different species of animal C) It is a dicot, pollinated by a few specific species of animals D) It is a dicot, pollinated by many different species of animal 29. When plants first colonized land, this new habitat posed a number of significant challenges and advantages. The primary challenge that plants had to overcome to make this transition to land was: A) Increased exposure to predation by insects B) Loss of buoyancy, with gravity limiting plant height C) Transport of water from roots to leaves D) Increased risk of drying Chapter 31 - Fungi 30. Fungi play a particularly important ecological role as decomposers. What ability do fungi have that no other organisms have (except a very few species of bacteria)? A) Fungi can decompose cellulose B) Fungi can decompose proteins C) Fungi can decompose chitin D) Fungi can decompose lignin 31. Most plant roots have fungal symbionts. Often, these are mutualistic relationships in which fungi and plants both benefit. How does the plant benefit from this relationship? A) The plant obtains nutrients such as phosphorus from the fungus B) The plant obtains organic molecules such as sugars from the fungus C) The plant obtains water from the fungus D) The plant obtains carbon dioxide from the fungus
32. In most fungi, hyphae are: A) diploid B) haploid C) dikaryotic D) tetraploid 33. The reproductive structures of this group of fungi include many of the mushrooms that we commonly eat. A) Chytridiomycota B) Zygomycota C) Basidiomycota D) Ascomycota E) Glomeromycota 34. In animals, why would you think fungal infections (such as athlete's foot) are so much harder to cure than bacterial infections? A) Fungi and animals are more closely related than bacteria and animals B) Fungi are more highly evolved than bacteria C) Fungi are part of a younger evolutionary lineage than bacteria D) Fungi are a source of many antibiotics that work against bacteria 35. Often, fungi will infect plant leaves, but this symbiotic relationship may benefit both the plant and the fungus. What is the benefit to the plant of a fungal symbiont in the leaf tissue? A) The fungus provides nitrogen and phosphorus to the plant B) The fungus provides sugars to the plant C) The fungus preys upon nematodes, preventing nematode infections of the plant D) The fungus produces compounds that deter herbivores from eating the leaves Chapter 35 - Viruses 36. Which of the following comparisons between viruses and organisms is NOT true? A) Viruses cannot self-replicate, organisms self-replicate B) Viruses all have RNA genomes, organisms all have DNA genomes C) Viruses have no metabolic activity, organisms do D) Viruses are not cellular, organisms are all composed of cells 37. You isolate a new virus and find that the virus has an envelope. This virus is most likely to infect which of the following organisms? A) Bacterium B) Plant C) Fungus D) Diatom E) Jellyfish 38. Viruses evolve more rapidly than most organisms. This, in large part, is why it is so difficult to produce effective vaccines against viruses. What characteristics of viruses allow them to evolve so rapidly? A) Viruses lack repair mechanism to correct mistakes following genome replication B) Viruses are reproduced very rapidly (high rate of genome repliction) C) Viral genome is protected by protein capsule D) A and B E) All of the above
39. The source of most viruses in humans appears to be animals. Viruses in animals evolve and a mutation within an animal virus may allow it to jump to humans. Over time, the virus co-evolves with the human host, and may become relatively common (such as the rhinovirus). Typically, as viruses co-evolve with humans, they: A) Become more virulent (more likely to cause severe disease or death) B) Become less virulent (become less likely to cause severe disease or death) C) Become capable of invading more tissue types within the human host D) None of the above 40. A retrovirus possesses: A) A DNA genome and Reverse Transcriptase B) A DNA genome and DNA Polymerase C) An RNA genome and Reverse Transcriptase D) An RNA genome and RNA Polymerase
SECTION 2: SHORT ANSWER QUESTIONS Short-Answer Questions: 1. Two populations of birds look very similar, but the males have territorial songs that sound different. What function would this difference in song likely serve if the two populations came in contact? [2 points total] Songs are markers of identity. The difference in territorial songs may mean that males of the different populations do not recognize each other’s territorial calls. 1) This could lead to overlapping among the populations (males with overlapping territories). 2) It may also lead to increased confrontation between males of the different populations. 3) Or it may lead to reinforcement of separation between the populations, as the females may recognize males of their own population but not males of the other population. The result would be less frequent selection of mates from the other population. I will accept any of these answers for two points. If the student says something kind of relevant, but not fully on point for any of these three outcomes, I will award 1 point. 2. Archaea differ from both eukaryotes and bacteria in the nature of their cell membrane phospholipids. In archaea, the fatty acid chains are highly branched, while they are not branched in bacteria or eukaryotes. What does this suggest about the ancestor to all three domains (Did it most likely have branched or nonbranched fatty acids)? What is the adaptive advantage to these fatty acids in archaea? Given the advantage for archaea, why do we not also see these branched fatty acids in eukaryotes? (3 points)
A. Suggests that straight chain fatty acids was the ancestral trait, found in the common ancestor to all three domains.
B. The branched chains increase the extent of hydrophobic interactions, permitting these membranes to remain intact even at high temperature (high temperatures reduce strength of van der Waals’ interactions, so having more hydrophobic side chains compensates for this effect). C. This same trait (more hydrophobic interactions) would make a membrane less fluid (more rigid) at lower temperatures. This would make cross membrane transport less efficient in eukaryotic cells that grow at lower temperatures.
3. Why is it likely that an archaeal species lacking a cell wall was ancestral to eukaryotic cells? Provide at least two clear lines of evidence that the ancestor was archael rather than bacterial. Provide one reason the ancestor would likely have lacked a cell wall. (3 points) Two lines of evidence that archaea are ancestral to eukaryotes could include: A) both have introns in their genomic structure, B) both have histones associated with their genomes, C) Archaea and eukaryotes have very similar ribosomal subunit size and structure, D) similar RNA polymerases, and both have multiple RNA Polymerases, E) Both archaea and eukaryotes have translation beginning with methionine. Likely lacked a cell wall because: A) Not all archaea and not all eukaryotes have cell walls, and the compositions of cell walls vary among cells that do have walls. For example, plant cells have cellulose walls, diatoms have silica walls, some archaea have protein walls, some protists have chitin walls. This suggests that cell walls evolved independently in various different lineages. B) A cell possessing a cell wall would not have been able to engulf a proteobacterium. Had the ancestor to eukaryotes had a cell wall, it would not have been possible for it to establish an endosymbiotic relationship with a proteobacterium. 4. Fungi and the roots of plants often form symbiotic associations. One advantage that plants gain from this association is access to phosphorus. Why are fungi more effective in extracting phosphorus from soils than are plant roots (1 point) Fungi secrete extracellular digestive enzymes that can digest organic matter liberating phosphorus (converting organic P into biologically available inorganic P). Also, fungi secrete acids that cause desorption of inorganic P from soil particles, making it available for uptake by plant roots. 5. Fungi have high surface area to volume. Given the mode of nutrition for fungi, why is this body plan (high surface area to volume) an advantage? (1 point) They obtain nutrients by direct absoption of soluble nutrients from the environment. A high surface area to volume allows them to more efficiently gain nutrients by absorption. It reduces the kinetic barrier to nutrient delivery.
6. In protists, photosynthesis is a polyphyletic trait. It is found in all members of the green algae, but only in a few members of other phyla, for example among the stremenopila, diatoms are photosynthetic, but other groups are not. The biochemical pathways of photosynthesis are nearly identical in green algae and in the diatoms. What does this suggest about the origins of photosynthesis in the stremenopila? Does it suggest that photosynthesis was an ancestral trait to both green algae and stremenopila? Or does it suggest independent evolution of photosynthesis in both lineages? Or does it suggest lateral transfer of the trait to stremenopila by secondary endosymbiosis? Explain your answer (2 points) This suggests lateral transfer by secondary endosymbiosis. That the trait is found in all green algae suggests it is ancestral to that lineage. That it is found only in the diatoms within the stremenoplia lineage suggests it is not ancestral to that lineage. That the biochemistry of the photosynthetic process is highly conserved between green algae and diatoms (and for that matter, cyanobacteria) suggests a single origin of the process rather than multiple independent origins. So, the most likely explanation is transfer of the trait from one lineage (green algae) to another group of protists (diatoms) via secondary endosymbiosis
