Biology Homework 2

1. A human eats a deer. Which of these terms applies to the relationship between the human and 2. 3. 4. 5. 6. 7. 8. 9. 10. the deer? a. Predation i. The human is the predator and the deer is the prey. Humans and sharks both eat fish. Which of these terms applies to the relationship between the human and the shark? a. Competition i. The human and the shark are both competing for a resource (fish). Humans who have pets tend to be healthier than humans who do not have pets. Which of these terms applies to the relationship between a human and a pet? a. Mutualism i. In mutualism, both members of the species pair benefit; in this case the human is healthier and the pet is getting room and board. Which of these terms applies to the relationship between a dog and a blood-sucking tick? a. Parasitism i. The tick benefits at the expense of the dog; the dog is the host and the tick is the parasite. An egret eats insects stirred up by grazing animals. Which of these terms applies to the relationship between the egret and the grazing animal? a. Commensalism i. In commensalism, one member of the species pair benefits and the other is unaffected; in this case, the egret is getting a meal and the grazing animals are unaffected. Plasmodium exhibits consumption in its interactions with mosquitoes and humans. Which process is not an example of consumption? a. Commensalism b. Herbivory c. Predation d. Parasitism i. Commensalism is a type of species interaction in which one participant benefits and the other participant is not affected by the interaction. Which form of Plasmodium is the immediate cause of anemia in humans? a. Merozoites b. Diploid Zygote c. Gametocytes d. Sporozoites i. Merozoites are produced in a human liver cell from sporozoites and circulate throughout the bloodstream, infecting and destroying the red blood cells. Which of the following statements about the Plasmodium parasite is true? a. Merozoites live off the hemoglobin and nutrients in red blood cells and divide to produce more merozoites, destroying red blood cells in the process. How do humans combat infection by the Plasmodium parasite? a. Cytotoxic T cells destroy infected liver cells by recognizing a Plasmodium protein bound to an HLA protein on the surface of those cells. i. Cytotoxic T cells do destroy infected liver cells by recognizing the Plasmodium CP26 protein bound to the HLA-B53 protein on the surface of those cells. The video describes a coevolutionary arms race between the Plasmodium parasite and its human hosts. True or false? One example of a coevolutionary arms race is when faster deer evolve and favor wolves and cougars that have stronger eyesight and senses of smell. a. True i. 11. 12. 13. 14. 15. 16. 17. True. A coevolutionary arms race involves two species that influence each other's evolution; faster deer favor predators with stronger eyesight and senses of smell to track them. Why doesn’t Dr. Logan feel the bed bug feeding on him? a. The bed bug injects an anesthetic as it feeds. What makes bed bugs different than most other blood-feeding parasites? a. Bed bugs prefer humans over other hosts. Many blood-feeding parasites carry diseases but bed bugs do not. What is the most logical explanation for this? a. The infectious agent is inactivated within the gut of the bed bug. Why do we often get an itchy red bump after being bitten by a bed bug? a. The proteins injected by the bed bugs trigger an inflammatory response in the human body. Bed bugs probably evolved from bat bugs. Which statement best describes how this likely happened? a. There were two populations of bat bugs, one feeding on humans, and one on bats. Reproductive isolation, mutation, and natural selection led to speciation. What does the bed bug illustrate in regards to evolution? a. Speciation can occur in just a few thousand years. Some scientists are conducting research on the “saliva” of bed bugs. Which of the following is the most logical medical benefit from this research? a. Using the anticoagulant to prevent blood clots in humans 18. 1. Roosting areas in buildings of any height are the fundamental niche of species 1. 2. Interspecific competition between the two bat species occurs because both species prefer the same roosting areas. 3. In parts of the city with only tall buildings (over two stories), competitive exclusion of species 1 may occur. 4. Roosting areas in buildings that are one to two stories tall are the realized niche of species 1 when species 2 is present. 5. The change in the roosting habits of species 1 after species 2 became established in the city is an example of resource partitioning. 6. The competition between the species for roosting areas is an example of a -/- interaction. 7. The changes in the eyes of species 1 are examples of character displacement. Two species that have identical niches cannot coexist in the same area. Competition between the species may cause them to use different niches (resource partitioning). In this example, resource partitioning is shown by bat species 1 roosting in short buildings (one to two stories) and bat species 2 roosting in tall buildings (three or more stories) when both species are present in the city. In the absence of resource partitioning, the inferior competitor may become locally extinct (competitive exclusion). Over many generations, competition may also cause a change in the characteristics of competing species (character displacement), as illustrated by the changes in eye structure of species 1. 19. Interspecific interactions can occur any time two species share space. Interspecific interactions include competition, predation, herbivory, parasitism, commensalism, and mutualism. Camouflage may prevent a predator from noticing potential prey, such as an octopus that changes the color and texture of its skin to match its surroundings. Other species mimic dangerous or distasteful prey; predators avoid both the model and the mimic. Chemical and mechanical defenses include plant toxins and sea urchin spines, respectively. Flocking is a behavioral adaptation in birds and is analogous to schooling or herding in other species; it may reduce the chance that any individual prey animal will be eaten by a predator. Some species use more than one form of defense against predators. For example, deer forage for food in herds, and their young (fawns) have spotted fur that acts as camouflage. Beetles have a hard external skeleton and forewings, which provide a mechanical defense, and many secrete chemicals that make them unpalatable 20. Parasitism is a +/– relationship, in which one organism benefits by harming another organism. For example, some species of hookworms enter a human host and eat blood. The hookworm benefits and the host is harmed by the loss of blood. Commensalism is a +/0 relationship, in which one organism benefits and the other organism neither benefits nor is harmed. For example, epiphytic orchids live on tree branches or tree trunks. The trees provide habitat for the orchids but usually are not affected by the orchids. Mutualism is a +/+ relationship in which both organisms benefit. For example, rumen microbes allow cows to digest grass, and the microbes benefit from a steady supply of nutrients. 21. Which one of the following animals would most likely be defined as a keystone species? a. Sea Otter 22. Which of the following terms do ecologists use to describe the community interaction where one organism makes the environment more suitable for another organism? a. Facilitation 23. According to the Shannon Diversity Index, which of the five blocks shown, with each containing 36 squares, would show the greatest diversity? 5 24. Species richness increases _____. a. As we travel Southward from the North Pole. 25. The following graph shows the average pH of the ocean over the last 20 million years of Earth’s history. In the last 20 million years of Earth’s history, the average pH has never gone below 8.0. Ocean acidity has been steadily decreasing from 20 million years ago to the present time. Average ocean pH has fluctuated over the millennia from just over 8.0 to about 8.3. Ocean acidity has been steadily increasing from 20 million years ago to the present time. 26. The oceans play an important role in regulating the amount of carbon dioxide in the atmosphere by absorbing atmospheric CO2. Atmospheric CO 2 reacts with seawater to produce carbonic acid, resulting in increased oceanic acidity (measured by lower pH values). In 2016, Earth’s atmosphere broke a record that had stood for approximately 16 million years: atmospheric CO2 levels measured at or above 400 ppm for the entire year. This increase in CO2 from a pre-industrial level of 280 ppm has already had an impact on oceanic pH, which has declined from pH 8.2 to pH 8.1 over the same time period -- a 30% increase in acidity. Scientists are studying how atmospheric CO2 concentrations and oceanic pH may change in the future. In work supported by the U.S. Department of Energy, researchers Denis Pierrot, Ernie Lewis, and Douglas Wallace developed a model to show how atmospheric CO2 levels and oceanic pH may change under three different carbon emission scenarios: ● An optimistic scenario ● A middle ground scenario ● A pessimistic scenario For more information about each of these scenarios, see Hint 1. The following data reflect predictions from Pierrot, Lewis, and Wallace’s model. Line Graph 27. The following graphs represent the future projections from Part B. 28. 1. In 2016, atmospheric CO2 was at 400 ppm, and oceanic pH was at 8.1. 2. Under the Optimistic scenario, CO2 concentrations in the atmosphere will increase but will remain under 600 ppm through 2090. 3. Under the Middle Ground scenario, CO2 concentrations in the atmosphere will get close to, but are not projected to exceed 700 ppm by 2090. 4. Under the Pessimistic scenario, CO2 concentrations in the atmosphere are projected to exceed 800 ppm by 2090. 5. Across all three scenarios, ocean pH falls below 8.0 by 2090. 6. From the information in the graphs, you can conclude that oceanic pH and atmospheric CO2 concentration are negatively (or inversely) correlated. 7. Although not reflected in this graph, you can infer that as atmospheric carbon dioxide increases, oceanic carbon dioxide concentrations also increase, suggesting that the two variables are positively (or directly) correlated. 29. Coral reef calcification rates are projected to steadily decline as atmospheric CO2 concentrations increase. True The data in this graph could also be plotted as a pie chart. False Although not reflected in the graph, based on how ocean acidification works, the relationship between oceanic pH and coral reef calcification rates can be predicted to be positively (or directly) correlated. True As atmospheric CO2 concentrations reach 840 ppm, or three times the preindustrial level, the calcification rate will be reduced to 30 mmol/m2/day. False Declining coral calcification rates suggests a decrease in the level of bicarbonates and an increase in the level of carbonates in seawater. False As atmospheric CO2 concentrations reach 560 ppm, or double the preindustrial level, the coral calcification rate is projected to be reduced by more than two-thirds from what it was at the preindustrial level. True Coral reef calcification rates are projected to steadily decline as atmospheric CO2 concentrations increase. The declining coral calcification rates reflect a decrease in the level of carbonates in seawater, which are critical for marine calcifiers like corals to build their skeletons. Long term, scientists are concerned that as the oceans become less hospitable to marine calcifiers, ocean food webs could collapse. Predators as varied as walrus, gray whales, sea ducks, and seals could suffer population declines since they all depend on marine calcifiers as a food source. 30. In an ecosystem, phytoplankton are _____. a. Producers i. Autotrophs, such as phytoplankton, are producers. 31. An earthworm that feeds on the remains of plants and animals is acting as a _____. a. Detritivore i. The earthworm is feeding on the remains of dead organisms. 32. When a human eats a steak, the human is acting as a _____. a. Secondary Consumer i. By feeding on a primary consumer, the human is acting as a secondary consumer. 33. A cow eating grass is an example of a _____. a. Primary Consumer i. By feeding on a producer, the cow is acting as a primary consumer. 34. A human who just ate a hamburger is eaten by a shark while swimming. The shark is acting as a _____. a. Tertiary Consumer i. The shark that ate the human that ate the cow that ate the grass is the tertiary consumer. 35. Tofu derives from plant, a primary producer located at the base of the productivity pyramid. A cow is a primary consumer that is one level up. It would be about 10 times more efficient to eat one pound of tofu, because 10 times the quantity of plants would be necessary to provide one pound of beef. 36. Why are food chains relatively short? a. There are only so many organisms that are adapted to feed on other types of organisms. b. Top-level feeders tend to be more numerous than lower-trophic-level species. c. Longer chains are less stable and energy transfer between trophic levels is inefficient. d. Food chain length is ultimately determined by the photosynthetic efficiency of producers. e. Top-level feeders tend to be small but are capable of conserving more energy. 37. Trophic efficiency is ________. a. the percentage of production transferred from one trophic level to the next b. usually greater than production efficiencies c. about 90 percent in most ecosystems d. a measure of how nutrients are cycled from one trophic level to the next e. the ratio of net secondary production to assimilation of primary production 38. While Rachel Carson was writing Silent Spring, a picture of how DDT influences bird populations was emerging. Scientists hypothesized that DDT was causing the observed decline in fish-eating bird populations. The assumptions and connections underlying this hypothesis were complex. In this activity, you will reconstruct those connections. This was the series of connections that led the researchers to hypothesize that farmers’ use of DDT was having a negative impact on bird populations. In science, you do not prove a hypothesis to be true, but rather you lend support to the hypothesis. Supporting just one of the connections shown above lends support to the hypothesis that use of DDT was causing declines in bird populations. 39. Based on the hypothesis that DDT was causing a decline in fish-eating bird populations in the United States, a group of scientists predicted that the amount of DDT in bird eggs was correlated with the thickness of the egg shells. For their experiment, they planned to visit a number of fish-eating bird populations and take 1 egg from 70 nests. In the laboratory, they would open the eggs to measure the concentration of chemicals such as DDT. They would also measure the thickness of the egg shells. The researchers had to decide which species of birds they would use in their study. Choosing the proper study organisms is very important because the species must be appropriate for the experiment, and practical to work with. Imagine that it is 1960, and the scientists have asked you to help them select the species of bird for use in their research. They have narrowed their options down to 6 species. Drag a check mark to species that would be good to use in the study; there may be more than one. Drag an X to species that would not be good for the study. Osprey and brown pelicans were both good candidates for testing the prediction that DDT in eggs was correlated with egg shell thickness. These species were not endangered, and they ate fish that could be contaminated with DDT from agriculture. Furthermore, these species were available within the United States, so they would be easier and less costly to work with. A team of researchers led by Lawrence Blus chose to use brown pelicans to test their prediction. They took 1 egg from 70 different brown pelican nests in California, South Carolina, and Florida. Then they compared the chemical composition of the eggs to the egg shell thickness. 40. In the case of DDT, some researchers and industry leaders were concerned that chemicals other than (or in addition to) DDT could be causing egg shell thinning. Blus and his colleagues also looked for a relationship between egg shell thinning and DDE (a breakdown product of DDT), PCBs, dieldrin, and mercury. This is an example of how scientists can simultaneously test multiple predictions and/or hypotheses. Blus and his team analyzed their data using regressions. A regression is used to compare two continuous variables, for example, a person’s height vs. foot length. In a regression, the slope measures how much the y value changes as a function of the x value. In this study, if the slope is very steep, that means that a small amount of chemical is causing a great change in egg shell thickness. The graph shows an adaptation of Blus's results. Notice that next to each line in the graph is a p-value. A p-value is a statistical measure of how likely it is that a relationship is due to random chance. For example, a p-value of 0.05 means that there is a probability of 0.05 (5%) that the results could be due to random chance. If there is a greater than 5% chance the results are due to chance, you cannot trust that a relationship between the variables really exists. In other words, even if you see a dramatic slope, if the p-value is greater than 0.05, you must treat the result as non-significant and conclude that there is not a relationship between the variables. Rank the chemicals according to how much they influence egg shell thickness. As you can see, multiple chemicals influence egg shell thickness. You can tell that DDE had the greatest impact on egg shell thickness because it’s the significant line with the steepest downward slope. Surprisingly, DDT was not significantly related to egg shell thickness. However, the use of DDT was still influencing bird populations because DDT degrades to DDE. Blus and his team revised their hypothesis to add the step of DDT degrading to DDE and ultimately causing bird populations to decline. If they had tested for only one chemical, they would have missed that link. It was studies like this that supported Rachel Carson’s book Silent Spring. The book made the public aware of the negative impact of pesticide use on wildlife. Silent Spring was published in 1962 and was influential in the environmental movement of the 1960s. In 1970, the United States government created the Environmental Protection Agency (EPA). The EPA’s mission includes regulation of pesticide use. In 1972, the agricultural use of DDT was banned, and bird populations started to recover. As you can see in the graph below, created from data from the Audubon Christmas Bird Count, brown pelican populations started to increase after DDT was banned. 41. Nitrifying bacteria convert _____ to _____. a. ammonium ... nitrates i. Nitrifying bacteria convert ammonium to nitrates. 42. _____ removes nitrogen from the atmosphere. a. Nitrogen Fixation i. Nitrogen fixation is the conversion of nitrogen gas to a form that can be used by plants (and other organisms). 43. Assimilation is indicated by the letter(s) _____. a. A i. Assimilation is the uptake of nutrients into an organism. 44. Nitrogen-fixing bacteria is(are) indicated by the letter(s) _____. a. D and E i. Both of these pointers are indicating nitrogen-fixing bacteria. Nitrogen fixation is the conversion of nitrogen to a form that plants can use. 45. Nitrification is indicated by the letter(s) _____. a. B i. Nitrification is the conversion of organic nitrogen-containing compounds to nitrites and nitrates. 46. Denitrifying bacteria convert _____ to _____. a. nitrates ... nitrogen gas i. Denitrifying bacteria convert nitrates to nitrogen gas. 47. Which one of these is a nitrate? a. NO3NO3 – is a nitrate. i. 48. Which one of these is a nitrite? a. NO2i. This is a nitrite. 49. Janzen’s first step was to figure out which reptile species have TSD. Fortunately, he could rely on the work of researchers that had come before him. When TSD was first discovered, many scientists set out to determine which species had TSD and which did not. These researchers were not conducting hypothesis-driven research but rather running experiments to collect data about the natural world. These descriptive studies are valuable, just as they were to Janzen in helping him identify his study organism. Whether research is hypothesis-driven or not, scientists may use manipulative or observational experimental methods. ● ● In a manipulative experiment, a scientist manipulates one or more variables in the study, specifically the independent variable(s). In an observational experiment, a scientist observes differences that naturally occur. For each of the studies described below, indicate if it is hypothesis driven and whether the scientist is employing observational or manipulative methods. Match the words in the left column to the appropriate blanks in the sentences on the right. Words can be used once, more than once, or not at all. 1. A physiologist incubates eggs in the lab at a range of temperatures to see what temperatures produce males and what temperatures produce females. This experiment is not hypothesis driven and is manipulative. 2. A biologist predicts that shade might influence ground temperature, and therefore turtle sex ratios. He records the sex ratio of turtle hatchlings in shaded and unshaded regions. This experiment is hypothesis driven and is observational. 3. An ecologist predicts turtles grow larger when no predators are around. She places turtles in an experimental pond system where half the ponds have predators and half the ponds have had the predators removed. This experiment is hypothesis driven and is manipulative. 4. A climatologist predicts that concentration of CO 2 in a city will be negatively correlated with the amount of wind in that city. He collects data and looks at the amount of CO2 in a city as a function of the wind speed in the city. This experiment is hypothesis driven and is observational. 5. A sociologist conducts a survey in Hawaii to describe people′s attitude about global climate change. This experiment is not hypothesis driven and is observational 6. A scientist determines the average wind speed, and variation in the amount of wind, in a number of locations to see which locations would be most suitable for wind turbines. This experiment is not hypothesis driven and is observational Prior to Janzen's work, scientists had conducted manipulative lab experiments demonstrating that painted turtles (Chrysemys picta) experience TSD. Janzen chose to use this species for his research. However, the lab was a controlled environment. Janzen wanted to find out how temperature influenced turtle sex ratios in the wild. 50. While Janzen was planning his descriptive, observational study with wild populations of painted turtles, he wanted to find out how much temperatures were predicted to rise over the next 100 years. He is not a climatologist, but fortunately, scientists can rely on work done by other scientists. When scientists look for scientific information, they use primary scientific literature. Primary literature often takes the form of a journal that is published multiple times a year. There are hundreds of journals devoted to different fields of scientific research. The journals include papers that describe in detail the methods, results, and conclusions from scientific studies. A hallmark of primary literature is that the papers are reviewed by other scientists before they are published. This so-called peer review helps ensure accuracy and reliability. As a student, you might not go to primary literature as a first step. You might seek out information in popular literature aimed at nonscientists. When considering what popular sources to use, it is important to evaluate their reliability. For instance, consider the credentials of the author, if the source has an agenda or bias, if primary sources are cited, and if the information is consistent with what you find in other reliable sources. Suppose you found the following sources for Janzen to use as references for the predicted rise in global temperature. Indicate if each source is an example of primary literature, and then decide if each source is reliable. If you are uncertain about a source, look it up online. The best choices are the two sources that are primary scientific literature. However, using other reliable sources to get started is not bad. Really good popular sources cite primary scientific literature. Avoid unreliable sources. Government sources are also generally reliable, even though they don’t technically fit the definition of primary literature. For example, the National Climatic Data Center is part of the National Oceanic and Atmospheric Administration, a government agency. Their web site (www.ncdc.noaa.gov) offers access to worldwide climate data collected by scientists. Using primary scientific literature and other reliable sources, Janzen discovered that the predicted rise in average global temperature, assuming that human activities continue on the same trajectory, is about 4°C over the next 100 years. 51. Janzen conducted an observational study in which he recorded the sex ratio of painted turtle hatchlings from numerous nests over the course of 6 years in Whiteside County, Illinois. His findings included: ● Nest temperature was directly related to the ambient air temperature. ● The temperature that produced a 50:50 sex ratio in a nest was similar to the environmental average temperature from the past 50 years. Therefore, even with temperature fluctuations from year to year, over time the ratio of males to females in the population was still around 50:50. The graph below summarizes the data Janzen collected over the course of his 6-year study. The temperatures on the x axis reflect the range of temperatures that Janzen recorded at different nests. He used this data to predict how a global temperature increase of 4°C might influence the sex ratio in painted turtle populations. 1. The x axis shows nest temperature. The y axis shows percentage of hatchlings that are male. 2. At low temperatures, only males are produced. 3. At high temperatures, only females are produced. 4. Between 21 and 25°C, as nest temperature goes up, percentage of hatchlings that are male goes down. 5. At the average nest temperature of 23°C, approximately 50% of hatchlings are male. 6. If the global temperature rises 4°C, approximately 0% of hatchlings will be male. At the environmental average temperature of 23°C, 50% males are produced. But what if that average temperature increased by 4°C to 27°C, as predicted by climate models? In 100 years, 0% of the hatchlings would be male. In fact, an increase of only 2°C would be enough to cause no males to be produced. If a population has no males, the females will have no males to mate with, no viable eggs will be laid, and the population will die out. Some years may be colder and produce males. However, Janzen conducted further research that demonstrated that turtle populations are still unlikely to be able to compensate for the predicted rapid loss of males due to an increase in nest temperatures. 52. Not all reptile species have temperature-dependent sex determination (TSD). And of the species that do, not every species produces males at low temperatures and females at high temperatures. The graphs below show how sex ratio is influenced by nest temperature in three other species compared to the painted turtle. A sex ratio that drifts from 50% males and 50% females is called biased. Notice how temperature changes do or do not lead to a biased sex ratio for each species. Look at the graph for the snake. If the temperature rises from the average nest temperature by 1°C, how much does the percentage of males change? For the tuatara, a 1°C increase would produce 0% males; therefore, the tuatara exhibits the most bias. For the alligator, a 1°C increase would produce 75% males. For the turtle, a 1°C increase would produce 25% males. Even though the bias for the alligator and turtle are in opposite directions, they are of the same magnitude. For the snake, a 1°C increase would still produce 50% males. The snake’s sex ratio does not change as a function of temperature because the sex of snakes is determined genetically, not by TSD. Does this mean that organisms with TSD are doomed? No. All species are different, and there will be differences in how they respond to increased temperatures. Species with TSD could be dramatically affected by climate change, but this does not have to be the case. Your actions can have powerful, direct, and immediate impacts on the future of numerous species. 53. In the figure, which of these countries has the highest per capita CO2 emissions? a. Australia