Population Ecology and Growth Models, Exams of Nursing

Download Population Ecology and Growth Models and more Exams Nursing in PDF only on Docsity! Page 1 of A population with a positive value of r will grow exponentially. A population with an r of 0.1 will decrease over time. A population with an r of 0 will have no births or deaths during the time period under consideration. Correct If the per capita rate of increase r > 0, the population is growing exponentially. Read about the exponential population growth model. rmax declines as N increases. At low values of N, the logistic growth and exponential growth (dN/dt = rN) models predict similar population growth. K is a constant value. Correct When N is small compared to K, the term (K – N)/K is close to 1, and the per capita rate of increase, rmax (K – N)/K, approaches the maximum rate of increase. As N increases, the exponential growth rate does not change, while logistic growth declines. Read about the logistic model of population growth. NURSING213 Homework 1 - Population Ecology Misconception Question 261 Part A Consider a population whose growth over a given time period can be described by the exponential model: dN/dt = rN. Select the correct statement about this population. ANSWER: Misconception Question 262 Part A Consider a population whose growth can be described by the logistic growth model: dN/dt = rmaxN[(K − N)/K]. Which of the following statements about this population is true? ANSWER: Misconception Question 263 Part A The graph shows the growth of a laboratory culture of Paramecium aurelia. Suppose that after 15 days, the researcher removed ~400 paramecia from the culture. How will the population growth rate (dN/dt) change as a result of this action? The growth rate of the Paramecium population will decrease. The growth rate of the Paramecium population will not change. The growth rate of the Paramecium population will increase. Correct The overall population growth rate is highest when the population size is half the carrying capacity. At this population size, the per capita rate of increase remains relatively high (one-half the maximum rate), and there are more reproducing individuals (N) in the population than at lower population sizes. Read about the logistic model and real populations. It is impossible to calculate the global carrying capacity for the human population. The global carrying capacity for the human population is limitless because technological advances allow food supply to keep up with global population growth. Estimates of the global carrying capacity for the human population depend on resource use per capita. Correct Read about the concept of an ecological footprint, the aggregate land and water area required by each person, city, or nation to produce all the resources it consumes and to absorb all the waste it generates. Page 2 of ANSWER: Misconception Question 264 Part A Select the correct statement about the global carrying capacity for the human population. ANSWER: Misconception Question 265 Part A Select the correct statement about the factors that limit the growth of a population. ANSWER: 14 234,000 130 585 29 Correct To get the population size N, multiply the number marked in the first catch, M1, by the total number caught in the second catch, C, and divide that by the number of marked recaptures in the second catch, M2: N = (M1 x C) / M2 Or: (130 x 90) / 20 = 585. 4 MendAliens per hectare 10 MendAliens per hectare 4,000 MendAliens per hectare 0.1 MendAliens per hectare 200 MendAliens per hectare Correct Population density is calculated as population size divided by area: 200 MendAliens / 20 hectares = 10 MendAliens per hectare. rose bushes maple trees sharks wheat oysters Correct The mark-recapture method works best for active species whose individuals tend to be highly mobile. Page 5 of Part A You are doing a mark-recapture experiment to determine the population size of the MendAliens living on an island in my back yard. Initially, you catch and mark 130 MendAliens, which you then release. Next, you capture 90 MendAliens, of which 20 are marked. What is your estimate of the population size of MendAliens living on the island in my back yard? ANSWER: Part B Assume there are 200 MendAliens living on an island in my back yard. If my island has an area of 20 hectares, what is the population density of MendAliens in terms of MendAliens per hectare? ANSWER: Part C The mark-recapture method would be best for sampling a population of . ANSWER: grasses robins humans elephants oysters Correct The mortality rate of robins remains relatively constant throughout their life span. juveniles larval and juvenile oysters prereproductive oysters adults larvae Correct Young oysters have a very high mortality rate; older oysters have a much lower mortality rate. Thus, most oyster populations consist primarily of older individuals. Page 6 of Activity: Investigating Survivorship Curves Click here to complete this activity. Then answer the questions. Part A Which of these species typically has a mortality rate that remains fairly constant over an individual's life span? ANSWER: Part B Oyster populations are primarily, if not exclusively, composed of . ANSWER: Part C Which of these organisms has a survivorship curve similar to that of oysters? ANSWER: humans grasses robins elephants cats Correct Grasses, like oysters, have a relatively high mortality rate early in their life span, after which the mortality rate decreases. oysters robins elephants cats grasses Correct The mortality rate of elephants, like that of humans, remains relatively low for much of their life span and then dramatically increases for older individuals. Hint 1. Consider the location of a population in the hierarchical organization of life. all the coyotes on Earth a spider and the fly it is about to eat all of the redwood trees that live in a forest all the plants that live near each other in a forest the earthworms that live in a grassland plus the earthworms that live in a forest Correct This includes the individuals of one species in one place that presumably interact, use the same resources, and are influenced by the same environmental conditions. Page 7 of Part D Which of these organisms has a survivorship curve similar to that of humans? ANSWER: Chapter 53 Pre-Test Question 1 Part A Which of the following is an example of a population? ANSWER: Page 10 of 0.1 0.5 1 10 Correct Survivorship for a Type I curve is nearly 1,000 times as great as survivorship for a Type III curve. Survivorship is equal for the two curves. Survivorship for a Type I curve is 100 times as great as survivorship for a Type III curve. Survivorship for a Type I curve is twice as great as survivorship for a Type III curve. Correct Supported Not supported Cannot be determined from this graph Correct Supported Not supported Cannot be determined from this graph Correct Part D At 50% of maximum life span, how does survivorship for a Type I curve compare to survivorship for a Type III curve? ANSWER: For each of the following questions, indicate whether the statement is supported or not supported by the data shown in the graph. Part E For species with a Type III curve, most individuals reach the maximum life span. ANSWER: Part F According to this graph, species that exhibit a Type III curve typically produce large numbers of offspring. ANSWER: Part G In species that exhibit a Type II survivorship curve, individuals are no more likely to die at one stage of the life cycle than another. Supported Not supported Cannot be determined from this graph Correct life span of individuals, expressed in 25-year intervals number of survivors, on a logarithmic scale percentage of the maximum life span of a species number of survivors, as a percentage of the population Correct Page 11 of ANSWER: Interpreting Data: Survivorship Curves of Albertosaurus and Four Modern Species Dr. Gregory Erickson studied the fossilized bones of a dinosaur called Albertosaurus to determine the age at which individual dinosaurs died. From this data he constructed a survivorship curve. The graph below compares the survivorship curve of Albertosaurus to that of four modern species. Can you interpret the graph to answer these questions? Part A What is shown on the x- axis? ANSWER: approximately 5 approximately 32 approximately 55 approximately 68 Correct about 8 about 100 about 500 about 800 Correct human elephant starling crocodile Correct The survivorship of the two species is roughly equal. The survivorship of Albertosaurus is about 3 times greater than that of the crocodile. The survivorship of Albertosaurus is about 10 times greater than that of the crocodile. The survivorship of Albertosaurus is about 100 times greater than that of the crocodile. Page 12 of Part B Look closely at the scale on the y-axis. What number would be represented by the point midway between the tick mark labeled 10 and the tick mark labeled 100? ANSWER: Part C In a population of 1,000 elephants, how many individuals would survive for 50% of the species’ maximum life span? ANSWER: Part D According to the graph, which modern animal has a relatively constant mortality rate throughout its life span? ANSWER: Part E At 50% of maximum life span, how does the survivorship of Albertosaurus compare to the survivorship of the crocodile? ANSWER: Kd life span number of nesting sites territory space competition Correct Density-dependent factors such as nesting space and food availability affect carrying capacity. Hint 1. Practice using the logistic growth equation The equation for calculating the population growth rate according to the logistic model is dN = rmax N (K−N) where dN/dt is the population growth rate, rmax is the maximum rate of increase for the species, N is the population size, and K is the carrying capacity. dtK When K = 2500, rmax = 1.0 per individual per year, and N = 750, by how many individuals is the population increasing per year? Express your answer as the number of individuals added to the population per year. Page 15 of ANSWER: Part B - Relationship between population size and growth rate A population of animals in a specific environment with a K of 2500 has an rmax of 1.0 per individual per year and exhibits logistic growth as follows: dN = rmax N ( K − N ) Arrange the following population sizes in order of decreasing growth rate. Rank the population sizes (N) from fastest to slowest growth rate. If two population sizes have the same growth rate, overlap them. (For help calculating growth rate, see Hint 1.) Kd 525 Page 16 of ANSWER: Hint 2. How do N and K affect the growth rate? In the equation for logistic growth, dN = rmax N (K−N) , how does the relationship between N and K affect the population growth rate, dN/dt? Drag the phrases on the left to the appropriate blanks on the right to complete the sentences. Not all phrases will be used. ANSWER: ANSWER: Page 17 of Correct The population growth rate is greatest when the population size is around 1250, or half of the carrying capacity (K = 2500). At N = 1250, the population increases by 625 individuals per year. At N = 1500, the growth rate slows to 600 individuals per year, the same as at N = 1000. Note that in the logistic growth equation, rmax N represents the exponential rate of increase, and (K − N)/K is the fraction of the maximum sustainable population size that is available for population growth. Part C - Graphing logistic population growth Use the data below to make a graph showing the logistic growth of a hypothetical population. Choose one row of data in the table to plot on each axis (shown here as x and y). Generation 0 1 2 3 4 5 6 7 8 9 Population size (N) 5 10 20 38 70 120 182 232 249 250 Population growth rate 5 10 18 32 50 62 50 17 1 0 To create the graph, first click on “add graph” and select the graph label “Population growth.” (For help using the graphing tool, see Hint 1.) Hint 1. How to plot data using the graphing tool To plot a graph and edit your data points once they are plotted, use these tabs that appear above the graph. 1. To begin plotting points, click on the tab. A “Select a Graph Label” window will open. From the drop-down menu, select “Population growth.” Correct Notice that the logistic growth of the population produces an S-shaped curve. If this population underwent exponential growth rather than logistic growth, the curve would be J-shaped, as shown in the graph below. Hint 1. Logistic population growth The equation for calculating the population growth rate, dN/dt, according to the logistic model is dN = rmax N (K−N) where rmax is the maximum rate of increase for the population, K is the carrying capacity, and N is the population size. On a graph of logistic population growth, dN/dt is represented by the slope of the plot. The size of the population affects dN/dt. When N is much smaller than K , dN/dt is small. When N is half of K , dN/dt is maximal. When N is close to K , dN/dt is close to zero. dtK Hint 2. What are differences between r-selection and K -selection? Page 20 of ANSWER: Part D - Analyzing a graph of logistic population growth The figure below shows the logistic growth of a hypothetical population of animals. Drag the labels to their appropriate locations on the graph. Classify each item according to whether it applies to K -selection, r-selection, or both. Drag each item to the appropriate bin. ANSWER: Page 21 of ANSWER: All attempts used; correct answer displayed K-selection (also called density-dependent selection) occurs when the population size, N , is close to carrying capacity, K. For example, K-selection would occur in an established elephant population in a protected area. On the other hand, r-selection occurs in uncrowded environments where N is much less than K. This type of selection would characterize a population of fast-growing weeds in a disturbed area. A population grows rapidly when N is much less than K, but as N approaches K, population growth approaches zero. If N exceeds K, population growth is negative, meaning that N declines. Hint 1. Which processes influence a population's growth rate? Deaths and immigration. Deaths and emigration. Births and immigration. Births and deaths. Correct Immigration is the movement of individuals into a population, so births and immigration increase a population's size. Hint 1. What is the intrinsic rate of increase of a population? Page 22 of Activity: Modeling Population Growth Click here to view this animation. Then answer the questions. Part A Which processes increase a population's size? ANSWER: Part B True or false? Factors that determine the per capita rate of increase of a population include the age of breeding and the number of offspring produced each year. Hint 1. Think about the parameter that differs between density-independent and density-dependent growth. Density-independent growth is also known as exponential growth. The per-capita rate of increase may exceed rmax during density-independent growth. A population that is experiencing density-independent growth levels off at the environment's carrying capacity. Density-independent growth can continue indefinitely in nature. Correct This statement is true. Hint 1. Remember that in the real world, the supply of resources affects growth. Environment with a low carrying capacity. Habitat with limited resources. Young populations with few individuals. Large number of individuals in the starting population. Correct Young populations with few individuals are more likely to experience exponential growth because they have not used up the supply of resources. Hint 1. Consider the variables in the equation for logistic growth. If N is less than K, the population will not grow. If the K and N values are similar, the amount of available resources is high. If N is greater than K, the population will shrink. If the K and N values are far apart, the population will grow very slowly. Page 25 of Which of the following statements about density-independent growth is true? ANSWER: Part F Under which of the following conditions would a population most likely experience exponential growth? ANSWER: Part G Which of the following statements about a population experiencing logistic growth is true? ANSWER: Correct This statement is true, since K is the maximum number of individuals that can be supported in a particular habitat over a sustained period of time. Hint 1. The maximum number of individuals that a particular habitat can support with no degradation of the habitat is symbolized by K. community survivorship niche carrying capacity biotic potential Correct Carrying capacity is the maximum population size that a particular environment can comfortably support with little increase or decrease over a relatively long period of time. Page 26 of Chapter 53 Pre-Test Question 6 Part A The number of individuals that a particular habitat can support with no degradation of that habitat is called . ANSWER: Interpreting Data: Logistic Growth Can you interpret this graph about population growth to answer these questions? Part A time, with duration increasing from left to right resources, with quantity increasing from bottom to top population, with size increasing from bottom to top resources, with quantity decreasing from bottom to top Correct exponential growth population size carrying capacity logistic growth Correct When the population reaches carrying capacity, it stops growing. As the population approaches carrying capacity, it grows more slowly. The population grows at a steady rate. As the population approaches carrying capacity, it grows more rapidly. Correct The population continues to grow at a constant rate. The population growth rate equals zero. The rate at which resources are used is equal to the rate at which they are supplied. The birth rate equals the death rate. Page 27 of What does the right y-axis represent? ANSWER: Part B What does the orange graph line represent? ANSWER: Part C Which of the following statements are true of logistic growth? Select all that apply. ANSWER: Part D Which of the following statements are true of a population at carrying capacity? Select all that apply. ANSWER: Page 30 of Part A - Graphing population growth Suppose that geckos from the mainland colonize two different Galápagos Islands, Daphne Major and Isabela Island. What happens to these two new populations over time? Plot the data below to see how each population grows. For the Daphne Major population, plot growth for Years 1-7. For the Isabela Island population, plot growth only for Years 1-4. (The data for Years 5-7 will not fit on this graph.) To plot the data for each population, click “add graph” and then select the appropriate graph label. Hint 1. How to plot data using the graphing tool To plot a graph or edit your data points once they are plotted, use these tabs that appear above the graph. 1. To begin plotting points, click on the tab. A “Select a Graph Label” window will open. From the drop-down menu, select “Daphne Major Population” to plot the data for that population. 2. As you move your cursor over the graph, the cursor will change to a crosshair and display the x and y coordinates of your cursor’s location: . 3. Move your cursor to the location of the first data point to be plotted, then click to plot the point. In this graph, Year should be plotted on this x-axis and Population size should be plotted on the y-axis. 4. After plotting the first point, the tool automatically enters the “add points” mode. (You can tell that the tool is in the “add points” mode because the cursor is still a crosshair.) If the cursor does not look like a crosshair and you still need to add more points, click on the plotted line to highlight it, then click . 5. If you need to change the location of a data point, click on the point to highlight it and then drag the point to the correct location. If you need to delete a data point, click on it to highlight it, and then click to remove the point from Page 31 of the graph. Page 32 of 6. Once you have plotted all the points for the Daphne Major population, click on the tab to begin plotting data for the Isabela Island population. From the drop-down menu, select “Isabela Island Population.” Repeat the steps above to plot the size of the Isabela Island gecko population. Hint 2. Can you practice plotting data points using the graphing tool? You can practice using the graphing tool by plotting data for the Daphne Major and Isabela Island gecko populations for Years 1-3. To plot the data for each population, click “add graph” and then select the appropriate graph label. ANSWER: ANSWER: Review exponential and logistic growth by watching the “Exponential Growth” and “Logistic Growth” segments of the animation. Then complete this exercise. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. ANSWER: Page 35 of ANSWER: Correct Exponential growth and logistic growth are two patterns of population growth often seen in nature. Exponential growth follows a J-shaped curve. Exponential growth occurs when resources are abundant. As the population gets larger, it grows faster and faster -- there seems to be no limit on population size. However, in nature, while exponential growth can occur for a period of time, it cannot continue forever. Logistic growth follows an S-shaped curve. Logistic growth can occur when resources are limited. As the population gets larger, its growth rate eventually slows. Population size levels off at carrying capacity. Page 36 of Part C - Exploring density-dependent and density-independent population regulation Earth is not filled to the brim with elephants, or ants, or ferns, or geckos. What prevents a population from growing forever? Many different factors limit population growth. Some of these factors are density-dependent, and others are density-independent. Drag a label under each graph to indicate whether it shows density-dependent population regulation or density-independent population regulation. Labels may be used once, more than once, or not at all. Hint 1. Defining density-dependent and density-independent factors that limit population growth A birth rate or death rate that does not change with population density is density-independent. In contrast, a death rate that increases as population density increases is a density-dependent factor that limits population growth. A birth rate that decreases as population density increases is also a density-dependent factor that limits population growth. Hint 2. How can you tell if a graph of birth rate shows density-dependent population regulation? Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. ANSWER: Hint 3. How can you tell if a graph of death rate shows density-dependent population regulation? Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. ANSWER: 1.8 density-independent death rate| does not change as population density increases. 2.4 graph of density-independent death rate would show a “horizontal line . 3.4 density-dependent death rate “Increases 2s population density increases. 4.4 graph of density-dependent death rate would show a “line that slopes up to the right - i" ANSWER: 2 5 g 2 £ lambs (%) Propartion dying Bridled gobies Daphne Major geckos 2 Offspring per female per year Death rate Isabela Island geckos i e888 S88 Tuvenil 200 300 400 500 600 Population size density-dependent birth rate a2 4 6 8 wi Initial density (am) density-dependent death rate ot 0 100 200 300 400 500 Population size density-dependent birth rate Adapted fram Biology by Campbell and Reece ) Pearson Education, Ine, and from Biolagical Science by Freeman @) Pearson Education, inc. 0 0 100 200 300 400 500 Population size density-independent death rate Pane 37 of the discovery of vaccines and the discovery of antibiotics the discovery of antibiotics the discovery of vaccines the advent of agriculture the Industrial Revolution Correct The advent of modern medicine is the third and most recent of the events listed here that have stimulated an increase in the population size of humans. at the carrying capacity There is insufficient information to answer this question. below the carrying capacity above the carrying capacity either at or above the carrying capacity Correct Not knowing how technological innovations will affect the human population means there is insufficient information to answer this question. Page 40 of Part C Which of these was the third of the major events that stimulated an increase in the size of the human population? ANSWER: Part D Currently, how large is the worldwide population of humans relative to Earth's carrying capacity for humans? ANSWER: Activity: Analyzing Age-Structure Pyramids Click here to complete this activity. Then answer the questions. Part A Ignoring migration, the age structure of a human population likely to increase in size will have what shape? ANSWER: Both a pyramid and a rectangle tapering toward the top result in a population that increases in size. Both an inverted pyramid and a rectangle tapering toward the top result in a population that increases in size. inverted pyramid pyramid a rectangle tapering toward the top Correct This would mean that most individuals are in the prereproductive years. Such a population is expected to increase. a rectangle tapering toward the top Both a pyramid and a rectangle tapering toward the top result in a population that decreases in size. inverted pyramid Both an inverted pyramid and a rectangle tapering toward the top result in a population that decreases in size. pyramid Correct In such a population the majority of individuals are in their postreproductive years. Such a population is expected to decrease. Both a pyramid and a rectangle tapering toward the top result in a population that remains stable in size. pyramid Both an inverted pyramid and a rectangle tapering toward the top result in a population that remains stable in size. a rectangle tapering toward the top inverted pyramid Correct Such a population is expected to have a relatively stable size. Page 41 of Part B Ignoring migration, the age structure of a human population likely to decrease in size will have what shape? ANSWER: Part C Ignoring migration, the age structure diagram of a human population likely to maintain a relatively stable size will have what shape? ANSWER: Activity: Human Population Growth and Regulation Changes in populations through time. Regular fluctuations in the population size of some animals. Number of individuals born each year in a population. Proportion of individuals at each possible age. Correct The changes in populations through time are known as population dynamics. Populations in developed countries grow more quickly than populations in less-developed countries. Predictions of a population's future take into account such factors as increasing survivorship and fecundity levels that remain the same. Age distribution in developed countries shows an hourglass pattern, with the greatest numbers of people being either very young or very old. Age distribution in less-developed countries is bottom-heavy, indicating that these populations are dominated by the very old. Correct These factors give clues about future public policy concerns in the population. Hint 1. Think about why a population would stop growing. Page 42 of Click here to view this animation. Then answer the questions. Part A What are population dynamics? ANSWER: Part B Which of the following statements about age pyramids is true? ANSWER: Part C True or false? The growth rate of a certain population increases very quickly for a time and then levels off to zero. The most likely reason that the growth rate leveled off to zero is that the environment reached its carrying capacity. ANSWER: A population increase of 20 million A population increase of 2 billion A time span of 20 years A time span of 50 years Correct r, the per capita rate of increase The percentage increase in the population The number of people added to the population annually in each decade The total population size Correct Page 45 of Part A What is represented by the distance between two vertical white gridlines on this graph? ANSWER: Part B What is represented by the vertical blue bars on this graph? ANSWER: Part C According to this graph, the world population doubled between . ANSWER: 1850 and 1950 1900 and 1925 1930 and 1975 1975 and 2000 Correct The population doubled from approximately 2 billion to 4 billion during this time interval. 1980–1990 1990–2000 2000–2010 2040–2050 Correct Supported Not supported Cannot be determined from this graph Correct Supported Not supported Cannot be determined from this graph Correct Page 46 of Part D Which decade had, or is projected to have, the highest annual population increase? ANSWER: For each of the following questions, indicate whether the statement is supported or not supported by the data shown in the graph. Part E During the 20th century, the human population increased from less than 2 billion to more than 6 billion. ANSWER: Part F Total population size is projected to increase through the middle of the 21st century. ANSWER: Part G Supported Not supported Cannot be determined from this graph Correct Supported Not supported Cannot be determined from this graph Correct Page 47 of The rate of human population growth is increasing. ANSWER: Part H From 1500 to 2010, the human population approximately followed the exponential growth model. ANSWER: Interpreting Data: Population Age Structure Can you interpret the diagram to answer these questions? Part A What do the bars on this graph represent? ANSWER: Correct the number of males and females born in different years the percentage of males and females in each age group the number of males and females in each age group birth rate or death rate for each age group Correct about 0.5 million about 1.0 million about 1.2 million about 0.5 billion cannot be determined from the graph Correct The people in that age class are past reproductive age. The people in that age class are of reproductive age. The answer cannot be determined from the graphs. The people in that age class have not yet reached reproductive age. Correct Page 50 of Part B What do the bars on the graphs represent? ANSWER: Part C In 2010, how many 25- to 29-year-old women lived in Niger? ANSWER: Part D The colors of the bars on the graphs indicate the life stage of the people in that age class. What does it mean if a bar is colored blue? ANSWER: Part E The 2010 age-structure pyramid for Niger indicates that the population of Niger . ANSWER: was increasing was stable was decreasing cannot be determined from the graph Correct children between 5 and 14 adults between 25 and 34 adults between 35 and 45 adults between 45 and 54 adults between 55 and 64 Correct a decline in the birth rate during the Great Depression of the 1930s a surge in the birth rate after World War II ended in 1945 the increased availability of oral contraceptives in the 1950s and 1960s an increase in the death rate during World War I and the influenza epidemic of 1917 Correct The proportion of the population made up of children (ages 0–15) will increase. The proportion of the population made up of adults of reproductive age will increase. The proportion of the population made up of older adults (65+) will increase. The answer cannot be determined from the graph. Correct Page 51 of Part F In Canada in 2010, which age classes contained the largest number of people? ANSWER: Part G In Canada in 2010, people between the ages of 45 and 54 made up the largest percentage of the population. What factor is most likely to have caused this bulge in the age pyramid? ANSWER: Part H Assuming that current trends continue, predict how the age structure of Canada in 2030 will likely differ from that in 2010. ANSWER: providing prenatal care providing childhood vaccinations providing long-term care for the elderly building new schools Correct total number of births and deaths time birth rate or death rate birth rate total population Correct Page 52 of Part I Based on a comparison of the age-structure pyramids, which of the following would likely be a higher priority in Canada than in Niger? ANSWER: Interpreting Data: Demographic Transitions Can you interpret the graph to answer these questions? Part A What does the left y-axis of the graph represent? ANSWER: Part B What does the green graph line represent? ANSWER: