MES Unit 4 chap 13

The graph shows the different trends in population growth in less developed regions of the world versus more developed regions of the world. Solid lines in the graph indicate past data, and dashed lines indicate future projections. (Projections of data are based on models, simulations, or extrapolations from past data.) According to the projected data, after what year will the majority of people in less developed regions be living in urban areas?

2018 For less developed regions, the urban and rural lines intersect in 2018. After that point is when urban populations are projected to surpass rural populations.

Which of the following statements are supported by the graph? Select all that apply.

- In 1950, urban populations in more developed regions and less developed regions were almost equal. - In 2050, urban populations in less developed regions are projected to reach 5 billion. - Rural populations are projected to drop in both more developed and less developed regions. - In 2050, rural populations in less developed regions are projected to drop below 3 billion.

The results from Angilletta's observational experiment show that urban ant populations have higher heat tolerance than rural ant populations. A reasonable explanation for this difference is that urban ants evolved higher heat tolerance over generations as individuals with lower heat tolerance died and failed to reproduce. In the urban heat island of a city, natural selection favors organisms with higher heat tolerance. Suppose you want to run a manipulative experiment to try to replicate that evolutionary process. You decide to take ants from rural populations and relocate them to several city locations. Then for the next 50 years, you measure the heat tolerance of the transplanted populations every 5 years. You predict that the thermal tolerance of the transplanted populations will increase over time. The following graphs are possible results from your experiment. Drag group 1 labels (blue) to match each description with the appropriate graph. Drag group 2 labels (pink) to indicate how well each graph supports the hypothesis that natural selection results in urban ant populations with greater heat tolerance.

1. more; strongly 2. slightly more; weakly 3. no change; not 4. less; not Graph 1 shows the greatest evolution of heat tolerance over the 50 years. It best supports the hypothesis that natural selection results in urban ant populations with greater heat tolerance than their rural relatives. When ants with low heat tolerance die, they do not reproduce. On the other hand, ants with high heat tolerance are more likely to survive and continue to reproduce. Therefore, genes for heat tolerance would become more common in the city population, and the average heat tolerance of that population would increase. You can visualize this shift on the graph below, which shows directional selection. In directional selection, one extreme phenotype is selected against. In this case, low heat tolerance is selected against in urban ant populations, resulting in an evolved population with a normal distribution that is shifted toward the right.

You work for the city planning agency in Houston and successfully pass ordinances designed to double population density. Based on the graph, predict the approximate change in carbon emissions.

50% decline Vancouver has double the population density of Houston and approximately 50% lower carbon emissions.

Compare the population densities of the most and least dense cities on the graph. What is the population ratio of the most- to least-dense cities?

7:1 Tokyo has a population density of 70 persons per hectare and Houston has a population density of 10 persons per hectare, for a ratio of 7:1.

Describe the relationship between carbon emissions and urban density as shown on the graph.

As urban density increases, per capita carbon emissions decrease. This statement matches the data pattern shown on the graph.

In this graph, urban population density is used as an indicator of sprawl (lower density = more sprawl), and carbon emissions per capita provide some measure of the environmental impact of the transportation system or preferences for each of the cities represented. Which city on the graph has both low to medium density (between 10 and 30 persons per hectare) and low carbon emissions?

Copenhagen Copenhagen has a low to medium density of 28 persons per hectare and low carbon emissions of 180 pounds of carbon per person per year.

Which of the following ideas was suggested by speakers in the video?

Future cities should repurpose compacted metal as building blocks for buildings. These waste materials can be repurposed within a city.

Which of the following best summarizes the future plans for cities?

Make cities self-sufficient. As resources are recycled, a city can develop its own internal resource streams.

Do you think a city can change the traits of the organisms that live there? Could there be differences between urban organisms and their rural counterparts of the same species? It has been established that cities have higher temperatures than nearby rural regions. As you move away from the city center, the temperature drops. And the larger the city, the higher the temperature. This phenomenon is known as the urban heat island effect, and it is due to features in the urban environment that affect the absorption of solar energy, the rate of heat loss, and patterns of air movement. One group of researchers wondered if the urban heat island effect in São Paulo, Brazil, could be affecting leaf-cutter ants (Atta sexdens) in that city. Mike Angilletta and his colleagues set out to determine if urban ants were more heat tolerant than their rural neighbors, and if so, how did that happen? It has been demonstrated that ectotherms (such as insects and reptiles) in warm climates tolerate higher temperatures than ectotherms in cooler climates. Angilletta hypothesized that urban heat islands could lead to similar differences in heat tolerance between urban and rural populations of leaf-cutter ants. He predicted that ants in urban areas would tolerate heat better than ants in nearby rural areas. Select the two best experimental designs for comparing the thermal tolerance of ants in urban areas to ants in nearby rural areas.

Measure the heat tolerance of many ants of the same species as a function of the distance they live from a city center. Measure the heat tolerance of many ants of the same species from a city center and from a rural area in the same region. In the two best experimental designs, as many variables as possible are controlled so that you can draw a conclusion about how your independent variable (urban vs. rural environment) correlates with your dependent variable (heat tolerance). Some of the variables that are important to control are the species of ant (you want to test only one species) and the climate (you want all your ants to be from the same climate). Poorly designed experiments might include ants of multiple species, too-small sample sizes, too many uncontrolled variables, or indirect measurements of heat tolerance.

Calculate the average population density of the cities on the graph. Does the city that has average population density also have average carbon emissions?

No, carbon emissions are actually lower than average in the city with average density. Copenhagen has average density (28 persons per hectare) but lower-than-average carbon emissions. Average carbon emissions are 360 pounds but Copenhagen has only 190 pounds of carbon per person per year.

How do the speakers in the video hope to treat waste generated by cities of the future?

They plan to rely more on recycling and upcycling. The goal is to no longer need landfills to store waste.

Angilletta chose to measure the heat tolerance of many ants of the same species from several locations in and around São Paulo. Ants were gathered from four urban locations and five rural locations, as indicated in the satellite image below. Sites 1-4 are urban, and sites 5-9 are rural. The ants from the different locations were then placed in a chamber at 42°C. Angilletta recorded the percent of ants moving every minute until all ants stopped moving. (An ant that has stopped moving is dead.) Ants that survive longer at that high temperature have a higher heat tolerance. The following graphs are possible results from Angilletta's experiment. Match each description with the appropriate graph.

graph 1: urban more than rural graph 2: urban slightly more than ruralgraph 3: urban slightly less than ruralgraph 4: urban less than ruralgraph 5: little to no differencegraph 6: flaw The results in Graph 1 are similar to what Angilletta found. The ants from urban locations died off more slowly than ants from rural locations. This demonstrates that the ants from urban locations have higher heat tolerance.

One of the speakers in the video made an analogy between a city and a very large tree. In this analogy, the root system of the tree was compared to __________.

the way soils, air, and water are needed to sustain people in the city Cities require tremendous resources to keep the people productive and alive.