Unit D: Changes in Living Systems

Chapter and Unit Review Questions

Chapter 1 Review Questions

Knowledge

Competition, transpiration, habitat, mutualism, population, trophic level, and producer were terms introduced in this chapter. Determine what term best matches each of the following definitions.

	a.	a group of organisms all of the same species
	b.	a division of organisms with a similar nutrition source
	c.	a symbiotic relationship in which both organisms benefit
	d.	a loss of water vapour from a plant through its leaves
	e.	an organism that uses solar energy to make food
	f.	an area in which an organism lives out its life
	g.	a struggle between organisms for limited resources

For each pair of terms, explain the differences in their meanings.

	a.	biodiversity, biomass
	b.	abiotic, biotic
	c.	food chain, food web
	d.	producer, consumer
	e.	habitat destruction, habitat fragmentation

3.	Identify three abiotic factors and three biotic factors that describe a forest ecosystem.
4.	Why is a food web more realistic than a food chain?
5.	Explain the importance of sunlight to an ecosystem.
6.	What is a biogeochemical cycle?
7.	Identify reasons why the transfer of energy and matter in a food chain is only about 10% efficient.

Applying Concepts

The “Interactions Between Species” table summarizes the interactions and relationships between organisms. Complete this table by adding the required information to the missing boxes. Note that the following system is used to describe the effects on a species:

+ means the species benefits from the interaction
– means the species is harmed by the interaction
0 means the species is neither harmed nor helped by the interaction

INTERACTIONS BETWEEN SPECIES

Type of Interaction	Effect on Species #1	Effect on Species #2	Description	Example
	+	+		butterflies and purple coneflowers
	+	0		cowbirds and bison
				tapeworms and bison
predation
			interaction where two or more organisms compete for limited resources

Use the following information to answer questions 9 to 14.

Lemmings

A lemming is a small rodent. It is about 150 mm long with a mass of approximately 80 g. It resembles a hamster. Lemmings live in the high Arctic where permafrost prevents them from digging burrows, so they use natural ridges and depressions in the ground for burrows and travel routes. It is amazing that these tiny animals remain active throughout the Arctic winter, foraging for food in spaces between the ground and the snow cover. As lemmings eat grasses and sedges, they generate wastes that are consumed by bacteria, fungi, and insect larvae, which then return key nutrients to the soil. Lemmings play a significant role in the Arctic ecosystem because they are the main food source for Arctic foxes and snowy owls. Other than human trappers, no animals prey on Arctic foxes.

Other members of this ecological community include musk-oxen and caribou, which both feed on lichens and other small plants. Mosquitoes, black flies, and a number of migratory birds also belong to the group. Musk-oxen and caribou encounter natural predators outside the tundra ecosystem when they migrate south in search of food.

9.	Sketch a simplified energy pyramid for this ecosystem.
10.	Sketch a food chain for this ecosystem that includes the Arctic fox.
11.	Suggest a reason why there are no tertiary consumers in this ecosystem.
12.	This graph shows how the population of lemmings changes in an area of the high Arctic.

	a.	A graph of the annual changes within the population of Arctic foxes is related to the graph in this question. Determine the years in which you would expect the population of Arctic foxes to peak. Support your answer.
	b.	No one really knows the reason for the four-year cycle within the lemming population. One theory has to do with the effect that the lemming population has on the available vegetation. Describe a possible mechanism for this theory.

13.	Identify organisms that would be examples of mutualism, competition, and parasitism.
14.	The low temperatures of Arctic soils mean that the rate of decomposition is very slow. This, combined with the high water content of ground in the summer, means that much of the tundra is covered in peat bogs or muskeg.

	a.	Concisely explain whether the tundra is considered to be a sink or a source for carbon.
	b.	If global warming occurs, explain how your answer to question 14.a. will change

Use the following information to answer question 15.

Three people gather for lunch. Here’s what each person eats.

The first person eats a piece of chicken. The chicken was fed only plant material.
The second person eats a vegetable salad. The salad contains no animal products.
The third person eats tuna from a tin. The tuna was a high-level predator in its ocean environment.

For the purposes of this question, assume that this one meal allows you to categorize the ecological role and trophic level for each person.

15.	a.	Describe each person’s ecological role.
	b.	Determine the trophic level for each person.
	c.	In reality, you can’t accurately classify a person’s ecological role based on just one meal. Explain why most people would be classified as omnivores. Refer to the food in a typical lunch to support your answer.
	d.	Concisely explain why it is not possible for someone at the lunch to have the ecological role of a producer.
16.	Use an energy pyramid to explain why it would be very rare for an ecosystem to have a sixth or seventh trophic level.

Use the information on the right to answer questions 17 to 21.

17.	Identify which type of organism assembles complex organic compounds from elements and simple compounds. Support your answer by providing two examples and by describing the process by which this happens.
18.	Identify which type of organism feeds on other living organisms as its source of essential elements and compounds. Support your answer by providing three examples.
19.	Identify examples of micro-organisms that feed on dead and decaying organic matter as their source of essential elements and compounds. Support your answer by providing two examples.
20.	Consider your answer to question 19. Micro-organisms that feed on dead and decaying organic matter return simple compounds to the soil, air, and water. Which group of organisms uses these simple compounds? Support your answer by providing two examples.
21.	Describe the carbon cycle in terms of this four-step process.

22.	You learned earlier in Chapter 1 that cowbirds lay their eggs in the nests of other birds. These other birds then unknowingly raise cowbird chicks at the expense of their own young, who usually starve or are kicked out of the nest by the larger and more aggressive cowbird chicks. Originally, cowbirds were found on the prairie landscape because they followed bison herds. Cowbirds prefer open spaces to dense forest.
	a.	Describe how the fragmentation of the boreal forest habitat could allow the population of cowbirds to expand their range farther north.
	b.	The fragmentation of the boreal forest habitat has reduced the number of songbirds that prefer the habitat of the forest interior to that of the forest’s edge. This is because fragmentation creates more edge habitat. Concisely explain why there are also drops in the populations of songbirds that prefer edge habitat in forests where agricultural expansion has fragmented habitats.
23.	Late one summer, ecologists discovered that fish were dying in a stream running through some farmland where nitrogen fertilizer was used to improve crop growth. Suggest an explanation for these events.
24.	Compare and contrast the relationships of predation and parasitism.
25.	Use your knowledge of the energy pyramid to describe the advantages to global ecosystems if more people switched to vegetarian diets.

Use the following information to answer questions 26 to 28.

Locate the video clip called “Career Profile: Rehabilitating Injured Wildlife” on the Science 20 Textbook CD. Play the video. Use the information provided to answer the following questions.

26.	Define the word raptor. Support your answer with examples.
27.	Describe the biomagnification of DDT through the food chain, and outline the resulting negative impact on the population of peregrine falcons.
28.	Describe the potential impact on an ecosystem if the population of raptors within that ecosystem begins to decline.

Ecological Footprint Calculator

In order to live, people consume natural resources for food, transportation, and housing. How much biologically productive land and water is required to provide you with the resources you consume and to absorb the wastes that you generate? The answer to this question is called your ecological footprint.

The ecological footprint is measured in global hectares or hectares of biologically productive space with world average productivity. In 2001 it was estimated that there were 2.3 billion global hectares of biologically productive water surface, made up of ocean shelves and fresh water. At the same time, there were 9.0 billion global hectares of biologically productive land, made up of crop land, grazing land, forest land, and built-up land. Note that the total of 11.3 billion global hectares of biologically productive area on Earth does not include deserts, ice caps, and deep oceans.

The average number of global hectares available for each person is determined by dividing the total number of biologically productive global hectares on the planet by the total number of people. Using data from 2001, the world population was 6.15 billion people, so the average is about 1.8 global hectares per person. Even though this is an estimate—based on many approximations—it is a very useful indicator both for charting trends over time and for comparing the demands put on Earth by people living in different countries.

How does your footprint compare to this value? Are you taking more than you should? You can determine answers to these questions by using the Internet to find an ecological footprint calculator. The ecological footprint calculator is simply an online questionnaire that uses your responses to produce a rough estimate of your ecological footprint.

If you use the key words ecological footprint calculator and Canada, you should be able to use the Internet to find an ecological footprint calculator.

29.	Determine your ecological footprint in global hectares.
30.	How many times larger is your ecological footprint than the global value of 1.8 global hectares? If everyone lived like you, how many planet Earths would it take to support the world’s population?
31.	Return to the ecological footprint calculator. Experiment to see what lifestyle changes you can make to lower your ecological footprint.

Chapter 2 Review Questions

Knowledge

1.	Describe the process of primary succession.
2.	List four examples of disturbances that could cause the process of secondary succession to begin.
3.	Explain two ways in which the process of secondary succession differs from the process of primary succession.
4.	Explain the difference between an open population and a closed population.
5.	Define carrying capacity.
6.	Use a labelled graph to describe the exponential growth of a population.
7.	Use a labelled graph to describe a population that has reached its carrying capacity.
8.	An owl is well adapted to a nocturnal hunting lifestyle. Explain how each of the following traits is an adaptation that makes the owl a more successful hunter.

	a.	the ability to fly	b.	a sharp beak and talons
	c.	huge eyes	d.	feathers that muffle the sound of flying

9.	What are the three main concepts of Darwin’s theory of natural selection?
10.	Define fitness as it applies to biology and the theory of natural selection.
11.	Define mutation. Compare how mutations can be beneficial, harmful, or neutral.
12.	Many people are reluctant to accept Darwin’s theory of natural selection. Suggest a possible reason for this reluctance.
13.	Explain how the finches that Darwin studied on the Galapagos Islands provided evidence for his theory of natural selection.
14.	List a disadvantage and an advantage of reproducing asexually.

Applying Concepts

Use the following information to answer questions 15 to 17.

The Beavers of Tierra del Fuego

Tierra del Fuego is a large island at the very tip of South America. Its closeness to Antarctica means that the climate is much cooler than most of South America. There were 25 pairs of Canadian beavers introduced to the island in 1946 to create a fur industry for the local people. Unfortunately for the people—but perhaps fortunately for the beaver population—the demand for fur coats dropped. By 1966 there were an estimated 2500 beavers on the island, by 1986 there were 30 000, by 1998 there were about 50 000 beavers, and some biologists currently put the estimated number of beavers at close to 125 000. There are more beavers living on Tierra del Fuego than there are people in its major cities.

The exploding beaver population has started to cause significant environmental damage. Beavers cut down stands of 100-year-old trees in weeks. This reroutes streams to cause an interruption of trout migrations, and it floods forests and roads. As a result, there is significant concern that some members of the Tierra del Fuego beaver population will find their way to the mainland of South America and cause similar problems.

15.	Describe what conditions exist on Tierra del Fuego that permitted the exponential growth of the beaver population.
16.	Identify similarities between the beaver situation in Tierra del Fuego and Australia’s rabbit situation.
17.	Describe differences between the rabbit situation in Australia and the beaver situation in Tierra del Fuego.

Use the following information to answer question 18.

Cold Adaptations

Canada’s Arctic region is an example of a habitat where the extreme cold presents a huge survival challenge. The other big challenge is that snow melts in the short spring and summer. This means that white-coloured animals lose the advantage of camouflage.

To cope with these harsh environmental obstacles, Arctic organisms have acquired several adaptations. Some organisms, such as caribou or humpback whales, only spend summers in the Arctic and migrate to warmer winter climates. Most organisms have thick layers of fat, called blubber, fur for insulation, and tiny ears to reduce heat loss. Some animals—such as the Arctic hare, Arctic fox, and a bird called a ptarmigan—are pure white in winter and brown or grey in warmer months to stay camouflaged in their changing surroundings.

18.

A polar bear is an example of an organism that has adapted well to the cold Arctic. It’s a carnivore that eats primarily seals. Polar bears usually hide and wait near breathing holes in the ice to capture the seals when they come up for air. How do the following polar-bear adaptations help them survive in their icy environment? Complete the table.

Adaptation	Reasons For Advantage
slightly webbed toes
white fur
a thick layer of fat and black skin underneath fur
female polar bears hibernating in dens with cubs until spring
ability to stand up on hind legs
covers its black nose when stalking a seal

19.	The climax community for Alberta’s boreal forest is mainly coniferous trees, like spruce and pine. When these evergreens drop their needles and the dead needles decay, they cause the soil to become acidic. Coniferous seedlings grow best in acidic soils, whereas other types of plant organisms—like grasses—have difficulty growing in acidic soil.
	a.	How is this strategy advantageous?
	b.	How might this strategy affect succession in the boreal forest?

Use the following information to answer questions 20 to 22.

The force of Mount St. Helens’ explosion in 1980 caused plant and animal communities to be destroyed in much of the area around the volcano. Lava and ash hardened into solid rock over the area’s soil. Biologists selected a small sample area and recorded the numbers and types of plant species growing in that area five years after the volcanic eruption. The biologists prepared a bar graph of their results.

20.	Is this disturbed area around the volcano going through the process of primary succession or secondary succession? Explain your answer.
21.	Draw three labelled bar graphs that would represent the likely numbers and types of species in the same area if biologists came back to record data 50 years, 100 years, and 200 years after the explosion.
22.	Why would it be unlikely for you to see an equal number of each type of organism in the sample area?

Use the following information to answer questions 23 to 25.

Kristy is a scientist studying two different species of insects. These insects are considered to be garden pests because they eat cabbage and lettuce. She starts with five male insects and five female insects of each species in two separate terrariums. Kristy labels these Terrarium #1 and Terrarium #2. She places a dish of water and 3 kg of a lettuce and cabbage mixture in each terrarium at the beginning and at the end of week one. Kristy records the number of insects in each terrarium over a period of seven days.

Day of Experiment	Number of Insects in Terrarium #1	Number of Insects in Terrarium #2
1	10	10
2	12	22
3	14	41
4	15	80
5	17	163
6	17	330
7	20	8

23.	Sketch a graph of the two populations by using Kristy’s data.
24.	Describe and compare the two populations. Use biology terms from Chapter 2.
25.	How would the results differ if both types of insects were placed in the same terrarium for the study?

Use the following information to answer questions 26 to 28.

Sickle cell anemia is a disease that results from a mutation. This mutation affects the red blood cells that carry oxygen. The mutation can be passed onto offspring. Carriers of sickle cell anemia have difficulty obtaining oxygen—this causes fatigue and blood flow complications. Figure D2.50 compares the red blood cells of an individual afflicted with the disease and a person who does not suffer from the disease.

Malaria is an infectious parasite carried by mosquitoes in warm countries. Untreated malaria causes rapid death. The malaria parasite lives in red blood cells but cannot infect cells that are sickled due to sickle cell anemia.

Figure D2.50: A normal cell and a sickle cell are highlighted.

26.	After looking at the diagram comparing the sickled red blood cell to the normal red blood cell, explain why sickle cell anemia makes the sufferers so ill.
27.	Hypothesize why sickle cell anemia is found in greater numbers in populations where malaria is found.
28.	What environmental change would cause a reduction in the number of individuals born with sickle cell anemia?

Use the following information to answer question 29.

Monkeys found in South America and Central America are called New World monkeys. They differ from the Old World monkeys of Africa and Asia because their noses are broad and flat with the nostrils facing outwards. Many New World monkeys have a prehensile tail that can wrap around a branch and support the animal’s weight as it hangs—this tail acts like a fifth limb.

29.	Use Darwin’s theory of natural selection to explain how the New World monkeys developed a prehensile tail.

Use the following information to answer questions 30 and 31.

August Weismann was a German experimental biologist who, in 1893, was investigating Lamarck’s ideas of acquired characteristics. Weismann cut off the tails of 22 successive generations of mice and looked for offspring that had shorter tails or no tails at all. Since the offspring did not have shorter tails, the results of his experiment did not support Lamarck’s ideas.

30.	Explain why the trait of not having a tail is not passed along to the offspring.
31.	Why is it still reasonable to study Lamarck’s ideas in spite of his incorrect conclusions?

Unit D Review Questions

Complete the table by comparing the processes of primary and secondary succession.

Description	Primary Succession	Secondary Succession
relative speed of process
starting conditions
events causing process to begin
resulting community

2.	Match each definition with its correct term from the following list.

a.	the total number of certain species that occupies a particular habitat at a particular time	doubling time exponential growth J-curve closed population open population carrying capacity S-curve population
b.	a distinctive shape of a graph for a population that is increasing and growing exponentially
c.	the amount of time it takes for a population to double in size
d.	a group of organisms that exists in a natural setting where births, deaths, immigration, and emigration all affect population numbers
e.	a rapid rise in population caused by ever increasing numbers
f.	the maximum number of individuals sustained for an indefinite period in a given environment
g.	a group of organisms existing in an artificial setting where immigration and emigration are not permitted and numbers are only affected by births and deaths
h.	a distinctive shape of a graph for population limited by factors such as disease, competition, and famine

Complete the following table of adaptations.

Type of Adaptation	How It Makes Organism More Successful	Example of Organism with Adaptation
speed	easier to catch prey and escape predators	cheetah or pronghorn
camouflage
bright colours
sharp spines
produces poison
thick fur or hair
horns or antlers

Complete this table by filling in the contributions that each scientist/researcher has made to the field of biology.

Researcher	Scientific Contribution
Malthus
Lamarck
Darwin

5.	Match each statement with its correct term in the following list.

a.	This takes place because more organisms are produced than can survive and only the organisms that are best suited to the environment survive to reproduce.	theory of evolution theory of natural selection fitness selective breeding gene mutation asexual reproduction
b.	This idea is that the nature of a population gradually changes form over geological time.
c.	Human-directed change is caused in a population as a result of breeding organisms that only have characteristics desirable to the breeder.
d.	This produces identical offspring, called clones, from a single parent cell without first sharing genetic information with another organism.
e.	The reproductive success of an organism is not a measure of an individual’s strength, speed, or health, although this may influence it.
f.	This is a change in the genetic instructions.
g.	This basic unit of inheritance is passed down from parent to offspring.

Close to where you live, a strip mine was started 100 years ago. The miners removed all the soil and exposed the raw bedrock as they removed the mineral ore. The soil and much of the broken rock were trucked away to be used for construction materials. The miners worked progressively outward from a central point over a period of 50 years to create a huge, bare, circular area. Imagine that you visit the site and make some observations. Make a sketch to show the following.

	a.	What type of organisms would you expect to find at the centre, or oldest, part of the mine?
	b.	What type of organisms would you expect to find at the outer edges, or youngest part, of the mine?
	c.	What type of organisms would you find in the surrounding area that was not mined?

Use the following information to answer questions 7 to 10.

Predators like wolves, cougars, and coyotes lived in the area with the elk until it was made into a game preserve in 1925. After 1925, the area was fenced in and predators inside the preserve were completely eliminated through hunting.

7.	What effect did the predators have on the elk population prior to 1925?
8.	Predict what happened to the elk population after 1925 when the area was fenced in and predators were removed.
9.	As illustrated in the graph, state one possible reason for the elk population’s decline after 1945.
10.	Infer what action the park biologists could have taken in 1955 to re-establish a more natural balance to the elk population.

Use the following information to answer question 11.

Hot Adaptations

Deserts and other arid regions are difficult habitats to live in because water is so scarce. Deserts can be extremely hot in the day, but because there is little water to absorb and hold the heat, they can also be freezing cold at night.

Desert animals must conserve water and cannot afford to sweat to cool themselves because it would waste too much water—instead, they have developed other adaptations. Many animals sleep in cool burrows during the day and are active only in the mornings and evenings when the temperature is moderate. Desert creatures are usually small with short fur or thin fur and large ears or wrinkles to give them an increased surface area from which to lose heat.

11.

A camel is an example of an organism that is perfectly adapted to the desert. How do the following camel adaptations help it to survive in the desert environment? Complete the table.

Adaptation	Reasons for Advantage
two sets of long eyelashes
wide, padded feet
nostrils that can open and close
a hump located on its back that is a reservoir for fat
thick, tan-coloured fur
a tough mouth and strong teeth

12.

Hypothesize why so many plants that first colonize in open areas of secondary succession might have sharp thorns, barbs (like thistles or stinging nettles), or a noxious taste.

13.

Some scientists predict that as human populations grow, freshwater resources will become an increasingly important export for Alberta. A pipeline to move this water could be built that would run directly from Alberta to dry cities in the United States, such as Los Angeles and Las Vegas. Justify the concerns you have regarding the possible export of fresh water from Alberta to the United States.

Use the following information to answer questions 14 to 21.

A biologist is studying the habitat of a small, isolated Arctic island. The island has populations of carnivorous Arctic foxes, a herbivorous bird called a ptarmigan, and a few insects in the summer. Because of the extreme wind, this island is much colder than the mainland. The only vegetation that grows well are small shrubs, lichens, and grasses.

14.	List the abiotic factors that may affect survival on the island.
15.	List the island’s biotic factors.
16.	Describe a relationship that may exist on the island.
17.	Sketch a likely food chain for the island.
18.	Sketch a likely energy pyramid.
19.	Explain why the Arctic fox is white/grey.
20.	Suppose hunters kill island Arctic foxes to the point of extinction for their valuable, thick, white pelts. How would this affect the population of remaining island species?
21.	A hunter’s campfire gets out of control and burns a large section of vegetation on the island.

	a.	What form of succession would take place following the fire?
	b.	How does fire affect the carbon cycle?

Use the following information to answer questions 22 to 28.

A recent study suggests a link between global warming and the predator-prey relationship of the Canadian lynx and the snowshoe hare. Scientists found that the fluffy snow from cold winters causes the lynx to sink into the snow, while the hare can escape more easily with this type of snow. Warmer winters melt and thin the snow. This provides an advantage for the lynx. Potential changes in the ecosystem’s climate due to global warming may affect normal cycles of the predator-prey relationship between the lynx and hare. The main herbivore in the ecosystem is the snowshoe hare. The lynx feeds almost exclusively on the hare.

22.	How would a reduction of the hare population affect the lynx population?
23.	How would a reduction of the hare population affect other ecosystem populations?
24.	Other than predation by the lynx, what other factors may affect the hare population size?
25.	Sketch the population change for the hare if the lynx population is decimated by disease.
26.	The snowshoe hare’s fur colour changes from white in the winter to brown in the spring and summer.

	a.	What is the advantage of this change?
	b.	Use the theory of natural selection to describe how the hare developed two fur colours.

27.	The global warming that benefits the lynx is linked to excessive amounts of carbon dioxide being released into the atmosphere. Relate three activities that add carbon dioxide to the atmosphere.
28.	Global warming has also caused hot, dry summers with several resulting forest fires. A biologist was surprised to see that the numbers of both hares and lynxes were greater in these burned-out areas a few years after the fires than they were in thick stands of coniferous trees.

	a.	Explain why hare and lynx numbers would be higher in these recently burned-out areas.
	b.	Predict the implications of human intervention that prevents future forest fires in the area.

Use the following information to answer questions 29 to 31.

A particular weed has been infesting crops in nearby fields. The weed has also spread into pastures and natural meadows, where it has had a negative effect on the native plants and animals. You are asked to conduct a field study to better understand this weed and the conditions that support its growth.

29.	Infer specific tests you will want to carry out to determine what abiotic factors affect the weed’s survival.
30.	Design an experiment in which you change one of the abiotic factors identified in question 29. Determine the impact of this change on the weed’s growth.

	a.	List the manipulated, responding, and controlled variables.
	b.	Describe the procedure.
	c.	Predict the expected results. Explain why you expect these results.

31.	A herbicide manufacturer studied the effectiveness of four of his herbicide spray products in terms of killing the weed. A crop was divided into five equal sections. Four of these sections was each sprayed with one type of herbicide.

	a.	Why was the fifth section not sprayed?
	b.	What is the manipulated variable for this experiment?
	c.	What is the responding variable?
	d.	List three controlled variables that would ensure accurate results.

32.	Mosquitoes can be so annoying that it’s tempting to wish they could somehow be completely eliminated from the environment. Comment on the possible negative consequences of removing mosquitoes from the biosphere.

Use the following information to answer questions 33 to 38.

The Biosphere II project was a huge contained-dome structure built in the Arizona desert. It was designed to simulate the processes of a natural ecosystem. More than 3800 species of plants and animals, including four male and four female scientists, were sealed in and meant to live there for one year. The scientists sealed inside were to study the interactions in the artificial environment that they built. In this closed system, all materials were to be recycled and no outside materials were to be brought in.

Despite careful planning and monitoring, carbon-dioxide levels inside the dome continually increased and air had to be pumped in before two months had elapsed. The failure of the project demonstrated a lack of a complete scientific understanding of ecosystems.

Imagine that you have been hired as a consultant to help design an improved self-contained habitat for humans to live off Planet Earth, on an orbiting space station, or on another planet like Mars.

33.	Identify essential organisms you would add to the environment, along with the people living there. Explain why you chose these essential organisms.
34.	Sketch a food web for the organisms you selected.
35.	Describe several important considerations you would incorporate into the habitat’s design.
36.	Explain how you would ensure that levels of carbon, oxygen, nitrogen, water, and wastes were maintained at appropriate levels.
37.	If the populations in your biosphere are isolated for a long period, how might this affect them from an evolutionary point of view?
38.	People already have a self-contained habitat on Earth.

	a.	How is your artificial environment similar to Earth?
	b.	How is your artificial environment different from Earth?
	c.	Given the challenges involved in creating a second habitat for humans, what does this suggest about people’s stewardship of their current habitat?