Ecology II - WEB Practice

Multiple Choice Identify the choice that best completes the statement or answers the question.

____ 1. Density, distribution, and growth rate are characteristics used to classify which one of the following? a. biomes c. limiting factors b. populations d. age structure ____ 2. Which of the following involves a situation in which a density-dependent factor influences a population? a. Several seasons passed during which rainfall was ample, winters were not severe and food for snow hares was in good supply. b. A hurricane severely disrupted a salt marsh and uprooted most of the marsh grass in an estuary. c. A forest fire on the north side of a mountain forced the white-tailed deer from the north side to move into the range of the white-tailed deer on the south side of the mountain, making food more scarce. d. After a heavy rain, pesticides that were applied to a cotton crop to control weevils ran off into a waterway that flows next to a field. ____ 3. On ten acres of native forest there are eight white-tailed deer, seven coyotes, 45 armadillos, and 231 loblolly pine trees. Which population has the highest density? a. white-tailed deer c. armadillos b. coyotes d. loblolly pine trees ____ 4. Which of the following statements is correct? a. Population size of predators increases when their prey is scarce. b. Competition for resources is density-independent when food is plentiful. c. Disease is density-dependent because transmission occurs more easily when a population is large. d. A change in average temperature is a density-dependent factor because fewer organisms can acclimate to variations in temperature. ____ 5. Young adult male chimpanzees look for mates outside their own population. The males then take the females back to their group. Which of the following occurs in females’ original population? a. emigration c. mortality b. immigration d. natality ____ 6. To assess a population’s growth rate, an ecologist must know how many individuals are born, how many died, and how many move away in a given period of time. What else must an ecologist know? a. how many individuals find mates b. how many individuals move in from somewhere else c. how many individuals carry communicable diseases d. how many individuals are young or old ____ 7. You are an ecologist collecting data about the declining growth rate of the critically endangered Philippine eagle. The eagles’ only known population is estimated to have about 350–650 individuals. Which of the following can you assume is zero? a. natality c. emigration b. mortality d. immigration ____ 8. A population’s emigration in one month totaled three individuals. During the same period, immigration was 17 individuals. Natality was 12, and mortality was 26 due to a parasite infection. What was the net effect on the population size? a. –14 c. +12 b. 0 d. +26 ____ 9. The country of Bulgaria has a negative growth rate of – 0.89 percent. The rate of immigration is 0.5 percent and the rate of emigration is – 0.5 percent. How do the birthrate and death rate of Bulgaria compare? a. The birthrate and death rate are equal in value, but they have opposite signs. b. The birthrate has a higher value than the death rate, but they have opposite signs. c. The birthrate has a lower value than the death rate, but they have opposite signs. d. The birthrate and death rate are both zero. ____ 10. What type of succession is most likely to happen in Figure 3-2?

Figure 3-2 a. primary b. secondary c. tertiary d. climax ____ 11. At which stage in Figure 3-3 are the most pioneer species found?

Figure 3-3 a. A c. C b. B d. D

Figure 3-4

____ 12. Look at the graph in Figure 3-4. What does this graph tell us about this species of plant? a. Too much sunlight can hurt them. b. They thrive in a lot of sun. c. Heat is damaging to them. d. They need plenty of water. ____ 13. Which of these species might be classified as a pioneer species? a. ponderosa pine c. aspen b. choke cherry d. lichen ____ 14. Compare primary and secondary succession. What is the distinction between them? a. Primary succession is the sequence of species that become established early in a newly colonized area, and secondary succession is the sequence of species that move in later. b. Primary succession is the establishment of a community in an area with no soil, while secondary succession is the establishment of a new community in an existing ecosystem that was disturbed. c. Primary succession is the establishment of a new community in an existing ecosystem that was disturbed, while secondary succession is the establishment of a community in an area with no soil. d. Primary succession is the sequence of plants that colonize a new area, while secondary succession is the sequence of animals that move in later.

Table 5-1 shows the population sizes for 6 different species in four different areas.

Area Species U Species V Species W Species X Species Y Species Z A 3 7 2 2 2 4 B 0 6 8 0 6 6 C 0 0 2 0 0 2 D 4 3 11 1 6 0

Table 5-1

____ 15. If the four areas in Table 5-1 were the only places in the world to find these organisms, which species most likely faces the greatest chance of extinction? a. Species U c. Species Y b. Species X d. Species Z ____ 16. Which area in Table 5-1 has the greatest biodiversity? a. Area A c. Area C b. Area B d. Area D

Figure 5-3

____ 17. What effect did the loss of species B have on species A and D in Figure 5-3? a. it caused the populations of A and D to decrease b. it caused the populations of A and D to increase c. it caused the populations of A and D to become extinct d. it had no effect on the populations of A and D ____ 18. Examine the graph in Figure 5-3. Which species were not affected by the loss of species B? a. species A, C, and E c. species C only b. species C and E d. species E only Figure 5-4

____ 19. Examine the food web shown in Figure 5-4. What would most likely happen to the organisms in this food web if the robin began to disappear? a. The hawk would be forced to start eating the dragonfly. b. Most of the organisms in the ecosystem would starve and die. c. The terrestrial organisms would starve, but the aquatic organisms would survive. d. There would be an overpopulation of caterpillars, which would kill many elm trees. ____ 20. Examine the food web shown in Figure 5-4. What would most likely happen to the organisms in this ecosystem if the algae began to disappear? a. The bass population would increase. b. All of the aquatic organisms would become overpopulated. c. The dragonfly population would likewise begin to disappear. d. The fox would begin to starve and be forced to emigrate to another area. ____ 21. Examine the food web shown in Figure 5-4. Suppose an herbicide is used to kill some of the algae in this ecosystem. The herbicide does not break down in the environment. Inside the cells of which organism would you expect to find the highest amount of herbicide? a. algae c. elm tree b. cougar d. minnow ____ 22. Examine the food web shown in Figure 5-4. The disappearance of which of the following pair of species would result in the total collapse of the food web? a. algae and dragonflies c. dragonflies and foxes b. algae and elm trees d. elm trees and bass

Short Answer A student grew a yeast culture on sterilized nutrient medium in a closed dish for five days. Each day, she took the same size sample from the dish and placed it on a special slide used for counting microorganisms (see the top half of Figure 4-2). She examined the samples under a microscope and drew the illustrations of her observations over the course of the investigation. Each dot represents ten yeast cells.

Figure 4-2

23. Which graph (A, B, or C in the bottom half of Figure 4-2) best pictures the growth of the student's yeast population? 24. Referring to Figure 4-2, what steps could the student take to ensure the accuracy of her results? 25. In Figure 4-2, how could the carrying capacity of the culture dish be increased? 26. What problem was this student investigating in Figure 4-2? 27. Why did the student use sterilized medium and keep the dish closed? Refer to Figure 4-2.

Figure 3-7

28. What type of succession is illustrated in the ponds in Figure 3-7? How do you know? Essay

Table 4-1

29. Evaluate the data in Table 4-1, and summarize the general trends shown in birthrates and death rates for the years 1900–1950. Include in your summary whether the population is decreasing or increasing and why. Relate the birthrates and death rates. The return of the soldiers from WWII (1945–1947) caused an exception to the general trend in 1950. What is the exception? Explain. Ecology II - Practice Answer Section

MULTIPLE CHOICE

1. ANS: B Populations are members of the same species that live in a certain area. They are often described using measurements of density, distribution, and growth rate.

Feedback A Check on page 92. B You are right! C That's not it. D Try again.

PTS: 1 DIF: Bloom's Level B REF: 92 NAT: LS_4d STA: III.5.3 TOP: 4-1 2. ANS: C Rainfall, weather, and pesticides are density-independent factors in an environment. A forest fire is also density-independent, but the movement of the deer into a population on the other side of the mountain is immigration. This increases the density of the south-side deer causing increased competition for food.

Feedback A Remind yourself of what density-dependent factors are. B Is a hurricane a density-dependent factor? C Correct. Immigration increases density in a population. D Rain and pesticides are not density-dependent factors.

PTS: 1 DIF: Bloom's Level D REF: 94–95 NAT: LS_4d STA: III.5.3 TOP: 4-2 3. ANS: D All of the organisms live on the same ten acres. There are 8 deer/10 acres, 7 coyotes/10 acres, 45 armadillos/10 acres, and 231 trees/10 acres. There are many more trees per acre than any of the other organisms, and so the trees have the highest density.

Feedback A Remind yourself of the way density is calculated. B There are fewer coyotes than any of the other organisms. C See page 92 for help. D This is correct.

PTS: 1 DIF: Bloom's Level C REF: 92 TOP: 4-1 4. ANS: C Disease is density-dependent because when individuals are closer together, disease spreads more easily.

Feedback A Try again. B Read more about competition on page 96. C Correct! D Is this a density-dependent factor?

PTS: 1 DIF: Bloom's Level C REF: 96 NAT: LS_4d STA: III.5.3 TOP: 4-2 5. ANS: A The females’ original population experiences a decrease in population size when the females leave the group. Emigration occurs when members of a population leave a location.

Feedback A Correct! B Are the females leaving their original population or moving in? C Mortality is the death rate. D Natality is the birthrate.

PTS: 1 DIF: Bloom's Level D REF: 97 STA: III.5.3 TOP: 4-3 6. ANS: B The four factors that influence a population’s growth rate are natality (how many are born), mortality (how many die), emigration (how many move away), and immigration (how many move in).

Feedback A Try again. B You're right! C This is not quite right. D Check on page 97.

PTS: 1 DIF: Bloom's Level C REF: 97 NAT: LS_4d STA: III.5.3 TOP: 4-1 7. ANS: D If the population of eagles being studied is the only known population, then immigration of individuals into the population from somewhere else is unlikely.

Feedback A There are probably some birds being born. B Some of the birds are probably dying. C Try again. D Correct!

PTS: 1 DIF: Bloom's Level E REF: 97 NAT: LS_4d STA: III.5.3 TOP: 4-1 8. ANS: B –3 + 17 + 12 – 26 = 0

Feedback A You should subtract the mortality. B Correct! C Immigration is the number of individuals joining the population. D Subtract emigration from the population size.

PTS: 1 DIF: Bloom's Level C REF: 96 NAT: LS_4d STA: II.1.3 TOP: 4-1 9. ANS: C People are not born fast enough to replace the ones who die, resulting in a declining population size, or a negative growth rate. This means that the birthrate has a lower value than the death rate.

Feedback A Check page 101. B Would this result in a negative growth rate? C Correct! D This would result in a population with no change in size.

PTS: 1 DIF: Bloom's Level E REF: 103 NAT: LS_4d STA: II.1.3 TOP: 4-4 10. ANS: B Secondary succession occurs after a fire disturbance.

Feedback A Check definition of primary succession on page 62. B Correct! C Re-read the section on succession and try again. D Check the definition of a climax community on page 63.

PTS: 1 DIF: Bloom's Level A REF: 62–63 NAT: LS_4c STA: III.5.4 TOP: 3-3 11. ANS: A Pioneer species are the first species to appear in a succession.

Feedback A That's right! B There would be some, but not the most, here. C Have a look at pages 62–64 again. D There would be the fewest here.

PTS: 1 DIF: Bloom's Level C REF: 62–64 NAT: LS_4c STA: III.5.4 TOP: 3-3 12. ANS: A As the sunlight increases, the rate of growth slows (it takes longer to grow).

Feedback A True. B How much is "a lot"? C Re-read the axes of the graph. Are we measuring heat? D Does the graph indicate water quantities? PTS: 1 DIF: Bloom's Level C REF: 61 NAT: LS_5e TOP: 3-1 13. ANS: D Only lichens do not require soil.

Feedback A See page 62. B This tree needs soil to grow. C Try again. D Right.

PTS: 1 DIF: Bloom's Level C REF: 62–63 TOP: 3-3 14. ANS: B This is the correct distinction.

Feedback A See pages 62–63. B Good job! C Did you get your definitions in the right order? D Recheck definitions and try again.

PTS: 1 DIF: Bloom's Level D REF: 62–63 NAT: LS_4c STA: III.5.4 TOP: 3-3 15. ANS: B The smallest population sizes face the highest probability of extinction.

Feedback A Look for the smallest populations. B That's correct! C Consider species with the fewest populations. D Consider species with the fewest populations.

PTS: 1 DIF: Bloom's Level C REF: 122–123 TOP: 5-4 16. ANS: A The highest biodiversity is the highest number of species.

Feedback A That's correct! B Think about how biodiversity is measured. C This area has the lowest biodiversity. D There is one higher than this one.

PTS: 1 DIF: Bloom's Level D REF: 116–117 TOP: 5-1 17. ANS: A Both A and D show decreases in population size.

Feedback A That's correct! B You may be reading the graph incorrectly. C Population A is not extinct. D Have another look at the graph.

PTS: 1 DIF: Bloom's Level D REF: 123–128 NAT: LS_4c STA: III.5.4 TOP: 5-6 18. ANS: C Only the population of species C remained steady after the loss of species B.

Feedback A The lines for A and E show changes. B The line for E shows a change. C That's correct! D The line for E shows a change.

PTS: 1 DIF: Bloom's Level D REF: 125 NAT: LS_4c STA: III.5.4 TOP: 5-6 19. ANS: D The robin keeps the caterpillar population in check. Without robins, the caterpillar population could grow out of control and consume too many elm leaves, thus threatening the trees’ health.

Feedback A Dragonflies are not a major part of the hawk diet. B Most of the organisms do not feed on the robin. C Try again. D That's correct!

PTS: 1 DIF: Bloom's Level D REF: 125 NAT: LS_4b STA: III.5.4 TOP: 5-6 20. ANS: C If most of the algae disappeared, the minnows would starve. This would cause the bass to consume more dragonflies since no minnows would be left as a food source.

Feedback A What are the bass eating? B Where does the energy for these organisms come from? C That's correct! D The fox will have other food resources.

PTS: 1 DIF: Bloom's Level D REF: 125 NAT: LS_4b STA: III.5.4 TOP: 5-6 21. ANS: B Due to the process of biological magnification, the concentration of a herbicide increases along with an ecosystem’s tropic levels.

Feedback A Refer to page 126 for more information. B That's correct! C What happens to the accumulation of some pesticides? D Is this a top predator?

PTS: 1 DIF: Bloom's Level D REF: 126 NAT: LS_4e STA: III.5.4 TOP: 5-5 22. ANS: B The algae and the elm trees in the ecosystem serve as direct or indirect food sources for all the other organisms.

Feedback A Dragonflies would not have this effect. B That's correct! C Where does the energy for the system come from? D Bass would not have this effect.

PTS: 1 DIF: Bloom's Level D REF: 125 NAT: LS_4b STA: III.5.4 TOP: 5-6

SHORT ANSWER

23. ANS: Graph C

PTS: 1 DIF: Bloom's Level B REF: 96 NAT: LS_4d STA: I.1.2 TOP: 4-1 24. ANS: Answers may vary. Grow more than one culture and average the results from each; have another student make counts using a second sample of equal size; have other students repeat the investigation and use the average of all the results obtained.

PTS: 1 DIF: Bloom's Level C REF: 92 NAT: IS_1b STA: III.5.3 TOP: 4-1 25. ANS: Answers may vary. Adding more nutrient medium would increase the carrying capacity.

PTS: 1 DIF: Bloom's Level C REF: 98 NAT: LS_4d STA: II.1.3 TOP: 4-2 26. ANS: Answers will vary. The student was comparing the growth pattern of a yeast population to that of other organisms previously studied. PTS: 1 DIF: Bloom's Level B REF: 92 NAT: IS_1b STA: I.1.2 TOP: 4-1 27. ANS: This was to prevent the culture from being contaminated by yeast cells in the air or by other microorganisms.

PTS: 1 DIF: Bloom's Level B REF: 92 STA: II.1.3 TOP: 4-1 28. ANS: Primary succession; the pond area is a natural site that underwent change from its original condition. This could also be secondary succession if the pond was created by humans or beavers.

PTS: 1 DIF: Bloom's Level D REF: 62–63 NAT: LS_4c STA: III.5.4 TOP: 3-3

29. ANS: Answers will vary. The birthrates for the years 1900–1940 have a general trend downward. There were fewer births each decade, except for 1950. The death rates decreased steadily throughout the entire period shown in the table. However, because birthrates are higher than the death rates, assuming immigration and emigration are similar and size, this information indicates that the population is growing. The notable exception in 1950 is that, against the trend, the birthrate jumped dramatically, likely because many men of reproductive age joined the population as they returned from World War II.

PTS: 1 DIF: Bloom's Level F REF: 102 NAT: IS_1f STA: II.1.3 TOP: 4-4