Chapter 42 Organisms in Their Environment

Chapter 42 Organisms in Their Environment

Name ______Date ______Hour ___

AP Biology Ecology Study Guide 2016

Please read the following chapters in the ecology unit and answer the questions that correspond to the sections. Please write your answers in a word/google doc and email them or write them on a separate piece of paper.

Chapter 42 – Organisms in their Environment

Chapter 43 – Populations

Chapter 44 – Ecological and Evolutionary Consequences of Species Interactions

Chapter 45 – Ecological Communities

Chapter 46 – The Global Ecosystem

Chapter 42 – Organisms in their Environment


  1. Identify three biotic components found in most forest ecosystems.
  2. Identify three abiotic components found in most forest ecosystems.
  3. Give one similarity and one difference between the bacterial community of the human gut and the bacterial community of a forest community.
  4. Explain three benefits that humans gain from “hosting” the microbial community of the human gut.


Climate diagrams summarize the temperature and precipitation data for a localized area. Answer questions 5-8 using the data in the following climate diagrams.

climate diagram jpg

  1. Select the diagram (A, B or C) that best represents climate near the equator and explain your choice.
  2. Select the diagram (A, B or C) that represents the latitude 30 degrees, where there is typically a high rate of evaporation from the surface, and dry, warm air sinking to the surface; and explain what type of biome would be found here.
  3. Select the diagram (A, B or C) that best represents a location that would have the longest growing season and explain your choice.
  4. Diagram C includes varying precipitation during the year. Select the month with the least precipitation and discuss why this reduction occurs at that time. Also suggest a biome type that might be found in a region with this pattern.
  5. Organisms’ activities are affected by interactions with abiotic factors. Explain how each of the factors below could affect the behavior and health of the following marine organisms:

Coral Reef / Fish / Sea Otter
Nutrient availability (less and more)
Temp. Change from 72 to 65 degrees
Salinity change from 32 ppt to 25 ppt
A significant pH change from 8.18 to 8.07


  1. Explain the term biome and discuss how biomes are defined. Describe the type of biome you live in, linking your description to the definition of that biome.
  2. Discuss whether or not the human gut can be considered a biome, and indicate your perception or how small the smallest biome can be.


  1. What is Wallace’s line?
  2. What kinds of barriers might limit the dispersal of terrestrial species? Or aquatic species?


  1. Identify two human activities that have altered ecosystems. For each, describe how humans have altered the ecosystem and the effects of the alteration on biodiversity.

42.6 – no questions

Chapter 43 - Populations


  1. Identify 3 populations (plants and/or animals) that are actively managed by humans. For each, identify two factors in their environment that affect its abundance.


  1. What factors other than birth and death rates affect the size of a population?

Below is a graph showing how densities of acorns, rodents (mice and chipmunks), and the black legged tick population vary over time in an oak forest of the state of New York.

  1. Describe the possible relationship between acorn and rodent densities.
  2. Describe the possible relationship between rodent and tick densities.
  3. Ticks are a parasite relying on blood meals to reproduce. Explain how physical features such as rainfall could influence their population.
  4. For the year 2000, calculate the number of ticks in the forest if the forest is 50 square kilometers in size.
  5. Identify an abiotic and a biotic factor that also could influence the population fluctuations seen in the figure.

The Life Table shows the survivorship and fecundity for all (n=210 hatchlings) the Cactus Ground Finches born in 1978 on Isla Daphne in the Galapagos archipelago.

  1. Identify the age range when the ground finches in this study were reproducing at their highest rate.
  2. Survivorship at age X, is the proportion of the original cohort that survived to age X. Calculate how many birds did not make it to one year of age.
  3. Explain why increased rainfall in 1983 is associated with increased fecundity.
  4. Fecundity is the average number of young per female. Assume that one-half of the population is female. Calculate the number of young born in 1983.
  5. Assume that a population of 25 women and 25 men, all aged 21 years old, colonizes a previously uninhabited island. Twenty babies are born the next year. In the space below, write in possible life table values for these twenty babies.

Year / Age / Survivorship / Fecundity
1 / 0 / 1.00 / 0.00
  1. Explain the survivorship and fecundity values you gave in the Life Table above.


  1. Explain why populations cannot grow multiplicatively for extended periods of time.
  2. Explain why human offspring continue to grow over a long period of time.


  1. Sidewalks can easily divide an area into small meta-populations for small organisms such as snails. For each of the barriers below, pick one organism that might be limited in its distribution due to that indicated barrier, and explain why you choose it.
  2. Parking lot
  3. Small road
  4. Interstate highway
  5. Housing developments

43.6 – no questions

Chapter 44 – Ecological and Evolutionary Consequences of Species Interactions


  1. For each of the relationships shown below, mark in the appropriate column if the first species mentioned is affected negatively (-), positively (+), or not at all (0). Do the same for the second species, then write the type of interaction in the third column. The first example is completed for you.

Example / Species 1 / Species 2 / Type of Interaction
American bison feeds on grasses / + / - / Consumer Resource
Wrasses (small fish) clean the teeth of larger fish
Mosquito feeds on the blood of a deer
Bread mold secretes penicillin that kills bacteria in the local area which generally have little to no effect on the mold
A cactus wren builds a nest in a cholla cactus without affecting the cactus
A hawk captures a small squirrel for food
A rabbit rests in the shade of a small bush
Deer create a trail through a forest where they routinely travel
Plovers (a bird) remove insects from the backs of large animals
  1. Explain how predation is different from parasitism.


  1. In a forest ecosystem, foxes prey on small mammals including rabbits and mice. Explain why foxes are unlikely to consume all of the rabbits, causing their extinctions.
  2. Explain what happens when two different species compete for the same resource in the same location at the same time.


  1. Fitness in the biological sense is not how fast you can run a mile or how many push-ups an athlete can perform. Define the term fitness in the evolutionary sense and give an example of fitness.
  2. Identify three ways that introduced species are inadvertently introduced to new areas.

Chapter 45 – Ecological Communities


32. Define an ecotone and give an example.


33. Define succession


34.Frequently after disturbances, such as a tree falling down or a fire, an ecosystem will go through a predictable succession of changes. But the original community is not always restored. Explain why.

Below is a food web found in the grasslands of Yellowstone National Park. Use the food web to answer the following questions.

35. Briefly describe what would happen if each of the following groups were removed from the park. Limit your answers to two trophic levels.

  1. coyotes
  2. all primary producers
  3. all consumers
  4. discuss two possible consequences of adding a new primary consumer, one that feeds only on grasses, to the park.
  5. Explain why there are fewer high-level consumers (wolves and weasels) than primary consumers in Yellowstone Park.


36. Explain how each of the following abiotic factors can affect the stability of populations.

  1. water
  2. nutrient availability
  3. availability of nesting materials and sites

37. Explain how each of the following biotic factors can affect the stability of populations.

  1. food chains and food webs
  2. species diversity
  3. population density
  4. algal blooms

38. Choose one human impact below and discuss how the impact accelerates change at local and global levels.

  • Logging
  • Slash and burn agriculture
  • Urbanization
  • Monocropping
  • Infrastructure development

39. Choose one item below and discuss how introduced species can exploit new niches free or predators or competitors while devastating native species.

  • Dulch elm disease
  • Potato blight
  • Small pox

45.6 – no questions

Chapter 46 – The Global Ecosystem


40. Identify one reason why NPP is higher in the equatorial regions.

46.2 – questions


41. Complete the table below for each of the three major biogeochemical cycles. Sinks are the locations where the nutrient is inaccessible for long periods.

Cycle / Fluxes / Pools / Sinks

42. Excess nutrients (nitrates) running into a body of water can create an algal bloom. Explain how the overabundance of algae can lead to anoxic zone (no dissolves oxygen) in the body of water.

43. Although nitrogen gas (N2) is approximately 78% of the Earth’s atmosphere, it is very often a limiting nutrient in many ecosystems. Explain why we need to constantly apply nitrogen as fertilizer to agricultural fields, despite its abundance in air.



Calculate the percent increase of carbon dioxide in the atmosphere in 2010 compared to the amount present in 1980.

45. Carbon dioxide is not the most potent greenhouse gas, yet it is the one most often discussed. Explain why.

46.5 and 46.6 no questions

Radjewski 2016