study island: Carrying Capacity
A forest ecosystem located in the northeastern United States currently contains 35 black bears. The ecosystem contains enough energy to support 42 black bears, enough water to support 54 black bears, and enough minerals to support 64 black bears. Assuming that this accounts for all of the resources needed by black bears in this ecosystem, how many additional black bears could the ecosystem support?
7 additional black bears
The red squirrel is a species of tree squirrel that can be found in parts of Europe and Asia. In an experiment, a researcher introduced small populations of red squirrels to two different ecosystems at the same time. The graph below shows the red squirrel population in both ecosystems over three years. Which explanation(s) could account for the different carrying capacities of the two ecosystems?
- The nature reserve may be much larger in area than the city park. -The number of trees in the city park may be limited by humans. -Increased human activity in the city park may disrupt mating opportunities.
What will most likely happen in an ecosystem if the population of one species grows unusually fast?
Another species that eats the same food will decrease in population.
In January, a small number of eastern cottontail rabbits were introduced into Red Forest. The population curve of the rabbits is shown below. According to the graph, the population of the rabbits increased rapidly at first, then leveled off in late March.Which of the following is the most likely explanation for why the population of eastern cottontail rabbits did not continue to increase rapidly?
As the population of eastern cottontail rabbits in Red Forest increased, food resources became scarce
A biologist studying alpine wildflowers notices that two populations of similar species are able to occupy the same niches. However, species A is mostly found at lower altitudes, while species B is mostly found at higher altitudes. What has most likely caused the realized niches of these two wildflower populations to be smaller than their fundamental niches?
Competition has restricted the ranges of both species.
Scientists have monitored a population of black bears in a temperate forest. The current population size is 400, and the forest's carrying capacity for black bears is 640. The scientists estimate the bears' population growth rate, in individuals per year, through the model below. In the model, N represents the population size in each year.The scientists predict that the bears' population will increase to 640 within the next five years. According to the model, what will happen to the population's growth rate during this time?
It will decrease to 0 as the population reaches its carrying capacity.
Natalie is studying a population of Eastern Cottontail rabbits inhabiting a forest ecosystem. The population size of the rabbits has held steady for many months, but a wildfire has recently destroyed half of the vegetation that the rabbits use as a main food source.What will likely happen to the Eastern Cottontail rabbit population in this ecosystem?
It will fall sharply at first, then hold steady at a lower level until the vegetation returns.
Reindeer (Rangifer tarandus) live in tundra ecosystems and feed primarily on mosses, lichens, and grasses. As average temperatures in the Arctic have increased throughout the 20th and 21st centuries, scientists have recorded an increase in the frequency of rain-on-snow (ROS) events in tundra ecosystems. These events, in which rain occurs immediately after snowfall, can result in impenetrable snowpacks that enclose ground vegetation in thick ice.A group of researchers monitored ROS effects on a population of the Arctic reindeer. First, the researchers recorded the population size and frequency of ROS events each year in an Arctic area from 1995 to 2015. These results are shown in graph 1 below. In the graph, a greater ROS value corresponds to a higher frequency of ROS events. Next, using the data from graph 1, the researchers modeled the effects of ROS frequency on population growth for years in which the reindeer population was at low, medium, and high densities. These models are shown in graph 2 below. What do these data suggest about how ROS events affect the carrying capacity of this population of reindeer?
ROS events decrease the reindeer's carrying capacity, and when there is a lot of competition among reindeer, the population reaches its carrying capacity below an ROS frequency of 2.
Earthworms, small insects, and microorganisms live in the soil and break down dead plants and animals. What would happen to an ecosystem if this process was compromised?
The carrying capacity of the ecosystem would be limited.
The red squirrel is a species of tree squirrel that can be found in parts of Europe and Asia. In an experiment, a researcher introduced small populations of red squirrels to two different ecosystems at the same time. One of the ecosystems was a large nature reserve. The other was a city park that was about one-fourth the size of the nature reserve. The graph below shows the red squirrel population in both ecosystems over three years. The graph shows that while the red squirrel population was higher in the nature reserve than the city park, the city park still had a carrying capacity significantly more than one-fourth that of the nature reserve. Which statement could explain why the carrying capacity of the city park was higher than expected?
The city park contains fewer natural predators of the red squirrel than the nature reserve
The soil in an ecosystem has high levels of nitrogen due to the burning of fossil fuels in a nearby industrial area. Scientists predict that these high nitrogen levels will cause a decrease in the rate of decomposition in the ecosystem over time. Why will this most likely cause a decrease in the carrying capacity of the ecosystem?
The ecosystem will be unable to efficiently recycle the remains of dead organisms.
Mistletoe is a parasitic shrub. It extends its root-like structures into a host tree's branches to absorb its water and minerals. Birds spread mistletoe as they feed on the mistletoe's seeds and then deposit them in nearby trees as waste. When a tree has a large amount of mistletoe on it, the mistletoe can take away almost all of the tree's nutrients. An oak tree that is covered in mistletoe is shown below. If mistletoe was introduced into a stable deciduous forest ecosystem, with a large population of oak trees, which of the following describes how the forest's oak trees would most likely change?
The oak trees' population would decrease below what the ecosystem could normally support.
Perching birds, such as cardinals, warblers, and robins, live in trees. Suppose a developer cuts down all of the trees in an area to build a housing subdivision. What would most likely happen to the perching birds living in that ecosystem?
The perching birds would be forced to migrate to another area
A bird species is introduced in an area. The bird species feeds on the same seeds as the bird species that already occupied the area. What is the most likely effect on the original bird species?
The population of the original bird species will decrease.
The graph below shows the size of a population of yeast cells (Candida albicans) over time Based on the information presented in the graph, which statement about this population is most likely true?
The yeast cells are able to reproduce without constraints.
A population of alligators lives in a wetland habitat. Which of these describes a density-dependent factor that could affect this population?
There is a decrease in prey animals in the ecosystem.
Two populations of birds in the same ecosystem begin to compete for the same food resources. What will most likely be the result of this interspecific competition?
There will be a reduction in the population size of one or both species.
After observing the flowers and bees in her garden, a scientist hypothesized that as new flowers bloomed on her rosebush, there would also be an increase in the amount of bees. To test her hypothesis, she recorded the flower and bee population sizes in her garden for 10 weeks during the spring. The averages from her data are displayed in the graph below. The graph provides evidence for which of the following?
When flower populations increase, the carrying capacity for bees also increases.
What can be said about the relationship between species 1 and species 2?
When the population of species 1 increases, the population of species 2 decreases.
The diagram below shows the growth curve of a population of bacteria in a closed system. Which of the following phases in the bacterial growth cycle is represented by the number 3?
steady state
A population of deer and a population of predators that hunt the deer have both reached maximum carrying capacity in the ecosystem they share. Which of the following events would most likely lower the carrying capacity of the deer population?
a decrease in habitat size due to human development or natural disasters
White-tailed deer are considered to be an overpopulated species in the central United States. Which of these events probably contributed the most to white-tailed deer exceeding their carrying capacity?
a decrease in natural predation of white-tailed deer
The amount of life that can be supported in a particular ecosystem is limited by which of the following?
all answers
Which of the following resources can be in limited supply in an ecosystem?
all answers
Which of the following might cause a population to have a high birth rate?
ample mating opportunities sufficient food and water resources
Runoff from a mine site flows into a lake and makes the water acidic. This would
decrease the number of plants and animals living in the water.
Which of the following might cause a population to have a high death rate?
destruction of the population's habitat increased competition with other populations
In any ecosystem, the basic resources that organisms need for survival are always in limited supply. Which of the following is a potential result of these limitations?
elimination of one or more species from an ecosystem, competition among members of an ecosystem for resources
The graph shows the number of weasels in a forest ecosystem over a period of three years. Which event could have caused the population change that occurred at 1.5 years?
exposure to a disease pathogen
The graph below shows the population data for frilled lizards in an ecosystem. A dingo is a type of wild dog that feeds on frilled lizards. Which segment of the above population curve shows dingos feeding on the frilled lizards most actively?
months 15 to 20
The red squirrel is a species of tree squirrel that can be found in parts of Europe and Asia. In an experiment, a researcher introduced two small, essentially identical populations of red squirrels into two different environments at the same time. The researcher measured a number of characteristics of each ecosystem and summarized his findings in the table below. The graph below shows the red squirrel population in both environments over three years. What limiting factors would have a greater effect on the city park population than on the nature reserve population?
space trees for shelter
Carrying capacity is the maximum number of individuals of a population that a particular ecosystem can support over time. Scientists observing a rabbit population in a North American forest originally calculated the carrying capacity of the rabbit population to be approximately 100 individuals. However, changes in the amount of available resources altered the rabbit carrying capacity in the ecosystem. The table below shows how the available resources and the rabbit population changed over a six-month period. Which of the following best explains the decrease in carrying capacity observed in the rabbit population?
the decrease in the amount of clean water