Check Ins

Which species would most likely represent humans if they were part of this ecosystem?

C

Different species of bumblebee compete for flower nectar in their ecosystem. While the flowers vary in the length of their petals, bumblebees vary in the length of a mouth part called a proboscis. Bumblebees demonstrate a preference for flowers that correspond to the length of their proboscis. Species with proboscises of similar length tend to occupy different areas. Species that live in the same area tend to have proboscises of different lengths. Q: Which of the following best explains the relationship between the different bumblebee species living in the same area?

The bumblebees have undergone niche partitioning due to competition.

Beaked whales feed at various depths, but they defecate at the ocean's surface. Nitrogen-rich whale feces deposited in surface waters supply nutrients for algae that are eaten by surface dwelling fish. Which of the following best predicts what would happen if the whale population decreased?

The surface fish populations would decline due to reduced populations of algae.

In the Arctic Ocean, the predominant primary producers are phytoplankton. Phytoplankton are consumed by zooplankton, which in turn are eaten by codfish. In years when there is more open water (less ice coverage), there are more zooplankton and fish than in years with less open water (more ice coverage). Based on the graph above, the difference is most likely because...

the ice blocks the light, so in years with more ice coverage, there is less photosynthesis by the phytoplankton

The population density at point Q indicates that

the reproductive rate equals the death rate

All of the following are density-dependent factors that limit animal populations EXCEPT

weather

To investigate whether an organism in the study is capable of both photosynthesis and respiration, a comparison of which treatment groups is most appropriate?

I and II

Which of the following statements best predicts the effect of increased cottonwood growth on the food web?

Increased cottonwood growth will provide more resources for cicadas, resulting in an increase in the kestrel population.

A photosynthetic organism would be represented by which species?

A

Which of the following is an example of a density-independent limitation on a population?

At higher temperatures, more tomato plants in a population become infested with nematodes than at lower temperatures.

In some species of bats, adult females regurgitate (bring up food from the stomach) to feed their young. In addition, adult bats regurgitate to feed other adults that have not recently eaten. The adults receiving the food may be unrelated bats who have previously participated in food sharing and are members of the same social group. Scientists claim that sharing among unrelated adult bats increases the fitness of the species. Q:Which of the following best supports the scientists' claim?

Bats that do not find food over a 24-hour period may die, preventing their alleles from being passed on within the social group.

In a study on seed germination of radish seeds, five beakers were set up containing equal numbers of seeds. The beakers were subjected to the conditions indicated in the table below. Q: Germination would be expected to occur first in which beaker?

Beaker 1

Ethylene gas is an organic molecule that serves many cell signaling roles in flowering plants. Which of the following best explains how a positive feedback mechanism involving ethylene works?

Cells of ripening fruit produce ethylene, which activates the ripening response in other fruit cells.

Which of the following describes the mechanism by which a plant stem grows toward light?

Cells on the dark side of the stem elongate more than those on the lighted side.

Which of the following investigations would enable researchers to test the claim that an increased concentration of algae has a negative effect on the number of aquatic invertebrates in the ecosystem?

Counting the number of aquatic invertebrates at different concentrations of chlorophyll a in the water

Which point on the curve in the diagram above best represents the carrying capacity of the environment for the population shown?

E

Ethylene is an organic compound produced by ripening fruits. In a controlled experiment, researchers found that ethylene gas stimulated the ripening process in newly harvested fruits. Which of the following describes the most likely connection between natural ethylene production and fruit ripening?

Ethylene gas is a chemical signal through which ripening fruits trigger the ripening process in other fruits.

The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees?

Eventually the other trees grow taller than the oak trees and form a dense canopy that shades the understory.

Which of the following observations best represents a mutualistic relationship?

Flowers produce nectar that bees gather to make honey, and in the process the bees pollinate the flowers.

Which of the following models best predicts the effect on the ecosystem if a deadly communicable disease is introduced into the wolf population?

Graph A Wolves decrease and Elk increase making an "X"

Researchers studied the diversity of macroscopic invertebrates in different areas of watershed ecosystems. They collected samples from 58 sites along 11 streams in the same geographical area. Their data were classified by stream type and can be found in Figure 1. The stream-type classifications range from the perennial stream type, which always has water, to the intermittent stream type, which is dry for more than nine months during the year. Q: Which of the stream types had a statistically lower macroscopic invertebrate species diversity than the seasonal streams?

Intermittent streams only

Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which ultimately leads to ripening. Q: Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to ripening of fruit?

Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

The human sleep-wake cycle is regulated by melatonin. The synthesis of melatonin is regulated by light exposure (Figure 1). The human body typically develops a sleep-wake rhythm that does not respond quickly to change. Q:Long-term exposure to extended periods of bright light after sunset is most likely to affect a person in which of the following ways? Responses

Melatonin synthesis will be inhibited, and the person will have difficulty sleeping.

Which of the following communities is likely to be most stable?

One with high species diversity

In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1. Q:Which of the following was most likely a direct consequence of the addition of phosphate to the lake?

The amount of energy available to consumers in the lake increased.

All of the following statements about the pyramid of biomass are correct EXCEPT:

The base of the pyramid generally represents primary CONSUMERS.

In a study on seed germination of radish seeds, five beakers were set up containing equal numbers of seeds. The beakers were subjected to the conditions indicated in the table below. Q:The experimental design allows testing of which of the following?

The effects of both temperature and oxygen on germination

As depicted in the diagram, honeybees communicate the location of flower patches to members of their hives with waggle dances that give information about the direction and distance to the flowers. Which of the following statements about how honeybees communicate the position of flower patches is most consistent with the model?

The farther the target flowers from the hive, the longer the waggle phase.

Scientists are studying the two primary vocalizations made by Belding's ground squirrels (Urocitellus beldingi). The trill call consists of a series of medium-pitched notes given rapidly, while the whistle call consists of a single high-pitched note. The objective of the experiment is to determine the function of each vocalization. Recordings of the calls were played to four different groups of squirrels, and the response of each individual squirrel was documented Q: Which of the following correctly identifies the dependent variable and the independent variable for the experiment?

The independent variable is the type of alarm, and the dependent variable is the percent of squirrels responding.

Decades of seal hunting eliminated many fur seal breeding colonies. Since that time, fur seals have recolonized several islands in the Pacific Ocean. Scientists studying the populations of fur seals on three recently colonized islands observed different population growth rates among the three populations. Q: Which of the following best explains the different population growth rates on the recently colonized islands? Responses

The islands differed in the amount of available space for breeding, resulting in higher growth rates on islands with more available breeding space.

Which of the following observations provides the best evidence that photosynthesis occurred in treatment group I

The mean pH of the samples increased after one hour.

Four groups of tomato plants were grown in the same greenhouse under identical conditions. Each group was then placed in a different room, each room having a different color of light, exposed to that single color of light from different directions for one week at a time. After each week, the biologists counted the number of tomato plants in the groups that were showing evidence of phototropism. Q: Which of the following correctly identifies the dependent and independent variables in this experiment?

The percentage of plants showing phototropism is the dependent variable, and the color of the light is the independent variable.

Figure 1 represents the feeding relationships between selected organisms in the Chesapeake Bay. Decades of overharvesting have reduced the populations of both blue crabs and rockfish. However, recent efforts have increased the number of rockfish in the bay. Based on Figure 1, what is the most likely result of the increase in rockfish?

The population of blue crabs will decrease because predation by rockfish will increase.

Scientists studying a wild population of mantled howler monkeys found the average birth rate to be 0.22 and the average death rate to be 0.12. At the start of the study, the population consisted of 13 monkeys. Q: Assuming no immigration or emigration, which of the following best describes the change in population size that will occur over the next year?

The population will increase because more monkeys are being born each year than are dying.

The graph below shows changes in a population of wild sheep that were introduced to the island of Tasmania in the early 1800's. Q:The type of population growth represented by that portion of the graph line enclosed in the bracket is most accurately termed

exponential

The traps of one species of pitcher plant, Nepenthes hemsleyana, do not contain digestive fluid. Instead they provide a suitable place for woolly bats (Kerivoula hardwickii) to sleep. The feces from the bat are released into the trap where nutrients in the feces are absorbed and provide the plant with the nitrogen it needs. Q: Which of the following best describes the relationship between the pitcher plant and the woolly bat?

The relationship is an example of mutualism because both the plant and the bat benefit.

Which of the following best explains the symbiotic relationship between the coral and the algae?

The relationship is an example of mutualism because the coral use sugars made by the algae and provide shelter for the algae.

An overlap in the niches of two species will most frequently result in

interspecific competition

Prairie dogs are small mammals that live in large colonies in burrows in the ground. Prairie dogs that are near their own relatives when a predator approaches are much more likely to issue a warning bark than those that are near unrelated prairie dogs. The prairie dogs that hear a warning bark are more likely to hide in their burrows than to remain above ground. However, the prairie dog that gives the warning bark is putting itself at increased risk of being identified and killed by the predator. QWhich of the following presents the most likely evolutionary explanation for the behaviors described?

The warning bark changes the behavior of the related prairie dogs nearby, allowing the prairie dog's family to have increased survival and reproductive success.

The graph above represents the number of individuals in a population of wolves and in a population of moose observed in the same isolated geographic area over a 40-year period, from 1955 through 1995. Which of the following statements about the two populations is best supported by the information presented in the graph?

The wolves were predators of the moose, which were otherwise reproductively successful.

Yellow-billed cuckoos typically hatch in midJuly. Emerging cicadas are a primary food source for nesting cuckoos. Which of the following best predicts the effect of wildfires on yellow-billed cuckoo populations?

The yellow-billed cuckoo population will decline because the cicadas will emerge before the hatching season begins.

Assume there are 50,000 joules (J) of energy available in trophic level II in the figure. According to the conventional model of energy flow in ecosystems, which of the following statements correctly describes the flow of energy in the system?

Trophic level IV has approximately 500 J of available energy.

Wolves, once native to Yellowstone National Park, were hunted to the point of complete extinction in the park. As a result, the elk population in the park flourished, putting extra demands on the carrying capacity of the park. Many other species, such as certain trees and beavers, were negatively affected by the increase in elk. Years later, wolves were reintroduced into the park. While the elk population decreased after the wolves returned, the beaver and songbird populations began to increase as did the populations of various plant species. Q:Which of the following best explains how wolves are a keystone species in this ecosystem?

Wolves help balance the population sizes of other species, allowing more species to thrive in the wolves' presence than in their absence.