A researcher found that the reproductive success of bumblebees decreased when the population density of honeybees increased. The decline in the number of bumblebees appeared to be a result of competition for nectar.
Which of these research topics would be considered an example of community ecology?
mutualism … parasitism
In tropical forests, there are plants known as ant-plants. These plants host ant colonies. When the ant colony is the species Petalomyrmex phylax, the presence of the ants protects the ant-plants from predation by herbivores. However, the ant species Cataulacus mckeyi takes advantage of the nesting place and nectar the plants provide without affording any protection to the plant. The interspecies interaction between the ant-plants and P. phylax is an example of _____ whereas the interaction between the ant-plants and C. mckeyi is an example of _____.
Two species of cattail in the same genus live at the margins of a lake but at different water depths. If the one that prefers shallow water is removed, the deep-water species occupies deep and shallow water.
Which of the following is an example of interspecific competition?
Some biologists have observed Egyptian plover birds land on the open mouth of a Nile crocodile without being eaten and remove leeches stuck firmly to the crocodile’s gums.
Which of the following is an example of mutualism?
Sea anemones coating the shallow-water coral reefs in Australia feed on fish and shrimp that wander too close to their tentacles.
Which of the following is an example of predation?
Squirrels in the forests of Wisconsin hide away hickory nuts and acorns, which they will eat during the long, cold winter.
Which of the following is an example of herbivory?
Early in the 20th century, the American chestnut population was devastated by a non-native fungal pathogen. It has never recovered.
One of the dominant tree species in the temperate deciduous forest in the eastern part of the United States used to be the American chestnut. Now, the dominant tree species are mixed oak and hickory trees and other hardwood trees. What is the reason for this change?
Grasshoppers are primary consumers.
Consider the following prairie food chain. Tall grass is consumed by grasshoppers that, in turn, are eaten by mice, and the mice are eaten by prairie kingsnakes. Red-tailed hawks prey on mice and prairie kingsnakes. When a red-tailed hawk dies, bacteria, beetles, fungi, and many types of worms help break down the body. Which of the following correctly identifies a trophic level in this ecosystem?
cacti would suffer from increased herbivory
Examine Figure 37.9, which shows a food web. If the snake population were suddenly reduced because of a virus that kills only snakes, we would expect that the population of _____.
a plant community with 12 different species, in which each species consists of only about 100 plants
Which of the following represents a community with the greatest species richness?
a keystone species
Without elephants, some of the grasslands in Africa would eventually become thickets or forests because elephants weed out trees and shrubs. Even though elephants make up a small percentage of the animals living on the grassland, the grassland would eventually cease to exist without them. In this community, elephants are _____.
This community is situated on the banks of the Mississippi River after a rare and widespread flood has occurred. The waters retreated about two months ago.
Which of the following best describes an example of a community experiencing secondary succession?
a tallgrass prairie in Oklahoma
Which of the following ecosystems is dependent on fire?
invasive species
Garlic mustard is a cool-season edible herb brought to North America by European settlers in the 1800s. It has no significant natural enemies in North America. It spreads rapidly. When established, garlic mustard becomes a permanent member of the community, often dominating the ground layer habitat. What term describes garlic mustard in the United States?
energy
What generally flows in one direction through an ecosystem, from producers up through each level of consumers, and is not recycled?
a tropical coral reef
Which of the following ecosystems would probably have the highest primary productivity? Assume that we are comparing similar sizes of each ecosystem.
50 kcal
In an ecosystem where 500,000 kcal of sunlight is available for producers, approximately how much chemical energy will be contained in secondary consumers?
producers
Our current ability to feed the people of the world would improve if people ate a diet that only consisted of _____.
soil
Which of the following is an abiotic reservoir?
the burning of larger amounts of wood and fossil fuels
The main cause of the recent increase in the amount of carbon dioxide in Earth’s atmosphere is _____.
water and phosphorus
Which of the following chemicals can be completely cycled abiotically using only geologic processes?
phosphorus and nitrogen
Correct Which of the following chemicals can lead to heavy algal growth when added to lakes and streams?
nitrite to nitrate
Which of the following bacterial conversions occurs as part of the nitrogen cycle?
nitrogen runoff from Midwestern farms in the United States.
What has been implicated as a contributing factor in the annual summer “dead zone” in the Gulf of Mexico?
deforestation
Soil erosion in Haiti is caused largely by _____.
potentially interacting populations
A community consists of _____.
mutualism
A lichen is composed of two organisms: a fungus and an alga. They depend on each other for survival. The term that describes their relationship is _____.
interspecific competition
When goats were introduced to an island off the California coast, the goats lived in the same areas and ate the same plants as the native deer. The deer population dwindled and finally disappeared. This is an example of _____.
the way the animal fits into its environment
The niche of an animal is _____.
Competition between the two species will be severe.
If the niches of two species are very similar, which of the following is true?
have similar niches
Two species of cuckoo doves live in a group of islands off the coast of New Guinea. Of 33 islands, 14 have one species, 6 have the other, 13 have neither, and none has both. What might best explain this? The two species of birds could _____.
competition
What type of population interaction benefits neither population?
+/+
Mutualism could be expressed by _____.
camouflage
Flounder look like the sea floor. This is an example of _____.
primary consumers
Herbivores are _____.
coevolution
A series of reciprocal evolutionary adaptations in two species is called _____.
parasitic
A tick has what type of relationship with a dog?
increased mortality in monkey species B
A species of malaria-carrying mosquito lives in a forest in which two species of monkeys, A and B, coexist. Species A is resistant to malaria, but species B is not. The malaria-carrying mosquito is the chief food for a particular kind of bird in the forest. If all these birds were suddenly eliminated by hunters, which of the following would be an immediate observable consequence?
autotrophs
Photosynthetic organisms are called _____.
poison ivy
Which of the following is a producer?
primary consumer
When you eat an apple, you are serving as a _____.
fungi and prokaryotes
The main detritivores in an ecosystem are _____.
primary and secondary consumers
Consider this segment of a food web: Snails and grasshoppers eat pepper plants; spiders eat grasshoppers; shrews eat snails and spiders; owls eat shrews. The snail occupies the trophic level(s) of _____.
species diversity
Species richness and relative abundance define the _____ of a community.
whose absence would cause major disruption in an ecosystem
Keystone species are those species _____.
Grass grows on a sand dune, followed by shrubs, and then trees.
Which of the following best illustrates ecological succession?
secondary succession
After clear-cutting, timber companies cannot afford to wait for the long process of _____ to occur naturally; they plant trees right away.
disturbance is inevitable
The current view of succession is that _____.
each existing community changes the environment
Succession of communities occurs because _____.
invasive species
Species that spread far beyond the original point of introduction and cause environmental or economic damage by colonizing and dominating a habitat are called _____.
energy used by primary consumers … energy used by secondary consumers
In an ecosystem, the _____ is always greater than the _____.
organisms are inefficient at converting the energy they consume to biomass
In ecosystems, organisms at the highest trophic levels usually contain less collective biomass than the organisms at lower trophic levels because _____.
This ecosystem could be powered by chemical energy obtained from inorganic compounds.
Review Figure 37.14, a drawing of a terrarium ecosystem. Energy input comes directly from the sun, and it is converted to chemical energy through photosynthesis. Interestingly, an unusual ecosystem can exist in the absence of sunlight. What could be the source of energy?
Community biomass is decreasing.
A study of metabolic rates in a terrestrial community showed that the energy released by respiration exceeded the energy captured in photosynthesis. Which of the following situations is most likely?
primary productivity is the rate at which biomass is produced
The relationship between biomass and primary productivity is that _____.
producers
In general, the biomass in an ecosystem will be greatest at the trophic level comprising _____.
not captured for use by living things
Most of the solar energy that reaches Earth is _____.
radiated from Earth as heat energy
In an ecosystem, almost all of the incoming energy will eventually be _____.
There is not enough available energy to sustain a fifth level.
In any food chain, the top level of consumers is quaternary (fourth). Why are there almost never any fifth-level consumers?
up to a 95% loss of energy
In the transition from each trophic level of the food chain to the next trophic level, there is _____.
It contains the energy captured by photosynthesis.
Which of the following best describes the base of a pyramid of production?
nutrients are recycled, but energy is not
The biggest difference between the flow of energy and the flow of chemical nutrients in an ecosystem is that _____.
contribute to the abiotic reservoir through recycling
The primary role of detritivores is to _____.
Many nutrients come from the soil, but carbon comes from the air.
Local conditions such as heavy rainfall or the removal of plants may limit the amount of nitrogen, phosphorus, or calcium available to a particular ecosystem, but the amount of carbon available to the system is seldom a problem. Why?
carbon dioxide
In the global carbon cycle, carbon flows from heterotrophs to autotrophs in the form of _____.
atmospheric
The phosphorus cycle lacks a(n) _____ component.
nitrogen
Bacteria are especially important in making _____ available to plants.
ammonia
The direct product of nitrogen fixation is _____.
ammonium ions to nitrate
Nitrification is the conversion of _____.
nitrates in the soil
The major source of nitrogen for most nonagricultural plants is _____.
denitrification … bacteria
Atmospheric nitrogen is replenished through the process of _____ by _____.
nitrogen
Some bacteria in the _____ cycle are symbiotic with the roots of legumes.
nutrient enrichment (nitrate and phosphate runoffs from land)
Eutrophication (excessive algal growth resulting in decreased concentrations of dissolved oxygen) in lakes is frequently the direct result of _____.
phosphorus
Various materials necessary for the existence of ecosystems are said to cycle through those systems. Which of these is the primary limiting resource for algae in freshwater lakes?
Sustainability
_____ is the goal of developing, managing, and conserving Earth’s resources in ways that meet the needs of people today without compromising the ability of future generations to meet theirs.
