Ecology to merge 22

The largest pool of carbon can be found in

sediments and rocks

Why is there a net flow of carbon from the atmosphere to the ocean?

The lower concentration of CO2 in the oceans as compared with the atmosphere leads to CO2 diffusing into oceans

Before the industrial revolution, the flux of carbon from the terrestrial to the atmospheric pools _______ the flux in the opposite direction. Today, the flux of carbon from the terrestrial to the atmospheric pools _______ the flux in the opposite direction.

Was about equal to; exceeds

DeLucia and colleagues have shown that increasing CO2 has led to increased NPP in a pine forest. If this result can be generalized, it suggests that forests could be a ________ of anthropogenic carbon and thus tend to ________ the greenhouse effect.

sink; offset

Increasing levels of CO2 in the oceans make them _____ acidic. This change affects the ability of marine organisms to form protective shells made up of ______ carbonate.

more; calcuim

Which statement about the global phosphorus cycle is true?

Because of the relatively high metabolic demand for phosphorus is the fixation of nitrogen gas, the rate of the nitrogen cycle is influenced by the availability of phosphorus.

Which statement best describes the effect of occlusion of phosphorus in soils on the flux of anthropogenic phosphorus from terrestrial to aquatic ecosystems?

It minimizes the flux, but that flux still has significant potential for negative environmental effects.

In eutrophic waters, algal growth is ______, leading to ______ decomposition rates and thus ____ levels of oxygen

increased; higher; lower

As nitrogen input increases, ______ remains nearly constant at first and then increases rapidly at higher levels of nitrogen input.

NO3 leaching and soil acidification

Which statement about the soils on the colorado plateau is false?

Humans have had little impact on the soil conditions.

Ho do plants and animals differ in how they uptake nutrients?

Plants take up simple chemicals, which they synthesize into larger molecules; animals take up larger, more complex molecules.

All other things being equal, herbivores generally must consume _____ food than carnivores in order to meet their nutritional needs. The reason is that plant material, per gram of carbon, contains ____ nitrogen than animal material does.

more; less

Chemical weathering of minerals in rocks is an important source of nutrients because it

releases soluble forms of nutrients.

Which of the following best describes the order of soil horizons in well-developed soil (from top to bottom)?

Organic matter, mineral nutrients, clay, bedrock

The atmosphere is composed of ______% nitrogen in the form of ______.

78; N2

Which of the following correctly describes the role of nitrogen fixation in the nutrient cycle?

N2 is taken up by bacteria that can change it into ammonium, a form that is usable by plants.

Earthworms contribute to decomposition by

breaking up litter into smaller particles, thereby increasing the surface area and allowing for more efficient chemical breakdown.

Which of the following would most likely lead to an increase in detritivore activity in warm, moist soils?

Filtering oxygen into cells

Decomposition of organic matter with a C:N ratio ______ than 25:1 (the optimal ratio for microbial growth) would result in a net release of nutrients into the soil. The reason is that microbial growth in this situation would be more limited by the ____ supply than by the ______ supply.

less; energy; nitrogen

According to measurements taken in the 1990s, the levels of inorganic nitrogen in Arctic ecosystems were substantially lower than the amount of nitrogen actually taken up by plants. Which of the following is a possible explanation for this pattern?

Arctic sedges can take up organic forms of nitrogen.

Which of the following is one example of the ways in which Arctic plan communities have avoided competition through resource partitioning?

Different Arctic plant species take up nitrogen at different depths of the soil.

When leaves change color during senescence

Chlorophyll is broken down and the plant reabsorbs up to 60-70% of the nitrogen in the leaves as well as carbs and starches are broken down and moved into stems and roots.

Suppose that the mean residence time of nitrogen in a section of soil is 3.5 years, and the mean rate of input is 150kg per year. If rates of input and output as well as the total pool size have remained roughly constant, what is the expected size of the total pool of nitrogen?

525kg

Which if the ecosystems have the slowest turnover rates of the elements (the greatest mean residence times)?

Boreal forests with large nutrient pools and low rates of litter input.

The residence times of nutrients in the soils of boreal forests are influenced the most by the

decomposition rates, which are slowed by the low soil temps and by secondary compounds.

When studying terrestrial ecosystems, ecologists commonly focus on an area that is drained by a single stream, which is also called a

catchment

Of nitrogen and phosphorus, which is the most limiting nutrient to primary production early in primary production? Why?

Nitrogen, because it takes a long time to accumulate in the soil through decomp.

Soluble phosphorus combines with iron to form a compound that is no longer useable by organisms. This process is an example of

occlusion.

Rivers and streams subject to high amounts of nitrogen pollution export less nitrate than would be expected because moving stream water is affected by the processes of ______ and _________.

denitrification; biological uptake

A nutrient poor lake with low primary productivity if referred to as

oligotrophic

In the 1950s, anthropogenic eutrophication of Lake Washington was caused by

phosphates from wastewater

Lindeman developed a classification of organisms based on

their roles in moving energy through the ecosystem.

A predatory wasp that feeds exclusively on herbivorous ants would be an example of a ________ and part of the ________ trophic level.

carnivore; third

Milkweed beetles are so named because they feed on the milkweed plant. They are an example of an _______ and are part of the _________ trophic level.

herbivore; second

A leaf from a deciduous forest that falls into a large stream and is consumed by insects would be a source or ______ energy for the stream ecosystem.

allochthonus

Which of the following is most likely to be an inverted pyramid?

a biomass pyramid in an aquatic ecosystem.

According to the studies done by Trites and Donnelly, the most likely reason for decline in the population of Steller sea lions in the gulf of alaska is

reduced pray quality

In Paine's studies of ecosystems in the rocky intertidal zone, removal of Pisaster sea stars led to a long term

increase in mussels of the genus Mytilus.

Higher trophic levels often have _________ concentrations of toxins due to the process of ______.

higher; biomagnification

Which statement about Flecker and Townsend's studies of an aquatic trophic cascade is false?

They demonstrated the importance of bottom-up effects.

Which trophic level generates the most dead organic material in most ecosystems?

First

Refer to the figure, showing the relationship between the total autotroph biomass in the ecosystem and the ratio of heterotrophic to autotrophic biomass for lakes, coastal ocean, and open ocean.

According to the figure, at 1,000 mgC/m2 of autotrophic biomass, lakes would be predicted to have a(n) _______ biomass pyramid, coastal oceans to have a(n) _______ biomass pyramid, and open oceans to have a(n) _______ biomass pyramid.

regular; regular; inverted

An earthworm eats primarily detritus. A robin that then eats the earthworm is operating on a trophic level _______ that of a rabbit that eats grass.

one level above

Which statement about the second law of thermodynamics is true?

It states that some energy will be lost in any transfer of energy.

Which statement about allochthonous inputs is false?

They are usually of higher quality than autochthonous inputs.

In bottom-up control, energy flow through the ecosystem is determined primarily by the

supply of resources limiting NPP.

If a robin with an assimilation efficiency of 30% and a production efficiency of 20% consumes 200 grams of worms, the expected increase in biomass of the bird will be _______ grams.

12

Which statement about the portfolio effect is true?

Greater diversity decreases the chances of the portfolio effect occurring.

In Paine's studies of the rocky intertidal zone, which species or group of species acted most like a keystone species?

Pisaster sea stars

In his studies of ecosystems in the rocky intertidal zone, Paine emphasized that

interaction strengths may vary among different pairs of species.

According to the studies by Dyer and Letourneau, high densities of Tarsobaenus beetles in a lowland wet tropical forest led to _______ herbivory and _______ production.

higher; lower

Suppose the trophic efficiency between producers and herbivores is 0.1, the tropic efficiency between herbivores and carnivores is 0.15, and primary production is 1,200 units per day.

18 units per day

Which graph shows the most likely relationship between the frequency of disturbance and the number of trophic levels in the ecosystem?

Graph D

Bald eagles, which feed mainly on fish, tend to have much higher concentrations of toxins than the fish have. The same situation occurs for many top predators. This phenomenon is referred to as

biomagnification.

Compared to carnivores, herbivores tend to have _______ assimilation energies because _______.

lower; plants contain many substances, such as cellulose, that are not easily digested

Which statement about the limitations of food webs is false?

In most cases, food webs cannot be used as conceptual tools for understanding the dynamics of energy flow in ecosystems.

Which graph shows the most likely relationship between the total amount of production and the amount of resources allocated to defense in an ecosystem?

Graph C

In the early 1970s, May criticized Elton and Odum's contention that simpler food webs should be more easily perturbed than more complex ones. May's criticisms were based mainly on his

mathematical analyses of random assemblages of organisms.

Which statement about keystone species is true?

It is possible for a species to behave as a keystone species in one part of its range but not in other parts.

A beetle that feeds exclusively on dead wood is an example of a(n) _______ and is part of the _______ trophic level.

detritivore; second

Which statement about PCBs is false?

They are found at highest concentrations in Inuit women who eat herbivorous caribou.

A predatory wasp that feeds exclusively on herbivorous ants would be an example of a(n) _______ that is part of the _______ trophic level.

carnivore; third

Decreases in _______ would tend to increase the number of trophic levels in an ecosystem.

disturbance frequency

Rank the amount of algal standing crop at the end of the three treatments in the Flecker and Townsend experiments from highest to lowest.

Introduced brown trout > native galaxias > no fish

Tuna eat sardines and other small fish. Suppose the consumption efficiency of tuna is 40%, the assimilation efficiency is 30%, and the production efficiency is 20%. If tuna eat 1,500 kg of sardines and other small fish, how much will be used to produce tuna biomass?

90 kg

In Dyer and Letourneau's studies of a trophic cascade in a lowland wet tropical forest, the Tarsobaenus beetles would best be described as

secondary carnivores.

In Paine's demonstration that removing the top predator in an intertidal food web led to lower species diversity, the top predator was a(n)

sea star.

A leaf from a deciduous forest that falls into a large stream and is consumed by insects would be a source of _______ energy for the stream ecosystem.

allochthonous

If a cow with an assimilation efficiency of 10% and a production efficiency of 20% eats 50 kg of grass, the expected increase in biomass of the cow would be

1 kg.

In which human communities would one most likely find the highest concentrations of PCBs?

Communities in the Arctic that eat mainly whale meat

What is the main limitation of removal studies to estimate interaction strength?

They are logistically demanding.

The diagram is an example of an inverted _______ pyramid, which is most likely to be found in a(n) _______ ecosystem.

biomass; aquatic

Hairston and colleagues argued that terrestrial ecosystems have a _______ proportion of autotroph biomass consumption compared to aquatic ecosystems because _______ is stronger in terrestrial ecosystems.

lower; predation

What links animals together in the context of ecological function is

their roles in moving energy through the ecosystem.

In an inverted trophic pyramid, _______ biomass is present in the secondary carnivores than in the primary producers. Compared to terrestrial systems, aquatic systems are _______ likely to feature inverted pyramids.

more; much more

In which sequence are the organisms' expected production efficiencies correctly ranked from highest to lowest?

Beetle > fox > mouse

Rabbits consume 4,000 kg of grass per month, and their secondary production is 200 kg per month. If their assimilation efficiency is 50%, what is their consumption efficiency?

More information is required to answer this question.

Which statement about keystone species is false?

If a species acts as a keystone species in one part of its range, it must act as such in all parts of its range.

Drosophila sechellia eat the Indian mulberry plant. Suppose the consumption efficiency of Drosophila is 20%, the assimilation efficiency is 40%, and the production efficiency is 30%. If flies eat 50 kilograms of the plant, how much will be used to produce fly biomass?

6 kg

If herbivores eat 320 kg of plants, and the total plant biomass is 1,600 kg, the _______ efficiency is _______%.

consumption; 20

In Paine's studies of ecosystems in the rocky intertidal zone, removal of Pisaster sea stars led to a long-term

increase in mussels of the genus Mytilus.

Refer to the figure, showing the relationship between the total autotroph biomass in the ecosystem and the ratio of heterotrophic to autotrophic biomass for lakes, coastal ocean, and open ocean. Based on the figure, at 100 mgC/m2 of autotrophic biomass, about how much of the total biomass in lake ecosystems would be expected to be in autotrophs?

50%

According to the studies by Berlow, the net effect of whelk in the absence of barnacles is

always negative.

Higher trophic levels often have _______ concentrations of toxins due to the process of _______.

higher; biomagnification

Which graph best describes the effect of whelks on mussel settlement?

Graph A when barnacles are absent; Graph B when barnacles are at high density

The devastating effects of DDT and other pesticides on nontarget birds and mammals were described by _______ in the book Silent Spring.

Rachel Carson

What are trophic levels?

Feeding levels divided into 4 levels

a.) First-primary producers-autotrophs-mainly plants and detritus.

b.) Second-primary consumers-Herbivores and detritivores

c.) Third-secondary consumers-primary carnivores

d.) Fourth-tertiary consumers-secondary carnivores

Why do we need to eat so much?

Second Law of Thermodynamics: during any transfer of energy, some is dispersed as unusable energy due to the tendency toward an increase in disorder. Available energy will decrease with each trophic level upward. We eat so much because we need to maintain our body temperature, and this takes a lot of energy.

Why are the trophic levels in a pyramidal shape?

Some of the biomass in the trophic level is not eaten, and a proportion of the energy at each trophic level is lost in the transfer to the next level above it. In aquatic ecosystems, the high consumptions rates and short life spans of the primary producers (phytoplankton) result in a biomass that is inverted relative to the energy pyramid. So, the pyramids are ecosystem dependent.

what is GPP

Gross Primary production is the amount of carbon fixed by the autotrophs in an ecosystem. It is equal to the total of all plant photosynthesis. Autotrophs convert photon energy into glucose.

what is NPP

Net Primary production is the balance between GPP and respiration. It is the energy left over for growth. NPP varies with precipitation, temperature, and growing season.

What happens to most of the NPP on earth?

Most of the biomass of plants decomposes and is lost as detritus. Animals do not consume it.

What consumes detritus?

Detritivores like earth worms

Why is NPP consumption varied by habitat?

35% of NPP is consumed by herbivores in the ocean, and 13% of NPP is consumed by land herbivores. Predatory carnivores control the herbivore abundance. some plants have defenses against herbivory, like caffeine and spines.

What limits Carnivorous abundances?

Limited food resources create competition for those resources.

What is secondary production?

Secondary production is the conversion of energy into growth and reproduction. It is the result of assimilation of nutrients after respiration.

What is the assimilation Efficiency?

It is the proportion of ingested food that is assimilated. it is calculated by (Energy assimilated/energy consumed.) Food that is ingested but not used as energy is lost to the environment as feces (detritus) or as urine. The quality of food determines assimilation efficiency, and the efficiency of the consumer. Plants have lots of cellulose and lignin, and are therefore hard to digest. Animal bodies, have very similar carbon: nutrient ratio to that of the animal eating them and so are assimilated more readily. herbivores and detritivores have much lower assimilation efficiencies than carnivores.

Is the Assimilation efficiency High for mammals?

yes, because we are very efficient digesters. We get rid of bulk fiber quickly, and digest highly assimilable foods slowly.

What is Production Efficiency?

The proportion of the assimilated food that is used to produce new consumer biomass. It is strongly related to the thermal physiology and size of the consumer. Production Efficiency is calculated by (Energy used for production/Energy assimilated).

Is Production Efficiency high for mammals?

No, because we lose most of our energy to maintain body temperature with heat production.