Ecosystem Energy Transfer Quiz

Questions and Answers

What term describes the amount of chemical energy in consumers’ food converted to new biomass during a given period?

Primary production

Biomass accumulation

Tertiary production

Secondary production (correct)

What fraction of total plant production do herbivores globally consume?

One-half

One-sixth (correct)

One-fifth

One-tenth

When a caterpillar feeds on a leaf, what portion of the potential energy in the leaf is used for secondary production (growth)?

One-eighth

One-third

One-fourth

One-sixth (correct)

What ultimately happens to the energy in feces after it is consumed by decomposers?

It is lost as heat Signup and view all the answers

What is the main purpose of the energy stored by herbivores as biomass?

To support the growth and reproduction of secondary consumers Signup and view all the answers

What happens to the energy used for the caterpillar's respiration?

It is eventually lost from the ecosystem as heat Signup and view all the answers

What is measured to determine the efficiency of animals as energy transformers?

Net secondary production Signup and view all the answers

What keeps most of the ecosystem’s production integrated rather than completely consumed by herbivores?

Role of decomposers Signup and view all the answers

What is the dry mass of primary producers in a typical trophic level?

809 grams per square meter Signup and view all the answers

Why can primary consumers in certain aquatic ecosystems have a larger biomass than their primary producers?

Producers grow and are consumed quickly, keeping their biomass low. Signup and view all the answers

What is the dry mass of secondary consumers according to the trophic levels presented?

11 grams per square meter Signup and view all the answers

What implication does energy flow through ecosystems have on human dietary choices?

Consuming primary producers directly is a more efficient method of utilizing biomass. Signup and view all the answers

What happens to the relationship between biomass and energy in ecosystems with inverted pyramids?

Consumers can exceed the biomass of producers due to rapid consumption. Signup and view all the answers

What constitutes assimilation in an organism?

The total amount of energy consumed for growth, reproduction, and respiration Signup and view all the answers

How does production efficiency differ from respiration in organisms?

Production efficiency is the percentage of energy stored for growth and reproduction Signup and view all the answers

Which group of organisms typically demonstrates the highest production efficiency?

Insects and microorganisms Signup and view all the answers

What is trophic efficiency?

The percentage of production transferred between trophic levels Signup and view all the answers

Why is trophic efficiency always lower than production efficiency?

It excludes energy in organic material not consumed Signup and view all the answers

What percentage of energy is typically transferred from primary producers to primary consumers?

Roughly 10% Signup and view all the answers

What factor most limits the number of top-level carnivores in an ecosystem?

Energy loss along the food chain Signup and view all the answers

What characterizes an energy pyramid?

Each tier represents the net production of different trophic levels Signup and view all the answers

Which type of ecosystem is likely to have an inverted biomass pyramid?

Aquatic ecosystems Signup and view all the answers

When calculating net primary production, what factors must be considered?

Gross production minus energy lost to respiration Signup and view all the answers

Understanding energy flow in ecosystems helps explain why food webs typically include only a limited number of trophic levels. What is this number?

Four to five Signup and view all the answers

Which variable describes the energy captured by primary producers from solar radiation?

Gross primary production Signup and view all the answers

In a salt marsh, how is energy density typically measured in biomass?

By drying, burning, and measuring heat produced Signup and view all the answers

What role do decomposers play in ecosystems?

They assist in nutrient cycling by breaking down organic matter. Signup and view all the answers

Which of the following factors most affects the rate of decomposition in an ecosystem?

Temperature and moisture levels Signup and view all the answers

In which ecosystem is organic material likely to decompose the fastest?

Tropical rain forest Signup and view all the answers

What happens to the atoms in an organism's body after it dies?

They are returned to the ecosystem through decomposition. Signup and view all the answers

What conclusion can be drawn about the relationship between temperature and litter decomposition rates?

Decomposition rates increase with higher temperatures. Signup and view all the answers

What type of organism primarily feeds on detritus in an ecosystem?

Decomposers Signup and view all the answers

Why is the decomposition process crucial for plant growth?

It recycles nutrients that are essential for new organic matter. Signup and view all the answers

What evidence supports that decomposition rates differ across ecosystems in Canada?

The mass of litter decreases four times faster in warm ecosystems compared to cold ones. Signup and view all the answers

What is the primary form of phosphorus that plants absorb for use in biological processes?

Phosphate Signup and view all the answers

What is the role of wind-blown dust in the phosphorus cycle?

It transports phosphorus from the atmosphere to land and sea. Signup and view all the answers

Which human activity has significant effects on the nitrogen cycle through reactive nitrogen gas release?

Agricultural fertilization Signup and view all the answers

What process primarily contributes to the addition of inorganic phosphorus to soil?

Weathering of rocks Signup and view all the answers

What was the effect of deforestation in the Hubbard Brook Experimental Forest on water runoff?

It dramatically increased water runoff due to lack of vegetation. Signup and view all the answers

What mineral demonstrated a significant increase in concentration in runoff after deforestation in the Hubbard Brook study?

Nitrate Signup and view all the answers

Which statement about the phosphorus cycle is accurate?

Phosphorus recycling is localized in ecosystems. Signup and view all the answers

What is a consequence of nutrient cycling in the Hubbard Brook Experimental Forest as identified by researchers?

Internal cycling conserves most mineral nutrients. Signup and view all the answers

What percentage of water added to the Hubbard Brook ecosystem is estimated to exit through the stream?

Around 75% Signup and view all the answers

Why is the flow of nutrients controlled primarily by plants in forest ecosystems?

Plants prevent nutrient leaching. Signup and view all the answers

Which process does NOT contribute significantly to the movement of phosphorus in the atmosphere?

Volcanic activity Signup and view all the answers

What is one of the largest reservoirs of phosphorus in the biosphere?

Sedimentary rocks Signup and view all the answers

What is the primary factor for the variations in nitrate concentration in deforested versus control watersheds in the Hubbard Brook study?

Absence of plant uptake Signup and view all the answers

Which factors, besides temperature, might influence decomposition rates in different forest ecosystems?

Soil pH Signup and view all the answers

In tropical rain forests, where is a majority of the ecosystem's nutrients stored?

Woody trunks of trees Signup and view all the answers

What is a primary consequence of slow decomposition rates in temperate forests?

Accumulation of organic material Signup and view all the answers

What role does peat play in the decomposition process within certain ecosystems?

It acts as a long-term carbon sink. Signup and view all the answers

Which factors can inhibit decomposition in swamp sediments?

Low oxygen levels and waterlogging Signup and view all the answers

How do biogeochemical cycles differ for gaseous elements compared to heavier elements?

Gaseous elements have local cycles, while heavier elements are recycled globally. Signup and view all the answers

What connection exists between reservoir A and reservoir B regarding organic materials?

Dead organic matter moves from reservoir A to reservoir B as peat. Signup and view all the answers

Which of the following elements is primarily cycled globally within ecosystems?

Nitrogen Signup and view all the answers

Which process is primarily responsible for moving inorganic materials from reservoir D to reservoir C?

Weathering and erosion Signup and view all the answers

What is primarily illustrated by nutrient cycle diagrams?

The availability of nutrients in each reservoir Signup and view all the answers

What happens to organic materials that are not assimilated by living organisms?

They become trapped in sediments. Signup and view all the answers

Which condition is most likely to enhance decomposition in an ecosystem?

Optimal oxygen availability with moderate moisture Signup and view all the answers

Why do aquatic ecosystems have a distinct nutrient cycling process?

Nutrients are carried as dissolved forms in water currents. Signup and view all the answers

Which process predominantly drives the water cycle in terrestrial ecosystems?

Evapotranspiration Signup and view all the answers

In the carbon cycle, which is considered the largest reservoir of carbon?

Sedimentary rocks Signup and view all the answers

Which factor primarily limits nitrogen availability to terrestrial plants?

Atmospheric nitrogen gas conversion Signup and view all the answers

What is a crucial biological process for removing carbon dioxide from the atmosphere?

Photosynthesis Signup and view all the answers

Which human activity has significantly impacted the global nitrogen cycle?

Use of fertilizers Signup and view all the answers

Primary production rates in ecosystems are heavily influenced by the availability of which resource?

Sunlight Signup and view all the answers

Which statement accurately describes the role of decomposition in the carbon cycle?

It converts organic matter back to CO2. Signup and view all the answers

What is the main driving force for evaporation in the water cycle?

Solar energy Signup and view all the answers

Which of the following is a significant form of nitrogen that plants can assimilate?

Nitrate Signup and view all the answers

Which process contributes to carbon emissions through human activity?

Burning fossil fuels Signup and view all the answers

What role do phytoplankton play in the carbon cycle?

They contribute to photosynthesis. Signup and view all the answers

How do terrestrial plants contribute to the water cycle?

Through transpiration Signup and view all the answers

What is a major human-induced source of additional carbon in the atmosphere?

Deforestation Signup and view all the answers

In which reservoir is most of the Earth's freshwater stored?

Glaciers and polar ice caps Signup and view all the answers

Study Notes

Secondary Production in Ecosystems

Secondary production refers to the conversion of chemical energy from food into biomass by consumers during a specific timeframe.
Herbivores, or primary consumers, typically consume only about one-sixth of total plant production in ecosystems.

Energy Transfer and Production Efficiency

A caterpillar utilizes only one-sixth of the energy from the leaves it eats for growth, with the rest used in respiration or lost in feces.
Energy from feces can be temporarily retained in the ecosystem but is mostly lost as heat when consumed by decomposers.
Production efficiency is determined by the percentage of energy from assimilated food saved for growth and reproduction rather than lost to respiration.
Birds and mammals have low production efficiencies (around 4-30%), while fishes have efficiencies of 10-20%, and insects and microorganisms exceed 40%.

Trophic Efficiency and Energy Flow

Trophic efficiency is the percentage of production that transfers from one trophic level to another, always lower than production efficiency due to losses at each stage.
Average trophic efficiencies range from 5% to 20%, meaning a significant amount of energy (approximately 80%-95%) is lost between levels.
Example: If 10% of energy is transferred from primary producers to primary consumers, only 1% of net primary production is available to secondary consumers.

Energy Flow in Salt Marsh Ecosystem

John Teal’s study on a salt marsh showed the energy flow among producers, consumers, and decomposers, measuring solar radiation and biomass.
Solar energy incorporated: Gross primary production at 34,580 kilocalories; Net primary production at 6,585 kilocalories.
Detritus leaving the marsh accounted for 3,671 kilocalories; significant losses occur through respiration of both producers and consumers.

Implications of Energy Loss

The loss of energy along the food chain limits the number of top-level carnivores an ecosystem can support, usually capping food chains at around four to five trophic levels.
An energy pyramid visually represents these losses, showing how net production decreases at higher trophic levels.

Biomass Distribution

Biomass pyramids typically demonstrate decreased biomass from primary producers to top-level consumers, illustrating inefficiencies in energy transfer.
Inverted biomass pyramids may occur in aquatic systems where rapid consumption and replacement by phytoplankton support larger populations of primary consumers (zooplankton).

Human Consumption and Energy Efficiency

Consuming meat is less efficient than obtaining energy directly from plants, highlighting food conversion inefficiencies.
A shift towards plant-based diets could better allocate resources and require less land to support human populations globally.

Ecosystem Energy and Nutrient Cycling

Ecosystems primarily rely on solar energy, while essential chemical elements are limited and need continuous recycling.
Organisms regularly assimilate nutrients, releasing waste and returning atoms to the atmosphere, water, or soil upon death.
Decomposers are key heterotrophs that break down organic matter, liberating nutrients for plants and autotrophs to utilize.

Decomposition Rates

Decomposition rates vary with environmental factors: temperature, moisture, nutrient availability.
In warmer ecosystems, decomposers function more efficiently, with litter decomposing significantly faster in tropical rainforests than in temperate forests.
On average, organic material decomposes in a few months to a few years in tropical rainforests; in temperate regions, it can take four to six years.

Impact of Temperature on Decomposition

Research conducted by the Canadian Forest Service demonstrated a fourfold increase in litter decomposition rates in warmer ecosystems compared to colder ones.
Conditions that hinder decomposition include excessive dryness or saturation, particularly in cold, wet areas such as peatlands, leading to significant organic matter storage.

Biogeochemical Cycles

Nutrient cycling involves both biotic (living) and abiotic (non-living) components, distinguished as global and local cycles.
Gaseous elements like carbon, oxygen, sulfur, and nitrogen exist globally in the atmosphere; others like phosphorus and potassium cycle more locally.
Nutrients in living organisms and detritus are transferred to other organisms through food webs and decomposition processes.

Water Cycle

Water is essential for life, influencing ecosystem processes like primary production and decomposition.
The oceans contain around 97% of the world's water, with glaciers and polar ice caps holding approximately 2%, and the remaining 1% found in lakes, rivers, and groundwater.
Key processes in the water cycle include evaporation, condensation, precipitation, and plant transpiration.

Carbon Cycle

Carbon is a vital building block in organic molecules and is cycled through processes like photosynthesis by plants, cellular respiration by consumers, and fossil fuel combustion.
Major carbon reservoirs include fossil fuels, soils, ocean sediments, and atmospheric CO2, where geological time scales play a role in carbon storage dynamics.

Nitrogen Cycle

Nitrogen is crucial for amino acids, proteins, and nucleic acids, with plants utilizing forms like ammonium and nitrate while animals require organic forms.
Natural nitrogen fixation occurs through bacteria and processes such as lightning. Human activity has increased nitrogen inputs through fertilizers and agricultural practices.

Phosphorus Cycle

Phosphorus is vital for nucleic acids, ATP, and skeletal structures; its most significant form is phosphate, which plants absorb.
Phosphorus accumulates primarily in sedimentary rocks, with localized recycling due to soil retention and limited atmospheric movement.

Hubbard Brook Experimental Forest Case Study

Research has been ongoing since 1963 on nutrient cycling in the Hubbard Brook Experimental Forest, focusing on how vegetation affects drainage and nutrient loss.
After clear-cutting a watershed, water and nutrient runoff increased markedly, particularly in the concentration of nitrate, leading to concerns about drinking water safety.
Internal cycling was found to conserve most minerals, while deforestation led to dramatic losses in nutrient retention, highlighting the role of vegetation in ecosystem productivity and nutrient control.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your understanding of the secondary production in ecosystems. This quiz covers the transfer of energy from primary producers to herbivores and highlights the efficiency of energy conversion in food webs. Explore the dynamics of food consumption and biomass production in ecological systems.