Podcast
Questions and Answers
Which of the following best describes the flow of energy in terrestrial ecosystems?
Which of the following best describes the flow of energy in terrestrial ecosystems?
- From consumers to producers, then back to the environment.
- From producers to the sun, then to consumers.
- Energy cycles continuously between trophic levels without a primary source.
- From the sun to producers, then upward to higher trophic levels. (correct)
The 10% rule explains that only about 10% of the energy is transferred from one trophic level to the next. What happens to the majority of the remaining 90% of the energy?
The 10% rule explains that only about 10% of the energy is transferred from one trophic level to the next. What happens to the majority of the remaining 90% of the energy?
- It is stored indefinitely within the tissues of the organism for later use.
- It is passed on to decomposers, which recycle it back to producers.
- It is used by the organism for metabolic processes and lost as heat. (correct)
- It is converted into matter and stored in biogeochemical cycles.
Which of the following statements accurately describes the relationship between the 1st law of thermodynamics and energy transfer in ecosystems?
Which of the following statements accurately describes the relationship between the 1st law of thermodynamics and energy transfer in ecosystems?
- Energy is constantly created and destroyed as matter cycles through an ecosystem.
- Energy is neither created nor destroyed, but it changes form as it moves through the ecosystem. (correct)
- The total amount of energy decreases at each trophic level due to new energy creation.
- Energy is created at the producer level and destroyed by apex predators.
If the producers in an ecosystem generate 10,000 J of energy, approximately how much energy will be available to the tertiary consumers, assuming the 10% rule applies?
If the producers in an ecosystem generate 10,000 J of energy, approximately how much energy will be available to the tertiary consumers, assuming the 10% rule applies?
Which of the following is an example of how matter is conserved in an ecosystem?
Which of the following is an example of how matter is conserved in an ecosystem?
How does the energy available change as you move up a food chain, and what implication does this have for biomass at each level?
How does the energy available change as you move up a food chain, and what implication does this have for biomass at each level?
Which of the following calculations correctly estimates the efficiency of energy transfer through a food chain with the following transfer percentages: 35% consumption, 90% assimilation, and 5% conversion?
Which of the following calculations correctly estimates the efficiency of energy transfer through a food chain with the following transfer percentages: 35% consumption, 90% assimilation, and 5% conversion?
What is the ultimate source of energy for terrestrial ecosystems, and how do producers harness this energy?
What is the ultimate source of energy for terrestrial ecosystems, and how do producers harness this energy?
Apex predators, also known as tertiary consumers, consume what?
Apex predators, also known as tertiary consumers, consume what?
How do biogeochemical cycles demonstrate the conservation of matter in ecosystems?
How do biogeochemical cycles demonstrate the conservation of matter in ecosystems?
What is the primary difference between a food chain and a food web?
What is the primary difference between a food chain and a food web?
In a food web, what do the arrows indicate?
In a food web, what do the arrows indicate?
What is a trophic cascade and what causes it?
What is a trophic cascade and what causes it?
Decline in wolf population leads to what?
Decline in wolf population leads to what?
If a grassy field has 1000 kg of producers, how many kg of tertiary consumers will it most likely support?
If a grassy field has 1000 kg of producers, how many kg of tertiary consumers will it most likely support?
In the provided food web, one organism is both a secondary and a tertiary consumer. Which of the following organisms fits this description?
In the provided food web, one organism is both a secondary and a tertiary consumer. Which of the following organisms fits this description?
In terms of trophic levels, how would you classify organisms that eat plants?
In terms of trophic levels, how would you classify organisms that eat plants?
Food webs shows how increase or decrease in what impacts the rest of the food web?
Food webs shows how increase or decrease in what impacts the rest of the food web?
What happens in the ecosystem when there is increase in python population?
What happens in the ecosystem when there is increase in python population?
If the energy produced by the plants in the ecosystem total 100,000 J, how much energy is available to a tertiary consumer?
If the energy produced by the plants in the ecosystem total 100,000 J, how much energy is available to a tertiary consumer?
Flashcards
Law of Conservation
Law of Conservation
Matter and energy are neither created nor destroyed; they only undergo transformation.
2nd Law of Thermodynamics
2nd Law of Thermodynamics
Each energy transfer loses some energy as heat, decreasing useable energy up the food chain.
10% Rule
10% Rule
This approximates that in the transfer of energy from one trophic level to the next, only about 10% of the energy is passed on.
Tertiary Consumers
Tertiary Consumers
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Secondary Consumers
Secondary Consumers
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Primary Consumers
Primary Consumers
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Producers
Producers
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10% Rule & Biomass
10% Rule & Biomass
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Food Web
Food Web
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Food Chain
Food Chain
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Trophic Cascade
Trophic Cascade
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Food Web Arrows
Food Web Arrows
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Study Notes
Trophic Levels and the 10% Rule
- Ecosystems rely on a continuous supply of high-quality energy to sustain the structure and function of transferring matter.
- Energy flows from the sun to producers at the lowest trophic levels, then upward to higher levels in terrestrial and near-surface marine communities.
- The 10% rule is an approximation stating that only about 10% of the energy is transferred from one trophic level to the next.
- Energy loss when moving from lower to higher trophic levels can be explained by the laws of thermodynamics.
Conservation of Matter and Energy
- Matter and energy are never created nor destroyed, but rather change forms.
- For example, a tree dies and its C/N/H2O/P are returned to the atmosphere and soil
- Sunlight (light energy) converts to glucose (chemical energy) in leaves.
- The first law of thermodynamics states that energy is never created or destroyed
- Biogeochemical cycles show conservation of matter (C/N/H2O/P).
- Food webs show conservation of energy.
- Example: A rabbit eats a leaf and the leaf's energy (glucose) is transferred and stored in the rabbit as body tissue (fat/muscle).
Second Law of Thermodynamics
- Every time energy is transferred, some is lost as heat.
- Usable energy decreases when moving up the food chain since organisms use the majority of the energy for movement and development.
- A trophic pyramid models how energy moves through an ecosystem because available energy decreases with each step up the food chain.
- According to the 10% rule in trophic pyramids, only about 10% of the energy transfers from one level to the next; the organism uses the other 90% of the energy and it is lost as heat.
Trophic Levels & Biomass
- Tertiary Consumers: Carnivores & omnivores (top/apex predators) that eat secondary consumers.
- Secondary Consumers: Carnivores & omnivores that eat primary consumers or herbivores.
- Primary Consumers: Herbivores that eat plants.
- Producers: Plants that convert sunlight into chemical energy (glucose).
- The 10% rule applies to biomass
- This is because energy is needed for growth and only 10% of the energy is transferred
Calculating Biomass & Energy
- To calculate available biomass or energy at the next level up, move the decimal place one spot to the left or divide by 10.
Food Webs
- Food webs show how energy and matter flow from organism to organism in an ecosystem.
- When one organism preys on or eats another, the matter (C/N/H2O/P) and energy (glucose, muscle tissue, etc.) are passed on to the predator.
- Arrows in food webs indicate the direction of energy flow; the arrow points to the organism taking in the energy.
- Food webs have at least two different interconnected food chains illustrating that organisms can exist at different trophic levels.
- Example: grass -> hare -> owl (secondary consumer) OR grass -> grasshopper -> robin -> owl (tertiary consumer).
- Food webs illustrate how increases or decreases in a given species' population size impact the rest of the food web.
- For example, an increase in python population would decrease frog/rat populations, increase grasshopper population, and decrease corn.
- Trophic cascade: the removal or addition of a top predator has a ripple effect down through lower trophic levels.
- For example, a wolf population decline can increase deer population which leads to overgrazing and a decline in trees.
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