Cycling of matter and energy in ecosystems

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レッスンノート

Feeding Types and Roles

Producers (autotrophs) make their own food via photosynthesis, e.g., plants.
Consumers (heterotrophs) obtain food by eating other organisms.
Herbivores eat only plants; carnivores eat other animals.
Omnivores eat both plants and animals.
Decomposers break down dead organisms and waste, recycling nutrients.
Scavengers are carnivores that eat dead animals.
Insectivores are carnivores that eat insects and small invertebrates.

Photographs of four different fungi growing on dead wood

Food Chains and Food Webs

A food chain shows the linear flow of energy and matter from one organism to the next.
Arrows in a food chain point from the eaten organism to the eater, indicating energy transfer.
A food web consists of interconnected food chains, showing multiple feeding relationships.
Producers are always at the start of a food chain, bringing energy into the ecosystem.
Most organisms eat multiple things, making food webs more realistic than simple chains.

A food web of the Southern Ocean

Trophic Levels: Primary, Secondary and Tertiary Consumers

A food chain such as grass → grasshopper → rat → owl shows how energy passes from one trophic level to the next.
Animals that eat producers directly, like the grasshopper, are primary consumers.
Animals that eat primary consumers, like the rat, are secondary consumers.
Animals that eat secondary consumers, like the owl, are tertiary consumers.
Each feeding step in a food chain is called a trophic level.

A simple food chain: grass, grasshopper, rat, owl

Energy Flow and Pyramids

The sun is the ultimate energy source for most ecosystems.
Energy flows through ecosystems, being converted from light to chemical energy in photosynthesis.
Energy is not cycled; it flows and is lost as heat at each trophic level.
Only about 10% of energy is transferred to the next trophic level; 90% is used for life processes or lost as heat.
An energy pyramid illustrates the decreasing energy and number of organisms at higher trophic levels.
Producers are the most numerous and form the base of the pyramid.

Energy pyramids for a marine ecosystem and a savanna ecosystem

Matter Cycling and the Carbon Cycle

Matter cycles in ecosystems; it is reused over and over again.
The carbon cycle moves carbon between living and nonliving parts of the ecosystem.
Carbon is released as CO2 through cellular respiration, decomposition, and burning of organic matter.
Photosynthesis removes CO2 from the atmosphere or water to produce glucose.
Carbon can be stored for long periods in rocks, fossil fuels, and the ocean.
Human activities like burning fossil fuels and deforestation increase atmospheric CO2.

The carbon cycle

Matter Cycles, Energy Flows: What Happens When Ecosystems Are Disrupted

Matter cycles through the living and nonliving parts of an ecosystem, while energy flows through it in one direction.
A model of a tide-pool ecosystem shows sunlight and carbon dioxide (nonliving) providing matter and energy to seaweed (a producer), which passes them on to a sea urchin, then a starfish, and finally to bacteria that decompose it.
The model distinguishes transfers of energy alone, matter alone, and both energy and matter together.
A disruption to one part of the model — such as pollution that clouds the water or a rise in temperature — can reduce how much energy the producer captures, slowing the cycling of matter and flow of energy through the whole system.
Because every part of an ecosystem is connected, a change to the living or nonliving parts can affect the stability of the whole system.

A model of matter and energy transfer in a tide-pool ecosystem

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練習問題

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1.What is the primary source of energy for almost all ecosystems?
Easy
- AThe sun
- BThe moon
- CGeothermal heat
- DChemical reactions
2.Which of the following is a producer?
Easy
- ACattail
- BGrasshopper
- CFrog
- DHawk
3.What do the arrows in a food chain represent?
Easy
- AThe direction of energy and matter flow
- BThe size of the organisms
- CThe speed of the organisms
- DThe number of organisms
4.Approximately what percentage of energy is transferred from one trophic level to the next?
Easy
- A10%
- B50%
- C90%
- D100%
5.Decomposers release nutrients back into the environment for producers to use.
Easy
True or false?
6.Which process removes carbon dioxide from the atmosphere?
Easy
- APhotosynthesis
- BCellular respiration
- CDecomposition
- DBurning fossil fuels
7.Which of the following are consumers? (Select all that apply)
Easy
- AHerbivore
- BCarnivore
- COmnivore
- DProducer
- EDecomposer
8.Which of the following is the correct sequence in a food chain?
Medium
- AProducer → Primary consumer → Secondary consumer → Tertiary consumer
- BPrimary consumer → Producer → Secondary consumer → Tertiary consumer
- CProducer → Secondary consumer → Primary consumer → Tertiary consumer
- DTertiary consumer → Secondary consumer → Primary consumer → Producer

もっと問題

9.Carbon can be stored in sedimentary rocks for millions of years.
Medium
True or false?
10.Which of the following processes release carbon dioxide into the atmosphere? (Select all that apply)
Medium
- ACellular respiration
- BPhotosynthesis
- CDecomposition
- DBurning fossil fuels
- EFormation of limestone
11.In a food web, which organism would be most affected if the arctic cod were removed?
Medium
- AHarbor seal
- BPhytoplankton
- CPolar bear
- DZooplankton
12.Why do energy pyramids have a large base of producers?
Medium
- ABecause only about 10% of energy is transferred to the next trophic level
- BBecause producers are the largest organisms
- CBecause producers reproduce quickly
- DBecause producers are at the top of the food chain
13.Arrange the following events in the carbon cycle in the correct order:
Medium
- Photosynthesis removes CO2 from atmosphere
- Animals eat plants and incorporate carbon
- Cellular respiration releases CO2 back to atmosphere
- Decomposers break down dead organisms
14.Match the organism to its trophic level in a food chain: grass → grasshopper → frog → snake → hawk.
Medium
- Grass
- Grasshopper
- Frog
- Snake
- Hawk
- Producer
- Primary consumer
- Secondary consumer
- Tertiary consumer
- Quaternary consumer
15.Which of the following are consequences of clear-cutting a forest? (Select all that apply)
Hard
- AIncreased carbon dioxide in the atmosphere
- BLoss of habitat for many species
- CIncreased photosynthesis
- DDisruption of the carbon cycle
- EIncreased soil erosion
16.In an ecosystem, matter cycles but energy flows in one direction.
Hard
True or false?
17.A food web shows that a certain bird eats both insects and seeds. How would you classify this bird?
Hard
- AHerbivore
- BCarnivore
- COmnivore
- DInsectivore
18.Match the process to its role in the carbon cycle.
Medium
- Photosynthesis
- Cellular respiration
- Decomposition
- Burning fossil fuels
- Removes CO2 from atmosphere
- Releases CO2 to atmosphere
- Releases CO2 from dead matter
- Releases stored carbon as CO2
19.If all the decomposers in an ecosystem were removed, what would be the most likely long-term effect?
Hard
- ANutrients would not be recycled, and producers would eventually run out of essential nutrients
- BProducers would grow larger because of less competition
- CConsumers would have more food available
- DThe ecosystem would become more stable
20.Carbon is created by plants during photosynthesis.
Hard
True or false?
21.Which of the following are examples of abiotic factors? (Select all that apply)
Hard
- AWater
- BSoil
- CTemperature
- DBacteria
- ESunlight
22.Arrange the following in the correct sequence of energy flow in an ecosystem:
Hard
- Sun
- Producer
- Primary consumer
- Secondary consumer
- Decomposer
23.In the carbon cycle, carbon can be stored in the ocean for thousands of years.
Challenge
True or false?
24.Match each feeding type to its correct description.
Easy
- Producer
- Carnivore
- Omnivore
- Herbivore
- Makes its own food
- Eats only animals
- Eats both plants and animals
- Eats only plants
25.Arrange the following organisms in a food chain, starting with the producer.
Medium
- hawk
- grasshopper
- grass
- frog
- snake
26.In a food web, if a disease kills all the grasshoppers, which organism would be most directly affected?
Medium
- AFrogs
- BHawks
- CGrass
- DSnakes
27.A scientist is studying a tide pool ecosystem. She removes all the sea stars (a top predator) and observes that the mussel population increases dramatically, outcompeting other organisms and reducing biodiversity. This is an example of which concept?
Hard
- AEnergy flow through a food chain
- BA trophic cascade
- CThe 10% rule
- DChemosynthesis
28.Complete the sentence.
Easy
Organisms that make their own food are called ____.
29.What is the term for organisms that break down dead plants and animals?
Easy
30.If a producer has 10,000 J of energy, how much energy (in joules) is available to the primary consumer?
Medium
31.What is the term for an organism that eats only plant material?
Easy
32.If a tertiary consumer has 50 J of energy, how much energy (in joules) was originally available at the producer level?
Medium
33.What is the name for the process by which some bacteria in deep-sea ecosystems produce food using chemical energy?
Medium
34.What is the term for organisms that feed on dead animals?
Medium
35.Complete the sentence about energy flow.
Medium
In a food chain, energy flows from the ____ to the ____.
36.Explain why decomposers are important in an ecosystem.
Medium
37.The tide-pool model shows sunlight and carbon dioxide (both nonliving) providing matter and energy to seaweed, which passes them on to a sea urchin, then a starfish, and finally to bacteria that decompose it. Explain how pollution that makes the water cloudy could disrupt the cycling of matter and flow of energy in this ecosystem.
Hard
38.Evaluate the statement: 'An insectivore is a carnivore.'
Challenge
39.If a producer has 10,000 J of energy, how much energy (in joules) is available to the primary consumer?
Medium
- A1100 J
- B1200 J
- C900 J
- D1000 J
40.If a tertiary consumer has 50 J of energy, how much energy (in joules) was originally available at the producer level?
Medium
- A55000 J
- B50000 J
- C45000 J
- D60000 J
41.A model shows meadow grass → grasshopper → cowbird → coyote, with three unlabelled boxes for nonliving matter and energy: one feeding into meadow grass only, one that meadow grass feeds and that in turn feeds every consumer, and one that every consumer feeds and that in turn feeds back into meadow grass. Match each box to what it represents.
Medium
- Box feeding only into meadow grass
- Box that meadow grass feeds, and that feeds every consumer
- Box that every consumer feeds, and that feeds back into meadow grass
- Sunlight
- Oxygen
- Carbon dioxide
42.The diagram shows a process that transfers energy in an ecosystem: energy from sunlight → energy in food molecules. In which of these organisms does this process occur?
Easy
- AEarthworm
- BOwl
- CMushroom
- DGrass
43.A food web includes white spruce trees, snowshoe hares that eat the bark and twigs of white spruce, and Canada lynx that hunt snowshoe hares. Which table best shows the ecological role of each organism? A) | Organism | Role | |---|---| | Canada lynx | primary consumer | | white spruce | producer | | snowshoe hare | secondary consumer | B) | Organism | Role | |---|---| | Canada lynx | secondary consumer | | white spruce | producer | | snowshoe hare | primary consumer | C) | Organism | Role | |---|---| | Canada lynx | producer | | white spruce | secondary consumer | | snowshoe hare | primary consumer | D) | Organism | Role | |---|---| | Canada lynx | primary consumer | | white spruce | secondary consumer | | snowshoe hare | producer |
Medium
- ATable A
- BTable B
- CTable C
- DTable D

復習ノート

## Cycling of Matter and Energy in Ecosystems - **Energy flow** is unidirectional: sunlight → producers → consumers → decomposers. Energy is lost as heat at each step. - **Trophic levels**: producers (autotrophs), primary consumers (herbivores), secondary consumers, tertiary consumers, decomposers. - **Food chains** show one path; **food webs** show interconnected paths. - **10% Rule**: Only about 10% of energy (5–20% efficiency) passes from one trophic level to the next. The rest is used for respiration or lost as heat. - **Photosynthesis**: \(6CO_2 + 6H_2O + \text{sunlight} \rightarrow C_6H_{12}O_6 + 6O_2\) - **Cellular respiration**: \(C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}\) - **Carbon cycle**: Carbon moves between organisms and the environment via photosynthesis and respiration. Decomposers return carbon to the soil/atmosphere. - **Primary production**: Gross primary productivity (GPP) = total energy captured by producers. Net primary productivity (NPP) = GPP – energy used by producers for respiration. NPP is available to consumers. - **Limiting factors**: Sunlight, water, nutrients (N, P) affect primary production. - **Chemosynthesis**: Some bacteria use chemical energy (e.g., hydrogen sulfide) to produce glucose, supporting deep-sea vent ecosystems. - **Carnivorous plants**: Obtain nutrients (e.g., nitrogen) by trapping and digesting insects, adapting to low-nutrient soils. **Key idea**: Matter cycles (e.g., carbon, water, nitrogen) while energy flows one way and is eventually dissipated as heat.

Trophic level: A step in a food chain or food web; each level represents organisms that share the same function in the energy flow (e.g., producers, primary consumers).
Food web: A network of interconnected food chains showing the flow of energy and matter among organisms in an ecosystem.
Photosynthesis: Process by which producers use sunlight, water, and carbon dioxide to produce glucose and oxygen: 6CO₂ + 6H₂O + sunlight → C₆H₁₂O₆ + 6O₂.
Cellular respiration: Process by which organisms break down glucose using oxygen to release energy, producing carbon dioxide and water: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy.
Gross primary productivity (GPP): Total amount of energy captured by producers through photosynthesis.
Net primary productivity (NPP): Energy remaining after producers use some for respiration; NPP = GPP – respiration by producers.
10% rule: Only about 10% of energy at one trophic level is transferred to the next; the rest is lost as heat or used for respiration.
Chemosynthesis: Process by which certain bacteria use chemical energy (e.g., from hydrogen sulfide) to produce glucose, without sunlight.
Decomposer: Organism (e.g., bacteria, fungi) that breaks down dead matter, releasing nutrients back into the ecosystem.
Carnivorous plant: A plant that traps and digests insects or other small organisms to obtain nutrients, especially in low-nutrient environments.

フラッシュカード

What is the ultimate source of energy for most ecosystems?

The sun.

What is a producer?

An organism that performs photosynthesis, converting sunlight into chemical energy (glucose). Examples: algae, grasses, trees.

What is a consumer?

An organism that eats other organisms to obtain energy. Consumers cannot make their own food.

What is a food chain?

A sequence showing the transfer of energy from one organism to another, starting with a producer and moving through consumers.

What is a trophic level?

Each step in a food chain or food web, representing a feeding position (e.g., producer, primary consumer, secondary consumer).

What does the direction of an arrow in a food chain represent?

The direction of energy flow, from the organism being eaten to the one that eats it.

Is energy flow in an ecosystem one-way or cyclical?

One-way (unidirectional). Energy enters as sunlight, passes through organisms, and is lost as heat at each step.

What is the 10% rule in energy transfer?

Only about 10% of the energy at one trophic level is passed to the next; the rest is used for respiration or lost as heat.

Why are there usually fewer tertiary consumers than producers?

Because energy is lost at each trophic level, so less energy is available to support higher levels.

What is photosynthesis?

The process by which producers use sunlight, water, and carbon dioxide to make glucose and oxygen.

What is cellular respiration?

The process by which organisms break down glucose using oxygen to release energy, producing carbon dioxide and water.

How does the carbon cycle connect photosynthesis and cellular respiration?

Photosynthesis removes CO2 from the air and fixes carbon into glucose; respiration releases CO2 back into the air, allowing it to be reused by plants.

What is gross primary productivity (GPP)?

The total amount of energy captured by producers through photosynthesis.

What is net primary productivity (NPP)?

The energy remaining after producers use some for respiration: NPP = GPP – respiration.

What percentage of solar energy typically enters producers?

About 1%.

What is a trophic pyramid?

A graphical representation showing the relative amount of energy or biomass at each trophic level, with producers at the base.

What is chemosynthesis?

A process where bacteria use energy from chemicals (e.g., hydrogen sulfide) to produce glucose, often occurring at deep-sea hydrothermal vents.

How do chemosynthetic bacteria obtain energy?

They use chemical energy from compounds like hydrogen sulfide, rather than sunlight, to convert CO2 into glucose.

What are decomposers and their role in matter cycling?

Decomposers break down dead organisms and waste, returning nutrients (like carbon and nitrogen) to the soil or air for reuse by producers.

Why is matter cycled but energy flows one way?

Matter (atoms) is recycled through ecosystems via processes like decomposition and photosynthesis, while energy is transformed and eventually lost as heat, requiring a constant input.

What are two nutrients that can limit primary production?

Nitrogen (N) and phosphorus (P).

What is a carnivorous plant?

A plant that traps and digests insects to obtain nutrients like nitrogen, allowing it to survive in nutrient-poor environments.

Name three types of traps used by carnivorous plants.

Pitfall trap (pitcher plant), flypaper trap (sundew), and snap trap (Venus flytrap).

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