Chapter 5: Interactions Within Ecosystems (pg

Unit B: Interactions in the Environment (Pg. 88 – 173)
Chapter 5: Interactions Within Ecosystems (pg. 120 – 145)
Name: __________________________
Date: ________________________
5.1: The Roles of Organisms in an Ecosystem (Pg. 122- 124)
Check Your Learning: Read Pages 122-124. Answer the following questions:
Explain the differences between producers and consumers.
Producers: get energy from food they make themselves. Most producers make food using CO 2, water, and energy from sun.
Consumers: They get energy by eating other organisms.
What are the raw materials of photosynthesis?
The raw materials of photosynthesis are CO 2 and water (H2O). Plants also need sunlight to perform photosynthesis.
What are the products of photosynthesis?
The products of photosynthesis are oxygen and sugars.
What happens to the products of photosynthesis?
The sugars made in photosynthesis are used by the producer for energy and to build up its body. Oxygen that the plant does not
use itself is released into the atmosphere. The food and oxygen may be used by animals when they consume plants and breathe
in oxygen.
What is the difference between detrivores and decomposers?
Detrivores get their energy by feeding on large parts of decaying animals and plants.
Decomposers feed on decayed matter left behind by consumers and detrivores.
What are the similarities between omnivores and carnivores?
Omnivores and carnivores are both types of consumers, and both eat animals.
What the differences between omnivores and carnivores?
Omnivores eat plants, but carnivores do not.
What role do scavengers play in ecosystems?
Scavengers eat the remains of dead organisms.
Define the followings:
an organism that makes its own food from non-living materials.
Consumer: an organism that eats other living things for energy.
Herbivore: an organism that eats plants only.
Carnivore: an organism that eats other animals only.
Omnivore: an organism that eats both plants and animals.
Scavenger: an organism that eats already dead animals.
Detrivore: an organism that feeds on large parts of decaying plant and animal matter and on waste material.
Decomposer: an organism that consumes and breaks down dead organisms or waste matter into simple substances.
Define the process of photosynthesis.
Photosynthesis is a process by which plants use water, carbon dioxide, and sunlight to produce sugars (food).
What is the equation for the stages of the photosynthesis?
Sun’s energy + water + Carbon dioxide  food (sugar) + oxygen
H2O + CO2 + light energy  sugar (C6 H12 O6 ) + O2
5.2: Food Chains and Food Webs (Pg. 125- 128)
Check Your Learning: Read Pages 125-128. Answer the following questions:
Define food chain and food web.
Food Chain: a sequence that shows how energy and nutrients are transferred from one organism to another in an ecosystem.
Food Web: a model that shows how food chains in an ecosystem are connected.
Create two food chains from the following list. Use Figure 4 to help you.
mallard duck
mosquito larva
freshwater calm
algae  mosquito larva  mallard duck  human
What is the role of producers in food chains and food webs?
Producers convert energy in sunlight into stored energy in food.
b) algae  freshwater clam  raccoon
a) What are the similarities between food webs and food chains?
They are both models that show how energy and nutrients pass from one organism to another in an ecosystem.
b) What are the differences between food webs and food chains?
In a food chain, each organism only has one source of food and is eaten by at most one other organism.
In a food web, every organism can have many food sources and can be the food source for more than one other organism.
Explain what may happen to a food web if one of the species of the web is removed.
If a species is removed from a food web, the food web could collapse, or it could reorganize depending on how many organisms
relied on the species that had been removed.
What is the initial source of the energy in all food webs and food chains?
The initial source of energy for most food chains and food webs is sunlight. Producers use energy in sunlight to make food.
Complete: A food chain can have just two components, a producer and a consumer. Other food chains are more complicated. A
producer may be consumed by a herbivore, also called primary consumer, which is then eaten by a carnivore, also called secondary
consumer. In some cases, another carnivore, also called tertiary consumer, eats the first carnivore.
Create a food chain at lease three organisms long that includes human beings.
Sun  crops  chicken  humans
organic matter  chicken  human
5.4: Energy Flow in an Ecosystem. (Pg. 132- 134)
Check Your Learning: Read Pages 132-134. Answer the following questions:
A chicken eats some grain. In your words, describe what happens to the energy in the food once the chicken eats it.
When a chicken eats the grain, about 30% of the energy in the grain is used to sustain the chicken, about 60% is wasted,
and about 10% goes to body growth.
What is a pyramid of numbers? How does it relate to a food chain?
A pyramid of numbers shows the total numbers of organisms at each level of the food chain.
How is a pyramid of numbers different from an ecological pyramid?
Ecological pyramid:
It is a diagram indicating which organisms in an ecosystem eat which other organisms.
Pyramid of numbers:
is a diagram that shows that relative numbers of different organisms in an ecosystem.
What happens to the total number of organisms at each level of a pyramid of numbers?
The total number of organisms at each level decreases as you move up the pyramid.
Explain in your own words why this occurs.
This occurs because only about 10% of the energy stored in the bodies of the organisms at each level is available to the
organisms at the next highest level.
What type of organisms always occupy the first level of an ecological pyramid or a pyramid of numbers?
The first level of the pyramid of numbers is always occupied by producers.
5.5: Matter Cycles (Pg. 135- 139)
Check Your Learning: Read Pages 135-139. Answer the following questions:
What is a cycle?
A cycle is a looping pattern of events.
Explain how detrivors and decomposers recycle matter.
They break down matter from dead organisms into forms that can be reused by living plants.
What is meant by the statement “Ecosystems are sustainable?”
This statement means that healthy ecosystems can be maintained indefinitely because matter is recycled.
In your own words, describe the carbon cycle.
Carbon dioxide from the air it taken in by plants, which use it to make sugars. Some of those sugars are used by animals that
eat the plants, and eventually the carbon in the sugars is either returned to the atmosphere as waste gas or buried in the ground.
Carbon is also released to the atmosphere when forests burn or when people burn fossil fuels.
In your own words, describe the water cycle.
Water evaporates. It rises and condenses and then falls as rain or other precipitation. Some of the water runs off the land back
into a river or stream and into the ocean. Some of the water moves through the ground, where plants take it up or people use
wells to get the water from deep underground.
Describe some of the ways that the supply of fresh water on Earth is at risk.
People use a great deal of fresh water for agriculture and industry. The water they use often becomes polluted. Large amounts
of energy and time are required to clean the water.
Define the followings:
The process used by living things to break down sugars for the energy stored in them.
The process in which a substance changes state from liquid to gas.
The change in state of a substance from gas to liquid.
Water in the liquid or solid state that falls to Earth.
Chapter 5: Chapter Review (pg. 144 – 145)
What are the “ingredients” of photosynthesis?
The “ingredients” of photosynthesis are carbon dioxide, water, and sunlight.
Create a food chain that has four organisms.
Kelp  sea urchin  sea otter  shark
What would happen to ecosystems if dead organisms did not decompose?
If dead organisms did not decompose, the bodies would quickly cover Earth and nutrients contained in the bodies would not be
recycled for other organisms to use.
Decomposers play an important role in which matter cycle?
Decomposers play an important role in The carbon cycle.
6. Explain the difference between a producer and a consumer.
A producer gets its energy from the sun. A consumer gets energy from the other organisms it eats.
7. For each of the following, explain the difference between the two terms:
a) food chain, food web: A food chain includes only one link to and from each organism. A food web can have many links going
to or coming from each organism.
b) carnivore, scavenger: A carnivore kills organisms for food. a scavenger eats the remains of organisms that are already dead.
c) detrivore, decomposer: Decomposers break down wastes and dead plant and animal matter into simpler substances, and
consume those substances. Detrivores consume larger pieces of wastes and dead plant and animal matter.
d) primary consumer, secondary consumer: A primary consumer eats producers. A secondary consumer eats primary consumers.
9. Explain what is meant by “Energy flows and matter cycles.”
It means that new matter is not created; it is recycled in an ecosystem. Energy cannot be recycled. It can flow only one direction
in an ecosystem. New energy must continually enter the ecosystem.
5.1: The Roles of Organisms in an ecosystem (Pg. 89)
What are the products of photosynthesis? What happens to these products?
a) Sugar
b) oxygen
Plants use sugars as food and store extra sugar as starch. Plants release extra oxygen into the ear..
What is the difference between herbivores and carnivores?
Herbivores: eat only plants.
Carnivores: eat only meat.
What role do decomposers have in an ecosystem?
Decomposers break down dead organisms and wastes into simple substances.
Key Question: How do different organisms in an ecosystem get food?
Producers can make their own food using non-living materials. Consumers must eat other organisms to get energy.
5.1: Complete a table: Roles in an Ecosystem (Pg. 90)
Producers: make food through
photosynthesis. (tomato plant)
Omnivores: eat plants and animals (bears)
Herbivores: eat plant (deer)
Carnivores: eat animals (wolves)
Detrivores: eat large parts of decaying
matter and waste (earthworms)
Decomposers: absorb nutrients from dead
organisms in the process of decay (fungi)
2) Which type of organism are you? How do you know?
I am an omnivore because I eat both plants and animals.
5.2: Food Chains and Food Webs (Pg. 04)
What is the difference between a food chain and a food web?
A food chain shows how one organism is connected to another organism in a straight line.
A food web shows how many food chains in an ecosystem are connected.
What are primary consumers?
Primary consumers are the first consumers in a food chain.
They eat producers.
What are secondary consumers?
Secondary consumers are the second consumers in a food
chain. They eat primary consumers.
What happens if a species disappears from a food chain?
The consumers that eat that species will have to fine other food, or they will die. Any organisms that the species used for food may
increase in population.
Key Question: How is energy passed through an ecosystem, beginning with the Sun?
Producers absorb sunlight and store the energy in sugars and starches. The energy passes to consumers that eat plants. Then, the
energy passes to consumers that eat other consumers.
5.2: Analyze a Food Chain (Pg. 95)
a) Which organism is the producer?
b) Which organism is the primary consumer?
The dandelion plant
The aphid
a) How does the dandelion plant get energy?
It absorbs sunlight. It stores the energy is starches.
b) How does the ladybug get energy?
It eats aphids, which get energy from the dandelion plants.
4) What would happen if the ladybug disappeared from this food chain?
The robins would have less food. they would have to find other sources of food. There may also be too many aphids, and the aphids
might eat all the dandelions.
5.4: Energy Flow in an Ecosystem (Pg. 98-99)
How do organisms use the energy they get from food?
Organisms use some energy for body functions. They also store some energy so they can grow and stay healthy.
Why do food chains usually have no more than four levels?
Food chains lose energy at each level. If a food chain has too many levels, the top consumers don’t get enough energy.
What is a pyramid of numbers?
A pyramid of numbers shows the number of organisms at each level of a food chain or food web.
Where are producers located in a pyramid of numbers? Why?
Producers form the base of a pyramid 0of numbers. They provide energy for the consumers in the ecosystem.
Key Question: How does energy loss affect the number of levels in a food chain?
Food chains lose energy at each level. If there are too many levels, the top consumers do not get enough energy. As a result, most
food chains usually have fewer than five levels.
5.4: Explore Energy in Food Chains (Pg. 100)
1) Does this food chain pass energy more effectively than a shorter food chain? Why?
No, this food chain loses more energy than a shorter food chain because there are more animals in the chain.
2) In Fig 1…How much of this energy does the mosquito larva pass to a sunfish?
About 10%
3) In a pyramid of numbers for fig 1, which organism would be at the base of the pyramid? Why?
The algae would be at the base. The algae are the producers that give energy to the rest of the food chain.
5.5: Matter Cycles (Pg. 105-106)
Earth is a closed system. What does this mean? No new matter enters Earth’s ecosystems and no matter leaves them.
What is evaporation? Evaporation is when a substance changes in state from a liquid to a gas.
Describe the evaporation stage in the water cycle.
The Sun warms oceans, lakes, and rivers. Some water turns to water vapour and rises in the atmosphere.
Why are cycles important to an ecosystem?
The amount of matter on Earth does not change. Cycles let organisms reuse the same matter many times.
How have humans affected the carbon cycle?
Humans have added more carbon dioxide to the atmosphere by burning fossil fuels.
Key Question: How do detrivores and decomposers recycle matter in an ecosystem?
Detrivores break down decaying matter into small pieces. Decomposers break down the small pieces into simple substances, which
go into the soil as nutrients. Plants use these nutrients to grow.
5.5: Analyze Cycles in Earth’s Ecosystems (Pg. 107)
Explain the role of each organism below in the carbon cycle.
An oak tree:
It uses sunlight, water, and CO2 from the air to make food.
A mushroom:
It breaks down dead plant matter and releases CO2 into the air.
A deer:
It releases CO2 into the air when it breaths.
Explain how each action affects the water cycle:
A farm uses large amounts of fresh water to grow crops.
The water cycle may not be able to supply water quickly enough to replace it. There could be less fresh water left to drink
Rain washes chemicals from a mine into nearby rivers and lakes.
The chemicals pollute the fresh water. Organisms could be harmed if they drink the polluted water.
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