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Level 1 Mission 1Pg 1 and 3: Ecosystem Readings
Boot Camp Files
Food Web Test Reading and Questions
Period:
The food chain represents the flow of energy through and cycling of matter in an ecosystem! It all starts with the producers, the
plants that trap the energy from the sun and turn the sun energy into the sugar (food) made out of carbon. Matter and energy are not
the same. The food made out of carbon produced by plants cycles in ecosystem while the energy moves through an ecosystem. All the
biological energy on earth, the energy in insects, your dog, and you yourself, comes from the sun. All the matter on earth will stay on
earth. How does it get work? The food chain!
The food chain begins with plants! Plants in the food chain are called producers because they trap sun energy in the form of
sugar and produce food. Producers do photosynthesis. During photosynthesis, producers remove carbon from carbon dioxide in the
atmosphere, and use carbon nutrients from the soil to make a sugar molecule full of the suns energy and carbon matter. In the
process, producers release oxygen in the atmosphere for animals to breathe. This sugar provides the energy and matter for all
animals on earth, even animals like carnivores that don’t eat the plants themselves. To see how the energy and matter get to the meat
eaters, just follow the arrows.
Plant Notes: What have you learned so far about plants (producers) and their role in the ecosystem? What are your thoughts about their role?
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Figure A: Food chain from the deciduous forest
All animals that eat food are called consumers. This includes herbivores, omnivores and carnivores. Herbivores that eat the
producers are called primary consumers (grasshopper), animals that eat herbivores are called secondary consumers (mouse) and
animals that eat carnivores are called tertiary consumers (snake and hawk). Some of the energy the producers captured from the sun
is lost as it travels up the food chain! This is because animals use the food they eat to make energy for their cells to function! The
energy is lost as heat to the atmosphere. When animals run and use a lot of energy, their bodies heat up! All the energy the herbivores
receive from the plants does not make it to the secondary consumers because the herbivores use some of the energy to live and
function. This energy is said to be lost as heat.
Energy Notes: What did you learn about how does energy move through an ecosystem? What are your thoughts on the food chain?
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Matter, in the form of carbon, cycles through the ecosystem in the same way as energy, except matter is not lost to the
environment! Producers get matter from the nutrients and carbon in the soil. Grasshopper babies eat the matter in plants to grow,
the mice will eat the matter in the grasshopper to grow, the snake will eat the matter in mice to grow, and the hawk will eat the matter
in snakes to grow. When any of the organisms defecate (science term for poop) or die, decomposers like bacteria and fungus eat and
break down the feces and dead organisms. In the process, the decomposers convert the matter and carbon from the dead organism
into nutrients. The decomposer puts the matter and nutrients back into the soil and the plants use the nutrients and carbon to grow.
Matter Notes: What did you learn about matter in the food chain? What are your thoughts on cycling matter?
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1. Which type of organism is the most important to the ecosystem: producer, consumer, or decomposer? No correct answer
Claim: ___________________________________________________________________________________________________________________________________
Evidence: What is their role in the food chain? Movement of energy? Cycling of matter?
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Reasoning: Why is this role more important than the other parts of the ecosystem?
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Not only is energy lost to the environment in each step of the food chain, the number of organisms in the ecosystem
decreases as the energy climbs the food chain. In most cases, there are fewer predators than there is prey. Scientists show these
relationships as trophic levels in a pyramid. Each level of producer or consumer is called a trophic, or energy level. Scientists
illustrate trophic levels as a pyramid because there are the most producers in an ecosystem, and the producers trap all of the energy in
an ecosystem. The primary consumers make up the next largest level because there are plants than herbivores and some of the
original trapped sun energy is lost to the environment because the herbivore used the energy to live. The secondary consumer is
smaller, and the tertiary consumer is even smaller because the number of organisms drops each step and the carnivore consumers use
some of the energy live, losing the energy to the environment.
Figure B: Trophic level pyramid of a food chain from the deciduous forest.
Trophic level notes: Focus question- Why do scientists design put the food chain into a pyramid?
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To truly understand how animals are related to other animals and producers in the food chain, one needs to study a food
web. A food web models the relationships between multiple animals in an ecosystem and is the ultimate who-eats-who guide to the
habitat. In some cases, animals can be more than one type of consumer. This is always the case with omnivores, but many carnivores
can be secondary and tertiary consumers.
Quick Thought: Why are omnivores more than one type of consumer?
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Figure C: Foodweb modeling the decciduous forest biome
Scientists can use food webs to make predictions about the balance and stability of the environment when an animal is
removed or added to the ecosystem. Illness, mass migration, and natural phenomenon like volcanoes, are some of the common ways
animals leave an ecosystem and its food web. When all of the organisms of one species die in every ecosystem, the species no longer
exists and is extinct. On earth, humans over hunted many animals, destroyed animal habitats, and forced many organisms to go
extinct. Animals can join the food web through migration. On Earth, humans move animals from ecosystem to another. When
animals are removed from a food chain, their predators have less food to eat. This can force a predator to find another food source.
Usually there are not enough animals for the original predator and the new predator, so there is decrease in population size. On the
other hand, the prey (of the removed organism) has one less predator eating it. This can lead to an increase in the population of the
former prey. The opposite effects can be noticed when a new species enters the food web. Their new predators will grow in
population because they now have more food, while their new prey will decrease in population because there is another predator
eating them. Although plants are the most important in maintaining the stability of an ecosystem, every animal plays a role in their
environment. Adding or removing animals to the ecosystem shifts the entire food web. If the change is large enough, one or more
species may go extinct.
Select a secondary consumer with a predator from the food web in Figure C. Pretend it goes extinct.
What animal went extinct, why did it go extinct, and how does it effect the rest of the ecosystem?
Claim: The ______________________ went extinct because ___________________________________________________________________________
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Evidence: What will happen to the population of its predator and prey if the animal goes extinct? Include their names.
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Reasoning: Why did the population of the predator and prey change the way it did?
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Extension: Select another animal from the food web not directly connected to the extinct secondary consumer. How
might this organism’s population change? Why?
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Even though the animals experience a large change in population size, the plant life usually is left unaffected by
individual animal additions or depletions. Trees make up the largest group and most stable group of the food web,
which is why they take the bottom spot in the trophic level pyramid. Plants rarely experience large changes to their
population when a species is added or removed from an ecosystem because there are many more plants than animals in
the environment. Plants experience large population shifts when there are changes to the climate, water, and other
abiotic factors. This will then impact all the other animals of the food web, it just depends if there is more or less food for
the primary consumers in the food web.
Decomposers are found at the very end of the food chain. They are not quite on the top, but loop the top of the
food chain back to the producers at the beginning. When animals die, the decomposers will break down their body into
tiny molecules of carbon. The tiny molecules of carbon enter the soil to become nutrients for future trees and plants to
grow. Eventually the carbon from dead animals is absorbed into the plant to become food for primary consumers to eat.
Some might argue that decomposers are just as important as producers because producers cannot grow with out the
nutrients the decomposers put into the soil! The decomposers provide essential elements plants need to grow, including
carbon.
Plants and trees do not only produce food and energy for all the animals, but also the producers of oxygen for
animals. The plants take the carbon dioxide that animals exhale and convert it to oxygen in a process called
photosynthesis. Photosynthesis is the same process that plants use to make sugar. Plants take in carbon dioxide, water,
and the energy from the sun to make oxygen for animals to breathe and sugar full of carbon for animals to eat. Through
photosynthesis plants make everything an animal needs to live.
1. Humans burn fossil fuels that pollute the air by adding carbon dioxide to the atmosphere? The carbon dioxide traps
the heat from sunlight and causes the temperature to rise. Berry vines are very heat sensitive and cannot grow in a
warm environment. How will global warming impact the foxes in the food web in figure C? Explain what will happen to
the producer and primary consumer.
2. What is going to happen to the population of three animals if humans bring small insects like ticks and ants that the
mice eat in the ecosystem of figure C?
3. How will planting more trees help reverse the effects of burning fossil fuels and creating lots of carbon dioxide
population?
Choose one of the questions below to answer.
4a.. What is wrong with the following food web? What needs to change and why?
4b. Josh said that he is the like the most important part of the ecosystem, the lion. Explain to Josh why the lion is not the
most important part of the ecosystem
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