Food web/chain
What is the original source of energy for most food chains?
The Sun
What is an organism that makes its own food called?
Producer
What can happen when one organism is removed from a food web?
Other populations can be affected.
What is an environmental change?
A change in the conditions of an ecosystem or environment
Grass decreases in an ecosystem. Which organism would most likely be affected first: a rabbit that eats grass or a hawk that eats rabbits? Explain.
The rabbit, because it directly depends on grass for food.
In the food chain grass → rabbit → fox, which organism is the producer?
The grass
What is an organism that gets energy by eating other organisms called?
Consumer
A new predator enters an ecosystem and eats many rabbits. What will likely happen to the rabbit population?
It may decrease.
Name one environmental change that could affect organisms.
Drought, wildfire, flooding, temperature change, habitat loss, etc
A rabbit population increases. Explain how this could eventually affect plants and another animal in the ecosystem.
More rabbits could eat more plants, decreasing plants and potentially affecting animals that depend on those plants.
What does an arrow in a food chain show?
The direction that energy moves from one organism to another.
Why are decomposers important in an ecosystem?
They break down dead organisms and return nutrients to the ecosystem.
If there are suddenly many more rabbits in an ecosystem, what could happen to the plants they eat?
The plant population could decrease.
A pond dries up. What might happen to fish living in the pond?
They may not survive or may move to another location if possible.
Scientists observe that an animal population decreases after a drought. Why isn't the population decrease alone enough to tell scientists exactly what happened?
Scientists need more evidence to determine the cause and whether organisms died, moved, or responded in another way.
In the food chain grass → grasshopper → frog → snake, what would most likely happen to the frog population if the grasshopper population decreased?
The frog population could decrease because frogs have less food available.
Why can changing one population affect other populations in an ecosystem?
Organisms depend on one another for food, energy, shelter, or other resources
Hawks are removed from a forest ecosystem. Rabbits are one of the hawks' prey. What is one possible effect of removing the hawks?
The rabbit population could increase, which could cause more plants to be eaten.
A forest becomes warmer and drier. Scientists notice that some animals leave the area. What type of response are the animals showing?
Moving to a new location.
Scientists find fewer grasshoppers after a drought. They also find that the amount of grass decreased. Which evidence would better support the idea that the drought affected the grasshopper population?
Evidence showing that grasshoppers depend on the grass for food and that both populations changed after the drought.
A drought causes the amount of grass in an ecosystem to decrease. Explain how this change could affect two different organisms in the food web.
Answers should connect the decrease in grass to organisms that depend on grass directly or indirectly.
A food web contains grass, rabbits, mice, snakes, and hawks. If the rabbit population decreases greatly, explain one possible effect on another population and why it could happen.
For example, hawks could have less food available and their population could decrease.
A student says, “Removing one organism from a food web will only affect that organism.” Do you agree or disagree? Use an example to explain your answer.
Disagree. Organisms are connected, so changing one population can affect other populations.
A drought causes grass to decrease from 100 plants to 40 plants. Rabbit numbers also decrease from 50 to 20. Explain how the data could support the idea that the drought affected the rabbit population.
The grass decreased substantially, and rabbits depend on plants for food, so the decrease in available food could have contributed to the decrease in rabbits.
Scenario:
A forest contains plants, insects, rabbits, mice, snakes, hawks, and decomposers. A long drought causes many plants to die. After several months, scientists observe fewer rabbits and mice. They also observe fewer hawks.
Question:
Use evidence from the scenario to explain how ONE environmental change could lead to changes in THREE different populations.
The drought caused many plants to die. With fewer plants, rabbits and mice had less food, so their populations could decrease. Hawks eat rabbits and mice, so fewer prey could cause the hawk population to decrease.