Food chains & webs
What is a food chain?
A sequence showing who eats who in an ecosystem
What is a trophic level?
A step in a food chain or web
What is the original source of energy for most ecosystems?
The Sun
What cycle moves water through evaporation, condensation & precipitation?
Water cycle
What is the correct term that refers to the distance above sea level?
altitude
What does a food web show that a food chain doesn’t?
Multiple interconnected food chains
What trophic level do herbivores belong to?
Primary consumers (2nd level)
What type of organism captures solar energy?
Producers (plants/algae)
What is the role of decomposers in the nitrogen cycle?
Break down matter and return nutrients to soil
How can humans reduce their impact on ecosystems?
Recycling, reducing emissions, protecting habitats
What do arrows in a food chain represent?
Direction of energy flow
Give an example of a tertiary consumer.
Owl, wolf, hawk, etc.
What happens to energy that isn’t transferred to the next level?
Lost as heat or used by the organism
What is one way carbon enters the atmosphere?
Respiration, combustion, decay
What is biomagnification?
Toxins build up in top consumers
Which organism type is always at the bottom of a food chain?
Producers (plants)
Why do top predators get the least energy?
Energy is lost as heat and waste at each level
Why do ecosystems usually have only 4–5 trophic levels?
Not enough energy left to support more levels
How do plants use nitrogen?
To build proteins
What happens when too many nutrients enter a lake?
Algae blooms, less oxygen, fish die
Why are food webs more accurate than food chains?
They show all feeding relationships, not just one path
How much energy typically passes from one trophic level to the next?
About 10%
How do decomposers fit into the energy flow?
They break down dead organisms and recycle energy/nutrients
What human activity increases nitrogen in water systems?
Fertilizer use
The buildup of nutrients in an aquatic ecosystem that can lead to “algae blooms” is called:
eutrophication