Food Chains
What is a food chain?
A single pathway showing how energy moves from one organism to another.
What is a food web?
A network of connected food chains.
What is a trophic level?
An organism's feeding position in an ecosystem.
What is the main source of energy for most ecosystems?
The sun
What is biomass?
The total mass of living organic matter.
In this chain, Grass → Rabbit → Hawk, which organism is the producer?
Grass
Why are food webs more realistic than food chains?
Organisms usually eat multiple types of food and may have multiple predators.
What organisms make up the first trophic level?
Producers.
What organisms capture energy from sunlight and make their own food?
Producers.
Which trophic level usually has the greatest biomass?
Producers.
In Grass → Grasshopper → Frog → Snake, what is the frog's trophic level?
Secondary consumer / third trophic level.
If the rabbit population decreases, name one organism that could be affected.
Fox or hawk.
What trophic level is a rabbit that eats grass?
Primary consumer / second trophic level.
What happens to available energy as you move up trophic levels?
It decreases.
Which usually has less biomass: producers or tertiary consumers?
Tertiary consumers.
What do the arrows in a food chain represent?
The direction that energy moves.
If mice decrease, what could happen to snakes? Explain.
Snakes could decrease because mice are one of their food sources.
What trophic level is a snake that eats a mouse that eats seeds?
Secondary consumer / third trophic level.
About what percentage of energy is typically transferred to the next trophic level?
About 10%.
Why does biomass generally decrease as you move up a biomass pyramid?
Less energy is available at higher trophic levels.
Explain why a food chain usually has only a few trophic levels.
Available energy decreases at each trophic level, so less energy is available to support higher-level organisms.
Why can removing one organism affect organisms that don't directly eat it?
Changes can ripple through connected feeding relationships in the food web.
Put these in the correct order:
Snake • Grass • Hawk • Rabbit
Grass → Rabbit → Snake → Hawk.
Why isn't all of the energy passed to the next trophic level?
Organisms use energy for life processes such as movement, growth, repair, and reproduction, and much of it is released as heat.
An ecosystem has:
Which level has the greatest biomass, and what pattern do you notice?
Producers have the greatest biomass. Biomass decreases at higher trophic levels.