Students explain why an energy pyramid narrows at the top, identify algae as producers in a pond food web, and predict effects of a frog population drop. Part B has five fill-in-the-blank problems about the sun as the original energy source, what a tertiary consumer eats, and the term for organisms that consume dead organic matter.
Tracing indirect food web effects — what happens two levels away when a middle-level population drops — requires flexible ecological reasoning.
Style:
Food Webs and Energy
Part A: Multiple Choice
Circle the best answer for each question.
1. Why does an energy pyramid get narrower at the top?
A) There are more predators than prey
B) Energy is gained at each level
C) Energy is lost as heat at each level so less is available
D) Top predators create their own energy
2. In a pond food web, algae are eaten by snails, and snails are eaten by fish. What role do the snails play?
A) producers
B) decomposers
C) primary consumers
D) top predators
3. If the frog population in a food web suddenly drops, what is the most likely effect?
A) Insect populations increase because fewer frogs eat them
B) Snake populations increase because they have more food
C) Plant populations decrease because frogs no longer eat them
D) Decomposer populations immediately disappear
4. Which organism would be found at the first trophic level?
A) hawk
B) grasshopper
C) grass
D) frog
Part B: Fill in the Blank
Write the correct answer on each line.
1. The original source of energy for almost all food webs on Earth is the sun.
2. A tertiary consumer eats secondary consumers.
3. Organisms that eat dead organic matter are called decomposers.
4. In an energy pyramid, the level with the least energy is the top.
5. Photosynthesis converts light energy into chemical energy stored in food.
Food Webs and Energy
★ Part A: Multiple Choice
Circle the best answer for each question.
1. Why does an energy pyramid get narrower at the top?
A) There are more predators than prey
B) Energy is gained at each level
C) Energy is lost as heat at each level so less is available
D) Top predators create their own energy
2. In a pond food web, algae are eaten by snails, and snails are eaten by fish. What role do the snails play?
A) producers
B) decomposers
C) primary consumers
D) top predators
3. If the frog population in a food web suddenly drops, what is the most likely effect?
A) Insect populations increase because fewer frogs eat them
B) Snake populations increase because they have more food
C) Plant populations decrease because frogs no longer eat them
D) Decomposer populations immediately disappear
4. Which organism would be found at the first trophic level?
A) hawk
B) grasshopper
C) grass
D) frog
★ Part B: Fill in the Blank
Write the correct answer on each line.
1) The original source of energy for almost all food webs on Earth is the sun.
2) A tertiary consumer eats secondary consumers.
3) Organisms that eat dead organic matter are called decomposers.
4) In an energy pyramid, the level with the least energy is the top.
5) Photosynthesis converts light energy into chemical energy stored in food.
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