AP Biology Questions on Food Chains and Trophic Levels

📚 Quick Study Guide

• 🌱 Producers: Autotrophs like plants that form the base of the food chain. They convert sunlight into energy through photosynthesis.
• 🌿 Primary Consumers: Herbivores that eat producers. Examples include grasshoppers and rabbits.
• 🦊 Secondary Consumers: Carnivores that eat primary consumers. Think of foxes eating rabbits.
• 🦁 Tertiary Consumers: Carnivores that eat secondary consumers. They are often apex predators, like lions.
• 🍄 Decomposers: Organisms like bacteria and fungi that break down dead organisms, returning nutrients to the ecosystem.
• ☀️ Trophic Levels: Each step in a food chain or food web. Energy decreases as you move up trophic levels.
• ♻️ Energy Transfer: Only about 10% of the energy at one trophic level is transferred to the next. This is often represented as $E_{n+1} = 0.1 * E_n$, where $E_n$ is the energy at level *n*.
• ⚖️ Biomass: The total mass of organisms in a given area or volume. Biomass also decreases as you move up trophic levels.
• 🕸️ Food Web: A complex network of interconnected food chains, showing the feeding relationships within an ecosystem.
• 🌡️ Impacts of Change: Alterations at one trophic level can cascade through the entire ecosystem, impacting other organisms.

🧪 Practice Quiz

1. Which of the following organisms occupies the first trophic level in a food chain?
   1. A) Grasshopper
   2. B) Snake
   3. C) Oak Tree
   4. D) Mushroom
2. What is the primary role of decomposers in an ecosystem?
   1. A) To produce energy from sunlight
   2. B) To consume primary producers
   3. C) To break down dead organic matter
   4. D) To provide oxygen to the environment
3. Which trophic level typically has the lowest biomass in an ecosystem?
   1. A) Producers
   2. B) Primary Consumers
   3. C) Secondary Consumers
   4. D) Tertiary Consumers
4. Approximately what percentage of energy is transferred from one trophic level to the next?
   1. A) 5%
   2. B) 10%
   3. C) 50%
   4. D) 90%
5. A rabbit eats grass. A fox eats the rabbit. Which organism is the secondary consumer?
   1. A) Grass
   2. B) Rabbit
   3. C) Fox
   4. D) Decomposer
6. What term describes all the interconnected food chains in an ecosystem?
   1. A) Trophic pyramid
   2. B) Food web
   3. C) Energy cycle
   4. D) Biomass distribution
7. Which of the following is an example of a primary consumer?
   1. A) Wolf
   2. B) Deer
   3. C) Hawk
   4. D) Mushroom