AP Biology Questions on Keystone Species and Community Interactions

📚 Quick Study Guide

• 🌱 Keystone Species: A species that has a disproportionately large effect on its environment relative to its abundance. Its removal drastically changes the ecosystem.
• 🦀 Community Interactions: The relationships between different species living in the same area. These include competition, predation, mutualism, commensalism, and parasitism.
• 🤝 Mutualism: A symbiotic relationship where both species benefit (e.g., clownfish and sea anemone).
• 🐺 Predation: An interaction where one species (the predator) kills and eats another species (the prey).
• 🌳 Competition: Occurs when two or more species rely on the same limited resource. This can be intraspecific (within the same species) or interspecific (between different species).
• паразиты Parasitism: A relationship where one species (the parasite) benefits at the expense of the other (the host).
• ➕ Commensalism: A relationship where one species benefits and the other is neither harmed nor helped.
• 📉 Trophic Cascade: Occurs when changes at one trophic level (e.g., removal of a keystone predator) affect multiple trophic levels below it.
• 🌍 Ecological Niche: The role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.

🧪 Practice Quiz

1. Which of the following best describes a keystone species?
   1. A species that is the most abundant in its community.
   2. A species that plays a crucial role in maintaining the structure of its ecological community.
   3. A species that is at the top of the food chain.
   4. A species that has no impact on its environment.
2. What type of community interaction benefits both species involved?
   1. Competition
   2. Predation
   3. Mutualism
   4. Parasitism
3. In a forest ecosystem, wolves are a keystone species. What would most likely happen if the wolf population drastically declined?
   1. The deer population would decrease.
   2. The biodiversity of the forest would increase.
   3. The ecosystem would remain unchanged.
   4. The deer population would increase, leading to overgrazing.
4. Which of the following describes commensalism?
   1. One species benefits, and the other is harmed.
   2. Both species benefit.
   3. One species benefits, and the other is neither harmed nor helped.
   4. Both species are harmed.
5. Sea otters are a keystone species in kelp forest ecosystems. They primarily feed on sea urchins, which consume kelp. If sea otters are removed, what is the most likely result?
   1. An increase in the kelp forest.
   2. A decrease in the sea urchin population.
   3. A decrease in the kelp forest due to overgrazing by sea urchins.
   4. No change in the kelp forest.
6. Two species of birds both feed on insects in the same tree. This is an example of what type of community interaction?
   1. Mutualism
   2. Competition
   3. Commensalism
   4. Parasitism
7. A tick feeding on a dog is an example of:
   1. Mutualism
   2. Commensalism
   3. Predation
   4. Parasitism