Keystone Species and Ecosystem Dynamics

The video discusses homeostasis in ecosystems, emphasizing the balance maintained by biotic and abiotic factors. It covers ecosystem stability, the impact of invasive species, and the roles of food chains and webs. The importance of keystone and foundation species is highlighted, along with homework instructions.

What is the primary role of homeostasis in an ecosystem?

• To increase the number of species

• To maintain a stable living condition for organisms

• To promote rapid growth of populations

• To eliminate non-native species

How can invasive species affect an ecosystem?

• By increasing biodiversity

• By disrupting homeostasis

• By providing more food sources

• By stabilizing the ecosystem

Why does the number of organisms decrease at each trophic level in an energy pyramid?

• Because of natural disasters

• Because energy is lost at each level

• Because organisms migrate to other ecosystems

• Because of increased competition

What is a key difference between a food chain and a food web?

• A food chain shows a single pathway of energy flow

• A food web shows a single pathway of energy flow

• A food chain shows multiple pathways of energy flow

• A food web is limited to three trophic levels

Why are food chains typically limited to four to five trophic levels?

• Because of the abundance of energy at higher levels

• Because of the decrease in energy available at higher levels

• Because of the increase in species diversity

• Because of the stability of ecosystems

What defines a keystone species in an ecosystem?

• A species that is the most abundant

• A species that has a large impact on its environment relative to its abundance

• A species that is not affected by changes in the ecosystem

• A species that is the least abundant

How do keystone species contribute to ecosystem stability?

• By controlling the population of other species

• By reducing the number of predators

• By eliminating invasive species

• By increasing the number of producers

Which of the following is an example of a keystone species?

• A species that migrates seasonally

• A predator that controls the population of multiple species

• A herbivore that eats only one type of plant

• A plant that provides food for a single species

What is the role of bees as a keystone species?

• They pollinate plants, allowing other species to reproduce

• They provide shelter for other species

• They are top predators in their ecosystem

• They control the population of herbivores

What should students focus on when summarizing their notes?

• Drawing diagrams of food webs

• Writing down every word from the lecture

• Highlighting key terms and main ideas

• Listing all species mentioned