1. According to the principles of ecosystem dynamics, what is the most direct consequence when an external factor, like a sudden storm, disrupts a stable system?
- A. The ecosystem immediately and permanently collapses.
- B. The rates of birth and death become unequal.
- C. All organisms in the ecosystem evolve new traits instantly.
- D. The birth rate and death rate both increase at the same pace.
2. A severe drought significantly reduces the amount of grass available in a savanna ecosystem. What is the most likely initial impact on the population of herbivores, like zebras, that feed on this grass?
- A. The birth rate will dramatically increase as zebras reproduce more to ensure survival.
- B. The population size will remain exactly the same, as the ecosystem is too strong to be affected.
- C. The death rate will likely increase due to starvation, causing the population to decrease.
- D. The zebras will instantly evolve the ability to eat other types of plants or animals.
3. After a forest fire, many plant and animal populations are drastically reduced. Over several years, new plants begin to grow and animal populations slowly increase, eventually stabilizing. What does this stabilization indicate?
- A. The ecosystem has returned to its exact pre-fire state.
- B. A new equilibrium has been reached under the new conditions.
- C. The ecosystem is now permanently unstable and will soon collapse.
- D. All the original species have been replaced by new ones.
4. What is the primary reason a population's size begins to shift after a significant disruption to its ecosystem?
- A. An imbalance between the number of births and the number of deaths.
- B. The organisms consciously decide to migrate to a new, more stable area.
- C. A sudden increase in the availability of all resources for every species.
- D. The genetic makeup of all the organisms in the population spontaneously changes.
5. A student observes that after a major flood, the fish population in a river has decreased. The student concludes the population will never recover. Why is this conclusion likely flawed?
- A. Fish populations are not affected by floods.
- B. The ecosystem will likely find a new balance over time.
- C. The decrease in fish is a sign of a healthier ecosystem.
- D. The fish will quickly adapt to live on land.
6. Which statement best describes a population that is in a state of dynamic equilibrium?
- A. The population size is rapidly increasing because the birth rate is very high.
- B. The population size remains relatively constant because the birth rate equals the death rate.
- C. No new individuals are being born and no individuals are dying within the population.
- D. The population is shrinking because the death rate is significantly higher than the birth rate.
7. A biologist observes a forest with a population of 800 foxes. In one year, there are 150 births and 150 deaths. How would this population be described?
- A. It is declining.
- B. It is growing.
- C. It is stable.
- D. It is migrating.
8. What is the primary condition required for a population to be considered stable over time?
- A. The number of deaths must be zero.
- B. The number of births must equal the number of deaths.
- C. The number of births must be much greater than the number of deaths.
- D. The environment must remain completely unchanged.
9. What is the most likely long-term outcome for a population if its birth rate consistently remains higher than its death rate?
- A. The population size will increase.
- B. The population size will decrease.
- C. The population will achieve dynamic equilibrium.
- D. The population size will not change.
10. Why is the term 'dynamic' used in 'dynamic equilibrium' to describe a stable population?
- A. Because the animals are physically active and moving.
- B. Because the population is not static; births and deaths are constantly occurring.
- C. Because the size of the population is always changing dramatically from year to year.
- D. Because the genetic makeup of the population is changing very rapidly.