Question
Tidal marshland A, which is adjacent to the San Francisco airport, has a Simpson’s Diversity Index of 0.65. Tidal marshland B, which is two
miles from the airport, has a Simpson’s Diversity Index of 0.80. An oil spill occurs at a location at the halfway point between the two
marshlands.
If both marshlands are equally contaminated by the oil spill, which marshland is more likely to recover from the oil spill?
(A) Tidal marshland A is more likely to recover, because its lower Simpson’s Diversity Index means that few species will be affected.
(B) Tidal marshland B is more likely to recover, because its higher Simpson’s Diversity Index means it has a wider variety of species and can better absorb the effects of a disturbance.
(C) Both ecosystems will be equally affected, because they are the same distance from the oil spill.
(D) Neither ecosystem will be able to recover, because oil is toxic to all organisms.
▶️Answer/Explanation
Answer: (B) Tidal marshland B is more likely to recover, because its higher Simpson’s Diversity Index means it has a wider variety of species and can better absorb the effects of a disturbance.
Explanation:
Simpson’s Diversity Index measures biodiversity the variety and abundance of species in an ecosystem. A higher value (closer to 1) means more diversity. Ecosystems with greater biodiversity are usually more resilient and better able to recover from disturbances like oil spills because they have more species that can adapt or fill ecological roles.
Evaluation of Each Option:
(A) Incorrect – A lower diversity index means fewer species, which usually makes the ecosystem less resilient, not more.
(B) Correct – A higher diversity index means more species variety, allowing the ecosystem to better withstand and recover from damage.
(C) Incorrect – Distance alone does not determine recovery; biodiversity plays a key role in resilience.
(D) Incorrect – While oil is toxic, ecosystems can recover over time, especially those with higher biodiversity.
Question
The Nile perch is a species of fish that was introduced into Lake Victoria in the 1950s. It has caused the extinction or near-extinction of several hundred native species in the lake. Which of the following is an accurate statement regarding the introduction of the perch to Lake Victoria?
(A) Eutrophication of a lake can decrease its carrying capacity.
(B) Humans can negatively impact the balance of an ecosystem.
(C) The Nile perch is a successful predator.
(D) The diversity in Lake Victoria is likely to increase because most extinction events are followed by a large increase in diversification.
▶️Answer/Explanation
Answer: (B) Humans can negatively impact the balance of an ecosystem.
Explanation:
The introduction of a non-native species, like the Nile perch, can disrupt ecosystems. This often leads to loss of native species and biodiversity, especially when the introduced species becomes a dominant predator. Such actions reflect the negative impact humans can have on ecological balance.
Option Analysis:
A. Incorrect – Eutrophication affects nutrient levels and oxygen in water, but this is not relevant to the Nile perch situation.
B. Correct – The Nile perch was introduced by humans, causing many native species to go extinct. This shows that human actions can upset ecosystem balance.
C. Incorrect – The Nile perch is a strong predator, but this option doesn’t directly address the human-caused ecological impact the question focuses on.
D. Incorrect – Extinction usually reduces diversity, especially in the short term. Evolutionary diversification takes much longer and is not guaranteed.
Question.
Which of the following best explains why many different species can live together within an ecosystem with limited resources?
(A) Each species lives in a slightly different habitat.
(B) Each species occupies a different niche.
(C) Each species inhabits a different biome.
(D) Each species makes up a different population.
(E) Each species functions at a different trophic level.
▶️Answer/Explanation
Answer: (B) Each species occupies a different niche.
Explanation:
A niche is the role a species plays in its ecosystem — what it eats, where it lives, and how it interacts with other organisms. When species have different niches, they can share the same space without directly competing for the same resources.
Option Analysis:
A. Incorrect – Different habitats may help avoid competition, but species can still live in the same habitat and not compete if they have different niches.
B. Correct – Different niches mean species use resources in different ways. This is the main reason they can live together with limited resources.
C. Incorrect – A biome is a large region, not a reason for species to live together in one ecosystem.
D. Incorrect – Being different populations doesn’t explain how species avoid competition for the same resources.
E. Incorrect – Species at different trophic levels may not compete, but many species at the same level can still live together by having different niches.
Question
A researcher is investigating the relationship between the existing species diversity in a community and the ability of an introduced nonnative species to destabilize the community. Which of the following graphs is most consistent with the claim that communities with high diversity are more resistant to change than are communities with low diversity?
▶️Answer/Explanation
Answer: D
Explanation:
High species diversity = More stable ecosystem = Less chance for invasive species to survive.
The idea is:
- If there’s more biodiversity, all the ecological niches are filled.
- So, invading species struggle to survive — they don’t find open space, resources, or unoccupied roles.
Best match to this claim:
- Graph D: Shows inverse relationship
- As species diversity increases, survival of invaders decreases.
That’s exactly what the researcher is suggesting.
Why not the others?
A: Says survival of invaders stays constant regardless of diversity – contradicts the claim.
B: Weird V-shape suggests mixed or unclear effect – not consistent with the strong claim.
C: Suggests more diversity = more invader survival – total opposite.
Question
Which of the following habitats contain the most bryophytes?
(A) Deciduous forests
(B) Deserts
(C) Ponds
(D) Oceans
(E) Grassland
▶️Answer/Explanation
Answer: (A) Deciduous forests
Explanation:
Bryophytes are non-vascular plants such as mosses, liverworts, and hornworts. They need moist, shady environments because they rely on water for reproduction and do not have vascular tissue to transport water internally. Therefore, they are most common in damp, forested areas.
Option Analysis:
A. Correct – Deciduous forests provide the moist, shaded environments that bryophytes need. The forest floor, tree bark, and rotting logs are often covered in mosses, making this the best habitat for bryophytes.
B. Incorrect – Deserts are dry and hot, with very little moisture, which is unsuitable for bryophytes.
C. Incorrect – While bryophytes need moisture, they do not grow inside ponds (aquatic environments). They grow on land, often near water, but not submerged.
D. Incorrect – Oceans are saltwater environments. Bryophytes are land plants and cannot survive in saline conditions.
E. Incorrect – Grasslands are generally too dry and exposed to support large populations of bryophytes, especially in open sunny areas.
Question
What could be used as evidence for evolution?
I. Selective breeding of domesticated animals
II. The fossil record
III. Homologous structures
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
Answer: D. I, II and III
Explanation:
Evidence for evolution includes observations and data that support the idea that species change over time through common ancestry. Key sources of this evidence include selective breeding, fossil records, and homologous structures:
- Selective breeding (artificial selection) shows how humans can cause evolutionary change in a short time.
- The fossil record shows gradual changes in species over long time periods.
- Homologous structures are body parts in different species that are similar in structure but may have different functions, indicating common ancestry.
Option Analysis:
I. Correct – Selective breeding demonstrates how traits can change over generations, showing how evolution works on a small scale.
II. Correct – The fossil record provides long-term evidence of gradual changes and extinct species, supporting evolutionary theory.
III. Correct – Homologous structures indicate that different species evolved from a common ancestor