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)
Explanation:
An ecosystem has limited resources like food, water, space, and shelter. The reason many different species can live together without direct competition wiping them out is because:
Each species occupies a different niche — their unique role or job in the ecosystem.
- A niche includes everything about how a species lives — what it eats, where it lives, when it’s active, how it interacts with other organisms, etc.
- By having different niches, species reduce competition for the same resources.
- This concept is known as resource partitioning, which allows for coexistence even in ecosystems with limited resources.
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:
What’s the claim?
Communities with high species diversity are more resistant to change from invading (nonnative) species.
So logically, this means:
More diversity = less survival of invaders
(The community is tougher and less likely to let outsiders thrive.)
Let’s examine the graphs:
| Option | Trend | Meaning | Conclusion |
|---|---|---|---|
| A | Flat line | Survival of invaders is unaffected by diversity | Not consistent with the claim |
| B | V-shaped | Initially declines then increases — makes no sense biologically | No |
| C | Positive slope | More diversity = more survival of invaders?? | Completely opposite |
| D | Negative slope | More diversity = less survival of invaders | Correct |
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)
Explanation:
Bryophytes are non-vascular plants, which include mosses, liverworts, and hornworts. They need moist, shaded environments to survive and reproduce because:
- They absorb water directly through their surfaces (no vascular tissue).
- They require water for reproduction, as their sperm must swim to reach the egg.
Why A. Deciduous forests is correct:
Deciduous forests have damp, shady areas, leaf litter, and moist soil, creating an ideal habitat for bryophytes. These forests offer both humidity and shade, which support bryophyte growth on soil, rocks, and tree trunks.
Why other options are incorrect:
B. Deserts: Too dry for bryophytes. Lack of moisture makes survival difficult.
C. Ponds: Too wet and submerged bryophytes prefer moist surfaces, not full aquatic life.
D. Oceans: Saltwater is unsuitable for bryophytes, which are mostly terrestrial or live near freshwater.
E. Grassland: Generally, too dry and sun-exposed for most bryophytes, though some may occur in shaded microhabitats.
Question
Permafrost; temperatures range from approximately -50° C to +25° C; a growing season of 60 days or less.
A. Tropical rain forest
B. Taiga
C. Artic tundra
D. Temperate grassland
E. Desert
▶️Answer/Explanation
Answer: (C) Arctic tundra
Explanation:
The characteristics listed:
- Permafrost (permanently frozen ground)
- Very cold temperatures (as low as -50°C)
- Short growing season (60 days or less)
These are classic features of the Arctic tundra biome.
Why C. Arctic tundra is correct:
- Located near the North Pole (high latitudes)
- Ground remains frozen most of the year
- Very short summers with limited plant growth
- Common vegetation includes mosses, lichens, and small shrubs
- Low biodiversity, adapted to harsh conditions
A. Tropical rainforest: Hot and wet year-round, no permafrost, and has high biodiversity.
B. Taiga (also called boreal forest): Cold but has longer growing seasons and no permafrost in many areas. It has coniferous trees.
D. Temperate grassland: Moderate climate, no permafrost, and longer growing seasons. Supports grasses, not frozen soil.
E. Desert: Can be hot or cold but generally dry. Does not have permafrost, and temperature extremes are different.