Examkin

Soru

Zorluk: Çok zorCause-and-Effect Relationships

The following passage is adapted from a scientific article on subarctic marine ecosystems.

In the subarctic Pacific, the rise in atmospheric carbon dioxide levels has initiated a subtle but destructive marine cascade. As the ocean absorbs excess carbon dioxide, the pH of the water drops, leading to ocean acidification. This decrease in pH reduces the availability of carbonate ions, which are essential building blocks for calcifying organisms. Consequently, the marine snail *Limacina helicina*, commonly known as the pteropod, struggles to construct and maintain its delicate aragonite shell, leading to widespread shell dissolution and high mortality rates within its populations. Because pteropods are a primary dietary staple for juvenile pink salmon (*Oncorhynchus gorbuscha*), the decline in pteropod density directly limits the nutritional intake of these young fish during their critical early marine residency. Deprived of their primary energy source, juvenile pink salmon suffer from stunted growth and lower survival rates, reducing the overall cohort size that returns to spawn. Ultimately, this depletion of the pink salmon population disrupts the terrestrial ecosystems of the Pacific Northwest, as riparian predators like grizzly bears receive fewer marine-derived nutrients, thereby impairing the nutrient cycle of the surrounding temperate rainforests.

Based on the passage, what is the correct causal sequence of events showing how atmospheric carbon dioxide accumulation ultimately impairs the nutrient cycle of temperate rainforests?

  1. 1Absorption of excess atmospheric carbon dioxide causes ocean acidification.
  2. 2Carbonate ion scarcity prevents pteropods from maintaining their shells.
  3. 3A shortage of primary prey limits the growth and survival of juvenile pink salmon.
  4. 4Fewer returning spawning salmon restrict the transfer of marine-derived nutrients to terrestrial predators.

Cevap

The correct causal sequence begins with the absorption of excess atmospheric carbon dioxide causing ocean acidification, followed by carbonate ion scarcity preventing pteropods from maintaining their shells. Next, the shortage of primary prey limits the growth and survival of juvenile pink salmon. Finally, fewer returning spawning salmon restrict the transfer of marine-derived nutrients to terrestrial predators, disrupting the forest nutrient cycle.
The correct causal sequence flows systematically from the primary geochemical change (acidification) to the direct physical damage on the base of the food web (pteropod shell dissolution), then up to the consumer level (salmon malnutrition), and finally to the terrestrial riparian predators (nutrient depletion).

Adım Adım Çözüm

1
Identify the initial geochemical trigger described in the text.
Ocean absorption of excess atmospheric carbon dioxide causes ocean acidification.
The text states that the rise in atmospheric carbon dioxide initiates the marine cascade by lowering the ocean's pH.
2
Trace the chemical consequence of ocean acidification on calcifying organisms.
The reduction in pH reduces carbonate ions, causing pteropod shell dissolution.
According to the passage, the decrease in pH reduces carbonate ions, which pteropods need to construct and maintain their shells.
3
Connect the reduction of the pteropod population to the trophic level directly above it.
A lack of pteropods limits the energy intake, growth, and survival of juvenile pink salmon.
The passage details that pteropods are a primary dietary staple for young salmon, and their decline limits salmon nutrition and growth.
4
Identify the link between the marine ecosystem disruption and the terrestrial nutrient cycle.
Fewer returning spawning salmon result in less nutrient transfer to land predators.
The text concludes that a smaller spawning cohort means riparian predators receive fewer marine-derived nutrients, impairing the forest's nutrient cycle.

Anahtar Kavram

Analyzing sequential, multi-step cause-and-effect relationships across different trophic levels and ecosystems.
Bu soruyu puanla

Konular

Cause-and-Effect Relationships

Bu konudan daha fazla soru