Question 1

If decomposers did not exist,the flow of nutrients would cease and the food chain would collapse.

Accepted Answer

Decomposers play a vital role in breaking down dead organisms and recycling nutrients back into the soil or water for plants and other organisms to utilize. Without decomposers, the nutrients would be locked up in dead organisms and the food chain would ultimately collapse.

Question 2

A midlatitude grassland is low in stability,yet shows high resilience when burned.

Accepted Answer

Midlatitude grasslands are characterized by a high frequency of disturbances, such as droughts, fires, and grazing. The grassland ecosystem has evolved to be resilient to these disturbances, and in fact, frequent burning can promote biodiversity and nutrient turnover. However, the grassland may not be as stable as other ecosystems, such as tropical rainforests, due to the frequent disturbances.

Question 3

Long-lived,stable chemicals tend to concentrate in a food chain in a process known as biological amplification.

Accepted Answer

Long-lived, stable chemicals such as pesticides and heavy metals can accumulate in the tissues of organisms, and as they move up the food chain, the concentration of these chemicals can increase. This is known as biological amplification or biomagnification.

Question 4

Fire can actually be beneficial to an ecosystem.

Accepted Answer

Fire can help to clear out dead and decaying plant matter, promote new growth, and create habitats for certain species. Some ecosystems have even evolved to depend on periodic fires for their health and survival. However, it should be noted that fires can also be harmful and destructive if they occur too frequently or at the wrong time of year. Fire management and prevention strategies are important for balancing the beneficial and detrimental effects of fire on ecosystems.

Question 5

If climate change occurs too rapidly,species may become extinct.

Accepted Answer

Rapid climate change can cause habitats to change too quickly for species to adapt, leading to extinction.

Question 6

Lake turnover occurs when the upper layers of water cool to about 4°C.

Accepted Answer

Lake turnover occurs when the upper layers of water cool to about 4°C, which leads to a mixing of the water layers in the lake. This can happen in both spring and fall, depending on the climate and location of the lake.

Question 7

A consumer that feeds on both producers and consumers is called a carnivore.

Accepted Answer

A consumer that feeds on both producers and consumers is called an omnivore, not a carnivore. Carnivores primarily eat other consumers.

Question 8

The material inputs of photosynthesis are the same as the outputs of the process of respiration.

Accepted Answer

The inputs of photosynthesis are carbon dioxide and water, while the outputs of respiration are carbon dioxide and water. Therefore, the material inputs of photosynthesis are the same as the outputs of respiration.

Question 9

Because of biological amplification of pollutants,you could get sick from eating oysters,even if the oysters themselves were not sick.

Accepted Answer

Biological amplification is the process in which pollutants become more concentrated as they move up the food chain. This means that even if the oysters appear healthy, they may have accumulated harmful pollutants in their tissues. When humans consume these contaminated oysters, they can also ingest high levels of pollutants, potentially leading to illness.

Question 10

Presently,the Antarctic food chain is being threatened by overexploitation and UV light.

Accepted Answer

The Antarctic food chain is indeed being threatened by overexploitation and UV light. Overfishing is a growing concern, as krill - a small shrimp-like crustacean - is harvested for use in fish feed, dietary supplements, and even cosmetics. The depletion of krill can have significant impacts on the Antarctic food chain, as it is a key food source for many species, including whales, penguins, and seals. Additionally, the hole in the ozone layer over Antarctica allows for more UV radiation to penetrate the atmosphere, which can harm phytoplankton and other organisms at the base of the food chain.

Question 11

Carbon in the ocean is often stored in the form of carbon dioxide and calcium carbonate.

Accepted Answer

Carbon in the ocean can be stored in various forms such as dissolved carbon dioxide, bicarbonate ions, and calcium carbonate (found in organisms such as corals and shells).

Question 12

Thermal stratification in lakes such as the Great Lakes enhances the dilution of pollutants.

Accepted Answer

Thermal stratification actually impedes the dilution of pollutants as it limits the mixing of water between different layers.

Question 13

In spite of improvements in pollution control,there is still a need for concern over the health of the Great Lakes ecosystem because of biological magnification.

Accepted Answer

Biological magnification is the process where pollutants become more concentrated as they move up the food chain, causing greater harm to top predators such as fish and birds. This can have negative impacts on the overall health of the Great Lakes ecosystem, despite improvements in pollution control measures.

Question 14

The oceans contain six times as much carbon as the atmosphere.

Accepted Answer

This is true. The oceans are a major carbon sink, holding approximately 50 times more carbon than the atmosphere and 10 times more carbon than land vegetation.

Question 15

As world population continues to increase,it will become necessary for a greater percentage of the population to eat lower on the food chain in order to ensure an adequate food supply.

Accepted Answer

As the world population increases, the demand for food will also increase. However, the production of meat and other animal-based products requires more resources, such as land, water, and feed, than the production of plant-based foods. Therefore, promoting a shift toward plant-based diets can help ensure a more sustainable and adequate food supply for the growing population.

Question 16

Today,more than half of the cultivated land in Canada and the United States is planted for animal consumption.This means that far more people are capable of being fed than if the land were planted with crops for direct human consumption.

Accepted Answer

Planting crops for direct human consumption is generally more efficient in feeding people than using land to grow feed for animals, as energy is lost at each trophic level in the food chain.

Question 17

If krill disappeared from the food chain,the effect would be catastrophic because krill serve as a major source of food for many other animals in the food chain.

Accepted Answer

Krill are a vital food source for many animals such as whales, penguins, seals, and fish. If they were to disappear, it would create a collapse in the food chain, leading to reduced populations of many other species and potentially causing a domino effect of ecological consequences.

Question 18

Eutrophication is part of the aquatic succession of a lake to a bog.

Accepted Answer

Eutrophication is a process where nutrient enrichment in a body of water leads to increased plant growth, often resulting in the transition from a lake to a bog over time as organic matter accumulates.

Question 19

Lake turnover occurs during the summer.

Accepted Answer

Lake turnover usually occurs in the spring and fall when water temperatures are changing, rather than in the summer when temperatures are more stable.

Question 20

Humans are responsible for relatively little nitrogen fixation.

Accepted Answer

Humans are responsible for a significant amount of nitrogen fixation through industrial processes such as the Haber-Bosch process, which converts atmospheric nitrogen into ammonia for use in fertilizer and other products. This process accounts for approximately 3% of global nitrogen fixation. However, natural processes such as lightning and biological nitrogen fixation by certain bacteria are responsible for the majority of nitrogen fixation on Earth.

Quiz 19: Ecosystem Essentials