Question 1

Which of the following are important biotic factors that can affect the structure and organization of biological communities?

Accepted Answer

Predation and competition are both biotic factors that can affect the structure and organization of biological communities by influencing population sizes and interactions between species. Choices A, B, D, and E are abiotic factors.

Question 2

Generally speaking, deserts are located in places where air masses are usually

Accepted Answer

Deserts are located in places where air masses are usually descending. Descending air is warming and can carry more moisture than ascending air, resulting in very low humidity and dry conditions.

Question 3

What is the limiting factor for the growth of trees in the tundra?

Accepted Answer

Permafrost is a layer of frozen soil that prevents the growth of trees in the tundra.

Question 4

Species introduced by humans to new geographic locations

Accepted Answer

Species introduced by humans can thrive in a new environment because they often face less competition and fewer predators than in their home environment, enabling them to outcompete and displace native species. This can lead to a decrease in biodiversity and destabilization of the ecosystem.

Question 5

Which of the examples below provides appropriate abiotic and biotic factors that might determine the distribution of the species in question?

Accepted Answer

This option provides specific abiotic factors (number of frost-free days) and biotic factors (competition between species of introduced grasses and native alpine grasses) that can affect the distribution of the species in question. The other options provide general abiotic factors (e.g. amount of nitrate and phosphate in the soil) and biotic factors (e.g. wildflower abundance and diversity) that may not directly relate to the species in question.

Question 6

Which of the following is responsible for the differences in summer and winter temperature stratification of deep temperate zone lakes?

Accepted Answer

Water is densest at 4°C, which allows for the formation of a temperature stratification in deep temperate zone lakes. In the summer, the warmer surface water remains separate from the cooler, denser water at the bottom of the lake. In the winter, the surface water cools and eventually freezes, allowing for mixing with the deeper water. This leads to a more uniform temperature throughout the lake. The abundance of oxygen in deeper waters and the sinking of winter ice do not directly contribute to temperature stratification. Stratification is caused by a thermocline, which is the layer of water where temperature changes rapidly with depth. While fall and spring turnovers can contribute to changes in lake stratification, they do not always follow a predictable pattern.

Question 7

Which marine zone would have the lowest rates of primary productivity (photosynthesis)?

Accepted Answer

The abyssal zone is characterized by very low light levels due to extreme depths, which results in very low rates of primary productivity.

Question 8

Turnover of water in temperate lakes during the spring and fall is made possible by which of the following?

Accepted Answer

The turnover of water in temperate lakes during the spring and fall is made possible by changes in the density of water as seasonal temperatures change. As the temperature of the water changes in the spring and fall, the water becomes more mixed and less stratified, allowing nutrients and gases to move between the upper and lower layers. The other choices may affect the temperature and density of the water, but do not directly cause turnover.

Question 9

Which of the following statements about the ocean pelagic biome is true?

Accepted Answer

Pelagic ocean photosynthetic activity is low relative to its size because it is nutrient-poor compared to coastal areas, limiting productivity.

Question 10

If a meteor impact or volcanic eruption injected a lot of dust into the atmosphere and reduced the sunlight reaching Earth's surface by 70% for one year, which of the following marine communities most likely would be least affected?

Accepted Answer

Deep-sea vent communities rely on chemosynthesis, which does not require sunlight, making them the least affected by a decrease in sunlight.

Question 11

Which series is correctly layered from top to bottom in a tropical rain forest?

Accepted Answer

The correct layering of a tropical rainforest from top to bottom is: emergent layer (the tallest trees), canopy (the layer below the emergents which forms a dense layer of foliage), under story (smaller trees and plants beneath the canopy), shrub/immature layer (young trees and shrubs), and ground layer (the forest floor).

Question 12

In temperate lakes, the surface water is replenished with nutrients during turnovers that occur in the

Accepted Answer

Turnovers occur in the autumn and spring in temperate lakes, where the surface water mixes with the deeper water layers, replenishing nutrients and oxygen.

Question 13

Which of the following can be said about light in aquatic environments?

Accepted Answer

Water selectively reflects and absorbs certain wavelengths of light, which affects how different colors are seen at various depths. This selective absorption and reflection influence the availability of light for photosynthetic organisms in aquatic environments.

Question 14

Which of the following investigations would shed the most light on the distribution of organisms in temperate regions that are faced with climate change?

Accepted Answer

Looking back at past changes in distribution of species can provide insights into how they may adapt and redistribute in response to future climate change. This historical perspective can inform predictions about the future distribution of organisms.

Question 15

If you are interested in observing a relatively simple community structure in a clear water lake, you would do well to choose diving into

Accepted Answer

Oligotrophic lakes are characterized by low nutrient levels, leading to clear water and a relatively simple community structure, making them ideal for observing such ecosystems.

Question 16

A certain species of pine tree survives only in scattered locations at elevations above 2,800 m in the western United States. To understand why this tree grows only in these specific places, an ecologist should

Accepted Answer

Investigating the various biotic and abiotic factors that are unique to high altitude is the best option to understand why this tree grows only in specific locations. This would help to identify the limiting factors that affect the survival of this species and why it is restricted to certain locations at high elevations. Studying the anatomy and physiology of the species (B), analyzing the soils (D), and collecting data on temperature, wind, and precipitation (E) could also provide useful information, but they would be secondary to investigating the unique biotic and abiotic factors at high altitude (C). Concluding that lower elevations are limiting to the survival of this species (A) is not necessarily supported by the given information.

Question 17

If global warming continues at its present rate, which biomes will likely take the place of the coniferous forest (taiga)?

Accepted Answer

As global warming progresses, temperatures in regions currently characterized by coniferous forests (taiga) are expected to increase, making these areas more suitable for species typical of warmer climates, such as those found in temperate broadleaf forests and grasslands.

Question 18

Imagine that a deep temperate zone lake did not "turn over" during the spring and fall seasons. Based on the physical and biological properties of limnetic ecosystems, what would be the difference from normal seasonal turnover?

Accepted Answer

Normally, during seasonal turnover, nutrient-rich deep water rises to the surface and nutrient-poor surface water sinks to the bottom. This process replenishes nutrients in the surface layers of the lake, which is essential for the growth of phytoplankton and other organisms. In the absence of turnover, nutrient depletion would occur in the surface layers, leading to a decrease in productivity of the lake ecosystem.

Question 19

Which of the following statements best describes the effect of climate on biome distribution?

Accepted Answer

The statement that best describes the effect of climate on biome distribution is that not only the average climate is important, but also the pattern of climatic variation. This means that the climate in an area may fluctuate in a certain way, such as having distinct wet and dry seasons, which can influence which biome is found in that location. Simply looking at average annual temperature and precipitation may not be enough to predict biome distribution accurately. Factors such as seasonal fluctuations and climate patterns need to be considered.

Question 20

Coral reefs can be found on the southern east coast of the United States but not at similar latitudes on the southern west coast. Differences in which of the following most likely account for this?

Accepted Answer

The presence of coral reefs is heavily influenced by ocean currents, which transport nutrients and provide the right temperature and conditions for coral growth. The western coast of the United States does not have the same ocean currents that promote coral growth as the eastern coast does.

Quiz 52: An Introduction to Ecology and the Biosphere