ENVS 200 quiz answers

Question 1

Which of the following best explains why the world is green, at least according to Hairston et al.?

Answer 1

The world is green because of top-down control on herbivores.

Question 2

Which of the following generalized successional sequences is correct?

Answer 2

annual -> herbaceous perennial -> woody shrub -> tree

Question 3

Which stage of community succession occurs when the most efficient competitors outcompete other species?

Answer 3

This stage is the climax stage

Question 4

If the number of predatory Orca whales determines the abundance of abalones, despite the fact that Orcas don’t prey on abalone, this would be called a/an ________ .

Answer 4

Indirect effect

Question 5

Which of the following examples of disturbance would be followed by primary succession?

Answer 5

A volcano erupts and creates new bedrock.

Question 6

Which of the following is an example of a trophic cascade?

Answer 6

A mountain lion preys upon deer and as a result the abundance of a grass species dramatically increases.

Question 7

If all trophic levels are being controlled by the abundance of resources available to plants it would be called _____________.

Answer 7

Bottom-up control

Question 8

In what type of community are species approximately equivalent in their ability to invade gaps and hold those gaps against other species during their lifetime?

Answer 8

Founder-controlled communities

Question 9

Species evenness is directly correlated to species richness:

Answer 9

False

Question 10

When conducting species measurements in a community, what is the difference between species richness and species evenness?

Answer 10

Richness measures the total number of species; evenness measures how equitably each species is distributed.​

Question 11

Using a simple model of species richness based on a one-dimensional continuum, what is one hypothetical way that species richness could increase?

Answer 11

The range of resource in the community expands.

Question 12

In which of the two examples of a community is species richness greater: A community with 100 species that can all be found equally within a 25 km radius of the area, or a community spread across the same area that has 100 species, in which 5% of the individuals are rare species.

Answer 12

The species richness is the same.

Question 13

The main source of nutrients such as calcium, iron, magnesium, phosphorous, and potassium in many terrestrial ecosystems is _______.

Answer 13

The weathering of parent bedrock and soil

Question 14

If consumption efficiency of an organism was .25, assimilation efficiency .25 and production efficiency .45 what would the trophic transfer efficiency of this organism be?

Answer 14

2.8%

Question 15

All the primary producer biomass produced is not consumed alive by herbivores. That which dies supports a community of _________?

Answer 15

Decomposers

Question 16

Where would NPP be lowest?

Answer 16

A subtropical ocean gyre

Question 17

In general, where would net primary productivity be regulated more by the availability of nutrients?

Answer 17

In a lake

Question 18

Which community would you suspect receives high levels of radiation but does not convert much of that radiation to biomass?

Answer 18

Death Valley desert in California, United States of America

Question 19

Which of the following statements is accurate regarding the total potential rate of net primary productivity (NPP) of Earth’s natural ecosystems?

Answer 19

Slightly more NPP is produced in terrestrial ecosystems and slightly less NPP is produced in the oceans

Question 20

In the 1960s, sulfur pollution in North America and Europe was a major cause of acid rain. Though sulfur pollution has been reduced due to regulation, pollution due to which compound appears to contribute to acid rain formation today?

Answer 20

Nitrogen

Question 21

Coastal marshes contribute little to no methane to the atmosphere due to high levels of ________.

Answer 21

Sulfate

Question 22

What action by humans has most accelerated the phosphorus cycle?

Answer 22

Mining phosphorus for fertilizer

Question 23

As atmospheric carbon dioxide levels have increased, the higher concentration should increase the diffusion of carbon dioxide into the oceans. However, there is a reduced net rate of carbon dioxide uptake by oceans. Why?

Answer 23

This is due to increased surface ocean temperatures that lower the solubility of carbon dioxide.

Question 24

According to the Rockstrom paper, which of Earth’s critical “life-support” systems has been perturbed most beyond the “safe” level?

Answer 24

Biodiversity

Question 25

The greatest contribution to the total human input of nitrogen per year is __________.

Answer 25

Manufacturing of synthetic fertilizer

Question 26

The sulfur cycle is important for many reasons, including ecological processes. Sulfate is critical to the decomposition process. Why else is the sulfur cycle so critical to life on Earth?

Answer 26

Because sulfate is an essential component of several amino acids

Question 27

One outcome of increased atmospheric carbon dioxide is that more carbon dioxide is taken up by the ocean, which may result in which of the following outcomes?

Answer 27

Acidification of the ocean and a disruption of organisms with carbonate shells

Question 28

The results of a study of southern dunlin in Sweden showed that _______.

Answer 28

The offspring of close relatives that mated were less likely to hatch.

Question 29

Which organization established globally recognized categories of protected areas?

Answer 29

International Union for the Conservation of Nature.

Question 30

You want to determine how a small population of a species may survive in the future as development around their habitat increases. You have data on the survivorship and reproductive rates of this age-structured population. Ideally, you will use the results of your research to inform land managers of predicted population sizes year by year and the probability of extinction during those years. What method would you use to do this work?

Answer 30

A population viability analysis

Question 31

Which of the following explains why conservation biologists would be particularly concerned about the effects of introduced species on an island?

Answer 31

Because islands tend to have high amounts of endemism

Question 32

Describe the relationship between population size and probability of extinction for island bird species (e.g., Figure 13.8).

Answer 32

It is an exponential relationship; the probability of extinction increases much more when populations fall below 100 pairs

Question 33

Why might it be important to preserve rare alleles in a population?

Answer 33

Because these alleles may be selected for in the future if environmental conditions change

Question 34

The fossil record tells us ________________.

Answer 34

That more than 99% of species that have ever lived are now extinct

Question 35

What is the total number of Earth’s species that have been identified?

Answer 35

1.8 million species