eco study guide

Question 1

Which of the following is an aspect of an animal’s niche?

a. the water in an area
b. amount of sunlight
c. the way it gets food
d. composition of soil

Answer 1

c. the way it gets food

Question 2

Several species of warblers can live in the same spruce tree ONLY because they
a. have different habitats within the tree.
b. don’t eat food from the tree.
c. occupy different niches within the tree.
d. can find different temperatures within the tree.

Answer 2

a. have different habitats within the tree.

Question 3

Why is it unlikely that a population stays at exactly its carrying capacity?

Answer 3

Organisms will continue to have offspring without regard for resource allocation. Similarly, migration will continue to affect the population.

Question 4

What is true about a Type II population?

Answer 4

Relatively stable death rate throughout life; similar chance of mortality at young age, middle age, and old age.

Question 5

Describe the survival strategies of being K-selected or r-selected. Name one pro and one con of each strategy.

Answer 5

K-selected: Small amount of offspring who are protected and given resources. Goal is to keep as close to all of the population as possible alive through old age.

Pro of K: Many resources per child means that the organisms can be large, and thus be less vulnerable to things like predators or interspecific competition.

Con of K: Not many offspring, so if you lose even a few, it can severely damage your population.

Question 6

Describe the competitive exclusion principle as it would apply to two populations of trees in the same area.

Answer 6

If two trees had the same niche in an area, there would be competition between them for access to resources such as sunlight, living space and water. Based on the competitive exclusion principle, only one population would be expected to survive, and the other would die off.

Question 7

Describe one human-caused change that is affecting climates or ecosystems. State its causes, its effects, and possible solutions to this issue.

Answer 7

ONE EXAMPLE:
Deforestation is a human-caused issue that is affecting ecosystems around the world. Humans cut down trees to make paper and to create land space to use for agriculture or industry. One effect of deforestation is losing one of the world’s major carbon sinks, as trees take in carbon dioxide from the atmosphere. This leads to an increase in atmospheric CO2, which is one of the leading causes of climate change. A possible solution to this would be to increase the amount of land that is being preserved and protected by governing bodies.

Question 7

What percent of climate scientists agree that climate change is both real and human-caused?
99.9%

Answer 7

99.9%

Question 8

How is habitat different from niche?

Answer 8

Habitat is just where something lives; Niche is where it lives AND what it does

Question 9

Explain what happens when a population overshoots its carrying capacity.

Answer 9

Competition for resources exceeds the availability of said resources, leading to a die-off.

Question 10

You are trying to determine the population size of a population of robins. On your first capture, you catch 250 robins and mark them. On your second capture, you catch 300 robins, and 60 of them were marked. How many robins can you estimate to be in the population?

Answer 10

(250 x 300) / 60 = 1250 robins in the population

Question 10

Identify whether the following examples are positive feedback loops or negative feedback loops:

A forest experiences a series of wildfires, burning away vegetation and exposing the soil. This leads to drier conditions, which make the forest more prone to future fires.

Answer 10

Positive - The last step makes the first step happen more.

Question 11

Identify whether the following examples are positive feedback loops or negative feedback loops:
Rising global temperatures cause polar ice to melt, which reduces the Earth’s ability to reflect sunlight. This leads to more heat absorption and further increases in temperature.

Answer 11

Positive - The last step makes the first step happen more.

Question 12

Identify whether the following examples are positive feedback loops or negative feedback loops:
Increased CO₂ in the atmosphere accelerates plant growth, which in turn allows plants to absorb more CO₂ through photosynthesis, reducing atmospheric CO₂ levels.

Answer 12

Negative - The last step makes the first step happen less

Question 13

Discuss the impact of adding an invasive species with no natural predators to an ecosystem.

Answer 13

Adding an exotic, invasive species into an ecosystem would affect many other populations in that space. They would grow out of control, outcompete other species for resources, and severely damage both the sustainability and biodiversity of the ecosystem that they are invading.

Question 14

Discuss the impact of removing a keystone species from an ecosystem.

Answer 14

Keystone species are vital to maintaining an ecosystem, and the ecosystem will drastically change without them. The populations that the keystone species keeps in check will grow out of control, causing a decrease in the populations that they eat. This will then have a ripple effect throughout the entire ecosystem.

Question 15

What could be a limiting factor? Give four examples.

Answer 15

Food availability
Habitat space
Water availability
Predators

Question 16

Explain what would happen if two mouse species tried to occupy the same niche in a meadow. (Use scientific terms learned in this unit)

Answer 16

The mice would face competition for resources. Based on the competitive exclusion principle, we could expect that only one type of mouse would be able to survive.

Question 17

Give three examples of resources that a plant would need in its niche in order to live.

Answer 17

Plants need water, nutrients from the soil, and sunlight. They also need CO2 from the air, and space to grow their roots.

Question 18

What would happen if there were no limiting factors?

Answer 18

The population would have no carrying capacity and would grow exponentially.

Question 19

How do carrying capacities and limiting factors relate to each other?

Answer 19

The limiting factors dictate what the carrying capacity can be.

Question 20

What is a limiting factor?

Answer 20

Any factor that influences the carrying capacity of a population.

Question 21

What is a carrying capacity?

Answer 21

The highest amount of the population that the ecosystem can sustainably support.

Question 21

Some orchids grow high on trees to get enough light for photosynthesis. The trees are unaffected by the presence of the orchids. The relationship between the orchids and the trees is an example of

Answer 21

commensalism

Question 22

Over time, some plants growing in an area are crowded out by other plants. The new plants use up water and nutrients needed by the previous plants. The disappearance of the first plants is due to

Answer 22

competition / competitive exclusion

Question 23

Under ideal conditions with unlimited resources, a population will grow

Answer 23

Exponentially

Question 24

Most of the worldwide human population is growing exponentially because why?

Answer 24

human populations have not reached carrying capacity yet.

Question 25

In order for a population to increase:

Answer 25

emigration and death are lower than immigration and birth

Question 26

Which will reduce competition within a species’ population?

Answer 26

fewer individuals

Question 27

Sea otters live in the ocean. Which of the following is NOT likely to be a limiting factor on the sea otter population?

Answer 27

Drought

Question 28

For most populations that are growing, as resources start to become less available, the population

Answer 28

reaches carrying capacity.

Question 29

The various growth phases through which most populations go until they reach carrying capacity can be shown on a:

Answer 29

a logistic growth curve.

Question 30

During some kinds of population growth, the size of each generation of offspring is larger than the generation before it. So, as the population gets larger, it grows more quickly. This situation is called

Answer 30

exponential growth.

Question 31

Which are two ways a population can decrease in size?

Answer 31

decreased birthrate and emigration

Question 32

The movement of organisms INTO of an ecosystem is called

Answer 32

Immigration

Question 33

The movement of organisms OUT of an ecosystem is called

Answer 33

Emigration.

Question 34

A wolf pack hunts, kills, and then feeds on a moose. In this interaction, the wolves are____

Answer 34

Predators.

Question 35

What would likely happen if the population of the bird species shown above (Figure 1) were to suddenly decrease?

Answer 35

The fish population would increase.

Question 36

A symbiotic relationship in which one organism benefits and the other is harmed is?

Answer 36

Parasitism.

Question 37

A symbiotic relationship in which one species benefits and the other is unaffected is?

Answer 37

Commensalism.

Question 38

A symbiotic relationship in which both species benefit is

Answer 38

Mutualism.

Question 39

An interaction in which an animal feeds on plants is called

Answer 39

Herbivory.