Question 1

Which of the following biological macromolecules contains nitrogen as a key component of its structure?

Accepted Answer

Proteins

Question 2

Nitrogen fixation is the process in which certain bacteria convert which of the following into a usable form for plants?

Accepted Answer

Nitrogen gas ($$N_2) $$into ammonia ($$NH_3)$$

Question 3

Approximately what percentage of energy is transferred from one trophic level to the next in a typical ecosystem, and why is some energy lost?

Accepted Answer

$$10\%$$; because energy is lost as heat and through metabolic processes

Question 4

If a grassland ecosystem has $$10,000$$ kcal of energy available at the producer level, how much energy would be expected to be available to secondary consumers, assuming $$10\%$$ energy transfer efficiency at each trophic level?

Accepted Answer

$$100$$ kcal

Question 5

Which of the following best describes a trophic cascade?

Accepted Answer

A chain reaction in which changes at one trophic level cause indirect effects on other levels

Question 6

What is the primary role of decomposers in an ecosystem?

Accepted Answer

They recycle nutrients by breaking down dead organic matter

Question 7

In the carbon cycle, which of the following is a major long-term storage site for carbon?

Accepted Answer

Fossil fuels and sedimentary rock

Question 8

Which nutrient is NOT commonly held in the atmosphere as part of its biogeochemical cycle?

Accepted Answer

Phosphorus

Question 9

Why are invasive species often more successful than native species in a new ecosystem?

Accepted Answer

They often lack natural predators or diseases in the new environment

Question 10

Which of the following best distinguishes a hypothesis from a prediction in the scientific method?

Accepted Answer

A hypothesis is a testable explanation; a prediction is a specific expected outcome if the hypothesis is correct

Question 11

What is habitat fragmentation and one of its potential consequences?

Accepted Answer

The division of large habitats into smaller, isolated patches; it can reduce gene flow and increase extinction risk

Question 12

Small, isolated populations are at greater risk of extinction than large, connected populations primarily because:

Accepted Answer

They are more susceptible to genetic drift and inbreeding

Question 13

What is a wildlife corridor and why is it important?

Accepted Answer

A strip of natural habitat connecting separated populations; it promotes gene flow and reduces inbreeding

Question 14

How does biomagnification affect organisms at higher trophic levels?

Accepted Answer

Toxins accumulate and become more concentrated in organisms at higher trophic levels

Question 15

Which of the following best defines a biodiversity hotspot?

Accepted Answer

A region with exceptional levels of endemic species and significant habitat loss

Question 16

What is a keystone species?

Accepted Answer

A species whose impact on its ecosystem is disproportionately large relative to its abundance

Question 17

Which of the following is an example of an ecosystem service?

Accepted Answer

The pollination of crops by bees

Question 18

How does deforestation typically impact biodiversity?

Accepted Answer

It reduces habitat availability and can lead to species loss

Question 19

What is the main goal of captive breeding programs in conservation biology?

Accepted Answer

To breed endangered species in controlled environments for eventual reintroduction into the wild

Question 20

A population of cheetahs experiences a genetic bottleneck. What is a likely consequence?

Accepted Answer

Reduced genetic variation, making the population more vulnerable to disease

Ecosystem Ecology and Biodiversity: Study Guide for Exam 3

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