Ecology and Human Impact

Question 1

Primary vs. Secondary pioneering Population

Answer 1

Primary:

Question 2

What are the steps of the nitrogen cycle?

Answer 2

Fixation → Nitrification → Assimilation → Ammonification → Denitrification

Question 3

What is nitrogen fixation?

Answer 3

The process of converting N₂ gas into ammonium (NH₄⁺) by bacteria.

Question 4

What is nitrification?

Answer 4

The conversion of ammonium into nitrates (NO₃⁻)

Question 5

What is assimilation in the nitrogen cycle?

Answer 5

When plants absorb nitrates from the soil.

Question 6

What is ammonification?

Answer 6

The process where decomposers convert dead organisms into ammonium.

Question 7

What is denitrification?

Answer 7

When special bacteria convert unused nitrogen in the soil back into N₂ gas and release it into the atmosphere.

Question 8

Why is nitrogen essential?

Answer 8

It is used to make amino acids and nucleic acids.

Question 9

Why can’t organisms use nitrogen gas (N₂) directly from the air?

Answer 9

Nitrogen must be transformed into a usable form like nitrates or ammonium.

Question 10

How is nitrogen made usable for organisms?

Answer 10

Through processes involving bacteria such as fixation and nitrification.

Question 11

What are the usable forms of nitrogen for plants?

Answer 11

Nitrates (NO₃⁻)

Question 12

What are the main processes of the water cycle?

Answer 12

Evaporation

Question 13

What is evaporation?

Answer 13

The process where water turns into vapor and rises into the atmosphere.

Question 14

What is condensation?

Answer 14

Water vapor cools and forms clouds.

Question 15

What is precipitation?

Answer 15

Water falls to the ground as rain

Question 16

What is collection/runoff?

Answer 16

Water gathers in bodies like rivers

Question 17

What does the phosphorus cycle help create?

Answer 17

ATP

Question 18

Where is phosphorus found in nature?

Answer 18

In rocks

Question 19

How does phosphorus enter the soil?

Answer 19

Through weathering of rocks by water like rain and rivers.

Question 20

How do plants and animals obtain phosphorus?

Answer 20

Plants absorb it from soil; animals eat plants or other animals.

Question 21

What do decomposers do in the phosphorus cycle?

Answer 21

They release phosphorus by breaking down dead matter.

Question 22

What is one role phosphorus plays in plants?

Answer 22

It helps with root and flower formation.

Question 23

How do humans impact the phosphorus cycle?

Answer 23

By adding fertilizers that run off into water systems.

Question 24

What is eutrophication?

Answer 24

Algal overgrowth due to phosphorus runoff that depletes oxygen and alters pH

Question 25

What are major sources of sulfur in the atmosphere?

Answer 25

Fossil fuel combustion and volcanic eruptions producing SO₂.

Question 26

How does sulfur return to the earth?

Answer 26

Through acid rain or weathering of rocks.

Question 27

How does sulfur move through living organisms?

Answer 27

Through consumption and decomposition of organisms.

Question 28

How does sulfur return to the soil?

Answer 28

Through decay and formation of fossil fuels.

Question 29

How do humans use sulfur from the cycle?

Answer 29

By extracting it from fossil fuels.

Question 30

What is a primary pioneering population?

Answer 30

The first organisms to colonize barren environments (e.g.

Question 31

What is a secondary pioneering population?

Answer 31

Organisms that colonize an area after a disturbance where soil already exists.