Biochemical Cycles (p1)

Question 1

What does the term biogeochemical refer to?

Answer 1

The movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth’s crust.

Question 2

What are essential components of all living things?

Answer 2

• Carbon (C)
• Nitrogen (N)
• Phosphorus (P)

Question 3

What elements are needed to make DNA, RNA, and proteins?

Answer 3

Nitrogen (N) and Phosphorus (P).

Question 4

What is unique about the phosphorus cycle compared to carbon and nitrogen cycles?

Answer 4

Phosphorus has no gaseous phase.

Question 5

What drives the cycling of elements in biogeochemical cycles?

Answer 5

Solar energy.

Question 6

What is photosynthesis?

Answer 6

The capture of light energy by pigments to convert carbon dioxide and water into high energy carbohydrates.

Question 7

What is respiration?

Answer 7

The release of energy from high-energy substances to drive metabolic processes.

Question 8

What are the main processes involved in the carbon cycle?

Answer 8

• Photosynthesis
• Respiration
• Food Chains
• Fossilisation
• Decomposition
• Combustion

Question 9

What is decomposition?

Answer 9

The breakdown of organic matter by microorganisms, releasing gases such as CO2 and methane.

Question 10

What is a carbon sink?

Answer 10

A reservoir that absorbs more carbon than it releases.

Question 11

What are the two types of carbon sinks?

Answer 11

• Abiotic sinks (e.g., limestone, oceans)
• Biotic sinks (e.g., humus, plants)

Question 12

What happens during dynamic equilibrium in the carbon cycle?

Answer 12

The in and out flows of carbon balance each other out.

Question 13

How does human activity affect the carbon cycle?

Answer 13

It disrupts natural equilibria, increasing atmospheric carbon dioxide.

Question 14

What is Carbon Capture and Storage (CCS)?

Answer 14

A process to capture carbon dioxide so it is not released into the atmosphere.

Question 15

What are the three types of Carbon Capture technologies?

Answer 15

• Post-combustion technology
• Pre-combustion technology
• Oxy-fuel combustion systems

Question 16

What is the role of nitrogen in biological systems?

Answer 16

It is an essential component of proteins, DNA, RNA, and chlorophyll.

Question 17

What are nitrogen fixing bacteria responsible for?

Answer 17

Converting atmospheric nitrogen into ammonia.

Question 18

What is nitrification?

Answer 18

The oxidation of ammonium ions to nitrites and then to nitrates by nitrifying bacteria.

Question 19

What is denitrification?

Answer 19

The reduction of nitrates in soil to nitrogen gas by denitrifying bacteria.

Question 20

What is leaching in the nitrogen cycle?

Answer 20

The loss of soluble substances like nitrates from the soil due to water movement.

Question 21

What are legumes?

Answer 21

Plants that can fix nitrogen from the atmosphere
They contain nitrogen fixing bacteria in their root nodules

Question 22

What is the process of nitrification?

Answer 22

The oxidation of ammonium ions to nitrites then to nitrates by nitrifying bacteria in the soil

Question 23

What is denitrification?

Answer 23

The chemical reduction, by denitrifying bacteria, of nitrates in soil to nitrogen and nitrogen oxide gases

Question 24

Define leaching in the context of soil.

Answer 24

The loss of soluble substances such as nitrates from the surface layers of the soil as it is carried away by water

Question 25

How can nitrogen be absorbed by plants?

Answer 25

In the form of nitrate compounds and ammonium compounds

Question 26

What is fixation in nitrogen cycle?

Answer 26

The process where nitrogen in the air is converted into ammonia by nitrogen fixing bacteria

Question 27

What role do fertilizers play in nitrogen levels in soil?

Answer 27

They contain ammonium nitrates and can increase nitrogen levels

Question 28

What are some processes that remove nitrates from the soil?

Answer 28

* Breakdown by certain bacteria * Harvesting crops * Raising animals * Rainwater runoff

Question 29

What is symbiosis?

Answer 29

When two organisms live intimately together to benefit both organisms

Question 30

Give an example of symbiosis involving nitrogen-fixing bacteria.

Answer 30

Nitrogen-fixing bacteria in plant root nodules

Question 31

What is the Haber process?

Answer 31

An industrial process to fix nitrogen and turn it into ammonia This is how fertiliser is made

Question 32

What are some effects of human activities on the nitrogen cycle?

Answer 32

* Increased leaching due to nitrate fertilizers * Changes in bacterial populations due to drainage * Increased decomposition from ploughing

Question 33

What is eutrophication?

Answer 33

The rapid growth of algae caused by excess nutrients, leading to oxygen depletion in water bodies

Question 34

What are organic fertilizers?

Answer 34

Natural fertilizers, such as manure, that release nutrients more slowly

Question 35

What is the significance of phosphorus in living organisms?

Answer 35

It is essential for making molecules such as DNA and ATP

Question 36

How does the phosphorus cycle differ from carbon and nitrogen cycles?

Answer 36

The atmosphere is not involved in the phosphorus cycle

Question 37

Where can phosphorus be found?

Answer 37

* In plants and animals (e.g. bones, ATP, DNA) * In sediments and rocks (e.g. apatite, calcium phosphate) * In water as dissolved phosphates

Question 38

What processes are involved in the phosphorus cycle?

Answer 38

* Absorption by roots * Food chains * Decomposition * Sedimentation

Question 39

What happens when crops are harvested in relation to phosphorus?

Answer 39

All phosphorus contained in the crops is lost from that area

Question 40

What are some problems associated with the phosphorus cycle?

Answer 40

* Limited availability due to slow weathering * Phosphorus is less mobile in the soil * Loss to sediments in marine ecosystems

Question 41

What human impacts affect the phosphorus cycle?

Answer 41

* Rapid mining of sedimentary deposits for fertilizer * Inappropriate farming practices leading to phosphorus loss * Phosphates in detergents causing eutrophication