Chapter 4: Energy & Matter in Ecosystems

Question 1

What is a biogeochemical cycle?

Answer 1

The cycling of matter through living and non-living components of an ecosystem.

Question 2

What is a geochemical cycle?

Answer 2

The chemical interactions that take place in crustal and subcrustal reservoirs.

Question 3

What is biomass?

Answer 3

The total mass of biological matter (living or dead) un a given area that can be used as energy

Question 4

What does GPP mean?

Answer 4

Gross primary productivity:
The total organic matter in an ecosystem produced by photosynthesis

Question 5

What does NPP mean?

Answer 5

Net primary productivity:
The amount of organic matter actually available to herbivores

Question 6

How can NPP be calculated?

Answer 6

Net production = gross production - energy used in respiration

Question 7

What is the 10% rule?

Answer 7

States that on average only 10% of energy from one trophic level is passed on to the next level, remaining 90% is lost as heat and waste.

Question 8

What are the 3 types of ecological pyramids? Briefly explain each

Answer 8

• Pyramid of numbers: Number of organisms on each trophic level
• Pyramid of biomass: Total dry organic matter at each level
• Pyramid of energy: Rate at which energy is transferred from one trophic level to another

Question 9

What are the 4 processes in the carbon cycle?

Answer 9

• Photosynthesis
• Respiration
• Decomposition
• Combustion

Question 10

What are the 4 major carbon sinks?

Answer 10

• Atmosphere
• Terrestrial
• Oceans
• Sediments

Question 11

What are the 5 processes in the nitrogen cycle?

Answer 11

• Fixation
• Nitrification
• Assimilation
• Ammonification
• Denitrification

Question 12

Explain nitrogen fixation

Answer 12

First step in the process of making nitrogen usable for plants. Bacteria change nitrogen into ammonium

Question 13

What is nitrification?

Answer 13

Process by which ammonium gets changed into nitrates by bacteria. Nitrates are what the plants can absorb

Question 14

Explain assimilation in the nitrogen cycle

Answer 14

How the plants get nitrogen. They absorb the nitrates from the soil into their roots. Then the nitrogen gets used in ammino acids, and chlorophyll

Question 15

What is ammonification?

Answer 15

Convert decaying material into ammonium. When an organism dies, decomposers turn nitrogen back into ammonium so it can re-enter the nitrogen cycle.

Question 16

What is denitrification?

Answer 16

Convert nitrates into atmospheric nitrogen. Extra nitrogen in the soil gets put back into the atmosphere

Question 17

What is an ecological niche?

Answer 17

The role an organism has in its ecosystem and the conditions it requires to persist. Includes food sources, feeding activity, spatial habitat, reproduction and relationships.

Question 18

What is the difference between a fundamental niche and a realised niche?

Answer 18

Fundamental: The reigion an organism could inhabit if there weren’t any interfering factors

Realised: The actual nicha a species inhabits

Question 19

What is the competitive exclusion principle?

Answer 19

States that 2 similar species cannot occupy the same niche in the same environment for a long period of time

Question 20

What is a keystone species?

Answer 20

A species with relatively low abundance but has a large influence over trophic levels, determining the coexistence of species in an area