Unit 6.5- Ecosystems

Question 1

Habitat definition:

Answer 1

The place where an organism lives

Question 2

Population definition:

Answer 2

All of the organisms of one species, who live in the same place at the same time and who can breed together

Question 3

Community definition:

Answer 3

All of the populations of different species, who live in the same place at the same time and who can interact with each other

Question 4

Niche definition:

Answer 4

The role of an organism

Question 5

Biotic factors in an ecosystem:

Answer 5

• Producers
• Consumers
• Decomposers

Question 6

Abiotic factors lethal at both extremes:

Answer 6

• PH

- Temperature

Question 7

Abiotic factors lethal at one extreme:

Answer 7

-Level of pollutants

Question 8

Cyclic changes definition (ecosystem):

Answer 8

These changes repeat themselves in a rhythm. e.g. tides

Question 9

Directional changes definition (ecosystem):

Answer 9

Changes that go in one direction. They tend to last longer than the lifetime of organisms within the ecosystem e.g. erosion

Question 10

Unpredictable/ erratic changes definition (ecosystem):

Answer 10

Changes that have no rhythm or constant direction. e.g. the effects of lighting or hurricanes

Question 11

What is the equation for ecological efficiency?

Answer 11

(Biomass at higher trophic level / biomass at lower trophic level) x 100

Question 12

How can net primary productivity be increased?

Answer 12

• Drought resistant crops
• Greenhouses
• Crop rotation
• Pesticides (insects)
• Fungicides (fungal infections)
• Herbicides (weeds)

Question 13

How can secondary productivity be improved?

Answer 13

• Harvesting animals just before adulthood, when the largest proportion of their energy is used for growth
• Selective breeding
• Antibiotics
• Supply animals with food so they don’t waste energy getting it themselves

Question 14

Climax community definition:

Answer 14

The final stable community that exists after the process of succession has occurred

Question 15

Deflected succession definition:

Answer 15

When succession is stopped or interfered with, e.g. grazing or when a lawn is mowed

Question 16

Pioneer species definition:

Answer 16

The species that begun the process of succession, often colonising an area as the first livings things there

Question 17

Succession definition:

Answer 17

Progressive change in a community of organisms over time

Question 18

In the nitrogen cycle, what are the nitrogen fixing processes?

Answer 18

• N2 in air fixed by RHIZOBIUM bacteria in leguminous plants
• N2 in air fixed by free living bacteria in the soil e.g. AZOBACTER
• N2 in air fixed by Haber process. Turned into ammonium and nitrate ions in fertiliser
• N2 in air fixed by lighting. Turns into nitrogen oxide and then nitrates in the soil

Question 19

In the nitrogen cycle, what are the nitrification processes?

Answer 19

In soil:

• Ammonium oxidated by bacteria e.g. NITROSOMONAS into nitrites
• Nitrites oxidised by bacteria e.g. NITROBACTER into nitrates

Question 20

In the nitrogen cycle, what are the decomposition and ammonification processes?

Answer 20

• Organic nitrogen in soil into ammonium

- Urea into ammonium

Question 21

In the nitrogen cycle, what are the denitrifyign processes?

Answer 21

-Nitrates in soil denitrified by bacteria into N2 in air