Assumed Test 3 Questions

Question 1

Name 3 ways atmospheric nitrogen is fixed.

Answer 1

• Nitrogen fixed by lightning
• Fixed by bacteria in soil
• Fixed by root nodule bacteria of legumes (Rhyzobium)

Question 2

What is the term used to describe the transition from the nitrogen being fixed to ammonium.

Answer 2

• Ammonification (performed by soil fungi and bacteria)

Question 3

What is the term used to describe the transition from the ammonium to Nitrites

Answer 3

• Nitrification

Question 4

What is the term used to describe the transition from the Nitrites to Nitrates

Answer 4

• Nitrifies

Question 5

How does Nitrogen reach the ocean?

Answer 5

• Brought by rain and run off and the activities of nitrogen fixing organisms. The sinking of nitrates and other nutrients make the ocean a relatively poor environment in terms of available nutrients.

Question 6

How much of the air is nitrogen?

Answer 6

• 80%

Question 7

Name 3 Carbon sinks/reservoir

Answer 7

• Consumers
• Sediments
• Coal, oil, gas
• Mantle
• Ocean

Question 8

What are the 3 types of respiration in the carbon cycle?

Answer 8

• Animal
• Plant
• Root

Question 9

Does photosynthesis belong in the carbon diagram?

Answer 9

YES

Question 10

Name 2 causes of climate change

Answer 10

• Burning of fossil fuels - burning them released carbon in to the atmosphere, contributing to the greenhouse affect as heat cannot escape earth.
• Deforestation - carbon released. Carbon cant be stored. Burning amazon is an example.

Question 11

Name 2 global affects of climate change

Answer 11

• Loss of biodiversity - animals cannot handle change in environment and cannot adapt.
• Rising sea levels - affect coastal towns.
• Coral bleaching - water heating up and destroying coral marine ecosystem

Question 12

Give an example of a good introduced species in Australia.

Answer 12

• Wasps lay eggs in caterpillars that then mitigate the growth of the caterpillar population
• ladybugs eat aphids and fertilisers
• Dragonflies control mozzie population

Question 13

Define Biomagnification:

Answer 13

Successively higher concentration of non bio-degradable chemicals (eg. pesticides, plastic) build up in tissues of organisms in high trophic levels of food chain.

Question 14

Define Bioaccumulation:

Answer 14

Toxins enter food web by building up in individual organisms.

Question 15

Name and describe 3 ways biomagnification occurs.

Answer 15

1. Persistance - substances cannot be broken down.
2. Bioaccumulation - concentration increases progressively
3. Low/non-existent rate of internal degradation. - mainly due to to water insolubility

Question 16

What is DDT

Answer 16

DDT is a pesticide.

Question 17

Outline the steps of dryland salinity

Answer 17

1. Human population increases - need more food
2. Farming increases to provide food - clearing deep rooted trees
3. Vegetation changes from deep rooted trees/shrubs to shallow rooted crops - reduced/no transpiration or evaporation
4. Water table rises bringing soluble salts to the surface

Question 18

What is dryland salinity and what causes it.

Answer 18

• Occurs naturally in the landscape, but nature generally has the ecosystem balanced so the salt does not cause a problem. However, human activity often upsets the equilibrium and salinity problems occur.
• Caused by a combination of land clearing and irrigation practices. It can reduce biodiversity and devastate ecosystems because the abiotic changes it causes leads to damaging biotic changes.

Question 19

What is secondary succession?

Answer 19

• A process of change in an ecosystem when a previously established community is taken over by a group of new organisms

Question 20

Steps for secondary succession

Answer 20

1. A natural or artificial disturbance occurs
2. Pioneer plants colonise the area and invertebrates enter the ecosystem
3. Slower growing trees begin to grow and stabilise the community. New herbivores, then carnivores and omnivores arrive as part of the food web
4. New community forms and eventually becomes a climax community

Question 21

Steps for Eutrophication

Answer 21

1. Excess nutrients enter a body of water
2. Algae grows and blooms in population
3. Algae blocks plants from sunlight. Algae then run out of food and die.
4. Bacteria bloom in population to break down the dead algae.
5. Bacteria use up all the oxygen in the water
6. Fish die as there is no oxygen in the water.