Chapter 6

Question 1

What is Pangaea

Answer 1

The supercontinent consisting of all the earth’s land masses. Split into two large land masses called Laurasia (north) and Gondwana (south)

Question 2

Why was Pangaea important to Australia

Answer 2

Important stage in the physical isolation that was to give Australia’s biota such distinctive characteristics

Question 3

What was Laurasia

Answer 3

The northern supercontinent formed after Pangaea broke up. Included North America, Europe, Asia, Greenland and Iceland

Question 4

What is Gondwana

Answer 4

The southern super continent that drifted apart to form Antartica, India, Africa, Australia and South America

Question 5

What is continental drift

Answer 5

The theory describing movement of continents resulting from movement of plates in the Earth’s crust

Question 6

How are ice cores used as an evidence of change

Answer 6

Drilling down into ice at the poles and within large glaciers produces cores that have preserved a continuous record of past climactic conditions. Trapped gas bubbles and the presence or absence of traces of organisms reveal information about changes in temperature and concentrations of atmospheric gases

Question 7

Define succession

Answer 7

The progressive change of communities over time

Question 8

Define nudation and give examples of what causes it

Answer 8

The development of bare sites with no organisms inhabiting the affected area. Caused by volcanic eruptions, cyclones, earthquakes and tsunamis

Question 9

What is a pioneer plant

Answer 9

A plant capable of invading bare sites, such as newly exposed soil surface

Question 10

What is primary succession

Answer 10

The colonisation of plants in a barren place

Question 11

What is an example of primary succession

Answer 11

Autotrophic organisms (lichens) are first to become established in harsh surroundings. Acids secreted by the lichens attack the rocky surface allowing dust particles to settle in cracks. Shallow soil makes it possible for mosses to grow. When they die they add nutrients.

Question 12

What is secondary succession

Answer 12

through natural disaster and human impact, dramatic changes to organisms occur. The cycling of matter and flow of energy are interrupted as the components of the ecosystem are affected

Question 13

What is a climax community

Answer 13

The end point in a community succession where the community has become relatively stable (eg old growth forests)

Question 14

What is an example of Australian climax communities

Answer 14

The old growth forests of Cooloola National Park in south east Queensland and the temperate rainforest pockets scattered throughout the east coast of Australia

Question 15

Effect of fire on ecosystems

Answer 15

Loss of vegetation, reduction of leaf litter and a decrease in animal numbers

Question 16

What is an urban ecosystem

Answer 16

An ecosystem with reduced biodiversity and us dominated by people. There is little recycling of matter and an increase in output of wastes into the atmosphere, land and water

Question 17

how much Habitat destruction has occurred in aus

Answer 17

Since 1750, more than 20% of Australia’s forests have been cleared for crops and grazing with nearly 90% of the vegetation cleared in fertile lands

Question 18

What causes land and soil degradation

Answer 18

Hard hooved animals compact the soil when they craze. Those creates opportunities for invasive, shallow rooted, introduced plants at the expense of the deep rooted native plants

Question 19

Define monoculture practices

Answer 19

When only one species of an organism is grown and biodiversity is reduced. Often requires extensive use of fertilizers and pesticides. Easy for pests to spread as natural enemies are no longer present

Question 20

Name the 5 ways the distribution of water for human use has changed ecosystems

Answer 20

• Irrigation (places demands on supplies of water)
• Engineering (construction of dams deprive vegetation of flooding essential for survival and fish can become stranded)
• Degradation of urban streams and waterways (Drains deliver stormwater into streams causing physical and chemical disturbance to marine ecosystems)
• Desnagging (removal of logs from waterways for boats which reduces breeding sites for fish and increases erosion rates)
• Drainage of wetlands (important for processing large quantities of pollutants that would normally pass downstream)

Question 21

How can introduced species become pests?

Answer 21

Without natural predators many introduced species become pests that affect habitats, food chains and the ecosystem. Examples include deer, camels, pigs cats and dogs

Question 22

Explain how commercial fishing is causing marine organisms to be at risk of extinction

Answer 22

• Hunting: sharks hunted for leather, fish meal and fertilizer
• Over fishing: penguins and seals compete with the fishing industry for food
• Pollution: abandoned fishing lines and plastic kill turtles, seals and birds
• By catch: As populations of fish decrease, there are fewer fish reaching reproductive age to sustain population growth
• Pollutants such as oil can disrupt marine ecosystems

Question 23

what is DDT

Answer 23

DDT was a commonly used pesticide as it was cheap and effective. IT affects the nervous system by interfering with normal nerve impulses DDT was a commonly used pesticide as it was cheap and effective. IT affects the nervous system by interfering with normal nerve impulses

Question 25

What are the effects of DDT

Answer 25

In humans can cause nausea, diarrhea, tremors
In animals can cause chronic effects on the nervous system. DDT is insoluble in water and is highly toxic to aquatic organisms

Question 26

Why was DDT used

Answer 26

• initially used by military in ww2 to control malaria, typhus, body lice and bubonic plague
• Farmers used DDT on crops as a pesticide
• Used in buildings for pest control