Science - The Earth

Question 1

1. What is a model? Can it change?

Answer 1

A model is a representation of an idea, object or a process used to test or explain something that is difficult to understand.

Yes, when you observations are made in the predictions of a model are no longer valid

Question 2

2. Label the layers of the earth.

Describe the composition of each layer of the earth.

Answer 2

Inner core: solid, mainly nickel
Outer core: molten rock and liquid state
Mantel: rocky layer, silicon, oxygen magnesium iron aluminium and calcium
Core: iron with liquid outer core
Crust: oxygen, silicon, aluminium, iron, calcium, magnesium, potassium and sodium
Lithosphere: rigid rocky layer composed mostly of basalt and granite
Asthenosphere: molten rock

Question 3

3. Describe the continental drift.

List the continents found in Gondwana and Laurasia.

Answer 3

The slow movement of the earth due to the motion and of the underlying tectonic plates.

Laurasia includes North America, Europe and most of Asia

Gondwana includes most of the present day South America, Africa, India, Australia and Antarctica

Question 4

4. What evidence is there to support the continental drift?

Answer 4

Alfred Wegener German polar researcher proposed the theory that the continents were joined together when he cut out a map of the continents, placed them side-by-side and they lined up.

Question 5

5. What a crustal plates?

Where are crustal plates located?

Answer 5

Crustal plates are the outer layer of the earth.

They are located in the continents and oceans they contain.

Seven largest plates are the
North American plate, Eurasian plate, African plate, Antarctic plate, South American plate, in the Indo-Australian plate and the Pacific plate.

Question 6

6. Do crustal plates vary in thickness?

Answer 6

Yes. The thickness ranges from 80 km to 5 km.

Question 7

7. What does plate tectonics mean?

Answer 7

The Theory that the the crust of the Earth is made of rock plates (tectonic plates) which rest on the mantle and have slowly moved throughout geological time, resulting in continental drift.

Question 8

8. Explain the term faults.

Answer 8

A break in the Earths crust, along with rock slides. Faults can occur wherever there is enough force to make the rock break.

Question 9

9. What is the relationship between plate tectonics and deep sea trenches, volcanoes, earthquakes and mountain ranges.

Answer 9

They are the result of convergent plate boundaries, where two or more tectonic plates meet whether it’s the ocean floor (deep sea trenches), a vent in the earths crust (volcanoes), movement within the earths crust (earthquakes) and geographical land surface with a considerable amount of slope (mountain ranges).

Impacts of a convergent boundary between an oceanic and continental plate include: a zone of earthquake activity that is shallow along the continent margin but deepens beneath the continent, sometimes an ocean trench immediately off shore of the continent, a line of volcanic eruptions a few hundred miles inland from the shoreline, destruction of oceanic lithosphere.

Question 10

10. Describe how convection currents occur. Identify where convection currents occur.

Answer 10

Convection currents in the magma drive plate tectonics. Where convection currents diverge near the Earth's crust, plates move apart.
Heat generated from the radioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the aesthenosphere. 
The aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the Earth that extends to 2900 km.

Question 11

11. What is the theory of plate tectonics? What evidence is there to support the theory of plate tectonics?

Answer 11

The theory of plate tectonics states that the crust of the earth is broken up into large pieces, or plates, that move around by floating on top of the liquid layer of the earth known as the mantle.

This theory was the result of decades of work and observations made of the earth’s surface. It is still the first model to neatly explain all the pieces of data scientists couldn’t explain when they thought the surface of the earth was stationary.

Question 12

12. Describe convergent boundaries, divergent boundaries, transform boundaries and fault lines.

Answer 12

Divergent boundary: When two tectonic plates move away from each other.

Convergent boundary: When two plates come together

Transform boundary: Two plates sliding past each other forms a transform plate boundary. Natural or human-made structures that cross a transform boundary are offset—split into pieces and carried in opposite directions.

Fault line: a break or fracture in the ground that occurs when the Earth’s tectonic plates move or shift and are areas where earthquakes are likely to occur.

Question 13

14. What causes a earthquakes and tsunamis?

Answer 13

Earthquakes are the vibrations caused by rocks breaking under stress. The underground surface along which the rock breaks and moves is called a fault plane.

A tsunami is a series of large waves generated by an abrupt movement on the ocean floor that can result from an earthquake, an underwater landslide, a volcanic eruption or - very rarely - a large meteorite strike.

Question 14

15. What is an epicentre?

Answer 14

The point on the Earth’s surface directly above the earthquake focus.

Question 15

16. How are earthquakes detected and measured?

Answer 15

The power of an earthquake is measured using a seismometer. A seismometer detects the vibrations caused by an earthquake. It plots these vibrations on a seismograph.
The strength, or magnitude, of an earthquake is measured using the Richter scale. The Richter scale is numbered 0-10.

Question 16

17. How volcanoes formed? What are some benefits of volcanoes?

Answer 16

Volcanoes are formed when magma from within the Earth’s upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits.

One benefit of volcanoes are that regions that have large deposits of volcanic soil (i.e. mountain slopes and valleys near eruption sites) are quite fertile.

Question 17

18. List some of the impacts volcanic eruptions has on earth

Answer 17

Volcanic eruptions can be extremely damaging to the environment, particularly because of a number of toxic gases emitted. Carbon dioxide emitted from volcanoes adds to the natural greenhouse effect.

Volcanic eruptions can alter the climate of the Earth for both short and long periods of time which can have an effect on farming for example.

Question 18

19. Identify and explain some technologies which have been developed to detect earthquakes and volcanic eruptions.

Answer 18

Earthquakes and volcanoes are detected by scientific instruments called seismometers. Modern seismometers detect and convert any small movement in the Earth into an electrical signal for use in computer systems.

Volcanoes and earthquakes are also detected by researching the history of previous activity. Monitoring data including gas, ground deformation, and satellite imagery can be used to assess or detect volcanic or earthquake activity.

Question 19

20. What factors are essential when building structures cycle that withstand natural disasters?

Answer 19

Using tough noncombustible surfaces that can with stand extreme heat, high winds and floods eg brick veneer, concrete, plastic insulation.

Question 20

21. What are cyclones?

Answer 20

Winds rotating inwards to an area of low barometric pressure.

Question 21

22. Describe El Niño

Answer 21

Sea surface temperatures are warmer than usual. It brings dry conditions and droughts.

Question 23

23. Describe the effect that floods have on the ecosystem.

Answer 23

The effects of flooding include loss of human life, damage to property, destruction of crops, loss of livestock, and deterioration of health conditions owing to waterborne diseases.

Question 24

24. Define ecosystems
    Define biotic and abiotic.
    Identify abiotic and biotic factors.

Answer 24

Ecosystem: a biological community of interacting organisms and their physical environment. Example, the ocean.

Biotic: relating to or resulting from living organisms (examples: Animals, jellyfish, plants, flowers, microorganisms, dead organisms and even animal waste)

Abiotic: physical rather than biological, not derived from living organisms.
Examples: climate, soil, temperature, sunlight

Question 25

25. Discuss how a change in abiotic or biotic factors can alter ecosystems.

Answer 25

Every Biotic and Abiotic factor effects or causes a change in the environment.

Abiotic factors such as sunlight availability and air and sea temperature can alter the ecosystems by affecting biotic elements like the growth of plants and animals in that ecosystem.

Question 26

26. Define producers and consumers. Identify producers and consumers within food chains and food webs.

Answer 26

Producers, or autotrophs, make their own organic molecules like though photosynthesis.

Consumers, or heterotrophs, get organic molecules by eating other organisms.

Question 27

28. What is biodiversity?

Answer 27

The variety of planet and animal life in the world or in a particular habitat.

Question 28

29. Define extinction.

Answer 28

Extinction is the end of an organism or a group of organisms, normally a species.

Question 29

30. Discuss the relationship between biodiversity and extinction.

Answer 29

One has great effect on the other. The large ecological and societal consequences of changing biodiversity should be minimized to preserve environments, to ensure they do not enter the phase of extinction.

Question 30

31. Identify and discuss management strategies to conserve the environment.

Answer 30

Australia example:

Murray-Darling Basin River System in south eastern Australia.

This environmental water management plan connects the Murray river and Darling river to the wetlands to ensure water is distributed to the natural habitats.

Question 31

32. What is a water cycle?

Answer 31

Water circulates between the earths oceans, atmosphere and land.

Question 32

33. What is the carbon cycle?

Answer 32

A process by which carbon moves from the atmosphere and its organisms and then back again.

Question 33

34. Discuss human affect on the water and carbon cycle.

Answer 33

Carbon cycle:
Burning of fossil fuels.
Global warming.

Water:
Deforestation of environments eg wetlands.
Leads to extinction of animals that thrive in these locations.

Question 34

35. What is the nitrogen cycle?

Draw the nitrogen cycle.

Answer 34

It is the biochemical cycle by which nitrogen is converted into various chemical forms as it circulates among the atmosphere in terrestrial and marine ecosystems.