Earth and Environmental

Question 1

Features of the main objects in the universe

Answer 1

Nebula: Giant cloud of dust and gas in space created by a supernova
Stars: Large balls of gas held together by their own gravity, producing heat and light
Solar system: The system involving the star and the planets/other features which orbit it
Galaxy: Large system of other solar systems and stars, dust etc. bound by gravity
Supercluster: Group of galaxies

Question 2

How does technology help us understand the universe?

Answer 2

Hubble telescope: observes comets and planets, and takes images which helps us learn about how galaxies are formed
Chandra X-Ray Observatory: Observatory in space which takes images defining the hot and turbulent areas of outer space
Spectroscope: Instrument which can measure properties of light, including the intensity and wavelength. This helps us figure out what elements light sources are made of

Question 3

What are distances in the universe measured by?

Answer 3

Light year (distance travelled by light in an earth year), around 9.46 trillion km

Question 4

Describe gravitational attraction

Answer 4

Gravity is a force objects impose upon each other, where the greater the mass, the greater the gravity. It can “curve” the fabric of spacetime

Question 5

Define scientific theory

Answer 5

Idea that tries to explain natural phenomena based on evidence present

Question 6

Outline the Big Bang theory

Answer 6

1. Universe was formed 14b years ago in an explosion from a singularity
2. Universe expanded and cooled over 15m years, where helium and hydrogen could be formed
3. The initial gas cloud collapses and the gravity lumps gas together to form galaxies

Question 7

Describe the evidence that supports the Big Bang theory

Answer 7

1. Doppler effect leading to redshift of emission spectra, suggesting universe is expanding
2. Faint electromagnetic radiation linked to the Big Bang
3. Abundance of hydrogen and helium indicates that the Big Bang occurred – if the creation was slower, then there would be less helium because many neutrons would have decayed before helium could be formed

Question 8

Traits of scientific theories

Answer 8

Must be testable through experimenting and may be modified or rejected due to new evidence

Question 9

Phenomena the Big Bang theory cannot explain

Answer 9

1. Light can distort intergalactic distances, but often in unexpected places with no observable matter
2. The outside of galaxies rotates as fast as the inside of galaxies which is inexplicable with modern understandings
3. The redshift seems to be accelerating, which contradicts the Big Bang theory which suggests the expansion of the universe has been slowing down over since the Big Bang

Question 10

Outline the Theory of Plate Tectonics

Answer 10

The inside of the earth is split into 4 sections - inner core, outer core, mantle and lithosphere. The densest layer sinks and the least dense rises to the top. The inner core is solid and the outer core melted liquid. The mantle is molten. Because of this property, the lithosphere floats on top and is moved by convection currents

Question 11

Explain convection in the mantle

Answer 11

Heat rises, and hence the hot material exposed to the inner core rises to the top. It cools down as the heat is expended, and sinks back down for the process to repeat. This usually happens in circles in a gear-like manner

Question 12

Features of divergent plate boundaries

Answer 12

Divergent plate boundaries are plates being pulled apart by convection currents. A rift valley is where the plates are being pulled apart, as the magma replaces some of the removed content. Mid-ocean ridges are the same, just underwater. Volcanism is regular because magma is pushed up from the mantle causing an eruption

Question 13

3 types of convergent plate boundaries

Answer 13

Oceanic vs continental describes the Andes mountains, and it has a continental volcanic arc. Oceanic vs oceanic describes Japan, where it has an island volcanic arc. Continental vs continental describes the Himalayas, where there is no volcanism.

Question 14

Identify Earth’s major mountain ranges and explain through plate tectonic theory

Answer 14

Himalayas are created by a continental vs continental boundary, where the India and Eurasian plates collide. The Andes mountain is created by an oceanic vs continental boundary, where the oceanic plate shifts under the continental. The European Alps are created by a continental vs continental boundary, where the African and Eurasian plates collide. The Ethiopian Highlands is a rift valley. The Atlantic Mid-Ocean Ridge is a rift valley.

Question 15

Describe hotspots

Answer 15

They occur where there is an unusually high amount of activity in the mantle in one area. Hotspots are stationary but the area above is not. One example of a hotspot is Hawaii

Question 16

Describe transform plate boundaries

Answer 16

AKA slip-strike faults, they are where two plates rub against each other. This is marked by long valleys around the border where the rock is weathered from the grinding. Earthquakes are common

Question 17

Explain how earthquakes are produced, their effects, and measured

Answer 17

They are produced when a slip-strike fault suddenly breaks a rock underground, creating a large vibration. Earthquakes cause destruction to natural and artificial habitats, and can cause more natural disasters e.g. tsunamis. They are measured by seismographs which record ground motion caused by seismic waves. This can then by described by the Richter scale

Question 18

Evidence for continental drift

Answer 18

South America and Africa have matching coastlines, identical fossils in faraway places are in one place in constructed Pangaea, distant mountain ranges are similar (e.g. Appalachian and eastern Greenland ranges), glacial deposit covers South America, southern Africa, India, Australia and Antarctica which is in one location on Pangaea

Question 19

Phenomena continental drift cannot explain

Answer 19

Some parts of the seafloor are estimated to be 350m to 2b years old, when they should only be 200m years old because by then they should be subducted into the mantle again. Continental crust has been found on ocean floor with shallow water fossils, suggesting land has somehow sunk. Some parts of the ocean floor extend 600km into the ground, suggesting it is connected to magma but that would contradict continental drift altogether