Science (Semester 2) Flashcards
What’s the difference between infectious and non-infectious diseases?
Infectious diseases: diseases that can be spread between individuals
Non-infectious diseases: diseases that cannot be spread between individuals
Name at least three examples of pathogens and the diseases caused by each.
- Macroparasite
A multicellular organism (etc. a tick) that is usually parasitic. Absorbs nutrients across the cell membrane.
Example disease: Cysticerosis - infection from eating undercooked contaminated meat, caused by tapeworm - Fungus
A unicellular or multicellular organism that feeds on organic matter.
Example disease: Tinea - fungal infection that occurs (often) between the toes - Bacterium
A unicellular organism with a cell wall but no nucleus or organelles
Example disease: Chlamydia - sexually transmitted infection
Explain at least one example of how science is currently helping society respond to outbreaks of disease
- Devil facial tumour disease
- Occurs in Tasmanian devils: symptoms include lesions and swelling on the face
- Caused by contagious cancer, spread by biting
- Caused Tasmanian devil to be protected and endangered
- Science research focused on monitoring spread of disease, learning more about the disease and managing it to avoid extinction of the Tasmanian devils.
- Discovery made: Tasmanian devils lacked genetic diversity related to fighting infection
- Avian influenza
- Has occured in many adaptations
- 2009: Swine flu pandemic (H1N1 strain) occurred
- Concern: virus will remain in bird populations and change into form that transmits directly form human to human, like Spanish flu.
- CSIRO researched gene silencing, which prevents mechanisms that viruses use to take over their host’s cells
- …in addition to early detection of the flu and vaccines
Outline the first line of defence against disease entering our bodies.
- Consists of physical and chemical barriers
- Stops pathogens from getting inside the body
What are the physical components of the first line of defence?
Skin
- thick layer of dead cells provides physical barrier
- natural flora colonise linings (skin, digestive system, lining of nose), reducing surface areas for pathogens to colonise.
- Breaks or damages to skin allow pathogens to enter.
Mucous membranes
- Lines entrances to body (etc. nose, ears)
- Produces mucus that traps foreign particles and directs them out of the body
Hairs and cilia
- Hairs within nose trap dust, dirt, microbes and pollutants
Urine, defecation and vomiting
- flushes out pathogens from the bladder area and digestive system
What are natural flora?
a community of microbes
What are the chemical components of the first line of defence?
Enzymes in tears, sweat and saliva
- Breaks down the cell wall of bacteria
Stomach acid
- Hydrochloric acid kills bacteria and parasites that have been swallowed
Outline the second line of defence against disease entering our bodies.
Seeks and destroys pathogens
Consists of general / non-specific immune responses
What are the non-specific immune responses in the second line of defence?
Blood clotting - stops additional infection through skin damage
Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
Outline the third line of defence against disease entering our bodies.
Targets remaining pathogens.
Consists of specific immune responses that create antibodies.
What are antibodies?
immune proteins produced in response to and counteracting a specific antigen
What is natural active immunity?
Natural active immunity occurs when antibodies remain in the blood after an infection is fought, and will react to the same pathogen again.
Outline the components of the immune systems and our body’s response to infection.
- First line of defence
- Physical and chemical barriers
- Stops pathogens from getting inside body
- Second line of defence
- Seeks and destroys pathogens
- Consists of non-specific immune responses such as:
- Blood clotting - to stop additional infection through skin damage
- Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
- Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
- Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
- Third line of defence
- Targets remaining pathogens
- Consists of specific immune responses that create antibodies
- Antibodies are protein molecules that bind to target pathogens.
- They remain in the blood after an infection is fought, and will react to the same pathogen again.
- This is called natural active immunity.
Give an example of a common medicine and its use.
Aspirin: used to reduce the symptoms of illness.
How are medicines used?
Medicines are used to:
- Change how cells work - Replace substances missing from your body - Destroy micro organisms and abnormal cells - Reduce the symptoms of illness
Recall the types of immunities.
- Natural active immunity
- Acquired active immunity
- Natural passive immunity
How does natural active immunity operate?
when a person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.
How does acquired active immunity operate?
a short-term immunisation by the injection of antibodies that are not produced by the recipient’s cells
How does natural passive immunity operate?
occurs during pregnancy, when antibodies are transferred from one person to another through natural means
How are non-infectious diseases acquired?
Diet and lifestyle choices
- poor supply of the proper nutrients to your body can affect the function of your cells
- EXAMPLE: Lack of Vitamin C = Scurvy
Genetic disorders
- Result of mutation in DNA or chromosomes at some stage
- EXAMPLE: Fragile X syndrome
Environmental factors
- Exposure to toxins, carcinogens and radiation
- etc. nuclear reactions that release a toxic amount of radiation
Outline the causes of some non-infectious diseases
Scurvy: diet and lifestyle choices, due to a lack of Vitamin C
Fragile X syndrome: inherited genetic disorder, caused by variation in the FMR-1 gene on the X chromosome
Skin cancer: environmental factors, overexposure to UV radiation
What causes congenital analgesia?
Inherited mutation/disorder in the SCN9A gene
- ability to transfer signal to dorsal root neurons blocked, so no pain propagation
What are the symptoms of congenital analgesia?
- Frequent physical injuries
- Absent or reduced sense of smell
- Lack of pain sensation
- Inability to feel foreign objects in eye
- Common mouth injuries
What does blood clotting do?
Stops additional infection through skin damage
What does inflammation do?
Increases the amount of blood (carrying white blood cells) reaching an infected area
What is the purpose of fever?
To heat up the body and destroy pathogens that cannot survive in extreme heat
What are phagocytosis?
Large white blood cells that envelope pathogens and destroy them via enzymes
Define pathogen.
a bacterium, virus, or other microorganism that can cause disease.
What is a macroparasite? Give an example of a disease that it causes.
A multicellular organism (etc. a tick) that is usually parasitic. Absorbs nutrients across the cell membrane.
Example disease: Cysticerosis - infection from eating undercooked contaminated meat, caused by tapeworm
What is fungus? Give an example of a disease that it causes.
A unicellular or multicellular organism that feeds on organic matter.
Example disease: Tinea - fungal infection that occurs (often) between the toes
What is a bacterium? Give an example of a disease that it causes.
A unicellular organism with a cell wall but no nucleus or organelles
Example disease: Chlamydia - sexually transmitted infection
Describe the transfer of heat energy by conduction, and provide an example.
Conduction: transfers heat via direct molecular collision (the transferred vibration of individual vibrating atoms)
Example: Placing metal into an open flame
Describe the transfer of heat energy by convection, and provide an example.
Transfers heat by visible movement of fluid
Example: Boiling water
Describe the transfer of heat energy by radiation, and provide an example.
- Transfers heat through electromagnetic energy (waves)
- Does not require contact between heat source and heated object
- All objects absorb and emit electromagnetic radiation.
- Example: sunlight reaching Earth and heating it
Contrast conductors and insulators.
Conductors: any material that conducts heat
Insulators: any material that obstructs the transfer of heat
How does heat spread in metals?
- Heat excites the positive metal ions in the lattice structure and makes them vibrate more.
- The free electrons gain kinetic energy from the excited metal atoms and move around while colliding with other atoms (some of which are vibrating less vigorously).
- The other atoms gain kinetic energy from the collision, and thus vibrate more vigorously.
The collisions transfer energy to the lattice in the form of heat. Thus, the metals heat up.
Solids can transfer heat via conduction / convection / radiation.
Solids can transfer heat via conduction and radiation.
Liquids can transfer heat via conduction / convection / radiation.
Liquids can transfer heat via conduction, convection and radiation.
Gases can transfer heat via conduction / convection / radiation.
Gases can transfer heat via conduction, convection and radiation.
What does radiation not require to transfer heat?
Molecules
Explain conduction and give an example.
Example: heating a metal rood with a bunsen burner
In a material:
- Higher-speed particles that have been excited by heat collide with slower-speed particles, and the ‘slower’ particles increase in kinetic energy.
- Eventually, the material is heated due to all the particles being excited.
Explain convection and give an example.
Example: Heating a saucepan of water
- Transfers heat by visible movement of fluid
- A fluid surrounding a heat source receives heat, becomes less dense and rises.
- The surrounding, cooler / denser fluid then sinks to replace it.
- The cooler fluid is then heated, and the process loops (forming a convection current).
Explain radiation and give an example.
Example: sunlight heating the Earth
- All objects absorb and emit electromagnetic radiation.
- The hotter an object is, the more radiation it emits
- The radiation is emitted by a heated surface in all directions and travels directly to its point of absorption at the speed of light
Give four examples of conductors.
- Copper
- Gold
- Iron
- Steel
Give four examples of insulators.
- Water
- Wood
- Glass
- Rubber
Define sound energy.
a form of energy associated with the vibration of matter
Explain what sound energy is.
Sound energy originates from the vibrations that result after an object applies a force to another object.
How is sound energy transferred?
in longitudinal waves which consist of compressions and rarefactions
Give an example of sound energy in action.
Playing the drums
What’s the difference between a compression and a rarefaction?
Compression: the areas of air where the particles are forced / squished close together
Rarefaction: the areas of air where the particles are spaced further apart
Define sound waves.
Sound waves: a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
Why do sound waves need a medium through which to travel?
A medium is required for vibrations to propagate, since sound waves consist of vibrations.
- As sound waves consist of compressions and rarefactions, a medium that can be compressed is required (thus elastic medium).
How do sound waves vary in speed depending on the density of the medium?
The less dense the medium, the slower the speed of sound due to the particles being further apart.
The more dense the medium, the faster the speed of sound due to the particles being closer together and vibrations being able to be propagated faster.
Why can’t sound travel through empty space?
- Matter must exist in order for vibrations to be propagated.
- Since a vacuum contains no matter, sound cannot occur.
How does light travel?
As a transverse wave.
Why does light not need a medium to propagate?
- Light is an excitation of the electromagnetic field.
- The EM field permeates everything in space, and is a nonphysical medium: the excitations of the field thus can propagate through matter and a vacuum.
- Thus, light doesn’t pass its energy from particle to particle like sound waves do.
In sound, ____ determines pitch.
frequency
With light, ____ determines colour.
frequency
Define frequency in sound.
how often the particles of the medium vibrate when a wave passes through the medium.
The faster the vibrations, the higher pitched the sound and vice versa.
Define frequency in light.
the number of waves that pass a point in space during any time interval (usually one second).
Measured in units of cycles (waves) per second, or hertz.
What is the wave equation, and what is it used for?
v = f × λ
Used to calculate wavelength, speed and frequency.
What does v in the wave equation stand for?
speed of the wave (m/s)
What does f in the wave equation stand for?
frequency of the wave (Hz)
What does λ in the wave equation stand for?
wavelength of the wave (m)
Correctly list the colours of the rainbow in order.
Red Orange Yellow Green Blue Indigo Violet
Give six examples of waves we cannot see.
Radio waves Microwaves Infrared radiation Ultraviolet radiation X-rays Gamma rays
Compare the speed of light to the speed of sound.
The speed of light is 900000~ times faster than sound. / much faster!
At what speed does sound move at?
343 m/s
At what speed does light in a vacuum move at?
300 000 000 m/s
Visible light is a ____ section of the electromagnetic spectrum.
small
What is a radio wave? Provide an example of its use.
A long wavelength, low frequency / energy EM wave.
Used in long distance communications / transmitting TV and radio programmes.
What is a micro wave? Provide an example of its use.
A short wavelength radio wave.
Used to cook food in a microwave.
- Water molecules in food vibrate at the same frequency as microwave waves: therefore transformed into heat which cooks the food.
What is infrared radiation? Provide an example of its use.
Part of the EM spectrum, at a frequency just below the visible spectrum’s red end.
- All objects emit infrared waves.
Used as a communications method for remote control.
What is ultraviolet radiation? Provide an example of its use.
A part of the EM spectrum, between visible light and X-rays. High-energy radiation.
The Sun produces UV rays, which are utilized by our skin to produce Vitamin D.
What are X-rays? Provide an example of their use.
High-energy EM radiation that appears on the spectrum above UV waves.
Used to see inside people, due to their penetrating nature.
What are gamma rays? Provide an example of their use.
The highest energy EM radiation which ionizes, and is thus biologically hazardous.
Example: radiotherapy to kill cancer cells.
Define refraction.
bending the path of light so that its direction of propagation changes, caused by the passing of light through two regions / mediums with different densities
Give three examples of situations that involve the refraction of light.
- Bending light / refraction through a rectangular prism
- Pencil in a beaker of water (‘disconnection of object’) / refraction through water
- Magnifying glass / refraction with lenses
- has to bend light to different angles to focus on a point
Predict the direction of the refracted ray when light travels from one medium into another.
Travelling from a less dense medium into a denser medium
- Ray of light slows down and bends closer to the normal.
- Mnemonic: LMC
- first medium Less dense
- second medium More dense
- light bends Closer to normal
Travelling from a denser medium into a less dense medium
- The ray of light speeds up down, and bends away from the normal.
- Mnemonic: MLA
- first medium More dense
- second medium Less dense
- light bends Away to normal
What is the difference between a concave surface and a convex surface?
Concave surface: curves inward
Convex surface: Bulges outward
What is the difference between a concave lens and a convex lens?
Concave lens: Causes light rays to diverge / spread apart
Convex lens: Causes light rays to converge / meet
What is the difference between a concave mirror and a convex mirror?
Concave mirror: Causes light rays to converge / meet
Convex mirror: Causes light rays to diverge / spread apart
What is an interface?
the surface between two mediums
Explain total internal reflection.
- When light passes from a more dense medium to a less dense medium, it is refracted away from the normal.
- If the refracted ray travels beyond 90° (the critical angle) to the normal along the interface, it reflects from the interface back into the denser medium.
Give an example of total internal reflection being used.
Cutting diamonds to make them sparkle.
- light is reflected through the internal reflection.
What is an optic fibre?
A very thin cable of glass or plastic that carries light.
How is total internal reflection used in fibre optics?
- Light getting in at one end undergoes repeated total internal reflection and emerges at the under end.
- This results in less signal loss, greater carrying capacity and immunity to electromagnetic interference.
- Hence, long distances can be covered easily.
Basic electrical circuits are either ___ or ____.
series or parallel.
What MUST basic electrical circuits contain?
- A power source
- A (or several) component/s / load/s that requires energy
- Connecting wires
Identify the rules for drawing circuit diagrams.
- Connecting wires shown as straight lines
- Where different wires meet at junctions, they are often shown as being joined at right angles
- Power source represented as a pair of parallel lines of different lengths
- Longer line = positive terminal
- Shorter line = negative terminal
Identify the correct devices for measuring current and voltage.
Voltmeter: used to measure voltage
Ammeter: used to measure current
Define current.
a measure of the amount of charge that goes part the point in the circuit in one second
What is the unit and symbol for current?
ampere
A
Define voltage.
a measure of the potential energy that electrons have
What is the unit and symbol for voltage?
volt
V
Define resistance.
a measure of how easily electrons move through a material
What is the unit and symbol for resistance?
ohm, Ω
What is the equation for Ohm’s law?
V = I x R
What does V stand for in Ohm’s law?
Voltage (volts)
What does R stand for in Ohm’s law?
Resistance (ohms)
What does I stand for in Ohm’s law?
Current (amps)
Explain how currents and voltages behave in series and parallel circuits.
- Series circuits
- The current passing through each component is the same
- The voltage through the circuit is the sum of the voltages across each component
- Parallel circuits
- Voltage across each component is the same
- Each individual component is supplied with the same voltage
- The total current in a parallel circuit is the sum of the current through each branch of the circuit.
- Voltage across each component is the same
Identify resistor colour codes.
Mnemonic: Buster Brown races our young girls but Violet generally wins.
Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Grey = 8 White = 9
What does Ohm’s law do?
It gives the resistance of a device as the ratio of its voltage and current.
What does it mean for a device to be energy efficient?
- A device is energy efficient if it uses less energy to provide the same function.
- less energy in the transformation to a given energy type.
What is the formula for energy efficiency?
Energy efficiency = (amount of usable energy / amount of initial energy) * 100
Why is the continued use of non-renewable energy an issue? Provide some specific examples.
- Non-renewable energy is harmful to the environment.
- Coal emits gases such as carbon dioxide (CO2), sulfur dioxide (SO2) and nitrogen (NO2).
- Carbon dioxide contributes to the greenhouse effect.
- Sulfur dioxide and nitrogen cause damage to the environment as acid rain.
- Thus, we can see how non-renewable energy has an impact.
What are the principles of green building design?
- Design
- Durability
- Energy efficiency
- Waste reduction
- Indoor air quality
- Water conservation
- Green products.
Expand on the principle of design in green building design.
- Smaller houses consume fewer resources both during construction and after occupation.
- Solar orientation is important, as it reduces the need for electrical energy to regulate temperature
- Example: longer walls of a house face north, so that exposure to the sun is minimised in summer and maximised in winter
Expand on the principle of durability in green building design.
- Attention to detail during construction ensures proper performance over the life of the building. This reduces the need for excess parts for repair, and thus impact on the environment.
- Moisture control
- Controlling leakage saves energy, and prevents damaging condensation from forming in cavities.
Expand on the principle of energy efficiency in green building design.
- Insulation is important. Air infiltration is kept as low as possible.
- The type of lighting used is paid attention to: for example, fluorescent lighting saves on cooling loads.
- Energy Star rated applicances cut down on energy use.
Expand on the principle of waste reduction in green building design.
Reduction of waste = better for environment
Expand on the principle of indoor air quality in green building design.
- Proper ventilation brings fresh outside in while exhausting stale inside air.
- Heat recovery ventilators retain indoor humidity in winter (an extra benefit)
Expand on the principle of water conservation in green building design.
- Low-consumption toilets prevent clogs and excess flushing
- Managing stormwater runoff maintains natural ground percolation that recharges aquifers
Expand on the principle of green products in green building design.
Sustainable products win.
Define the theory of continental drift.
the gradual movement of the continents across the earth’s surface through geological time.
Define the theory of sea floor spreading.
the process of new oceanic crust moving away from the middle of the ocean and pushing the plates away.
Sea floor spreading helps explain ___________________.
Sea floor spreading helps explain the theory of continental drift.
How was the theory of plate tectonics created?
By combining the continental drift theory with the sea-floor spreading theory.
Examine the evidence for continental drift.
- Coasts of continents could “fit” together
- Rock layers/fossils from ‘fitting’ continents matched
- Living animals in widely separated lands are similar
- Geological similarities between eastern South America and western Africa
Examine the evidence for sea floor spreading.
- Samples of the deep ocean floor show that balsatic oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached, and sediment cover is thinner nearer the ridge
- The rock making up the ocean floor is younger than the continents (no samples over 200 million years old, contrasting max ages of over 3 billion years for the continental rocks)
- Magnetic patterns on opposite sides of mid-ocean ridges are mirror images of each other
Give two pieces of evidence for the theory of plate tectonics.
- The outlines of the continents fit together well enough to suggest they were once joined.
- The same fossils are found on different continents far apart, which can only be explained if the continents were once joined together.
Describe Wegner’s theory of Continental Drift.
Earth’s continents were once joined together in a giant continent called Pangaea. However, they gradually drifted apart over millions of years.
What evidence is there to support Wegner’s theory of Continental Drift?
- The same type of fossilised animals and plants were found in South America and Africa.
- The shape of the east coast of South America fits the west coast of Africa, like a jigsaw
- Matching rock formations and mountain chains are found in South America and Africa.
What is the theory of Plate Tectonics?
- Earth’s outer shell is divided into several plates that glide over the mantle.
- In essence: The structure of the Earth is not stationary.
- Parts are constantly moving and changing, especially on the surface.
Identify the major tectonic plates.
- African
- Antarctic
- Eurasian
- Indo-Australian
- North American
- Pacific
- South American
Explain the idea of Pangaea, and how the continents have reached their current positions.
- Pangaea was a supercontinent that existed 300 million years ago.
- It was comprised of the seven current continents joined together.
- It broke apart about 175 millions ago.
- The continents reached their current position through gradual continental drift.
Explain how a mid-ocean ridge is formed.
- Convection currents in the mantle cause hot magma to rise and create magma where two tectonic plates meet at a divergent boundary
- The mantle rock moves away from the ridge on each and creates tension.
- The rock carries the sea floor along with it.
- The ridge cracks, and a rift zone forms along with shallow earthquakes.
- The rock cools, becomes denser, and gravity causes it to sink back into the mantle.
Determine the age of the Hawaiian Islands.
Each island is successively older toward the northwest.
How do volcanic eruptions occur?
- Magma, which is at a temperature of over 1200C, is under pressure from the solid rock above it that squashes it.
- The difference in densities leads the magma to rise.
- Magma rises towards the surface of the earth in order to relieve the pressure. The gases within it begin to escape (and form bubbles).
- The density of the magma determines the nature of the eruption.
- If magma is thin and runny, gases escape easily and thus the magma flows out of the volcano when erupting.
- If the magma is dense/thick, gases cannot escape easily. The pressure inside increases until the gases escape violently and explode.
- The magma blasts through the main volcanic vent.
- It breaks apart into pieces, which can vary in size from tiny particles of ash to boulders.
- The magma blasts through the main volcanic vent.
- Magma that lands on the surface of the Earth is called lava. The cooler temperatures on the surface help the lava to solidify quickly.
How do earthquakes occur?
- Tectonic plates that are sliding against each other become jammed.
- The pressure builds up until the rocks break and the plates jolt free.
- This release in energy causes seismic waves, which causes vibrations on the earth - an earthquake.
- Damage occurs near the epicentre.
- Epicentre: the place above the focus (the spot underground where the rock breaks).
What is a transform boundary?
a fault line where tectonic plates can slide past each other
Identify two examples of a transform boundary.
- San Andreas Fault in western North America
- Alpine Fault in New Zealand
What is a convergent boundary?
a region where two tectonic plates move towards one another and collide
What is a divergent boundary?
a region where two tectonic plates move away from each other, and new crust forms from magma that rises to the Earth’s surface between the two plates
Explain the difference between transform, convergent and divergent boundaries.
Transform boundary: a fault line in which two tectonic plates slide against one another
Convergent boundary: a region where two tectonic plates move towards one another and collide
Divergent boundary: a region where two tectonic plates move away from each other, and new crust forms from magma that rises to the Earth’s surface between the two plates
What are the three possibilities / collisions of plates along converging boundaries?
- Ocean-to-continent collision
- Continent-to-continent collision
- Ocean-to-ocean collision.
Explain ocean-to-continent collision, and recall the different geological features and natural events that can occur there.
- Oceanic plates collide with continental crust, and subduction occurs
- The oceanic crust gets pushed down into the mantle because it’s denser than the continental crust
- Mountains form along the crumpled edge.
- Volcanoes form as the subducting plate melts and the molten material rises back up through the crust.
- An ocean trench forms at the line of plate contact on the edge of the continent.
Explain continent-to-continent collision, and recall the different geological features and natural events that can occur there.
- Two continental plates (with similar densities) collide.
- Thus, no subduction occurs.
- The edges of the two plates crumple and fold into high mountain ranges.
Explain ocean-to-ocean collision, and recall the different geological features and natural events that can occur there.
- Two oceanic plates collide.
- The older, denser crust subducts below the newer crust, creating a deep ocean trench.
- This subduction creates a line of undersea volcanoes that may reach above the ocean surface as an island arc.
Relate boundaries to new landforms.
- Transform boundaries
- Form strike-slip fault lines
- Form oceanic fracture zones
- Convergent boundaries
- Ocean-to-continental collision
- Mountain chains (subduction), volcanoes (material from subducting plate), ocean trench (at point of contact)
- Continent-to-continent collision
- Mountain chains (crumpling of plates)
- Ocean-to-ocean collision
- Ocean trench (subduction), island arc
- Ocean-to-continental collision
- Divergent boundaries
- Rift valley, ocean w/ mid-ocean ridge
Link what can happen along a transform boundary to at least one event in history
The release in energy causes earthquakes.
EXAMPLE: magnitude 7.8 earthquake that destroyed San Francisco in 1906
- rock of transform fault slipped up to 5 metres
Define focus (earthquake).
Focus: the location underground at which rock breaks / an earthquake occurs
Define epicentre (earthquake).
the location above the focus / point on the surface of the Earth directly above where an earthquake has occurred
What are the methods used to measure earthquake intensity?
Richter scale and Mercalli scale.
What does the Richter scale do?
describes the earthquake’s magnitude by measuring the seismic waves that cause the earthquake
What does the Mercalli scale do?
describes the intensity of an earthquake based on its observed effects
What are the types of seismic wave?
S (secondary), P (primary) and L (Love / surface).
What are P (primary) waves?
- Longitudinal waves
- Travel through Earth’s core
- Shake ground in the direction they are propagating.
What are S (secondary) waves?
- Shear waves
- Do not travel through liquid (etc. core)
- Shake the ground perpendicular to the direction in which they’re propagating
What are L (Love / surface) waves
- Lower frequency than body waves
- Fastest surface wave, moves ground side-to-side
- Surface waves are almost entirely responsible for the damage and destruction associated with earthquakes.
What is the amplitude?
The height of the strongest wave.
Explain the formation of a tsunami by an undersea in an earthquake.
- An undersea earthquake changes the shape of the seafloor.
- An extra ‘lump’ of water is raised by the seafloor. The water collapses to produce a series of waves, the tsunami.
Describe diverging boundaries and how they produce rift valleys on land which eventually widen to produce new seas.
- Two tectonic plates move away from each other.
- Hot mantle rock rises from within the earth. It lifts the continental crust and thins it out.
- Cracks form and large slabs of rock sink into the cracks, forming a rift valley.
- The continental crust separates, and a narrow sea forms. The valley eventually widens to form an ocean with a mid-ocean ridge.
Discuss what the Earth may look like if continental drift continues into the future.
- It is certain that a supercontinent will form.
- This would result in mountain-building and major climate changes.
- New species would emerge, and some organisms would be driven to extinction.
- Volcanic activity would increase, as the supercontinent would insulate the Earth’s mantle.
Predict one possible outcome for the Earth’s continents if they continue to drift
- North and South America are currently moving west from Africa and Europe.
1. Modelling: Africa will continue drifting north and join up with Europe. North and South America will merge with Asia into a supercontinent called Amasia. The Mediterranean Sea will be replaced with the Mediterranean Mountains.
2. Paleomap Project: the collision of North America with Africa and South America with South Africa to form a new supercontinent called Pangaea Proxima that encircles the old Indian Ocean. The Pacific Ocean would stretch half way across the planet.
Identify at least two devices a geologist might use in their work and explain what they measure
- Magnetometers: used to measure changes in the Earth’s magnetic field
- Seismometers: used to measure movement in the ground.
- Seismic surveys: used to produce images of the various types of rocks and their location underneath the Earth’s surfaces
Describe magnetometers and their use by geologists.
- an instrument used to measure changes in the Earth’s magnetic field
- Placed around a fault line for monitoring.
- Remote areas give the most reliable results, as large iron or steel objects affect the readings
- Helps geologists understand what causes earthquakes and predict them
Describe seismometers and their use by geologists.
- an instrument used to measure movement in the ground
- usually caused by earthquakes or volcanoes
- Consists of an internal mass attached to an immobile frame.
- The mass swings / move relative to the stable frame to measure ground movement.
- A computer records the amount of movement of the mass to produce a seismograph, which is an indication of the strength of movement in the ground.
Describe seismic surveys and their use by geologists.
- used to produce images of the various types of rocks and their location underneath the Earth’s surfaces
- Send sound waves into the Earth and use the time taken for the wave to bounce back as an indication of the different structures of materials in the Earth’s layers.
- The way in which the sound waves reflect off points of physical change can indicate the type of rock, and any fractures or abnormalities within the layer.
Explain how a volcanic eruption in one part of the world can affect many other areas
- Dependent on the size and type of eruption.
- They produce large amounts of carbon dioxide (CO2), which contributes to the greenhouse effect.
- Atmospheric haze occurs.
- Large eruption columns inject ash particles and sulfur-rich gases into the troposphere and stratosphere, and those clouds can circle the globe within weeks of the volcanic activity.
- The small ash particles decrease the amount of sunlight reaching the surface of the earth and lower average global temperatures.
- The sulferous gases combine with water in the atmosphere to form acidic aerosols that also absorb incoming solar radiation and scatter it back out into space.
- The gases in plumes can combine with water in the atmosphere to form acid rain, destroying crops and killing livestock.
- Ash and aerosols particles suspended in the atmosphere scatter lights of red wavelengths, resulting in brilliantly colored sunsets and sunrises around the world.
Explain what has caused the various volcanoes in the Southern Volcanic Zone of South America.
The subduction of the Antarctic Plate under the South American Plate.
