Science Exam Revision PDF

Term 1 - Physics Waves and Particle Model Transverse Waves: Move perpendicular to the direction of the wave, e.g. water waves Longitudinal Waves: Move in the same direction as the energy, including compressions and rarefactions, e.g. sound waves. Electromagnetic Spectrum In order from longest to...

Term 1 - Physics Waves and Particle Model Transverse Waves: Move perpendicular to the direction of the wave, e.g. water waves Longitudinal Waves: Move in the same direction as the energy, including compressions and rarefactions, e.g. sound waves. Electromagnetic Spectrum In order from longest to shortest wavelength. Radio Waves - used for communication Microwaves - Used for cooking Infrared - Transmits heat Visible Light - the section we can see; (red, orange, yellow, green, blue, indigo and violet) Ultraviolet - Can cause cancer X-rays - Can be used for medical purposes, like body imaging. Gamma Rays are highly penetrating and can kill cancer cells. Wavelength, Frequency & Speed Wavelength: The distance from one trough to another Frequency: How many wavelengths pass a particular point per second. Amplitude: The height of the wave from the normal Crest: The maximum displacement of the wave Trough: The minimum displacement of the wave. V = lambda times f Where V = velocity (speed) Lambda = wavelength F = frequency Electricity is measured with watts Energy is measured with joules Pitch: Pitch is determined by the frequency, a higher frequency means higher pitch. How is the sound produced: By sound waves passing through the vocal cords, and vibrating. Law of Conservation of Energy - That energy can neither be created nor destroyed only transformed or transferred. Kinetic Energy: The energy something has because of its motion Potential Energy: The stored energy something has because of its position. Transformed Energy: Energy is changed from one form to another Transferred Energy: Energy is transferred from one object to another Work Energy: The energy to the force you are working on (push & pull) Power Energy: The energy to perform the work Heat Energy - Heat will move from a hotter object to a cooler object until they are both the same temperature. Conduction: When two solids are touching their particles vibrate. The warmer objects particles will vibrate faster causing the cooler particles to vibrate faster as they bump them. Convection: This happens between fluids, the hotter liquid will rise as it is less dense, the colder fluid will sink and be warmed by the heat source. This continues in a convection current. Radiation: All objects radiate heat, it does not require a medium to travel through. Conductors: Easily transfer heat and allow electrons to freely flow through. Insulators: Don’t allow electrons to flow through. Sound & The Ear Parts of the ear: Outer Ear - - Pinna - acts as a funnel, collecting sound and directing it towards the - Ear Canal - runs horizontally through the air and allows sound to travel through Middle Ear - - Ear Drum - flap of membrane that vibrates when sound enters. - Ossicles - 3 smallest bones that vibrate with sound, they are the hammer (malleus), anvil (incus), and the stirrups (stapes). Eustachian Tube - Helps adjust the air pressure, connected to the nose and the back of the throat. Semicircular Canals - Help keep the ear balanced Inner Ear - - Cochlea - a snail-shaped feature that is filled with liquid and many millions of tiny hairs that vibrate. - Auditory Nerve - sends these vibrations as electrical impulses to the brain which interprets it as sounds. Process: 1. Sound waves is created by vibrating particles, which bump into each other forming longitudinal waves. 2. Pinna funnels these sounds towards the ear canal. 3. Travel down the ear canal to the ear drum which vibrates. 4. This vibrates the ossicles, hammer, anvil, stirrups 5. This vibrates the fluid in the cochlea, also vibrating all the hairs. 6. This sends signals to the auditory nerve which is connected to the brain. 7. Your brain process this information and hears it as sound. Light & The Eye Lens: A curved transparent object that bends light. Convex Lens: Fat in the middle, skinny on the outsides. It makes light cross to a focal point (converging) and then diverge outwards to form an image. Concave Lens: Makes light diverges and is fat on the top and bottom and skinny on the inside. Converging: Moving towards one point Diverging: Moving away from the point. Focal point: The point where the rays converge or diverge. The eye structures: Cornea: A clear part of the sclera. Iris: The muscles that controls how much light enters via the pupil. Lens: Convex lens that focuses light onto the retina. Retina: Contains photoreceptors, allowing you to make sense and see things. Optic nerve: Sends impulses to the brain. Sclera: Outside layer of the eye, that helps it keeps its shape. Choroid: Stops reflection of light. Blind Spot: where optic nerve leaves the retina. Pupil: A hole in the eye that allows light to enter. Virtuous Humour: Liquid part of the eye containing nutrients, and helps the eye keept its shape. Aqueous Humour: Liquid part of the eye containing nutrients, and helps it keeps it shape. Photoreceptors: Light-detecting cells (rods - night vision), (cones - colour & brightness) Reflection & Refraction Reflect: Light is bounced back from a surface Perfect Reflection: Light is reflected at the same angle it hit Diffuse Reflection: Light is reflected back at many different angles. Absorb: Light is absorbed. Transparent: Light can pass through. Translucent: Some light can pass through. Opaque: No light can pass through. Transmits: Light passes through. Angle of incidence always equals the reflected ray on a smooth surface. Refraction: The bending of light as it passes through one medium to another. In a more dense medium the light will bend towards the normal In a less dense medium, the light will bend away from the normal. Colour & Absorption If there is a green apple the apple will reflect only green and absorb all other colours. White means all light is reflected. Black means all light is absorbed. Term 2 - Biology Senses and Control The 5 senses: Tactile (touch), gustatory (taste), olfactory (smell), vision (sight), auditory (hearing) The 5 sense organs: Nose, Skin, Eyes, Tongue, Ears Response Pattern: Receptors - sensory neurons - coordinators - motor neurons - effectors STIMULI: Something that sets off a reaction EFFECTORS: Muscles/glands that produce a response to the stimuli. Reflex Actions: The reflex actions are a quick response to the stimulus and does not involve the brain. Reflex Arc: Stimuli - receptors - sensory neurones - replay neurone - motor neurone - effector Nervous System & Neurons Purpose: Allows you to detect and respond to changes in the environment, by relaying messages back and forth. Synapse: Connects the neurons Neurons: Long cells that carry electrical signals. Types of neurons: Sensory - Collect information from the outside world. Motory - Receives impulses from the receptors and causes a reaction. Inter - Allows us to communicate and perceive. Parts of a neuron: Soma - contains the nucleus Dendrite - Protects the cell body and connects the neurons Axons - Carry the messages down the neuron Myelin Sheath - Speeds the process up Central Nervous Systems: The brain and spinal cord Peripheral Nervous System: Consists of the nerves that are connected to muscles. Endocrine System Purpose: To transmit messages via chemical signals through hormones in the bloodstream. Major Glands: Brain, thyroid gland (metabolism), adrenal gland (adrenaline), pancreas (produces insulin), testes, and ovaries.  - Hormone circulation takes longer than the nervous system. What do they control? - Metabolism - Growth - Reproduction - General Homeostasis Cascades: Some hormones trigger more hormones. Homeostasis - Our body wants to be 37 degrees Celsius. Purpose? Homeostasis helps to keep the body regulated, and blood levels, temperature, and Ph all balanced. Negative Feedback Loop: - When a variable triggers a counteracting response to even it out. - When you become too hot your body counteracts this by sweating. - When you become too cold your body counteracts this by shivering. EXAMPLE: 1. Blood sugar rises 2. Insulin sends a signal to the liver 3. Glucose becomes stored as glycogen 4. Blood sugar drops 5. Glycogen turns back to glucose and is released by the pancreas. 1. Homeostasis 2. Variable throws out of balance 3. Counteracts response 4. Homeostasis 5. Repeats Positive Feedback Loop: - Instead of a counteracting response, you intensify the variable. - E.g. when a baby is born you want more contractions This is not part of homeostasis but is still very important. Male Reproductive System PARTS: Testes: Where the production of sperm occurs. Scrotum: The supporting sac that helps it maintain a temperature 3 degrees cooler than the external environment. Epididymis: Connects the testes to the vas deferens. Penis: Contain the urethra and spongy tissue. Semen: Contains sperm cells and other enzymes Urethra: Tube that travels through the penis allowing urine and sperm to exit. Vas Deferens: Tube that travels from the epididymis to behind the bladder. Seminal Vesicles: Secrete liquid into the semen Prostate Gland: Secretes liquid that is added to the semen. Bulborethral Gland: Secretes liquid that lubricates the urethra. Female Reproductive System, Pregnancy & Birth PARTS: Ovaries: Contain a hundred thousand eggs, released once per month in ovulation. Fallopian Tube: Connects the ovaries to the uterus. Uterus: Where the baby grows and develops, it helps nourish the baby. Cervix: A narrow tube that widens during pregnancy. Vagina: Muscular tube that leads from the cervix to outside the body. Menstrual Cycle: - Typically goes for 28 days but this changes depending on the female. - Menstruation occurs when an egg is ovulated but not fertilized, and is the shedding of the endometrium. - Ovulation occurs on days 14 -15, halfway through the cycle. PMS: causes anxiety, depression, and sleep problems. Fertilisation/Pregnancy - Fertilisation occurs when the egg and the sperm fuse together, creating a zygote. - It occurs in the fallopian tube and contains half-male and half-female chromosomes. STEPS: 1. Fertilisation occurs when sperm and egg fuse together. 2. The zygote divides and redivides to form embryos.  3. It is planted in the uterus 4. Divides to form the body. 5. A foetus is formed. Labour & Birth Labour - the process of the baby exiting the female body. - Occurs roughly 40 weeks after conception - Caused by an oxytocin release - Uterus walls contract to push the baby and placenta out. Myometrium: Muscular layer that helps move the baby into the right position. Induced Labour: A drug is administered to stimulate labour. Premature Baby: The baby is born before 37 weeks. 3 STAGES OF LABOUR 1. Dilation - 6 - 36 hours - The cervix gradually widens - Allows foetus to pass from the uterus to the vagina - The cervix needs to be 10 centimetres before the next stage. 2. Expulsion - 30 -60 minutes - Starts at full dilation, ending with the baby exiting - Allows the foetus to be pushed down into the vaginal canal. - The umbilical cord is cut. 3. Placental - few - 30 minutes - Starts after the birth of the baby, ending with the delivery of the placenta. - Sometimes drugs are administered to hurry the process. KEY POINTS: - The direction the baby enters is important - Headfirst: Safest & Easiest - Breech Birth: Bottom and feet first = dangerous - C (caesarean section) section: Doctor surgically removes the baby through the abdomen. Immune System - Line of Defence Aim: To prevent the escalation of disease. Pathogens: Bacteria, viruses, fungi & parasites. Antigen: Identifies a pathogen FIRST LINE OF DEFENSE - This is a barrier preventing pathogens from entering the body. - It includes: - The skin, mucus membrane, hairs and cillia, gastric juice, tears, weat, saliva and ear wax. SECOND LINE OF DEFENSE - This is a non targeted and non specific approach. - It includes: - Blood clotting to close breaks, inflammation (increase in white blood cells), and fever as some pathogens can’t survive at higher temperatures. - White blood cells (phagocytes) constantly screen the body destroying any foreign substances. THIRD LINE OF DEFENSE - This is a slower more targeted immune response - Pathogens contain proteins and antigens, antigens betray the presence of the pathogen. - Lymphocytes - carry antibodies, which chemically fit to specific antigens. - When an antibody meets an antigen it reproducess quickly and makes copies of the antibodies. - B cells - produce antibodies - T - cells - the fighters of the pathogens KEY DEFINITIONS: Bacteria: Tiny single-celled organisms, some are harmful, and some support life, e.g. whooping cough Virus: Microscopic organism that infects its host, e.g. colds Fungi: A wide variety of organisms that reproduce via spores. Prions: A protein that can cause disease by causing healthy proteins to fold abnormally. Leukocytes: Help clear toxicity and waste - Phagocytes: Trigger immune response - Lymphocytes: Destroys foreign cells Lymphatic System: Vessels that help clear bodily waste Antigens: Betray the presence of invaders Immunity: Eradicating threats, and recognises cells for quicker and correct response. T-Cells -search for infected cells B Cells: Produce Antibodies Types of Diseases Non Infectious: - Not caused by pathogens - Caused by: Inheritance: Passed on by parent to offspring, generally not curable - Diabetes  Nutritional: Not getting all the nutrients the body needs - Scurvy Environmental: Environment causes the disease - asbetosis - They are generally long-term. Infectious - Diseases caused by pathogens - They can be transmitted from person to person, or animal to person. - Many can be prevented by vaccines or antibiotics. Vaccinations: Vaccinations are when a small less strong dose of the disease is admitted into a person's body. This teaches the immune system how to kill it and therefore gaining immunity, or lessen the effects of the disease. HERD IMMUNITY: Indirect protection from an infectious disease, that happens when a population is immune through enough people being vaccinated so the disease can not spread. Antibiotics: Antibiotics work by killing bacteria or stopping their multiplication. Antibiotic resistance occurs when bacteria change so that the medicine can’t kill them. To prevent this it is important to only use them when prescribed, take full dose, and only stop when instructed, do not take more than required. Asexual & Sexual Reproduction Asexual: You can create genetic copies of yourself and do not require a mate. Advantages: More offspring, and if no male species survive the species can still reproduce. Disadvantages: Genetic mutations can’t be eliminated, and this can eradicate entire species. Sexual: Offspring is a combination of parent genes. Advantages: Genetic mutations can be eliminated, allowing for evolution. Disadvantages: You need both genders, less efficient, and time-consuming. Types of Asexual Reproduction: 1. Binary Fission - A single parent cell is doubled and DNA divides into two cells. 2. Budding - A small growth on the surface of an organism breaks off. 3. Fragmentation - The organism breaks into fragments and these develop into new individuals. 4. Parthenogenesis: The embryo develops from the unfertilized cell. Term 3 - Chemistry The Periodic Table Groups: The columns in the periodic table. Periods: The rows in the periodic table. Atomic Number: Orders the elements and represents the number of protons and electrons. Atomic Mass: The atoms weight and protons pluns neutrons. Metals: Left hand side of the periodic table. Non Metals: Right hand side of the periodic table Metalloids: The middle of the periodic table. Important groups: 1. Alkali metals 2. Alkaline earth metals 17. Halogens 18. Noble gases Atom Structure - Electrons: Arranged in shells around the nucleus - Each shell must be filled in turn - First shell: Max 2 electrons - Second Shell: Max 8 electrons - Third Shell: Max 8 electrons Where they are found: Electrons: Orbital Shells, negative charge. Protons: Nucleus, positive charge. Neutrons: Nucleus, negative charge. - Electrons are held in the shell as opposite charges attract. - electrons to protons - Electrons are smaller than neutrons and protons Flame Tests What do they do? Flame tests help you indentify unknown metal ions based on the colour the flame burns. How do they work? When the metal ion is placed in the flame they become excited and jump out of their orbital shells, when the energy is released and they return back down they emit different colours specific to the element. Everyday uses: - Chemists - Fireworks - Identifying unknown metals Common Compounds - Sodium Chloride - Carbon Dioxide - Nitrous oxide Reactivity & Stability - An atom is stable when it does not have excess energy and has a full valence shell. Reactivity depends on: 1. How many electrons are in the valence shell - the easier it is for an atom to gain a full valence shell the more reactive it will be. 2. How far the electrons are from the nucleus Metals: The further the valence electrons are from the nucleus the more reactive it will be be because there is less attractive force making it easier for them to loose electrons and gain a full outer shell. The further down the group the more electrons shells and therefore more reactive as you move down. Non Metals: The further the valence electrons are from the nucleus the less reactive it will be beceause there is less attractive force making it harder to gain electrons and a full outer shelld. Non metals want to try and gain electrons. Valency - Valency is the amount of electrons that an atom must gain or lose in a chemical reaction. - A valence shell is the outside electron shell of an atom. Bonding Ionic Bonding: Electrons are never lost, ionic bonding is when an atom loses or gains electrons.. Ionic compounds are formed through ionic bonding between an anion and a cation. Covalent bonding: When similar atoms (metals) react they share electrons, represented with a straight line, usually done between metals. Anions and Cations Ions are formed when atoms gain or lose electrons to become stable. Anion: Gains electrons and thus becomes negatively charged. Cation: Loses an electron and becomes positively charged. Naming ions: - All metal ions have the same name as the atom, e.g. sodium becomes a sodium ion. - All non-metal ions have different parent names, you commonly add ide. Ionic Compounds - Form when cations and anions join together, as things with opposite charges attract. - Common compounds: Sodium bicarbonate, Carbon dioxide, sodium chloride. Compounds & Formulas - Ionic; put positive first, and negative second, roman numerals should be included if needed and the overall charge should be zero. Swap and drop method: 2+ - Ca F 1. Swap the numbers from the charges 2. Drop these numbers to subscript 3. Determine whether it can be divided by a common factor It will become: CaF2 Chemical and Molecular Formulas: 1. Write the word equation 2. Replace name with chemical symbols Equations have Products - reactants Balancing Equations: An equation is balanced if there is the same number of atoms. Electron Diagrams Bohr Model Lewis Dot Diagram Law of Conservation of Mass In chemical reactions no matter is lost or gained, which is why formulas must be balanced. pH Scale - pH scale goes from 0 to 14 - Most acidic to least acidic - A pH of 7 is neutral, e.g. water Acids: Contain hydrogen ions, are corrosive, sour, and conduct electricity. Bases: Alkaline, taste bitter, neutralise acids, release hydroxide ions. Litmus Paper: Used to determine pH level. Indicators: The resulting colour can be compared to a reference chart. Acid Reactions Neutralisation Reaction: Acids + Bases = Salt + Water (neutral substance) Acid Carbonate Reaction: Acid + Carbonate = Salt+ Water+ Carbon Dioxide + heat Acid Metal Reaction: Acid + Metal = Hydrogen Gas + Salt Radioactivity Half Life: The half life of a radioisotope is the time taken for half its radioactive decay to occur. - There are three main types, alpha, beta, and gamma. Isoptoes: Same number of protons and electrons but different number of neutrons. Types of radioactivity: Alpha radiation: The weakest type of radiation and can not penetrate through mose matter. Beta Radiaiton: Goes through air and paper but can be stopped by aluminion. Gamma Radiaiton: Highly penetrating and can damage tissue and DNA cells. Chemical Reactions: Involve change in arrangement of electrons Nuclear Reactions: Changes in the nucleus of an atom. Stable Nuclei: Enough neutrons to hold nucleus together. Unstable Nuclei: Too many protons so they repel each other, radioactive. Radioactive Decay: When nuclei trys to stabilize themselves by throwing out particles. Natural Radioactivity: Atoms nucleus spontaneously breaks down and releases radiaiton. Light elements; more stable, less reactive Heavy elements: unstable, very radioactive. Uses of radioactivity: In medicine: - Ionizing radiation can cause damage to human, but can be used for nuclear imaging and radiotherapy. - Smoke alarms - positively and negatively charged plate create current, when smoke enters this is disrupted and sets off an alarm. - Sterilization - gamma rays are emmitted destroying microorganisms on food. - Foil thickness - beta emmitter wont pass through if too thick, too many will pass through if too thin. Everyday Benefits of Chemical Reactions: - Cooking - Medicine - Food - Combustion - Buliding - Creating new materials Term 4 - Sustainable Planet Biotic & Abiotic Factors Biotic: A component of the environment that is alive or was once alive. E.g. bacteria, fungi, plants, and animals Abiotic: Relates to things in the environment that are not living. E.g. temperature, rainfall, soil type, and water salinity. Ecosystem: The interaction between biotic and abiotic features. Food Chains, Food Webs and Energy Flows IMPORTANT TERMS: Producers: Capable of producing their own food and energy via photosynthesis Consumers: Obtain food by eating other organisms Decomposers: Feed on dead or decaying organisms, recycling the nutrients. Autotrophs: Producers in a food chain Herbivore: Only eats vegetation. Carnivore: Only consumes meat Omnivore: Feeds on both plants and animals Food Chain: A feeding heirachy, representing the flow of energy. Food Web: Many food chains linked together (more accurate) Arrows show the flow of energy Photosynthesis: The process by which plants, algae and others capture energy from the sunlight to create organic molecules. Cellular Respiration: The process by wihch organic molecules from food react chemically releasing energy and carbon dioxide. Trophic Level: An organisms position relative to the primary energy source of the food chain.  - Energy flows throughout an ecosystem, and matter cycles within it. STEPS: 1. Energy enters via photosynthesis 2. Powers the producer life via cellular respiration 3. Energy moves through primary consumers to secondary consumers. 4. Some is used for cellular respiration, releases carbon dioxide and heat 5. Dead producers and consumers and waste makes matter and energy for decomposers 6. Decomposer transform this into organic matter 7. It flows out as heat Food Webs: - A model of the feeding relationship - The arrow represents the transfer of matter and energy - Producers are down the bottom - Photosynthesis equation: 6CO2 6 H20 = 6 02, C6 H1206 Ecological Pyramids: - Show a relative amount of energy in each trophic level - Only about 10% of the original energy is transferred to the next level. - Number pyramids show how many organisms there are in each level. The Cycles Biogechemical Cycle: A pathway by which a chemical substance through the biotic and abiotic components of the earth. CARBON CYCLE: Natural: 1. Plants capture carbon dioxide from the air, through photosynthesis 2. They use this to create polymers allowing them to grow and have energy 3. Animals then eat the plant, and other animals eat animals providing them with carbon dioxide 4. Through digestion they break down the polymers of the plant into monomers so they can be used for growth and DNA creation. 5. Through respiration the carbon is released from the animal back into the atmosphere. Why we need carbon? We need carbon for DNA, growth and energy, it is the basic building block of most of our cells. Carbon can also decompose into the ground where it is compressed as fossil fuels. Human Impact:  - Huge quantities of carbon is compressed under the earth and hasn’t been part of the cycle for millions of years. - Human extract this in the form of fossil fuels and combust it, releasing the stored carbon. - This adds too much carbon to the atmosphere, increasing heat and amplifying the greenhouse effect. - Carbon dioxide also dissolves in water creating more acidity. THE NITROGEN CYCLE Why is it required? - To make proteins Plants can take in nitrogen as the form of nitrates in the soil, animals can eat these plants. Fixing: Process of nitrogen in the atmosphere being turned into nitrate. Denitrifying: A bacteria in the soil can break down nitrates and return nitrogen to the atmosphere, used if there is excess nitrogen however it reduces the fertility of soils. How it occurs? 1. Nitrogen Fixing Bacteria - Turns nitrogen from the atmosphere into ammonia. 2. Decomposers - Break down dead organisms returning the nitrogen to the soil as ammonia. 3. Nitrifying Bacteria - turns ammonia into nitrate. 4. Lightning (cause by volcanoes) - causes nitrogen to react with oxygen producing nitrous oxide which dissolves in the rainfall entering the ocean and soil. 5. Ocean - blue green algae can fix nitrogen providing sources of it to plants. STEPS: 1. Fixation - bacteria changes nitrogen into ammonia 2. Nitrification - Ammonia is changed into nitrates that plants can absorb. 3. Assimilation - How the plants get the nitrogen, commonly from the soil. 4. Ammonification - Part of the decaying process, decomposers turn nitrogen back into ammonia. 5. Denitrification - Extra nitrogen in the soil is released back into the atmosphere. Human Impact: - Burning fossil fuels adds nitrous oxide which dissolves in rain, upsetting the balance and making water more acidic - Fertiliser can cause excess nitrogen which is denitrified and therefore causes a loss in soil fertility. - If too much nitrogen is in the aquatic system excessive amount of blue green algae can be toxic to plants and animals. PHOSPHORUS CYCLE - Only cycle that does not involve the atmosphere What is it required for? - Growth and microbes in the soil - DNA and RNA Steps 1. Weathering - phosphorus is stored in rocks and weathering breaks these down allowing it to travel into water sources and the soil. 2. Absorption by Humans and Animals - once in soil and water plants and fungi can absorb it and be eaten by animals, or it can be drunk. 3. Return to the environment by decomposition - Animals excrete waste, and decompose. This can be used for mineralisation which converts organic phosphorus into inorganic phosphorus which can be used by plants. 4. Sediment to Rocks - Phosphorus in sediment becomes rocks over time, and the cycle can repeat. Human Impact: - Fertilisers containing phosphorus make the levels to high driving the growth of algae which can be toxic to animals and plants. Key Terms, The four Spheres Nitrogen Fixation: Process in which nitrogen gas from the atmosphere is converted into ammonia by bacteria living in the soil or the roots of legumes. Denitrification: Soil bacteria converts nitrogen compounds in the soil back into nitrogen which is released into the atmosphere. Photosynthesis: Sunlight is used to change carbon in the atmosphere into biomolecules that can be used for energy. Transpiration: When water evaporates from the surface of plants and leaves. Decomposition: Nutrients in dead organisms are returned to the soil. Cellular Respiration: The breakdwon of sugars in living things returns carbon to the atmosphere. Evaporation: Liquid water changes into gas form. Condensation: Water vapour changes into liquid form. Precipitation: Condensed water falls back down to earth. Hydrosphere: All the water on earth. Biosphere: Consists of all the living things on earth. Atmosphere: All the gases surrounding the earth. Geosphere: All the non living features of the earth. Climate Change - Co 2 in the air traps heat - The more carbon, the more heat that is trapped. - When digging fossil fuels carbon dioxide is released and due to deforestation there is not as many trees to store it causing the acceleration of the greenhouse effect and warmer temperatures. - This melts ice meaning less heat is reflected. Greenhouse gases: Gases that trap heat inside our atmosphere and insulate the earth. Greenhouse effect: - A process by which radiation from the sun is absorbed by greenhouse gases such as carbon dioxide and nitrous oxide. The gases insulate the earth keeping it within a temperature range suitable for human life. Global warming/Accelerated greenhouse effect: - Human activity is the leading cause and accelerates the greenhouse effect. - E.g. combustion of fossil fuels & deforestation. Danger: - Rising sea levels - More severe storms - Loss of food and biodiversity To improve: - Find more ways to generate electricity sustainably - Stop deforestation as trees store carbon - Recycle rubbish as landfill produces more heat Structure of the Earth Mechanical: Lithosphere - the solid outer layer of the earth that consists of the crust and the mantle - Composed of tough rigid rocks that are cool - Divided into tectonic plates - Very strong and hard to deform Asthenosphere - the soft mantle layer on which the tectonic plates move. - The middle section of the manta - Rocks really hot - It is denser and weaker, meaning the rocks can move in convection currents. Mesosphere - the strong lower part of the mantle. - Rocks can still move but slower due to the high amount of pressure - Very high temperatures Compositional: Crust: The thin solid outermost layer of the earth. - Continental crust: thicker and less dense - Oceanic crust: thinner and more dense Mantle: The layer of rock between the crust and the core - Has never be seen and is observed through underwater volcanoes and seismic activity. Core: The central part of the earth - Outer core - made of iron and nickel and is liquid - Inner core - still iron and nickel but solid due to the high amount of pressure Continental Drift - Alfred Wegener proposed the theory of continental drift - Earths continent were once all together - pangea - There was 4 key pieces of evidence supporting it. 1. Coastlines appear to fit together 2. Fossils of the same species found in different continents 3. Identical rock formations found on different parts of the continents 4. Evidence of drastically changed climates What are fossils? - Remains of plants and animals have been preserved. His theory was rejected until the discovery of tectonic plates as there was no big enough strength that could’ve done this. PLATE TECTONICS - Tectonic plates make up the lithosphere and float moving with the asthenosphere - Seafloor Spreading: When oceanic plates move away from each other, diverging This forms cracks allowing magma to come through and create new seafloor. Convergence: When plates move closer together Divergence: When plates move further apart Subduction: When one plate moves under the other PLATE BOUNDARIES: - Divergent: The plates are moving apart - Convergent: The plates are moving together - Transform: The plates are sliding past each other. Natural Disasters Caused by Plate Movements Undersea Volcanoes - When 2 oceanic plates diverge it forms undersea volcanoes Mountains - When 2 continental plates converge the rock will crumple and rise up to form mountains. Volcanoes 1. The oceanic plate moves towards the continental plate 2. The continental plate is less dense a moves over it 3. Subduction - oceanic plate moves under the continental plate 4. Melting - oceanic plate may go deep enough it melts. 5. Cracks form due to increased pressure which results in magma seeping up into weak spots. 6. This causes volcanic events due to a build-up in pressure.