Year 9 Chemistry: Periodic Table Notes PDF

1 - Periodic Table For test your Chemistry revision: Go to Moodle -> Science -> Year 9 -> Chemistry 1. Recall that the periodic table is organised by atomic number The periodic table is organised by atomic number (vertical = groups, horizontal = periods) 2. Distinguish between Atomic Mass/Weight a...

1 - Periodic Table For test your Chemistry revision: Go to Moodle -> Science -> Year 9 -> Chemistry 1. Recall that the periodic table is organised by atomic number The periodic table is organised by atomic number (vertical = groups, horizontal = periods) 2. Distinguish between Atomic Mass/Weight and Mass Number of an element. Atomic weight/mass of an element is the average mass of the atom measured in atomic mass units (daltons, D). The mass number is the sum of the protons and neutrons in an atom. Atomic number is the amount of protons in an atom. 3. Recall that each element has a particular location i.e. group and period and what that location signifies for each element The position of the element in the periodic table gives information about the structure, state of matter (at room temp.) properties and behaviour in chemical reactions. The location also determines valence electrons and the atomic number and weight. 4. Explain that the current periodic table is the product of developments over time through history with many changes and modifications having been made in that time, with reference to: o the significance of the work of Newlands, Meyer, Mendeleev and Moseley o The problems associated with arranging the periodic table in order of atomic weights Time Contributor Periodic Table Developments 2000 years ago Ancient Greeks Thought that everything was made of air, earth, fire and water (4 elements) 1661 Robert Boyle (Irish Suggested that elements were substances that can’t chemist) be broken down into a simpler substance. This was the beginning of modern chemistry 1789 Antoine Lavoisier Created a list of 33 elements grouped by metals and (French nobleman) non-metals. Some of these were compounds but he  was unaware at the time. 1820s Jons Jakob Used chemical symbols in order to abbreviate Berzelius (Swedish element names. Used the weight of hydrogen to chemist) develop a system of atomic weights. Hydrogen was 1 because it was the lightest. Berzelius combined all current knowledge into one system. 1829 Johann Dobereiner Aware of 40 elements and some groups of three (German chemist) elements had similar properties (named triads). Instrumental groupings with patterns of chemical behaviour and atomic structure. 1864 John Newlands Identified a pattern between elements behaviour for (English chemist) every 8 elements. Named this the Law of Octaves but most people disagreed. 1869 Dmitri Mendeleev Wrote the name and properties of elements on small (Russian chemist) cards, rearranged in order of atomic weight and created the periodic table. Proposed the law “Elements have properties that recur or repeat according to atomic weight.''Mendeleev predicted 21 unknown element properties through this. 1894 William Ramsay Used refrigeration to liquefy and separate air (Scottish chemist) components and identified helium, neon, krypton and xenon. All of these are noble gases with full valence shells, hence unreactive. 1913 Henry Moseley Refined order of some elements and changed the (English physicist) periodic law into “Elements have properties that recur or repeat according to atomic number. 1940 Glenn Seaborg (US Used a cyclotron to bombard uranium atoms with scientist) neutrons and created neptunium and plutonium (unstable and radioactive atoms) Today N/A Element 118 is called ununoctium (1-1-8-ium), named after latin. This element is unstable and thought to be a solid even though it should be a noble gas like other elements in group 18. 5. Distinguish between metals and non-metals according to their properties 6. Recall the name, symbol, colour, features and uses of at least three common metals (eg Cu, Fe, Pb) Metal State at Colour Use Features room temp. Nickel (Ni) solid Grey In coins and High melting point, malleable, batteries ductile, rust resistant Gold (Au) solid Yellow In jewellery Non-reactive, conductive, ductile, and electronics malleable Aluminium (Al) solid Grey Wrapping and Non-toxic, thermal conductivity, storing food, corrosion resistance malleable, making cans ductile 7. Recall the name, symbol and special properties of at least two metalloids (eg Si and Ge) Metalloid Special Properties Silicon (Si) Solid at room temperature, metallic lustre, brittle, semiconductor Arsenic (As) Poisonous, brittle, semi-metallic, tarnishes in oxygen 8. Recall the name, symbol of at least two non-metals (eg Cl, Br) Hydrogen (H), Helium (He) 9. Distinguish between the groups and the characteristics within them including alkali metals, alkali earth metals, transition metals, metalloids, halogens and noble gases. Group Characteristics Alkali metals High thermal and electrical conductivity, lustre, ductility and (1 valence electron) malleability. They have one valence electron (in outermost shell), and its weakly bound (group 1) Alkali earth metals Highly reactive, conduct electricity, have low ionisation energy, (2 valence electrons) electron affinity and electronegativity. (group 2) Transition metals Less reactive than alkali metals, form coloured ions of different (2 valence electrons) charges. Some are unreactive, others are used as catalysts. Transition metals are unstable and display behaviour between s and p block elements (elements to the far left or far right of the table) (group 3-12) Metalloids Metalloids are shiny, brittle substances that are solid at room (3-6 valence electrons) temperature. They have electronic band structures and are similar to semiconductors. They have weakly acidic oxides. (group 13-16) Halogens Form acids when combined with hydrogen and salts when combined (7 valence electrons) with metals. Highly reactive, toxic and electronegative, and are diatomic in pure form. (group 17) Noble gases Inert and stable because of a full outer shell. Don’t react with other (8 valence electrons elements to form compounds. Colourless and odourless gases in besides helium) room temp. Melting and boiling points are close; low liquid range. (group 18) 10. Identify the activity series Series of metals based on reactivity from lowest to highest 11. Explain the link between periodic table groups and the number of electrons in valence shells The link between periodic table groups and the number of valence electrons is that groups on the left of the periodic table have a lower amount of valence electrons (starts from 1) while on the right side there's 8 valence electrons (a full shell). 12. Review electron configuration for the first 20 elements. https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3 DNIwcDnFjj98&psig=AOvVaw0HkKQKZGv9vS26uDrsOgqC&ust=1669850165392000&source= images&cd=vfe&ved=0CA8QjRxqFwoTCOij2OTC1PsCFQAAAAAdAAAAABAI 13. Write formulae for simple ionic compounds using valency and name the compound formed. Cross multiplication determines the chemical formula (cation and anion symbols (+,-) are meant to be at top) Compound Name Formula Cation Anion lithium fluoride LiF Li+ F- sodium chloride NaCl Na+ Cl- calcium chloride CaCl2 Ca2+ Cl- iron(II) oxide FeO Fe2+ O2- aluminium sulphide Al2S3 Al3+ S2- iron(III) sulphate Fe2(SO3)3 Fe3+ SO32- 14. Recall valencies of the following polyatomic ions (covalent bonding): acetate, nitrate, sulphate, hydroxide, carbonate, phosphate, ammonium. Acetate: -1 (7 valence electrons) Nitrate: -1 (7 valence electrons) Sulphate: -2 (6 valence electrons) Hydroxide: -1 (7 valence electrons) Carbonate: -2 (6 valence electrons) Phosphate: -3 (5 valence electrons) Ammonium: +1 (1 valence electron) 15. Compare the properties of the elements in a compound, and the compound itself (eg magnesium chloride, magnesium oxide, etc) Nitrogen trihydride - NH3 (Ammonia) - colourless, highly irritating gas with a pu`ngent, suffocating odour Nitrogen - colourless, odourless, tasteless and mostly diatomic nonmetal gas Hydrogen - colourless, odourless, tasteless, non-toxic, and highly combustible —------------------ Carbon dioxide - CO2 - colourless, odourless, non-toxic, and non-combustible gas at atmospheric temperatures and pressures, that is soluble Carbon - an inert substance, insoluble in water, diluted acids and bases, as well as organic solvents. Oxygen - colourless, odourless, tasteless, non-combustible gas —------------------ Sodium chloride - NaCl (Table salt) - white conductive crystals which do not have an odour but possess a taste Sodium - soft metal, reactive and with a low melting point Chlorine - two and one half times as heavy as air, has an intensely disagreeable suffocating odour, and is exceedingly poisonous —------------------ Magnesium oxide - MgO - odourless and non-toxic particles in a white powder form with high hardness, high purity and a high melting point. Magnesium - Magnesium is a silvery white metal and very light. Oxygen - colourless, odourles s, tasteless, non-combustible gas 16. Distinguish metallic, ionic and covalent bonding in terms of electron loss and gain, or electron sharing. Metallic bonding- Metallic bonding is caused by metal ions/atoms being held together due to electrons moving around the molecules of the metal, which give it electrical and heat conductivity. Ionic bonding- Ionic bonding is when valence electrons are given to another atom as the negative and positive ions attract each other through electrostatic charges. It is between nonmetals and metals. Covalent bonding- Covalent bonding is when valence electrons are shared and the atoms are combined together, and it is done to complete atoms’ outermost electron shells. It occurs between two nonmetals. 17. Explain why metals are good conductors (Metallic bonding) and identify that delocalised electrons enable electrical conductivity and which elements possess this characteristic. Metals are good conductors because they have multiple delocalised electrons which are moving around atoms in the metal and this enables the metal to conduct electricity. Some highly conductive metals are silver, copper and gold. 18. Identify that most nonmetals are covalent (eg Cl 2 , Br 2 ) Most nonmetals are covalent. 19. Illustrate electron-dot diagrams of simple covalent compounds such as water and methane, and recall three properties of covalent compounds) 20. Classify compounds into electrolytes and nonelectrolytes. Electrolytes are compounds/minerals in the body that conduct electricity and nonelectrolytes are compounds/minerals in the body that don’t conduct electricity. Electrolyte examples - Sodium, calcium, potassium, chloride, phosphate, and magnesium Nonelectrolyte examples - Sugar and ethanol 2 - The Universe 1. Describe the main features of galaxies, stars, planets, nebulae, solar systems, nova, supernova, quasars, pulsars and black hole Galaxy- They’re systems of dust, gas, dark matter and planets with somewhere between a million or trillion stars, held together by gravity. Most have supermassive black holes at their centres. Star- Stars radiate light and possess different colours based on their temperature. Their mass is higher than planets and their surface temperature varies between 2500 and 50,000 Kelvin (K). Planet- Planets orbit stars, have a sufficient size for gravity to force them into a spherical shape and clear away any other objects of similar size near its orbit. (Neptune-like = ice giant) You Nebula- Nebulae are made of dust and gases (hydrogen and helium) and gravity brings dust together to form larger clumps. Stars are born in a nebula and nebulae are formed by gas and dust from the explosion of a dying star. Solar system- The sun contains 99.8% of the system’s mass and all planets revolve around it in a disc-like shape. The solar system contains between 200-400 billion stars as well as belts of asteroids and gases. The solar system was formed 4.6 billion years ago and is a part of the galaxy called the Milky way. Nova- Exploding stars which have their luminosity increasing from several thousand to 100 thousand times are defined as novas. They then fade to their regular obscurity after some hours or days. Novas occur when stars steal gas from a nearby star and the energy releases a large amount of light energy. Supernova- Supernovae are large rapid brightenings that last a couple weeks and are caused by the collapse of a start under its own weight. They’re caused when the pressure in a nova starts to decrease and gravity overtakes, and the star collapses in seconds, resulting in a large explosion. Quasars- Quasars are astronomical objects of high luminosity found in the centre of some galaxies and powered by gas spiralling at high velocities into an extremely large black hole. Pulsars- Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Pulsars have very strong magnetic fields which funnel jets of particles out along the two magnetic poles. These accelerated particles produce very powerful beams of light. Black hole- Black holes are large regions where gravity is strong enough to capture light and electromagnetic waves. They have three layers, which include the outer and inner event horizon and the singularity. 2. Identify the structure and composition of stars 98% of a star’s composition is helium and hydrogen, while the other 2% consists of gases like oxygen, nitrogen and carbon. Stars are main-sequence stars for most of their lives which includes a core, radioactive and convective zones, a photosphere, chromosphere and the corona. The core is where nuclear fusion takes place to power stars. 3. Define a light year A light year is the distance that light travels in a year. The speed of light is nearly 300,000km/s, so a light year is about 9.46 trillion km. 4. Determine the distance in light years between the Sun and its nearest star The nearest star to the sun is called Proxima Centauri. This star is 4.2465 light years away from the sun 5. Define an astronomical unit An astronomical unit is a unit of length that is equal to the average distance between the earth and the sun, which is right under 150 million km. 6. Determine the distance in AU for all the planets in our solar system Sun → Mercury - 0.4 AU Sun → Venus - 0.7 AU Sun → Earth - 1 AU Sun → Mars - 1.5 AU Sun → Jupiter - 5.2 AU Sun → Saturn - 9.5 AU Sun → Uranus - 19.8 AU Sun → Neptune - 30AU 7. Explain how stellar parallax is used to calculate distance between Earth and stars. Stellar parallax is the apparent motion of a star which shifts due to distant background stars and the Earth’s rotation and revolution. Stars only appear to move in comparison to other objects and their placement in the background. Through stellar parallax, the shift of the star after 6 months is measured through the equation for parallax angles, and then the angle of shift is used to calculate the distance between Earth and the star. 8. Describe how different cultures describe different constellations and outline different stories that accompany these descriptions. Aboriginals Djulpan (Orion) - The constellation depicts the three stars in Orion's belt as three brothers fishing in a canoe who were banished into the heavens for eating king-fish which was against the law in the king-fish clan. Ancient Greeks Centaurus - Centaurus was the name of the first Centaur. The constellation is primarily associated with Chiron (Cheiron), a wise, immortal being who was King of the Centaurs. He was said to be skilled in the healing arts, and to be a scholar and a prophet. Ancient Romans Andromeda - Few other women have received so much praise for their beauty as Andromeda in Greek and Roman Mythology. Andromeda was a legendary Ethiopian princess who was saved by the Greek hero Perseus from a terrible sea-monster. Together, Perseu is s and Andromeda lived a happy life until they became constellations in the sky 9. Explain why astrology is a pseudo-science Astrology is a pseudoscience because astrologers try to find explanations for phenomena in space, but they don’t critically evaluate the validity of their explanations. Astrology also hasn’t displayed its effectiveness in controlled studies, hence regarded as pseudoscience. 10. Outline the importance of the invention of the telescope in investigating the universe The telescope opened our eyes to the universe as they showed that the Earth isn’t the centre of the universe, which was once believed to be true. Telescopes helped with the discovery of new planets and stars, craters and mountains on the moon, predicting geography and weather around Earth, understanding gravity and other fundamental laws, light that radiates from the sun and stars, and ultimately determining the speed of light. 11. Describe, using examples, the relationship between technological advances and increased scientific knowledge and understanding of the universe Technological advances allowed further exploration of the universe and understanding certain types of phenomena, therefore increasing scientific knowledge and understanding of the universe as a whole. Space probes were an important technological advancement that increased scientific knowledge of the universe through studying the atmosphere and composition of space, moons, planets and celestial bodies, by using scientific tools that they are given. Some space probes are exploring beyond our solar system, such as NASA’s Voyager 1. Space telescopes were another important technological advancement as they provide detailed images of the universe, allowing discoveries of galaxies, planets, stars and other celestial bodies. The JWST improved scientific discoveries a lot in 2022, due to good resolution images that highlighted old galaxies and faraway stars and planets. 12. Provide at least two examples of Australian contributions to the study of the Universe Aussat was Australia’s first national communication satellite system launched in 1985 which contributed as a communication satellite that transmitted telephone and television signals over great geographical distances. WRESAT (weapons research establishment satellite) was the first Australian satellite ever and it was launched on the 29th november, 1967. It was built by using a modified American redstone rocket. WRESAT completed 642 orbits of Earth and transmitted all its information to 73 tracking and research stations around the world. 13. Provide at least two examples of current research into the universe. Literally only the JWST, nothing else has been done in 2022 for research into the universe. JWST discovered new exoplanets, moons and galaxies, which were all very far from Earth. 14. Outline the requirements to support human survival in space such with specific reference to ★ oxygen, nitrogen and water; ★ radiation issues; ★ waste and energy management Humans require oxygen and water in space for survival, as the basic needs for hydration and breathing. Nitrogen is required for maintaining total pressure in the space cabins. Radiation in space puts astronauts at positions of radiation sickness, cancer risks, central nervous system diseases and degenerative diseases. It is prevented by passive shielding by materials like water, polyethylene and aluminium. Waste is put in bags and placed into bags which go into designated vehicles that return the trash to Earth or burn it in space. Energy is managed by using solar cells to convert sunlight into electricity. 15. Explain the difference between emission and absorption spectra The emission spectra consists of all the radiation emitted by atoms or molecules. The absorption spectra consists of light frequencies that are transmitted, with occasional dark bands which symbolise that the light energy was absorbed by the electrons in ground state to reach higher energy states. 16. Explain red shift and how it can be used to measure the movement of galaxies Red shift is when the wavelength of light is stretched so light seems like it shifted towards the red part of the spectrum. Simultaneously, the frequency and photon energy of the electromagnetic radiation is decreased. When galaxies move further away from Earth, the sound and light waves are stretched out, giving them a lower pitch and making them seem like they're on the red side of the spectrum. 17. Outline how scientific thinking about the origin of the universe is refined over time through a process of review by the scientific community 18. Briefly explain the main events of the Big Bang in relation to the creation of the Universe. Around 13.7 billion years ago, everything in the entire universe was condensed in a very small singularity, a point of infinite density and heat. Suddenly, an explosive expansion began, ballooning our universe outwards faster than the speed of light. The 4 main stages of the theory are the heavy particle era, light particle era, radiation era and the matter era. 19. Explores some of the key evidence that supports the Big Bang Theory Yes… 20. Describe the role of gravity in the formation of the Universe Gravity’s role in the formation of the universe is that it dictates the structure of the universe from the way cosmic bodies form to the way they orbit around massive stars or planets. 21. List and briefly explain some of the evidence that supports the Big Bang Theory Key pieces of evidence that support the Big Bang Theory include the measured abundance of elements in the universe, the observed expansion of space and the discovery of cosmic microwave background (CMB) 22. Relate colours of stars to their surface temperature 23. Describe the features of the H-R diagram The Hertzsprung-Russell diagram shows the relationship between a star's temperature and its luminosity. It is also often called the H-R diagram or colour-magnitude diagram. The chart was created by Ejnar Hertzsprung and Henry Norris Russell in about 1910. Typically, The vertical axis of the HR diagram may show the star's absolute magnitude, relative magnitude, absolute luminosity or its luminosity relative to the sun. Magnitude and luminosity of a star are correlated; greater the magnitude entails greater luminosity. 24. Predict the main features of a star based on its position in the H-R diagram. ​ 25. Apply the features of the H-R diagram to describe the typical life cycle of a star of one solar mass. Stars are born in nebulae and condense into balls of gas before contracting under their own gravity. The condensing matter will go to 15 million centigrade and form protostars, which is when nuclear reactions fuses hydrogen to form helium. The star releases energy and becomes a main sequence star for 10 billion years, before all the hydrogen forms helium. An outer shell forms which expands, while helium fuses to form carbon, and the star is now a red giant. The helium runs out and the gases near it are called planetary nebulae. The remaining core becomes a white dwarf star, before it dies and becomes a black dwarf star. 26. Explain the difference between the apparent and absolute magnitude of a star While apparent magnitude is a measure of the brightness of an object as seen by a particular observer, absolute magnitude is a measure of the intrinsic brightness of an object. 3 - Inside the Atom 1. Development of the atomic model 1. Identify that matter is made up of atoms Matter is made up of atoms 2. Describe what a scientific theory is and how they are revised or disproved A scientific theory is a theory based upon observations and evidence, but it isn’t a confirmed fact. It can be disproved through the conduction of experiments, and if different observations are made, then the theory would be incorrect, but if it's true, then it would become a fact. 3. Describe the following models of atoms, including their limitations: Dalton Thomson’s Plum Pudding Model Rutherford’s atomic model Bohr’s atomic model Schrodinger’s atomic model https://docs.google.com/document/d/1PQ1sPbifo6Q2KRGzmo8IDQDT3_5ApPWIiYsfNQ3DZ1s/ edit (research notes for the assignment, covers this indicator) 2. Subatomic Particles 1. Recall Rutherford’s gold foil experiment and its implications for the structure of the atom Rutherford’s gold foil experiment involved radiating alpha particles at gold foil, and based on scintillations, deductions were made. Alpha particles bounced off gold foil, leading to more scintillations, but without the foil, there was less indication. The conclusions are that metals with higher atomic mass reflected more alpha particles than lighter ones, and most of the atom is empty with a mass concentrated nucleus. 2. Draw and label the structures within an atom 3. Calculate the numbers of protons, neutrons and electrons in an atom given its mass and atomic numbers Mass number = total number of protons and neutrons Atomic number = number of protons (which is equal to number of electrons) 4. Explain the relative atomic mass scale and how atomic numbers and mass numbers are determined The relative atomic mass of an element is defined as the weight in grams of the number of atoms of the element contained in 12.00 g of carbon-12. To calculate the relative atomic mass of chlorine, the average mass of one atom of chlorine is found by considering 100 atoms of chlorine. The atomic and mass numbers are determined by protons and neutrons. 5. Describe the concept of an isotope and compare and contrast their structure. An isotope is a different form of an element that has an equal amount of protons but a different amount of neutrons in their nuclei, hence differing in relative atomic mass but not in chemical properties. They can also be considered as radioactive forms of an element. There isn’t much difference in the structures besides their mass. 6. Determine the relative atomic weight of an element given the relative abundance of isotopes The relative abundance of an isotope is the percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element. Change each percent abundance into decimal form by dividing by 100. Multiply this value by the atomic mass of that isotope. Add together for each isotope to get the average atomic mass. 7. Construct an electron shell diagram for elements in the periodic table with an atomic number up to 21 Electron shell structure = 2,8,8,3 (up to 21) 8. Observe the results of a flame test and relate them to the energy changes in electrons moving shells Chloride Colour Strontium Chloride red Copper Chloride green Barium Chloride yellow Potassium Chloride purple  Lithium Chloride N/A Calcium Chloride Dark orange Sodium Chloride orange This relates to the energy changes in electrons which are moving through the shells because the heat in a flame leads to the conversion of metal ions into atoms, which get chemically excited and emit visible light, and the colour corresponds to the wavelength of each particle. 3. Radioactivity 1. Identify that not all atoms are stable Not all atoms are stable 2. Compare alpha, beta and gamma radiation: How they are produced Properties Uses Radiation Produced Properties Uses Alpha Alpha particles form -Relatively slow and heavy -Remove static electricity from the decay of the -20 million m/s -Give power to tools in oil heaviest radioactive -Mass of 4 protons industry elements like uranium -Stream of positively -Used as a source of fuel charged particles Beta Beta particles come -Half of a thousandth a -Treating eye and bone from an atom’s proton’s mass cancer nucleus during -Carries either one electron -Testing item thickness radioactive decay or one proton -Used in -Can reach speeds near light radioimmunotherapy Gamma Gamma particles are -Pure energy, similar to light -Sterilise medical produced by some of but have more energy equipment the hottest objects in -Radiation hazard to entire -Killing cancerous cells the universe like body -Gamma-ray astronomy supernova explosions -High frequency in -Used as tracers in or regions near black electromagnetic spectrum medicine holes. -Emitted from decay -Used in nuclear industry 3. Describe the use of a Geiger counter to detect background radiation Geiger counters are used to detect and measure ionising radiation. It works by radiation splitting atoms into free electrons and positive gas ions. Each rush to the opposite charged wire, crashing into each other and creating an ‘ionising avalanche’, creating a pulse, travelling to the counter and getting measured. This is widely used in applications such as radiological protection, experimental physics and nuclear industry. 4. Describe half-life and calculate half-life when given an exponential decay curve. The half life of an element is how long it takes for it to half its radioactivity. Can successfully calculate half-life when given an exponential decay curve. 5. Describe the effects of radiation on the human body and evaluate the dangers of radiation -Damage to DNA in cells -Acute Radiation Syndrome (ARS) (radiation sickness) -Cutaneous Radiation Injuries (CRI) -Can lead to cancer later in life -Skin burns and cardiovascular diseases 6. Describe nuclear power and how a nuclear power plant works (Fukushima and Chernobyl are good discussion topics about the dangers of radiation) Nuclear power is a clean and efficient way of boiling water to make steam, which turns turbines to produce electricity. Nuclear power plants use low-enriched uranium fuel to produce electricity through a process called fission—the splitting of uranium atoms in a nuclear reactor. Nuclear power plants receive water from lakes or rivers, and pumps move it to the pressure vessel, where uranium is stored and nuclear fission takes place, releasing energy and converting the cold water into steam, which moves to the turbines. These push the steam to the electric generator, producing electricity which gets carried around a city. 7. Outline the uses of radiation in medicine -Using radiopharmaceuticals -Treats hyperthyroidism, thyroid cancer, lymphomas and bone pains  -Medical imaging (x-rays to show images of parts of the body) -Monitoring tumour responses and checking whether they’re malignant or benign 8. Evaluate the benefits and problems associated with medical and industrial uses of nuclear radiation Benefits Problems Helpful with killing cancer Very dangerous to human body Diagnoses illnesses Can be used as weapons (nuclear and atomic bombs) Useful with inspecting metal parts Causes contamination to environment Carbon dating (archaeology) Slightly increases cancer chances Sterilising food and medical equipment Generates a lot of radioactive waste in production (difficult to deal with Energy on the Move Conduction - The transfer of thermal energy with direct contract Convection - The transfer of of heat energy through particles Radiation - The transfer of energy through waves Examples of conductors Examples of insulators - Metal - Glass - Steel - Plastic - Gold - Wood - Silver Conductors quickly transfer heat energy whereas insulators slow down the transfer of heat energy. Process of conduction Conduction is a heat transfer process that occurs when there is a temperature difference between two objects or regions in contact with each other. It involves the transfer of thermal energy from the region of higher temperature to the region of lower temperature through direct physical contact between particles. - Particle Vibration: In a substance at a higher temperature, the particles have higher kinetic energy and are vibrating more vigorously. Conversely, in a substance at a lower temperature, the particles have lower kinetic energy and are vibrating less energetically. - Heat Flow: When two objects or regions with different temperatures are in direct contact, the more energetic particles from the hotter object collide with the less energetic particles in the colder object. These collisions transfer kinetic energy from the hotter particles to the colder particles. - Increase in Particle Energy: As the hotter particles collide with the colder ones, the colder particles gain kinetic energy, causing them to vibrate more vigorously. This increase in kinetic energy results in an increase in the temperature of the colder object or region. Process of Convection Convection is a heat transfer process that occurs in fluids (liquids and gases) and involves the bulk movement of the fluid itself. This movement results in changes in the distribution of thermal energy among the fluid particles. - Temperature Difference: Convection typically starts with a temperature difference within the fluid. For example, in a fluid like air or water, one region may be heated, causing the particles in that region to gain kinetic energy and become more energetic. - Density Differences: As particles in the heated region gain energy, they become less dense and tend to rise. This is because the increased kinetic energy causes the particles to move apart slightly, reducing the fluid's density in that region.  - Transfer of Energy: As the less dense, heated fluid rises, it displaces cooler, denser fluid from another region. The cooler fluid then moves in to replace the rising, heated fluid. This continuous circulation of fluid creates a convection current. Process of Radiation Radiation refers to the emission of energy as electromagnetic waves or particles. The process involves the generation and release of this energy from a source, which can be a natural occurrence or a human-made device. - Generation: Radiation begins with the creation of energy in a source. This could be due to various processes such as nuclear reactions, radioactive decay, or electromagnetic oscillations. - Propagation: The energy generated in the source then propagates through space in the form of electromagnetic waves or particles. These waves can travel through air, vacuum, or other mediums. - Interaction: The radiation interacts with matter it encounters. Depending on the type of radiation, this interaction can include absorption, reflection, scattering, or transmission through the material. - Absorption and Exposure: When radiation is absorbed by matter, it can deposit energy into the atoms or molecules of the material. This absorption can lead to various effects, such as heating or ionisation. Wave - a travelling disturbance that transfers energy from one location to another, but not matter. Mechanical Wave is a wave that is an oscillation of matter and is responsible for the transfer of energy through a medium. - Need a medium ( hence cannot travel through a vaccum). - (eg: water,sound and seismic waves) Electromagnetic waves are a wave created by a fusion of electric and magnetic fields. - Do not need a medium to travel through  - All electromagnetic waves travel through a vacuum at the same speed (eg: radio waves microwaves) Longitudinal waves are those waves in which the particles of the medium move parallel to to the propagation of the wave - It's made of rarefactions and compressions - It acts in one dimension - The particles of the medium vibrate back and forth along the same path that the wave travels - The particles in a longitudinal wave do not move song the wave - ONLY energy travels from one place to another - (Eg: sound waves, Tsunami waves, vibrations in a spring ) - Type of mechanical wave Transverse waves are those waves in which the particles of the medium move perpendicular to the direction of the waves. - It acts in two dimensions - It is made of troughs and crests - Energy is transferred through the vibrations of the particles that make up that type of wave. - (Eg: Vibrations in a guitar string, electromagnetic waves) - Type of mechanical wave d Crest - highest point Trough - lowest point Amplitude - the maximum distance between a point on the graph of the wave and its equilibrium Wavelength - The distance from the "crest" (top) of one wave to the crest of the next wave is the wavelength, or trough. Equilibrium - The equilibrium position is in the middle of a wave (vertically). The equilibrium position is used to show the amplitude of a wave with the greater the amplitude the greater the displacement from the equilibrium position. Speed of a wave Units: Frequency (Hz) Wavelength of the wave (m) Sound Wave is a mechanical longitudinal wave that requires a medium to propagate and transfer energy. It arises from the vibrations of an object, which then causes the surrounding medium;s particles to vibrate in kind. The medium’s displacement is perpendicular to the wave’s direction (longitudinal). The movement leads to areas of compression ( where particles are close together) and rarefaction ( when they are spread apart.) A compression is a region in a longitudinal wave where the particles are closest together. (regions of high air pressure ) A rarefaction is a region in a longitudinal wave where the particles are farthest apart. (regions in of low air pressure) Sound can travel in the form of transverse waves. But this can occur only when sound travels through a solid or the upper surface of a liquid. Frequency - The frequency of a sound determines its pitch. Because the pitch of a sound is directly proportional to its frequency, low-frequency sounds are described as having a low pitch, while high-frequency sounds are described as having a high pitch. Amplitude - Loudness of sound is proportional to the square of the amplitude of the vibration producing the sound Density - The greater the density of a medium, the slower the speed of sound. Electromagnetic Spectrum - The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation - radiation is the emission of energy in the form of electromagnetic waves or subatomic particles. 7 types of electromagnetic waves in the Electromagnetic Spectrum Radio waves - are the lowest frequency waves in the EM spectrum. It is used to carry other signals to receivers that translate these signals into usable information Radio and television stations all produce radio waves that carry signals, received by the antennae in your television, radio or cell phone. Microwaves - are the second - lowest frequency waves in the EM spectrum. Due to its high frequency, it can penetrate obstacles that interfere. It carries radar,landline phone calls and computer data transmission as well as cooking your dinner! Infrared waves - are in the lower - middle range of frequencies in the EM spectrum, between microwave and visible light. It is used in remote controls and imaging technologies. Longer wavelength forms produce heat and include radiation emitted by fire, the sun and other heat producing objects. Visible Light Rays - waves that let you see the world around you. The different frequencies of visible light are experienced by people, just like the colour of rainbows. Frequencies move from lower wavelengths as reds, up to higher visible wavelengths, detected as violent hues. Objects are perceived as different colours based on which wavelengths of light an object absorbs and which it reflects. Ultraviolet waves - Uv waves are the cause of sunburn and can cause cancer in living organisms. High-temperature processes emit UV rays, detected from stars in the universe. It assist astronomers on the structure of galaxies. X rays - are extremely high- energy waves with wavelengths ranging from 0.03 and 2 nanometre, a little bit larger than an atom. Emitted by a source with very high temperatures like the sun’s corona. Natural sources of x -ray include pulsars,supernovae and black holes. X -rays are used in imaging technology to view bone structures within the body. Gamma rays - are the highest - frequency EM waves that are only emitted by pulsars, neutron stars, supernovae and black holes. Gamma wave wavelengths are measured on the sub atomic level and can actually pass through the empty space within an atom.  The speed of sound in air is ~ 343 m/s and the speed of light is 3x1010 m/s. In other words, light travels 186 thousand miles in 1 second, while sound takes almost 5 seconds to travel 1 mile. - Light behaves in different ways with different objects - Light cannot travel through Opaque objects ( wooden table top) , it either gets absorbed or reflected. - Reflection - Is the bouncing of light off a solid material - If an opaque object is shiny, it will reflect light in an ordered way and we see a clear image. - Eg: plane mirror ( flat mirror). Light behaves in a predictable way when it reflects from a flat opaque surface, no matter how rough or smooth. Law of reflection states - The law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror all lie in the same plane. Furthermore, the angle of reflection is equal to the angle of incidence. angle of incidence ( i ) = angle of reflection (r) The normal line is always at right angles (90º) to the surface. - Curved mirrors - Appear long , short or otherwise distorted - Used in cars and shops to help see a wider range of view. Two different types of curved mirrors: Concave Curve and Convex Curve) - It still obeys the law of the reflection , however since the surface is no longer flat, there are many angles that the incidence ray enters. Convex mirrors - Diverge or spread out light - the reflecting surface of the convex mirror bulges outside Concave mirrors - Converge hence focus light - Satellite focuses on radio waves. Refraction - The bending of light as it passes from one transparent material to another it's called reflection ( view becomes distorted). eg: Refraction causes mirages, explains how lenses work , makes straight objects appear disconnected in water. Refracted Ray - The amount of refraction ( bending of light ) depends on the optical densities of the mediums. Optical Density - the ability of a material to transmit light through it. Materials with different optical densities have different refractive indexes. - Higher the optical density. slower the light travels through it The way light bends depends on which medium has the higher optical density. - Ray travels from a less dense to a more dense medium. Such as air to water, it slows down hence light bends closer to normal - Ray travels from a denser medium to a less dense medium, from glass to air, its speeds up and the light bends away from the normal - Generally liquids have a higher optical density than gas , and solids have a higher optical density than liquids. m. The only time light doesn’t refract is when it enters a new medium directly along the normal. It still changes speed but there is no bending of the light - Lower optical density , the faster light travels Lens - usually a curved piece of transparent material Concave lenses - thinner in the centres , compared to the edges Light rays are diverging or spreading , focus is on the other side of the lens Convex lenses - thicker in the centres than in the edges Light rays are converging or focusing. - Focal point - where the rays cross - Focal length - the distance between the focal point and the lens Total internal reflection - The phenomenon which occurs when the light rays travel from a more optically denser medium to a less optically denser medium The angle of incidence must be greater than the critical angle for it to work. Critical angle - The critical angle is the angle of incidence where the angle of refraction is 90°. 6.3. Electric circuit - a path for transmitting an electric circuit ( electrons gain electric potential energy at the power source , battery.) Simple Circuit can be constructed with two pieces of wire, a resistor and power supply. A resistor - resist the flow of electric current A completed circuit Connecting wires Power supply Switch - stops the flow of the electrons in order to control the circuit. Voltage - a measure of the potential energy ( stored energy per charge) of electrons have ( potential difference) - Voltmeter- measures voltage, si unit - Voltage ( V) - must be connected parallel Electric current - the amount of charge that goes past a point in a circuit per second, 6.242 x 10 ^ 8 equals 1 coulomb. One coulomb passes a given point in 1 second is an ampere. - Ammeter - measures electric current , si unit - Ampere (A) - must be connected series Resistance - Resistance is a measure of the opposition to the flow of current in an electrical circuit. Units ohms. Ohm's law - Series Circuit - globes are connected side by side Parallel circuit - has two or more branches and the current splits between these branches and come back afterwards. Body System and Responses Body systems and Responses 9.1 Plants detect changes in the environment to survive Plants respond to external stimuli such as light, fire and water due to their internal and external receptors. How do plants respond to changes in the environment ? 1. Plants need light to survive - To maximise light exposure, plants engage in phototropism in which cells of a plant that are in the dark elongate. This lengthening causes the plant to bend towards the light 2. Plants need water to survive - Hydrotropism is a process that results in a plant’s roots growing towards water. The roots have specialised receptors that cause the roots to grow downwards. These receptors also detect changes in pressure in the soil. More pressure means more water, and so the roots of the plants grow towards these areas of increased pressure 3. Deciduous plants - Plants that lose leaves during changing seasons are deciduous where the shorter days during winter means less light for photosynthesis and plants detect the change in temperature so as to trigger a reduction in the amount of growth hormone being sent to the leaves. 4. Epicormic buds - Epicormic buds are growth points that lay dormant under the trunk of a tree until they are stimulated. When a bush! re burns the higher plant shoots, the inhibition of the growth hormones ceases, which stimulates rapid growth from the epicormic buds. The new leaves  that come from the epicormic buds allow the tree to photosynthesise, which keeps the plants alive after a bushfire. 9.2 Animals respond to changes in the environment Stimulus - A stimulus is any information an organism receives that might cause it to respond Receptor - A structure that detects a stimulus or change in the normal functioning of the body Five senses Sight - Photoreceptors convert light into electric signals. One message is sent to the iris telling it to constrict and close the pupil, the second message is to the brain via the optic nerve which tells you what you are looking at. Hearing - Vibrations of sound waves enter your ear and causes the eardrum to vibrate. These vibrations are transferred along the tiny bones of the middle ear, detected by hair cells in the cochlea which convert vibrations into nerve impulses for the brain to interpret as sound Smell - Chemoreceptors, detect chemicals in the air and then send messages to the brain, which interprets the message and tells us what we are smelling. Taste - Taste buds on our tongue contain special receptor cells that react to chemicals in foods Touch - The bottom layer of skin, called the dermis, contains many nerve endings that can detect temperature (thermoreceptors), pressure (mechanoreceptors) and pain (pain receptors). Information is collected by these receptors and sent to the brain for processing and reaction. Response to stimuli examples - temperature changes, resulting in humans sweating to cool down or shivering to warm up - changes in pressure, resulting in tickling sensations or pain. 9.3 The nervous system controls the body Definitions CNS (Central nervous system) - the brain and spinal cord. PNS (Peripheral nervous system) - All the neurons (nerve cells) that function outside the brain and spinal cord. Somatic Nervous System - the part of the nervous system that controls the muscles that are attached to the skeletal system Autonomic Nervous System - the part of the nervous system that controls involuntary actions such as heartbeat, breathing and digestion. Roles CNS (Central nervous system) - examines external and internal environment, which creates messages to maintain homeostasis that are sent via the PNS PNS (Peripheral nervous system) - Part of the nervous system consisting of the nerves, receptors and effectors (transmit and act on messages from CNS Somatic The somatic nervous system (SNS) is also known as the voluntary nervous system. The somatic system is the part of the peripheral nervous system responsible for carrying sensory and motor information to and from the central nervous system. It contains nerves that send information to the brain and spinal cord, made of sensory neurons that inform the central nervous system about our five senses; and nerves that send information from the brain, which contain motor neurons responsible for voluntary movements, such as walking or lifting an object. Autonomic The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. The sympathetic division does the following: Prepares the body for stressful or emergency situations—fight or flight When receptors detect stress, messages are sent through nerves (nervous system) to the adrenal glands which release the hormone adrenaline (endocrine system). This hormone increases the heart rate, blood pressure and cell metabolism, which help cope with the situation.It slows body processes that are less important in emergencies, such as digestion and urination. The parasympathetic division - Rest and Digest Parasympathetic system: This helps maintain normal body functions and conserve physical resources. Once a threat has passed, this system will slow the heart rate, slow breathing, reduce blood flow to muscles, and constrict the pupils. This allows us to return our bodies to a normal resting state, rest and digest. and their main functions The cerebrum or outer section of your brain is divided into four lobes or sections. These lobes have special functions. - The frontal lobe is located at the front of the brain. Its functions include emotions, reasoning, movement and problem solving. - The parietal lobe manages the perception of senses, including taste, pain, pressure, temperature and touch. - The temporal lobe is located in the region near your ears. It deals with the recognition of sounds and smells. - The occipital lobe is at the very back of the brain. It is responsible for aspects of vision. 9.4 Neurons are the basic unit of the nervous system Definitions Neuron Neurons are information messengers. They use electro-chemical signals to transmit information between different areas of the brain, and between the brain and the rest of the nervous system (Simple: Nerve signals are electro-chemical impulses) Cell body Cell body or stoma. This part contains all the necessary components of the cell, such as nucleus, endoplasmic reticulum and ribosomes (for protein synthesis) and mitochondria. If the cell body dies, the neuron dies. Axon Transmits signals away from the cell body to other cells (neurons or effector cells). It carries the electrochemical message (nerve impulse or action potential) along the length of the cell. Depending on the type of neuron, they can be covered in a thin layer of myelin sheath, like an insulated wire. Myelin is made of fat and protein, and it helps to speed the transmission of a nerve impulse. Myelinated neurons are typically found in the peripheral nerves (sensory and motor neurons) while non-myelinated neurons are found in the brain and spinal cord. At the end of the axon will be a synaptic knob, which stores chemicals called neurotransmitters in vesicles. The electrochemical message travels at up to 120 m/s in a myelinated neuron. It is much slower in a non-myelinated axon. Myelin Sheath a fatty layer that covers the axon of a nerve cell Dendrite the part of a neuron (nerve cell) that receives the message and sends it to the cell body Synapse The places where neurons connect and communicate with each other are called synapses. Synaptic a bulb at the end of the axon of a neuron which stores and releases neurotransmitter Terminal molecules to stimulate the following neuron Neurotransmitt Neurotransmitters are chemical messengers which carry messages from one nerve ers cell across a space to the next nerve, muscle or gland cell.  Neuron Neurons are information messengers. They use electro-chemical signals to transmit information between different areas of the brain, and between the brain and the rest of the nervous system (Simple: Nerve signals are electro-chemical impulses) Sensory a nerve cell that carries a message from a receptor to the central nervous system Neurons Motor Neurons a nerve cell that carries a message from the central nervous system to a muscle cell Interneurons a nerve cell that links sensory and motor neurons; also known as a connector neuron Passage of information through a neuron, across the synapse and to the next cell  - At a synapse, the axon terminal of one neuron is in close proximity to the dendrite of another neuron - Information travels along the first neuron to the axon terminal, via an electro-chemical signal. - At the axon-terminal, this signal triggers the release of a chemical, called a neurotransmitter, which travels across the synaptic cleft to the dendrite of the second neuron. - The neurotransmitter attaches to a receptor on the dendrite of the second neuron, generating a second electro-chemical signal. Enzymes break down the neurotransmitter, so that the signal is not continuously transmitted. Simply 1. Axon terminal releases neurotransmitters from vesicles when stimulated by electrical signal (Nerve Impulse) 2. This chemical message crosses the synaptic cleft (synapse) 3. The neurotransmitters bind to receptors on the dendrites of the next neuron passing the message on (electrical). Explain how sensory, motor and interneurons communicate information around the body Sensory neurons detect information from our surroundings or within our bodies and send these signals to the central nervous system (CNS). In the CNS, interneurons process and integrate this information, making decisions about how the body should respond. Once the response is determined, motor neurons carry signals from the CNS to muscles, glands, or other effectors, prompting them to take action. This communication system enables us to perceive stimuli, process information, and generate appropriate responses, allowing us to interact with our environment and maintain bodily functions. 9.5 The nervous system controls reflexes Define reflex Reflexes are involuntary actions that your body makes in response to particular stimulus Stimulus Response model Stimuli are detected by the receptors, and the message gets sent to the spinal cord and the brain via the sensory neurons. The spinal cord and brain form the control centre of the nervous system. The interneurons in this control centre pass the message on to other interneurons as your brain determines the most appropriate response to a stimulus. Once this is done, the motor neurons pass the message on to the muscles In this case, the muscles are called the effectors because they are the cells that cause the body to respond. This simple pathway is called the stimulus response model. Reflex Arc and examples of reflex actions A reflex arc is a nervous pathway that allows for a very rapid, unconscious response to dangerous stimulus. All reflex actions have evolved to help us survive. Example - In a reflex action, a response occurs before sensory information is consciously perceived. When a receptor detects a stimulus, it sends a message to a sensory neuron, which then transmits an electrochemical message to an interneuron located in the spinal cord. This interneuron swiftly sends two messages: one to the brain and the other directly to the muscles via the motor neuron, causing a rapid reaction like a twitch or withdrawal. This quick response is crucial as it reduces harm to the individual by reacting even faster to a stimulus, bypassing the need for the information to go through the brain, ensuring a very fast response and potentially preventing harm. This entire process is known as a reflex arc, and it prioritises speed. Reflex Stimulus Response Survival value Coughing Irritant in Rapid expulsion of air Prevents lungs being respiratory system damaged or infected, so that gas exchange remains efficient Swallowing Food particles Contraction of the Prevents food entering the make contact with muscle of the epiglottis, respiratory system, so that back of the throat which closes off the lungs are not damaged entrance to the trachea Pupil reflex Increased light Iris muscle (effector) Prevents bleaching of retina intensity contracts which expands so that vision remains clear the iris area which contracts the pupil which lets in less light 9.6 The endocrine system causes long-lasting effects Definitions Endocrine system - a collection of glands that make and release hormones Hormones - a chemical messenger that travels through blood vessels to target cells Target cell - a cell that has a receptor that matches a specific hormone Flight or fight response The “Fight or Flight Response” is a good example of the nervous and endocrine systems working together. When your body senses danger (for example, spotting a wild animal coming towards you), this sensory stimulus triggers a response in the brain. The pituitary gland coordinates the response of the endocrine system. Among other things, it stimulates the adrenal cortex to release adrenaline. This leads to: The rate of respiration increases to increase the amount of oxygen available. heart rate increases to pump more blood around the body. the liver releases glucose into the bloodstream as a source of extra energy. blood is diverted away from the extremities (you go pale) and from the digestive system. Dilation of pupils Examples of common hormones Difference between the two main types of hormones Characteristic Peptide Hormones Steroid Hormones Chemical Structure Composed of amino acids Derived from cholesterol Primarily synthesized in endocrine Produced in various tissues, such as glands Synthesis Location glands, such as the adrenal and the brain cortex and gonads Response to stimuli is slower, may Release Regulation Rapid response to stimuli; released quickly require gene transcription and protein synthesis Receptor Location Surface of target cells Located within target cells on Cell Peptides travel through the bloodstream until they find and interact with specific These can pass through the cell Mechanism of receptors on the surface of their target membrane and move directly into Action cells. This causes the target cells to the target cells. respond Insulin (regulates blood sugar), Estrogen, Testosterone, Cortisol Examples Adrenocorticotropic hormone (ACTH), (stress hormone) Growth hormone (GH) Slower, with effects that may take Speed of Action Relatively fast response hours to days to manifest Duration of Action Short-lived effects Longer-lasting effects Primarily reproductive and Target Tissues Many different tissues and organs metabolic tissues  Often involved in long-term Regulation of Often involved in short-term regulation of regulation of metabolism and gene Metabolism metabolism expression 9.7 Homeostasis is the interaction of internal body systems Define homeostasis and label the advantages Homeostasis is THE MAINTENANCE OF A CONSTANT INTERNAL ENVIRONMENT) Homeostasis maintains optimal conditions for enzyme action throughout the body, as well as all cell functions. It is the maintenance of a constant internal environment despite changes in internal and external conditions. In the human body, these include the control of: ❖ blood glucose concentration ❖ body temperature ❖ water levels. Explain how hormones regulate blood glucose The body converts the carbohydrates from food into glucose, a simple sugar that serves as a vital source of energy through cellular respiration Blood sugar levels are a measure of how effectively the body uses glucose. These vary throughout the day. However, in most instances, insulin and glucagon keep these levels within a healthy range. When the body does not convert enough glucose, blood sugar levels remain high. Insulin helps the cells absorb glucose, reducing blood sugar and providing the cells with glucose for energy. When blood sugar levels are too low, the pancreas releases glucagon. Glucagon instructs the liver to release stored glucose, which causes blood sugar to rise. Islet cells in the pancreas are responsible for releasing both insulin and glucagon. The pancreas contains many clusters of these cells. There are several different types of islet cells, including beta cells, which release insulin, and alpha cells, which release glucagon. Define and explain the difference between positive and negative feedback loops Positive Feedback Loop - In a positive feedback loop, the response to a change in a system amplifies or reinforces that change, pushing the system further away from its original state. It encourages the system to continue in the same direction as the initial change Negative Feedback Loop - In a negative feedback loop, the response to a change in a system opposes or counteracts that change, helping to maintain or restore the system to its original state or a setpoint. It promotes stability and regulation. Describe an example of a negative feedback loop Thermoregulation and Homeostasis: - Normal Body Temperature Range: Homeostasis is the body's ability to maintain a stable internal environment despite external changes. One critical aspect of homeostasis is the regulation of body temperature, which is typically around 98.6 degrees Fahrenheit (37 degrees Celsius). - Temperature Sensors: To achieve homeostasis in terms of temperature, the body contains temperature sensors, primarily in the skin and the hypothalamus (a region in the brain). These sensors constantly monitor the body's temperature. - Negative Feedback Mechanism: When the body's temperature deviates from the normal range, a negative feedback loop is initiated as part of the homeostatic process: - High Body Temperature (Hyperthermia): If the body's temperature rises, such as when you're exposed to a hot environment or engaged in physical activity, the temperature sensors detect this increase. In response, the body activates cooling mechanisms, such as sweating and vasodilation (widening of blood vessels near the skin). Sweating allows for heat dissipation through the evaporation of sweat, and vasodilation increases blood flow to the skin, enhancing heat loss. - Low Body Temperature (Hypothermia): Conversely, if the body's temperature drops, for instance, in a cold environment, the sensors detect the decrease. In this case, the body activates warming mechanisms. These mechanisms include shivering (muscle contractions that generate heat) and vasoconstriction (narrowing of blood vessels near the skin) to reduce heat loss. 9.8 Pathogens cause disease Pathogen: A pathogen is a microorganism (like bacteria, viruses, fungi, or parasites) that can cause disease or illness in a host organism. Antibiotic: An antibiotic is a type of medication that inhibits the growth or destroys bacteria, effectively treating bacterial infections in humans and animals. Identify types of pathogens and provide examples - Bacteria: Examples include E. coli, Streptococcus. - Viruses: Examples include Influenza virus, HIV. - Fungi: Examples include Candida (causes yeast infections), Aspergillus. - Parasites: Examples include Plasmodium (causes Malaria), Tapeworm. Provide examples of pathogens:  - E. coli: A type of bacteria that can cause food poisoning. - Influenza virus: Causes the common flu. - Candida: A fungus causing yeast infections. - Plasmodium: The parasite responsible for Malaria. Explain how penicillin can kill bacteria cells without harming human cells: - Penicillin targets the bacterial cell wall, which is a structure unique to bacteria. It inhibits the bacteria's ability to build and repair their cell walls, eventually leading to the destruction of the bacterial cells. Human cells do not have a cell wall, so penicillin does not harm them. Relate scientific discoveries to the development of the 'germ theory': - The 'germ theory' was developed through significant scientific discoveries by Louis Pasteur, Robert Koch, and others. Pasteur's work on fermentation and disease demonstrated that microorganisms caused specific phenomena. Koch's postulates established a method to link a particular microorganism to a specific disease, solidifying the germ theory and revolutionizing medicine's understanding of infectious diseases. 9.9 The immune system protects our body 1. Define immune system, white blood cells, phagocytes, B cells, antibodies, T cells, memory cells, immune and vaccination: ○ Immune System: The body's defense mechanism protecting against infections and diseases. ○ White Blood Cells: Essential cells that combat infections and foreign substances in the body. ○ Phagocytes: A type of white blood cell that engulfs and destroys harmful microorganisms. ○ B Cells: White blood cells that produce antibodies to neutralize invaders. ○ Antibodies: Proteins created by the immune system to neutralize specific pathogens. ○ T Cells: White blood cells that orchestrate the immune response and directly attack infected cells.  ○ Memory Cells: Specialized cells that "remember" previous infections, aiding faster and stronger responses upon re-exposure. ○ Immune: Refers to being resistant to a specific disease or infection. ○ Vaccination: A preventive measure involving the administration of a vaccine to stimulate the immune system, providing protection against specific diseases. 2. Describe some of the first and second line defence mechanisms of the body against infection: ○ First Line Defense: Physical barriers like skin and mucous membranes that block entry and inhibit the growth of pathogens. ○ Second Line Defense: Inflammatory responses, fever, and phagocytosis (engulfing and destroying pathogens) carried out by white blood cells to combat infections. 3. Explain the processes involved in developing acquired immunity: ○ Acquired immunity is achieved through exposure to pathogens or vaccination. The immune system recognizes specific pathogens, mounts a response, and generates memory cells. Upon subsequent exposure, the immune system reacts faster and more effectively. 4. Compare naturally acquired immunity with vaccinations: ○ Naturally Acquired Immunity: Results from encountering and recovering from an infection. It is slower to develop but provides long-lasting immunity. ○ Vaccination: Deliberate exposure to a weakened or inactivated form of a pathogen through a vaccine. It prompts the immune system to create a response without causing the disease, providing immunity with reduced risk and faster response upon exposure. 9.11 Societies influence scientific research 1. Describe where Australia spends most of its health budget: ○ Health Budget Allocation in Australia: Refers to how financial resources for healthcare are distributed within the country. ○ Main Allocation Areas: Public Health Initiatives: Such as health promotion and disease prevention programs. Hospitals and Healthcare Services: Funding for hospitals, medical equipment, and healthcare professionals. Medications: Budget allocation for subsidizing medications and pharmaceuticals. 2. Be able to compare causes of death in high-income and low-income economies:  ○ Comparing Causes of Death: Involves examining the reasons for mortality in both high-income and low-income countries. ○ Comparison: High-Income Economies: Common causes include heart disease, cancer, stroke, and lifestyle-related diseases. Low-Income Economies: Often dominated by infectious diseases, malnutrition, childbirth-related complications, and lack of access to healthcare. 3. Describe the difference between an epidemic and a pandemic: ○ Epidemic: Occurrence of a disease in a specific geographic area or community, affecting a larger number of people than usual within that region. ○ Pandemic: Widespread outbreak of a disease, usually across countries or continents, affecting a significant portion of the global population. Plate tectonics - Plate tectonics is the theory that the Earth’s lithosphere is composed of many large plates that move slowly over time. Evidence for plate tectonics includes: Coastlines appear to fit together like a jigsaw puzzle Spread of fossils of multiple species show the continents were previously joined Earthquakes occur at boundaries of plates Today we can measure the movement of the plates Formation of newer crust at diverging boundaries (eg: rift valleys) Alfred Wegener hypothesized that all of the modern-day continents had previously been clumped together in a supercontinent he called Pangaea (from ancient Greek, meaning “all lands” or “all the Earth”). Over millions of years, the continents had drifted apart. Evidence: Coastlines appear to fit together like a jigsaw puzzle Spread of fossils of multiple species show the continents were previously joined he tectonic plates move over time. This is continental drift. At some boundaries between plates new oceanic crust is forming as the plates move apart and magma comes up at the boundary to form new crust, filling the space made by the shifting plates. Sea floor spreading required a mechanism for it occur. The plates had to be able to slide and required a force to make it happen. A liquid layer (mantle) allows plates to slide over it. Movement of heat via convection currents is a mechanism that provides force for the movement of plates. Pangaea was the original supercontinent that existed when all the current continents were clustered together. Over time they moved apart and eventually ended up in their current positions. Convection currents drive the plates apart at divergent boundaries. At convergent boundaries the plates are forced together. This can cause plates to buckle and fold, but usually results in one plate sliding under another. Transform boundaries are sliding past each other, convergent are pushing towards each other and divergent are pulling away from each other. At transform boundaries earthquakes are common. At convergent boundaries earthquakes and volcanoes occur, as well as folds, mountains and valleys. At divergent boundaries such as rift valleys, new crust forms. This can be a valley that becomes a lake or ocean, or could form undersea ridges. At convergent boundaries crust is being destroyed. For this reason they are sometimes called destructive boundaries. At divergent boundaries new crust is being formed. Divergent boundaries are also known as constructive boundaries. Convergent boundaries At ocean-ocean boundaries undersea volcanoes can form volcanic islands. At continental-ocean boundaries, the oceanic crust subducts under the continental crust and volcanic ranges form inland from the boundary. At continent-continent boundaries thrust and pressure can cause very high pressure. Mountain ranges, deep valleys and metamorphic rocks formed under very high pressure. Where a convergent boundary exists between two continental plates two situations can occur. If the rocks are ‘plastic’ (able to be deformed by pressure) folds will form. Synclines and anticlines. If the rocks at a convergent boundary are brittle (break under pressure) then the inward compression pushes one side up over the other at the break. This is called a reverse fault. If the boundary of two continental plates is divergent, cracks form and the rock can slip. This is called a normal fault. Block mountains: form at normal faults due to upward pressure. Mid-ocean ridge: formed at oceanic divergent boundaries as magma fills the gap between the plates. Trenches form where an oceanic plate subducts underneath a continental plate. Island arcs form at convergent oceanic-oceanic boundaries as magma is pushed back up from over the subducting plate. Volcanoes often form at convergent boundaries. The subducted plate melts as it is dragged deeper into the mantle. If it contains liquids such as water, these form gases and change the density and pressure. This creates an upthrust of magma, resulting in the formation of volcanoes. Along the West coast of South America the Antarctic and Nazca plates are subducting underneath the South American plate. The subducted plates are oceanic and contain a lot of water. The melting lithosphere turns to magma and hot gases such as water vapour. This causes low density and high pressure, leading to an upthrust of magma, forming volcanoes on the surface inland from the subduction zone. Magma chambers beneath the Earth’s surface hold vast amounts of magma. Pressure can build up here from converging plates or the formation of gases. Eventually the pressure builds up enough to force the magma out to the surface, resulting in a volcanic eruption. Eruptions can be very violent as they also release a build up pressurised gases and volcanic ash over large distances. Earthquakes are the release of tension built up in fault lines. This tension is caused by rocks pushing against each other over time. The pressure can build to enormous amounts before being suddenly released. The released pressure causes violent seismic waves of force, known as earthquakes. If an earthquake occurs underneath the ocean (or close to it), the resulting shift in the plates can cause the movement of water to fill spaces created between displaced tectonic plates. This can result in the sudden movement of vast quantities of water, creating large waves known as tsunamis. These waves increase in size as they get closer to shore. The focus of an earthquake is the centre point where the tension and force is released. The epicentre is the point on the Earth’s surface directly above the focus. P waves are the fastest waves, followed by S waves then L waves. P waves are compressional, transverse waves. S waves are transverse, shear waves. Both P and S waves are body waves that can travel through all layers of the Earth. Rayleigh and Love (L) waves are surface waves. They move only along the Earth’s lithosphere, move at slower speeds and create a lot of damage with their rolling and back and forth sheer. The Richter scale is a logarithmic (base 10) scale measuring earthquakes based on energy released as measured by a seismograph. Because it is logarithmic, every point increase on the scale represents 10x as much energy released. The Mercalli scale measures an earthquake based on the impact to people, eg damage to cities. The mercalli scale is linear. Volcanic eruptions can be preceded by a rise in surface temperature nearby, the release of volcanic gases or by an increase in seismic activity. Earthquakes cannot be predicted with current technology, but seismic data can locate the epicentre and assist in sending aid to the correct regions. arge volcanic eruptions can send vast plumes of ash into the atmosphere, causing global dimming. The eruption of mount tambora in 1815 released so much volcanic ash, the resulting global cooling dropped global temperatures by 3oC and led to ‘the year without a summer’. Global food crops were affected and famine was widespread. Volcanic eruptions can cause widespread acid rain and the falling of volcanic ash