Science Semester 2 PDF

Science Semester 2 Created @November 22, 2024 10:27 AM Class 08SCID Type Revision Status Done Reproduction Making a new individual Reproduction is the process by which parents pro...

Science Semester 2 Created @November 22, 2024 10:27 AM Class 08SCID Type Revision Status Done Reproduction Making a new individual Reproduction is the process by which parents produce new individuals. The new individuals are called offspring. The two main basic methods of reproduction include: -Sexual reproduction: usually requires two parents -Asexual reproduction: means without sex, and so only needs one parent Sexual reproduction happens when a sperm from a male enters an egg from a female and fertilises (fertilization) Sperm (male) and eggs (female) are special reproductive cells call gametes Fertilization results in a cell called zygote Some species have individuals that have both male and female sex organs means they can produce both sperms and eggs Individuals with both sex organs are known as hermaphrodites such as: snails, fish etc. Cell Division and Gametes Cells normally reproduce by splitting into two to form two identical cells, each cell containing all the genetic information it needs a Mitosis Sperm and eggs are formed by a different type of cell division called meiosis and occurs only in the male and female reproductive organs Each gamete splits into four cells, all different from one another The new gamete only has half the genetic information that a normal cell has which means in order to obtain the full amount of genetic information, a sperm cell needs to fertilise an egg cell. The single fertilised cell has all the genetic information that will allow it to grow into a new individual. The fertilized cell is known as a zygote; it then divides repeatedly by mitosis Each cell splits in two, doubling the number of cells at each division until a new individual is formed Reproduction in Animals Males Females - Have organs called testes, which produce sperm. - The ovaries make the egg cells. - Sperm pass from the testes to the outside of the - The eggs pass from the ovaries down tubes called body through a tube called the sperm duct oviducts. Science Semester 2 1  - The eggs may then be fertilised outside or inside the female’s body. Fertilisation Internal External - Happens inside the body - Happens outside of the body - All land animals use internal fertilisation, as do - Most fish reproduce externally. some water-based animals. - The water stops the sperm from drying out and the - Copulation is the act of sex and allows a male to sperm can swim through it. transfer sperm to the female. - This can happen in different ways (mammals: the male inserts the penis into the female and in the octopus the male transfers sperm with one of his tentacles. Comparing Reproductive Organisms: Flowers & Pollination Development: The change in form and structure of an individual over its life from zygote to adult. Internal The young develops inside the mother’s body, usually in the uterus. Remain in the uterus until birth. Cats, dogs, cows, horse, sheep, whales and humans are all examples of mammals that go through this type of development. Sexual reproduction in flowering plants - Flowers are reproductive structures in plants that produce gametes and allow fertilisation to occur, this results in a seed To form a seed: Pollen is produced in the anther. The pollen is deposited on the stigma. This transfer of pollen is known as pollination. The pollen grain develops into a long tube called the pollen tube. This tube grows down through the style to the ovary and into the egg. In the ovary, the egg is inside a structure known as the ovule. The male gamete passes down the pollen tube to join the female gamete in the ovule. After the gametes join, a seed gradually develops. - Seeds develop in the fruit - A fruit is the remains of the ovary, plus all the seeds it contains (some appear as seed cases or pods) - A seed is a capsule containing a new plant, called an embryo (early stage of development) - The embryo in a seed is dehydrated and requires water and warmth before it will grow. - The embryo then sprouts out of the seed in a process called germination. - The embryo begins to make its own food when it reaches sunlight above the ground. Asexual Reproduction No joining of egg and sperm. Science Semester 2 2  - The young grows from part of the parent’s body or from an unfertilised egg. - The individual is produced by mitosis. Asexual reproduction in animals can happen in a number of ways including, Budding Fission Parthenogenesis Budding Hydra are small freshwater animals that grow to around 10mm long and can reproduce both sexually and asexually. The young hydra grows from a bud on the side of its parent, and will soon break off the parent and lead a separate life Other animals that reproduce in this way are corals and some sponges. Fission Some sea stars can reproduce asexually, begin splitting near the mouth and divide into two. Splitting in two is a method of asexual reproduction. The ability to regrow arms helps sea stars to survive on coral reefs. Rough waves may break a sea star into pieces, if there is some mouth tissue attached then they will grow arms to form a new, complete sea star. Parthenogenesis A type of asexual reproduction where offspring develop from eggs that have not been fertilised by a male. Happens in water fleas, aphids, bees and a small number of reptiles and fish. Cloning The process of producing identical individuals through reproduction. Asexual reproduction always produces clones. A clone is an exact copy of a particular individual. Humans can produce clones using a process called cloning, the clone has the same features as the parent from which it was copied. Cloning in agriculture Used in agriculture to copy a plant with a desired characteristic; and then produce a crop of near identical plants. Each plant in the crop then has the same desired characteristic Can improve plants so that they produce more fruit, vegetables, seeds, oils, perfumes, flowers or medical drugs; farmland becomes more productive (yield). Advantages of cloning: Can be used to produce plants that are resistant to certain insects or diseases, such as fungus. Another advantage is that fruit and vegetables can be similar in appearanc Science Semester 2 3  Cloning plants Involves taking many small sections from one desirable plant and then growing them into complete plants. An entire crop can be grown as the process can be repeated to make as many copies of the parent plant as needed. Plant tissue culture A method of cloning plants that is carried out in a laboratory. Is expensive but is widely used because it is quick and can be used all year round in any climate Cell tissue culture A method where individual cells are cloned, instead of part of a plant. Cells don’t always copy exactly and variations can occur. The more often a cell divides, the more changes there will be; the new plants will be different to the parent plant. Plant breeders can select plants that have the characteristics they want (resistance to disease or drought, better fruit or faster growth).Plant tissue culture A method of cloning plants that is carried out in a laboratory. Is expensive but is widely used because it is quick and can be used all year round in any climate Cuttings Another cloning technique Similar to tissue culture but does not need expensive laboratories and equipment. Often used in plant nurseries, vineyards, orchards and in home gardens The process follows simple steps: Cuttings Another cloning technique Similar to tissue culture but does not need expensive laboratories and equipment. Often used in plant nurseries, vineyards, orchards and in home gardens Reproduction Roles of human reproductive systems The role of the female reproductive system is to produce a baby The role of the male reproductive system is to produce and deliver sperm The main structures of females: 1. Ovaries 2. Fallopian tubes (also known as oviducts) 3. Uterus (‘womb’) 4. Cervix 5. Vagina Ovaries: Function: Where eggs are produced (single egg = ovum) Science Semester 2 4  There are two ovaries, (which are about the size and shape of almonds) which produce female hormones (oestrogens and progesterone) and eggs (ova). The ovaries are held in place by various ligaments which anchor them to the uterus and the pelvis. Ovulation: Once an egg is mature, it ruptures and the egg is ejected from the ovary into the fallopian tubes. This is called ovulation. Ovulation occurs in the middle of the menstrual cycle and usually takes place every 28 days in a mature female. It takes place from either the right or left ovary at random. Fallopian tubes Function: The tubes that the egg passes along on its way to the uterus; this is where fertilisation occurs if a sperm and egg meet. The fallopian tubes are about 10 cm long The egg is moved along the fallopian tube by the wafting action of cilia (hairy projections on the surfaces of cells at the entrance of the fallopian tube) and the contractions made by the tube. It takes the egg about 5 days to reach the uterus and it is on this journey down the fallopian tube that fertilisation may occur if a sperm penetrates and fuses with the egg. Uterus Function: Thick walled muscular organ with a hollow cavity about the size of a pear that exists to house a developing fertilised egg. The thick wall of the uterus is composed of 3 layers: The inner layer is known as the endometrium. If an egg has been fertilised it will burrow into the endometrium, where it will stay for the rest of its growth. The myometrium is the large middle layer of the uterus, which is made up of interlocking groups of muscle. It plays an important role during the birth of a baby, contracting rhythmically to move the baby out of the body via the birth canal (vagina). Cervix Function: A ring of muscle that tightens to hold the uterus closed while the baby is developing (this protects the baby in the womb); it contracts and opens when the baby is about to be born. Vagina Function: Where the sperm is deposited and is also the birth canal. The vagina is a fibromuscular tube that extends from the cervix to the vestibule of the vulva. The vagina receives the penis and semen during sexual intercourse and also provides a passageway for menstrual blood flow to leave the body. The Menstrual Cycle - Reproduction in males and females is controlled by chemicals called hormones that are produced in the body and travel around in the blood. - Menstrual cycle includes menstruation (period): the thickened lining breaks down if the egg is not fertilised and implanted and passes out of the body. - On average, females experience a 28-day menstrual cycle with 3 main stages: 1. Tear down 2. Rebuild Science Semester 2 5  3. Extra nutrients/blood for potential baby…. No baby? Then the process happens all again Hormones 1. Follicle stimulating hormone (FSH): Causes follicles to move 2. Luteinising hormone (LH): Makes egg burst out of follicle. This is called ovulation 3. Oestrogen: Makes the lining of the uterus go thicker and increases blood support Male Reproductive Systems The role of the male reproductive system is to produce and deliver sperm The main structures of males: 1. Testes 2. Epididymis 3. Vas Deferens (Sperm Duct) 4. Seminal Vesicles 5. Urethra 6. Prostate gland Testes Function: Produce Sperm The paired oval testes hang in the scrotal sac (scrotum). The testes hang outside the body because the temperature inside the body is too high to produce sperm, so they are produced in the testes at about 3 °C lower than body temperature. Epididymis Function: Collect the immature sperm from the testes. As the sperm make their long journey through the epididymis they become mature sperm. This journey takes about 20 days and during its course the sperm become fertile and they also become able to move in a swimming motion Vas Deferens (Sperm Duct) Function: A thick walled tube which transports sperm from the epididymis up to the prostate gland. Joined to the epididymis (Sperm duct) is the vas deferens The vas deferens empties into the ejaculatory duct, which passes through the prostate gland to merge with the urethra. Seminal Vesicles Function: Add fluid to sperm Fluid is added to the sperm from glands called seminal vesicles (contains various chemicals, such as sugars that provide an energy source for the sperm) Urethra Function: Where fluids (sperm or urine) exit from The urethra serves as the tube down which urine passes from the bladder through the penis to the outside and also the tube down which semen (mixture of sperm with other fluids) is ejaculated. Science Semester 2 6  Prostate Gland Function: 1. More difficult to urinate 2. More difficult to ejaculate The prostate is a walnut-shaped gland that surrounds the urethra. Along with the seminal vesicles it produces the fluid secretions that support and nourish the sperm. Without this fluid to dilute them the sperm cannot move easily. After the age of 40 the prostate enlarges and can press on the urethra. An enlarged prostate is often the cause of urinary problems in older men. Puberty - The time in a person’s life when they become sexually mature and able to reproduce. - Many physical changes occur during this time and take several years to complete. - The time when puberty begins varies greatly. - For girls, puberty usually begins at 12 years of age. - For boys, puberty usually begins at about 13 years of age. Every person’s body is different – you reach puberty when your body is ready Changes in Males Changes in Females The early changes of puberty are increased levels of The early changes are increased levels of hormones some hormones such as testosterone such as FSH and LH. These hormones cause an increase in oestrogen Enlargement of the testes The breasts begin to enlarge Sperm formation by the testes Hair growth on the armpits and groin Growth of the penis A sudden increase in height The voice ‘breaking’ to become deeper Periods Hair growth on the face, arms, chest and groin Widening of the hips Increased muscle and bone growth and strength More fat deposited around the hips Sudden increase in height and chest capacity Wet Dreams Testes drop Pregnancy Fertilisation and Conception Copulation When two individuals join together for sexual reproduction. In humans, it is also called sexual intercourse. Ejaculation Release of 300-500 million sperm Sperm to egg, not an easy task Go wrong direction : 2 paths – only 1 leads to an egg Science Semester 2 7  Get attacked by female’s white blood cells Acidic environment Current Once the egg is found… A protective layer around the egg dissolves Once one sperm gets through & enters egg Instant biochemical change in zygote (so no more sperm allowed in) After gametes fuse… the zygote develops The first cell of the new individual is called a zygote. The zygote begins to divide as it travels down the fallopian tube. The zygote keeps dividing until it forms a hollow ball of cells called a blastocyst. Implantation in the uterine wall - The blastocyst reaches the uterus about five days after fertilisation and it burrows into the wall in a process called implantation. Endometrium= outer lining of uterus ◦ Becomes placenta Uses mother’s nutrients Continues development The Embryo - The developing baby is referred to as an embryo for the first 8 weeks. - A baby usually takes 38 weeks to develop from - This is a critical period of development as all the fertilisation to birth. different cells, such as nerve, muscle and bone are developing. - The baby can be damaged by smoking, alcohol and other legal and illegal drugs. Around the 7th week… Baby’s body is “told” by DNA to become either male or female (biological sex determination) This comes from chromosomes (packaged DNA): DNA determines baby’s sex XX = Female XY = Male Depends on which egg & sperm get together. The father determines baby’s biological sex. Foetal development Development Membranes surrounding baby (placenta) Contains amniotic fluid Breaks just before birth = “water broke” Science Semester 2 8  Amniotic Fluid The “water” – surrounding baby Buoyant ‘balloon like’ cradle for baby Protection (shock absorber) Free movement Placenta Placenta Highly folded series of membranes and blood vessels which allows nutrients and oxygen from the mother to enter the baby. The placenta is connected to the embryo by the umbilical cord; contains blood vessels from the embryo. Mom’s & baby’s blood do not circulate together Can have 2 different blood types Diffusion Once an embryo…now a foetus - Most of the major organs and systems have been formed when the embryo is about 9 weeks old. - The external appearance looks more human like. - It increases in size and the organs mature so they can function at birth and the developing baby is now called a foetus. Gestation The period during which the baby develops in the uterus. - A baby develops for about 266 days (38 weeks). - Doctors usually talk about “weeks pregnant” as menstrual cycles vary in length, and they can’t be sure when ovulation occurred. The weeks pregnant are usually counted 14 days before fertilisation, birth is at ‘40 weeks’ or 280 days from the last menstruation Labour & Birth - Birth is part of the process called labour (can last a few hours to a day or more. 1. Pain in the abdomen is the first sign of labour (uterus contraction & relaxation) 2. The contractions become stronger, more painful and occur closer together which is a sign that birth is not far away. 3. The cervix dilates, relaxing and widening causing the amniotic sac to burst and then the baby begins to pass through the cervix. - After baby is born the mum delivers placenta (“afterbirth”) that detaches from uterus Substances and Change Starting Notes Every substance in the universe is made up of building blocks known as atoms. Only 100 types of atoms. Science Semester 2 9  These atoms can be arranged in different combinations to make different substances. Unlike lego, atoms are round and are so small that they cannot be seen with the most powerful optical microscope. Scientists must use a scanning tunnelling microscope (STM) to obtain images of atoms such as the copper atoms shown below. The Atom Atoms consist of: Neutrons (Neutral Charge) and Protons (Positive Charge) in the nucleus. Electrons (Negative Charge) in the electron shells (can be seen as an electron cloud) Elements Substances that are made up of just one type of atom. E.g. Copper is an element because it is only made up of only copper atoms. They each have a unique set of characteristics that are referred to as properties. These properties determine whether an element is classified as metallic or non-metallic. The properties also determine how the elements can be used. Metallic Elements Non-Metallic Elements Tend to be shiny or can be polished to make Tend to be dull (not shiny). them shiny (lustrous). Do not conduct heat or electricity (insulators). Solid at room temperature (except Mercury). Break or crumble when you bend them (brittle). Good conductors of heat and electricity. Have lower melting and boiling points than Can be bent and hammered into sheets metals. (malleable). Tend to be solids or gases at room temperature. Can be stretched into wires (ductile). The Periodic Table 118 known elements (only 98 occur naturally – the rest must be made in a laboratory) All of the known elements are displayed in a table called the periodic table. Lists the elements from lightest to heaviest and helps scientists to understand some of their properties. Groups These are the vertical columns in the table. There are eight groups and the transition metals have their own special group. All elements in the same group have the same number of electrons in their outer shell (valence electrons) As you go down a group the elements become more reactive. Periods These run across the periodic table. All elements in the same period have the same number of electron shells e.g. those elements in period 1 have 1 electron shell Science Semester 2 10  Chemical Symbols Often, the chemical symbol of an element comes directly from its name. E.g. Calcium is given the symbol Ca Sometimes, the chemical symbol of an element does not appear to relate to the name at all. E.g. Potassium has the symbol K Sodium - Na Atoms in Elements Elements are made up of just one type of atom. The atoms in elements can be arranged in different ways. The atoms can exist: As single atoms In clusters of atoms called molecules In large grid like structures called crystal lattices The way the atoms are arranged in an element determines many of the physical properties of the element. For example: whether the element is solid, liquid or gas, its melting and boiling point, how well it conducts heat or electricity and if it bends or breaks when a force is applied. Monatomic Elements An element that is made up of individual atoms. Rare, with only six of 98 occurring naturally. Examples include: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn) – Nonmetallic gases. Helium is monatomic and has a low density that makes it lighter than air which allows it to float. Molecular Elements Molecules are clusters of two or more atoms bonded (joined) together All the molecules are identical, with the same size, shape, number and type of atoms The oxygen you are breathing right now is made up of billions of oxygen molecules Scientists represent oxygen gas by the molecular formula O2  ​ Some elements are made up of molecules with more than two atoms. For example, phosphorus molecules commonly have four atoms, giving it the molecular formula P4  ​ Crystal Lattices Grid like structures that repeat the same arrangement of atoms over and over. All metallic elements form crystal lattices whereas only a few non-metallic elements form crystal lattices. Science Semester 2 11  Metallic Lattices 80% of elements are metals. The atoms in metals form lattices rather than molecules. Lattice structure makes metals dense, strong and solid at room temperature (mercury is the only exception). Important materials for construction and manufacture of a large variety of objects. The atoms can slide and move over each other without breaking the lattice; metals can be bent, drawn into thin wires or hammered into thin sheets. Non-Metallic Lattices Only a few non-metallic elements form lattices. Example: Carbon forms crystal lattices to make graphite and diamond. In graphite, the carbon atoms form sheets that are stacked on top of each other. They can slide across each other. The lead in grey-lead pencils is also made of graphite mixed with clay and as you write, the thin layers of graphite are slowly rubbed off onto the page. Compounds Most substances we encounter every day are made up of more than one type of atom. These forms of matter are known as compounds Each compound has a unique set of characteristic properties. The properties of compounds are usually very different from the properties of the elements that make them up. Some compounds are made up of molecules (water, wax and vegetable oil). Other compounds form crystal lattices. Molecular Compounds All the molecules in a compound are identical in size and shape, and have the same number of atoms Scientists use chemical formulas to represent the molecules of a compound. The chemical formula for a molecular compound is also known as a molecular formula (describes how many of each atom make up the molecule). The number of each type of atom in the compound is written in subscript (written below the line). Lattice Compounds Science Semester 2 12  Compounds can also form crystal lattices. The atoms are bonded very strongly to each other, so these compounds tend to be hard solids at room temperature Examples include table salt (NaCl) and beach sand. Have different chemical formulas than the molecular formulas for molecules. Example: The lattice for table salt can be seen on the right. The scientific name is sodium chloride and its chemical formula is NaCl. Molecular Formulas Chemical and Physical Change Chemical and Physical changes occur in substances. Physical relates to the structure of the particles and the substance itself whereas in chemical change it relates to the molecules and particles inside the structure. Physical Change Chemical Change Expands - Balloon Inflating Colour Change - Leaves becoming orange Contracts - Crushing a can Production of Gas - Photosynthesis Changes Form - Crushing a can Precipitation Occurs - H2 ​ + O = H2 0(Water) ​ Changes State of Matter - Melting Ice Temperature Change - Combustion Reversable Irreversible Terms for Change Solid - Liquid = Melting Liquid - Solid = Freezing Liquid - Gas = Evaporation Gas - Liquid = Condensation Solid - Gas = Deposition Gas - Solid = Sublimation Word Equations SkillBuilder Word equations Chemists usually don’t use detailed descriptions or diagrams to describe what is happening in a Science Semester 2 13  chemical reaction. Instead they use a shorthand description known as a chemical equation. The simplest chemical equation is a word equation. A word equation lists the reactants taking part in the reaction and the products that form. All chemical equations are written in the form: reactants → products The arrow indicates that a chemical change has taken place. Chemical Reactions Combustion Combustion is the term given to any chemical reaction that involves burning with oxygen to release light and heat. Sometimes combustion releases so much energy so quickly that an explosion occurs. An explosion happens when petrol is ignited. Likewise, when hydrogen ( H2 ) is heated with oxygen (O2 ), they react explosively to produce water vapour (Figure 7.3.6). The word ​ ​ equation for this reaction is: hydrogen + oxygen → water vapour Photosynthesis Photosynthesis is a series of chemical reactions that uses sunlight to convert water (H2O) and carbon dioxide (CO2) into oxygen (O2) and a form of sugar called glucose (C6H12O6). The word equation for photosynthesis can be summarised as: carbon dioxide + water → oxygen + glucose Respiration The process of obtaining energy from food is known as respiration. Respiration involves a chemical reaction that converts oxygen and glucose into carbon dioxide and water vapour, while releasing energy. The word equation for respiration is: glucose + oxygen → carbon dioxide + water vapour Corrosion Corrosion is a chemical reaction that can cause damage to metals. For example, iron (Fe) and steel (an alloy of iron) have chemical properties that cause them to react slowly with water and the oxygen gas in air. The product is iron oxide (F e2 O3 ), commonly known as rust. The word equation for this reaction is: ​ ​ iron + water + oxygen gas → iron oxide Energy Starting Notes 5 Forms of Energy Kinetic Energy (Movement) Potential Energy Sound Energy Light Energy Electrical Energy Science Semester 2 14  Units for Energy Energy is measured in Joules 1000 Joules in a Kilojoule 1 000 000 joules in a Megajoule Stored Energy (Potential Energy) Stored energy gives objects the potential to make things happen! Known as Potential energy E.g. Photosynthesis! 3 types of Potential energy Gravitational potential energy (GPE) is energy stored in an object when it is above the ground. The greater the height of an object the more gravitational potential energy it has. Chemical energy is energy stored in substances. This energy is released by your body when you digest food, and by cars when fuel is burnt. Wood, paper, apples, petrol and batteries all contain chemical energy. Elastic potential energy is energy stored in a stretched or squashed spring. Stretched rubber bands also store elastic potential energy, which is released when they are let go. Energy: Transformation and Transfer Energy can be transferred from one object to another and can also be transformed from one type of energy into another type of energy. For example, a TV converts electrical energy into sound, light and heat energy. The transformations can be shown in an energy flow diagram. Energy Transfer Energy transfer is when energy is passed between objects e.g.: kicking a ball (kinetic energy from your foot is transferred to the ball, making the ball move) Heat Transfer Heat transfer can happen in three ways: Conduction Convection Radiation Conduction The transfer of heat through direct contact Science Semester 2 15  Conductors Substances that transfer heat easily are known as conductors Insulators Materials like wood, feathers, air and plastics are all very poor conductors of heat, and sometimes can block heat transfer completely. Such substances are known as insulators. Convection The transfer of heat through the movement of fluids (fluids don’t only mean liquids they also include air) The hot air is less dense then cold air so the cold air is pushed downwards resulting heat to be transferred. Radiation Heat transferred from a heat source reaching you by travelling Sound Energy Sound Waves Sound is a type of energy produced by vibrations The vibrations push the nearby air particles Like waves Vibrating air particles have kinetic energy But the air particles do not travel Characteristics of sound Pitch – the faster the particles vibrate, the higher the pitch Frequency – the number of waves that travel past a particular point (Hertz Hz) Wavelength – the length of one wave in meters Loudness – how far the particles move - high kinetic energy = loud (decibel dB) Science Semester 2 16  Frequency, wavelength and speed The speed of sound depends on the material the sound travels through. - The closer the particles - the faster the sound will travel Light Energy Light Waves Light Energy travels as a wave but travels much faster than sound Light does not need a material to travel through so it can reach Earth from the sun through empty space Electromagnetic Radiation Energy is released from the sun is called electromagnetic radiation. Light is a form of electromagnetic radiation The complete range of electromagnetic radiation released from the sun is called the electromagnetic spectrum Light Energy Can Be… The colours we see are the wavelengths that are reflected or transmitted E.g. Red shirts look red since the dye molecules in the fabric have absorbed the wavelegnths from the violet/blue end of the spectrum. Red light is the only light that is reflected from the shirt. Concave vs Convex Lenses Science Semester 2 17  Concave mirrors curve inward Convex mirrors curve outward Geology Introducing Geology – The Earth and its rocks Mine: Equinox oil drilling in the Great Australian Bight, off South Australia Refer to "The Earth and its rocks (Ch 8.1)" : Read p. 325 and answer these questions. 1. What is Geology? The science of earths physical structure and substances 1. Label the different structures of the earth (A – G) ocean, crust , asthenosphere, mantle, outer core, core, inner core 3. How do scientists know what is inside the earth? Scientists know what is inside the earth by gathering information from earthquakes, meteors and volcanic eruptions which gives geologists data on the earth and it’s structure. 4. Group research work. You need to work in groups of four. Each student in your group has to find out at least 5 pieces of information about a layer in the earth. Collate all the information in the table below. Find out the thickness, temperature, rocks and minerals present, etc. Earth’s layer Information minerals found Earth's crust is (i) can range from in the Earth's The Earth's made up of (ii) 3 to 43 miles the air crust include: crust is its continental Crust (iii) (4.8 to 69 temperature at amphiboles, lightest, most crust (lighter) (iv) kilometers) the surface to micas, garnet, buoyant rock and oceanic (v) around 870°C calcite, and layer. crust (denser) olivine. Mantle (i) 2,900 1000°C olivine, garnet, The transfer of arth's mantle (ii) kilometers (1832°F) near and pyroxene. heat and plays an Science Semester 2 18  (iii) (1,802 miles) its boundary The other material in the important role (iv) with the crust, major type of mantle helps in the evolution (v) to 3700°C rock found in determine the of the crust (6692°F) the mantle is landscape of and provides magnesium Earth. Activity the thermal oxide. Other in the mantle and mantle drives plate mechanical elements tectonics, driving forces include iron, contributing to for plate aluminum, volcanoes, tectonics. Heat calcium, seafloor liberated by the sodium, and spreading, core is potassium. earthquakes, transferred into and orogeny the mantle (mountain- where most of building) it (> 90%) is convected through the mantle to the base of the lithosphere. (i) The outer core Temperature: (ii) Thickness: Rocks and Outer core is creates Earth's between Outer Core (iii) 2,200 minerals: liquid liquid part of magnetic field, 4,500° and (iv) kilometres iron and nickel. the core which protects 5,500° Celsius (v) all life on Earth. Earth’s core is the very hot, very dense centre of our planet. Earth is Rocks: the divided into The inner core, inner core is three main formed 1-1.5 composed layers. The billion years primarily of iron dense, hot ago, rotates and nickel and inner core slightly faster (i) Heat: 10,800º F has the highest (yellow), the Thickness: 760 than the rest of (ii) or about the density among molten outer miles (∼1,220 the Earth. Its Inner Core (iii) same all other layers. core (orange), km) properties offer (iv) temperature of The inner core the mantle valuable (v) the sun is made mostly (red), and the insights into the metals such as thin crust planet’s early gold, platinum, (brown), which history and the palladium, supports all life forces shaping silver, and in the known its structure. tungsten. universe. Earth’s core is the very hot, very dense centre of our planet. 1. A mineral is the building block of rocks. Define a mineral (refer to chapter 6.3 if needed): A mineral is a naturally occurring substance found in solids which are not made by any living organism 2. Why do scientists use the Rock Cycle? It helps them to find out where the energy is coming from Scientists study the rock cycle to understand how rocks can change and how they relate to Earths history. Science Semester 2 19  3. Name the three types of rocks, how are they formed and where would you find them. Summaries in the table below. Name of rock Where is it found? How are they formed? Granite Granite can be found all over the world the large Granite is formed during the cooling of molten amounts in North America,South America, Europe rock and Asia. Andesite It is formed when crust under goes subduction Andesite is found in the Andes mountains. where it melts and returns to the earths surface Basalt is formed by rapid cooling of molten Basalt Basalt is found all over the planet. lava. 1. Rock cycle shows each of these rocks can be changed into the other types by a variety of processes. Explain what happens during these processes: Weathering - Weathering refers to the breaking down or dissolving of rocks and minerals on the Earth's surface. There are two main types of weathering: physical and chemical. Erosion - Erosion is the process by which the surface of the Earth gets worn down. Deposition -Deposition is a geological process where material carried by wind, water, or ice is left or deposited in a new location. Compaction and cementation - compaction is when sediment is pushed together by the weight of water and other sediment pushing down on it. Cementation is the last stage in the cycle and happens when sediment is glued together by minerals such as silica and calcium carbonate as the minerals infiltrate pore space between compacted sediment. Melting - If enough heat is applied to a substance, then it will change state from a solid to a liquid (melting) Crystallisation - crystallisation is the process of formation of solid crystals from solution, melt or by deposition directly from a gas phase. Metamorphosis -he process of basic and usually rather sudden change in the form and habits The rock cycle: Label the missing parts in the diagram using pg. 326 Discover – Weathering (Homework Task if not finished) In Geology, weathering is the process by which rocks are broken down into smaller pieces. There are three types of weathering: physical, chemical and biological. Read p. 327 – 329 and summarise how each of these processes actually break down the rock. Physical Weathering Chemical Weathering Biological Weathering Wind: The physical forces of wind act on the loose rocks, acid rain: Acid rain can Animals: Small animals can leaving them sculptured and denudated. Wind forces carry affect things like rocks by burrow into a rock and break small particles and rocks that collide with the rocks, which its acidic nature.Chemical it downPlants: Plants can also end ups wearing them away. Temperature change: The Weathering: This occurs enter a rock and as the plant change of temperature contributes to expansion of when the rock’s minerals grows the rock slowly breaks contraction of the rocks. When the temperature of a rock are chemically altered or downBiological Weathering: rises, the rock expands. When the temperature of the rock dissolved. Processes This type involves the decreases, the rock contrancts. This is because the outer involved in chemical disintegration of rocks and surface is more exposed than the inner surface. Water weathering include minerals due to biological and ice: Water and ice break down a rock since when water hydrolysis (reaction with activity. This can occur Science Semester 2 20  enters a crack of a rock it freezes which slowly expands water), oxidation (reaction through physical processes, crushing the rock. Crystallization of salt: Water breaks with oxygen), carbonation such as the growth of roots in down the molecular structure of salt and when water dries up (reaction with carbon cracks in the rock, or through the 2 elements join together. Physical Weathering: This dioxide), and acid rain chemical processes, such as type is also known as mechanical weathering, where the rock (where rainwater is more the production of organic is broken down into smaller pieces by physical forces. acidic than normal, often acids by lichens and mosses Physical weathering can occur due to temperature changes due to pollution). that live on the rock surface. (thermal expansion and contraction), freeze-thaw cycles (where water freezes and expands in cracks, causing them to widen), plant roots growing into cracks, and abrasion from water, wind, or ice carrying sediment that grinds against rocks. Igneous Rocks Sedimentary Rocks Metamorphic Rocks Forms when magma or How are they lava is crystalised Rocks made from sediments, Metamorphic rocks form when formed? overlaying sediments compact intense heat causes existing rocks Can also be formed when sediments to remove excess water to physically or chemically alter or magma or lava crystalises creating a sedimentary rock change. between layers of rock beneath the surface - Granite - Slate - Basalt - Conglomerate - Schist - Obsidian - Mudstone - Gneiss Examples - Pumice - Sandstone - Marble - Scoria - Breccia - Quartzite - Dolerite Science Semester 2 21 Science Semester 2 22