Science EOYE 2024 Revision PDF

Science EOYE 2024 REVISION Year 9 21/11/2024 Cells & Microscopes Characteristics of a Living Being (All living beings must show all 7 characteristics as well has having cells) Movement All living organisms show movement of one kind or another. Respiration Living organisms must be able to carry ou...

Science EOYE 2024 REVISION Year 9 21/11/2024 Cells & Microscopes Characteristics of a Living Being (All living beings must show all 7 characteristics as well has having cells) Movement All living organisms show movement of one kind or another. Respiration Living organisms must be able to carry out the process of burning up food to obtain energy to move, grow and repair. Sensitivity Living things react to changes around them. Growth When living things feed they gain energy and grow in size.. Reproduction All living things produce young. Humans make babies, seeds can germinate and grow into new plants. Excretion Excretion is the removal of waste from the body. If this waste was allowed to remain in the body it could be poisonous. All living things need to remove waste from their bodies. Nutrition All living organisms must be able to obtain food in order to grow & repair their tissues. Two types of Non-Living Beings - Those which were never part of a living thing (e.g. stone, gold) - Those which were once part of a living thing (e.g. rubber, jam) 1 Parts of A Cell Cell Part (Organelle) Function Plant Cell Animal Cell Cell membrane Controls the Present Present movement of substances in and out of the cell Cell wall Provides strength Present Not present and structure to the cell Cytoplasm Provides the shape Present Present of the cell Vacuole Stores food, water Present Present and waste in the cell (Has a large vacuole) (Has a small vacuole) Chloroplast Provides energy Present Not Present through photosynthesis Mitochondria Provides energy Present Present through respiration Nucleus The control center Present Present of the cell- looks after the growth and the reproduction of the cell Differences between a Plant Cell and a Animal Cell Plant Cell Animal Cell 1 Regular in shape, larger in size Irregular in shape, smaller in size 2 Has chloroplast Does Not have chloroplast 3 Has cell wall Does Not have cell wall 4 Has large vacuole Has small vacuole 2 Why do plant cells have a chloroplast while animal cells don’t? While the plant receives energy from photosynthesis, which is done using sunlight, carbon dioxide and water. Meanwhile, an animal cell doesn’t need a chloroplast since it receives energy by eating food and doesn’t need to use photosynthesis. Why do plant cells have a cell wall while animal cells don’t? While the plant cell relies on the cell wall for structure and strength inside the plant, the animal body doesn’t need to have to rely on an organelle since it has only ways of structural support such as the skeleton and bones. Why do plant cells have a larger vacuole than an animal cell? While the plant cell relies on the vacuole to store food, water and waste, the animal body doesn’t need to rely on an organelle since it has organs to store food, water and waste in such as the liver, stomach and bowels. The function of the following microscope parts: a. Coarse focus knob: Moves the stage up and down over large distance to focus onto the specimen b. Fine focus knob: Moves the stage slightly in order to perfect your focus c. Stage: holds the slide d. Stage clip: holds the slide in place e. Eyepiece lens: magnifies the specimen 3 Magnification: To work out the magnification of the microscope you multiply the magnification of the eyepiece and the magnification of the objective lens. Preparing a Microscope Slide: Function of the coverslip: protects the lens/ prevents the specimen from drying/ prevents the specimen from moving Why are chemical stains often used when preparing microscope slides: Stains colors/darkens the transparent cell structures and makes them visible. Why must your specimen be thin and transparent: So that light can pass through it and it can be viewed. What do you need to be careful of when laying the coverslip on the specimen? To prevent the formation of air bubbles. Often placed at an angle of 45 degrees. Name the stain used for plant and animal cells. Plant cell- iodine solution Animal cell- methylene blue Why do you think it is important to hold the coverslip at the sides only? To prevent making fingerprint marks on the slide which will allow a quality image What does the stain do? Stains colors/darkens the transparent cell structures and makes them visible Why is it important that we start at the lowest objective lens and move up to the highest? What might happen if we started with the highest objective lens first? Starting with the lowest power prevents breaking the slide and damaging the lens. Whereas while starting with the highest power, one can damage the lens and slide/ find it difficult to locate the specimen. 4 Biological Drawings RULES Always use a sharp pencil, never use a pen. Drawings should be large – usually half a page minimum. The drawing should be centered in the space & sufficient room left for labels. Outlines should be sharp & clear. Color or shading is not used although some careful dots can be used to show variation in texture or contrast. When drawing objects seen through a microscope, don’t try to draw all the objects in the field of view; draw a large representative diagram showing two or three objects. Lines to labels must be ruled & should not cross. Each drawing must have a clear descriptive title. The title must give an idea of the scale (magnification) or viewed through hand lens or by the unaided eye. In some biological drawings descriptive information about the material is written about the drawings together with the labeling of different structures. 5 Nature of Matter How to find the volume of a shape: Regular: V=L✕W✕H Irregular: Water Displacement Method Everything is made of matter. Matter refers to the “stuff’ everything is made of. In science we call the “stuff” particles. When a substance is heated the particles will a) gain energy b) move more fastly/rapidly. Substances will diffuse faster if they are a: GAS Substances will diffuse faster if they are: HOTTER Expansion: When things get heated up, the particles gain energy and the gaps between the particles expand. Contraction: When things get cooled down, the particles lose energy and the gaps between the particles contract. Diffusion: When particles are in warmer atmospheres, they tend to move faster because the particles gain energy and move around. As they move around the gaps between the particles get bigger. STATE Rate of movement Spaces between particles Forces between particles moving freely and rapidly wide spaces between them not held together at all Gases 6  moving around freely but slowly fairly close together held together to some extent Liquids but free to move around vibrating or moving very slowly very close together, almost held together very firmly Solids touching Movement of States of Matter: Solid: The solid is in a fixed state that doesn’t have any space for it to move. Liquid: The liquid particles move around but not as freely Gas: The gas particles move around freely. Arrangement of States of Matter: Solids: Fixed state Liquids: Close together but not in a fixed shape Gas: Widely separated Physical Changes: - Is when one state changes into another state - Is reversible - No new substance is formed but there could be a change in shape, size or state of matter. Chemical Changes: - The change of one chemical substance to another - Is irreversible - A new substance could be formed and that there might be a change in the object’s physical and chemical properties. State Change Triangle Changes in States of Matter: Solid to Liquid: Melting Liquid to Solid: Freezing Gas to Liquid: Condensation Liquid to Gas: Evaporation Gas to Solid: Sublimation Solid to Gas: Reverse Sublimation Melting, evaporation and sublimation all require the substance to be heated. This affects the particles by giving them more energy and making them move faster and further apart. 7 Freezing, condensing and reverse sublimation all require the substance to be cooled. This affects the particles by taking away energy and making them move slower and closer together. Compounds, Mixtures & Elements Matter can be broken down into two categories: 1. Pure Substances: A material that is composed of only one type of particle. All the compounds or elements in a substance are the same. - Elements - Compounds 2. Mixtures: Physically combined structures that can be separated into their own components. They are not chemically bonded and so can be separated. Elements: Compounds: Mixtures: - A pure substance is - A pure substance - Physically combined made of one type of composed of two or structures that can be atoms. more types of atoms separated into their - Atoms are made of chemically bonded to original components. protons, neutrons and each other. They are NOT electrons. - E.g. water (H2O) CHEMICALLY BONDED - 118 different elements compound made up of so we can separate - E.g. carbon, hydrogen 2 hydrogen atoms and them/ one oxygen atom. - E.g. mud- contains water and sand. They are not bonded and can be separated. e.g) (a) compounds- D,C (b) elements- A,B (c) mixtures- E 8 Adding Potassium Permanganate crystals to water until the color disappears: What happened to the purple color? (What are our observations) The more times you dilute the water with potassium permanganate, the less color there is on the water. What does this tell us about the size of the particles? The more diluted the water got, the more the particles in the water moved apart and separated until they couldn’t be seen by the human eye. Air, carbon dioxide and helium Balloons are left for several days: What happens to the balloons? (What are our observations) The helium balloon is big in size and hangs right up. It has smaller particles. The next day, it had gotten smaller in size. The air balloon is hanging upside down and is small in size. It has bigger particles. The balloon had gotten smaller in size. The CO2 balloon is small in size and hangs upside down. It also has bigger particles. The balloon had gotten smaller in size. What does this tell us about the size of the particles? The smaller the particles are, the more particles can escape. That is why the helium balloon which had small particles got smaller while the air and CO2 particles were bigger in size so less particles were able to escape. What does this tell us about the mass of the particles? The particles would get lighter since more particles would leave the balloon. 50 ml of meths is added to 50ml of water in a measuring cylinder What happened when we added the meths to the water? The beaker measures up to 97ml after adding the meths to the water. What does this tell us about the size of the particles? 9 The size of the particles of the meth and the water are both small. When put together, the particles come together and some particles stay in the small gaps in between the water particles. What does this tell us about the spaces between the particles? The particles of the water are tiny and have spaces in between each particle. When you mix the meth and the water together, some particles from the meths squeeze into the gaps in between the water particles. Potassium Permanganate crystals are added to hot water or cold water What happened in each beaker? When potassium permanganate crystals are added to hot water, the potassium permanganate quickly dissolves and diffuses while when added to the cold water, the potassium permanganate takes a long time to dissolve and diffuse. What does this tell us about the speed of the particles? When added to the hot water, the particles diffuse faster because they gain energy from the hot water while when added to the cold water, the particles diffuse faster because they lose energy from the cold water. What does this tell us about the diffusion of the particles? When put into a hot atmosphere, particles gain energy and move faster while when put into a cold atmosphere, particles lose energy and move slower. Air freshener is sprayed into the air at the front of the room What happened when we sprayed the air freshener? The front of the class immediately smelt the air freshener, followed by the center of the class and then by the back of the class. The longer the smell stayed, the further it spread out. What does this tell us about the movement of the particles? 10 The particles of the air freshener gained energy and moved faster around the room, bumping into each other and spreading out. This movement is called diffusion. What is the key idea about particle movement that is shown in the experiment? Particles gain energy and spread out. The air particles diffused and spread around the room. Trying to compress air, water or wood in a syringe What happened when we tried to compress air, water or wood in a syringe? When we tried to compress the air, we easily were able to push the syringe and push the air out. When we tried to compress the water, the water sprayed out of the syringe. When we tried to compress the wood, we were unable to compress it since it didn’t move. What does this tell us about the spaces between particles in each state of matter? It was easy to compress air since air particles have a spread out structure with big spaces in between. It was easy to compress water since water particles have a spread out structure with small spaces in between. It was impossible to compress wood since the wood particles have a fixed, close together structure which doesn’t have any space in between the particles to move. A metal ball and ring- the metal ball is heated What happens when we heat the metal ball? (What are our observations?) Before heating the ball, the ball could easily go through the metal hoop. After heating the metal ball, the metal ball expanded and couldn’t go through the metal hoop. Once it cooled down again, the metal ball was again able to go through the metal hoop. What does this tell us about the energy of the particles? When the particles inside the metal ball get heated, they gain energy and the gaps between the particles expand. What does this tell us about the spaces between the particles? When the metal ball got heated, gaps between the particles expanded. When the metal ball cooled down, the gaps between the particles contracted. 11 Energy There are two types of energy: - Potential Energy: The stored energy, and the energy from something’s height from the ground. - Active Energy: The energy of movement. It comes from the motion of waves, particles and moving objects. Chemical Potential Energy: Energy that is stored in the bonds between the atoms. Found in substances like petrol and food. Gravitational Potential Energy: Energy stored in objects due to their height above the ground Elastic Potential Energy: Energy stored in stretched or squashed objects. Examples include springs and rubber bands. Kinetic Energy: Energy due to an object’s motion. Examples include moving cars, running and swimming. Electrical Energy: The movement of electrically charged particles. Found in wires, generators and lightning. Light Energy: The energy of electromagnetic waves. Found in microwaves, X-Rays and visible light. 12 Sound Energy: Energy produced by vibrating objects. Examples include speech, ultrasound and music. Heat Energy: Caused by the movement of atoms. Found inside all hot objects. Energy Changes 1) Energy Transfer: Energy transfer is the movement of the same energy type from one place or object to another. For example: If you sit in the sunshine, the heat energy transfers from the sun to you. If you kick a soccer ball, the kinetic energy transfers from your foot to the ball. 2) Energy Transformation: Energy transformation is the changing of energy type from one form to another. For example: As a ball rolls down a hill, gravitational potential energy is transformed into kinetic energy. This is because the ball gets faster, as it gets less high. This is the energy equation: Gravitational Potential Energy → Kinetic Energy Law of Conservation of Energy: Energy can’t be created or destroyed but it can be transformed from one form to another. Useful vs Wasted Energy: Energy transmissions are never perfectly efficient. When energy is changed from one form to another, some of the initial energy is changed to a form which is not useful or wanted. 13 Calculating Energy Efficiency Energy efficiency can be calculated using the following formula: E.g. a 100W light bulb converts 20W energy into light (20 ÷ 100)✕100= 20% energy efficiency. Renewable and Non-Renewable Energy Advantage Disadvantage Renewable Energy - won’t run out - High upfront costs - Has lower - Intermittent (not maintenance always available- requirements unfavorable - Save money weather) - echo-friendly - Limited storage capability Non-Renewable Energy - Easier to access - Cause pollution - High energy out - Runs out of supply 14 Types of Renewable Energy: Solar - used to convert the Sun’s energy into electricity Wind Power - is used to turn wind turbines and make electricity Hydroelectric Energy - uses the energy of the waves to turn turbines that make electricity Geothermal power - were formed in the Carboniferous period millions of years ago (before the dinosaurs) Biomass - uses the energy from plants and waste materials to make electricity Tidal Energy - comes from the movement of water in the sea by the tides. These tides happen twice a day. Wave power - is generated from running water. Dams are built across a lake or river in a valley to trap water. The water flows through tunnels and turns the turbines which make electricity. Types of Non-Renewable Energy: Fossil Fuels: uses the heat that come from deep rocks under the surface of the Earth Nuclear Energy: is made from radioactive uranium ore which occurs naturally in the ground Benefits and Challenges of Renewable Energy Benefits Challenges - Renewable energy sources can not - Some renewable sources rely on be used up certain factors such as lots of wind, - Renewable energy does not produce rain (for hydropower) and sunny greenhouse gasses of pollution days (for solar power) - In New Zealand, there is good - Some types of renewable energy access to geothermal energy, wind disturb natural environments and power and water for hydroelectric can be expensive to set up power Heat Transfer: This is the transfer of heat energy from a higher temperature object to a lower temperature object. 15 Three Types of Heat Transfer - Conduction: the flow of heat through a solid when particles gain energy and vibrate faster. This energy is passed to adjacent particles throughout an object. - Heat transfer takes place between objects by direct contact. - Objects that are good at conducting heat (metals) are called thermal conductors. - Objects that can not conduct heat (fur, wool, plastic) are called thermal insulators. - Convection: Transfer of heat through the movement of liquid and gasses. - This is because liquids and gasses expand when they are heated, which makes them less dense in particles rising, the colder liquids are more dense and sink down. - Radiation: Heat transfer occurs through electromagnetic waves without involving particles. - White shiny surfaces are good reflectors of heat and so don’t absorb heat very well. When hot, they cool down by emitting heat quite slowly. - Black dull surfaces are good absorbers of heat and so absorb heat well and heat up faster. When hot, they are good emitters of heat so cool down more quickly. Good Absorbers: Dull, dark colored objects make good absorbers. Good Reflectors: Light colored, shiny objects make good reflectors. 16