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Science - Coggle Diagram

- - - - Positive and negative charges exist; unlike charges attract, while like charges repel.
    - - Simple experiments demonstrate electrostatic charges produced and detected through friction.
    - - Charging involves adding or removing electrons from a body.
    - - Electrical conductors allow the flow of electricity; examples include metals.
      - Insulators hinder the flow; examples include rubber and plastic.
    - - Current is the flow of charge; in metals, it's due to a flow of electrons.
      - Potential difference (p.d.) is measured in volts (V).
      - Electromotive force (e.m.f.) of a source is also measured in volts (V).
    - - Ammeter (in series) measures current; voltmeter (in parallel) measures potential difference.
    - - Resistance (R) equals potential difference (V) divided by current (I).
    - - Lamps in parallel circuits remain independent; if one fails, others stay lit.
    - - In series circuits, current is the same at every point.
      - In parallel circuits, the current from the source is larger than in each branch.
    - - Calculate combined resistance for resistors in series.
      - Combined resistance for resistors in parallel is less than either alone.
    - - Fuses prevent overloading; choose the appropriate size for circuit protection.
- - - - Transfer of pollen from anther to stigma.
      - Mechanisms: Insects/animals and wind.
      - Insect-pollinated plants have specific adaptations.
      - Wind-pollinated plants produce abundant, light, smooth pollen.
    - - Flowers are reproductive organs of plants.
      - Typically contain both male and female reproductive parts.
      - Pollen, the male gamete, is produced by plants.
    - - Petals: Brightly colored to attract insects.
      - Scent & Nectar: Attract and guide insects to reproductive parts.
      - Number of Pollen Grains: Moderate for efficient transfer.
      - Pollen Grains: Heavier, may have hooks for sticking to insects.
      - Anthers: Inside flower, stiff, ensuring contact with insects.
      - Stigma: Sticky to catch pollen.
    - - Petals: Small, dull, often green or brown.
      - Scent & Nectar: Absent (no need to attract insects).
      - Number of Pollen Grains: Very large for better chances of pollination.
      - Pollen Grains: Smooth, small, and light for easy wind dispersal.
      - Anthers: Outside flower, swing loosely to release pollen.
      - Stigma: Outside flower, feathery to catch drifting pollen.
    - - Start of growth in the seed.
      - Requires water, oxygen, and warmth.
      - Seeds swell, enzymes in the embryo activate, growth begins.
      - Temperature affects germination.
      - Seeds do not require light for germination.
    - - Fusion of pollen nucleus with ovum nucleus in ovule.
      - Pollen tube grows to reach female nucleus in the ovary.
      - Germination of pollen occurs on the right kind of stigma.
  - - - Chlorophyll, in chloroplasts, traps sunlight for energy.
      - Oxygen is released as a byproduct.
      - Process: Plants make carbohydrates from CO2 and H2O using light energy.
    - - Cross-section of a leaf:
      - Epidermis, mesophyll cells, stomata, guard cells, veins (vascular bundles).
      - Chloroplasts in mesophyll cells are the site of photosynthesis.
  - - - Enters through stomata on leaf surface.
      - Diffusion pathway: atmosphere → air spaces around spongy mesophyll tissue → leaf mesophyll cells → chloroplast.
    - - Plants need water for photosynthesis.
      - Pathway: ROOT → STEM → LEAF.
      - Root: Root hair cells, xylem in root cortex cells.
      - Stem: Xylem in vascular bundle.
      - Leaf: Xylem in vascular bundle in mesophyll cells.
    - - Photosynthesis equation: 6H2O + 6CO2 → C6H12O6 + 6O2.
      - Requires chlorophyll and sunlight.
      - Respiration occurs day and night: glucose + oxygen → carbon dioxide + water.
      - Net intake of carbon dioxide and net output of oxygen during the day.
    - - Transports glucose produced in photosynthesis to all parts of the plant.
      - Carries glucose for growth and storage as starch.
    - - Osmosis: movement of water from an area of high concentration to an area of low concentration.
      - Water enters root hair cells by osmosis.
    - - Open during the day, closed at night.
      - Gas exchange and water evaporation occur.
      - Found in higher concentration on the underside of the leaf to reduce water loss.
      - Guard cells control stomatal opening and closing.
      - Water enters as a liquid and leaves stomata as a gas.
    - - Movement of molecules from an area of higher concentration to an area of lower concentration.
      - Oxygen, CO2, and water vapor move through diffusion.
    - - Mitochondria are the site of respiration.
      - Oxygen diffuses from air spaces between mesophyll cells to mitochondria.
      - Carbon dioxide diffuses from mitochondria to air spaces.
    - - Xylem transports water and minerals from roots to other parts.
      - Phloem transports glucose for distribution.
      - Vascular = vein; Xylem is above Phloem in vascular bundles.
    - - Collection of cells of the same type.
      - Vascular tissue includes xylem and phloem.
  - - - Contain chloroplasts for photosynthesis.
      - Have a rigid cell wall made of cellulose.
      - Typically have a large central vacuole.
    - - Lack chloroplasts.
      - Lack a cell wall but have a flexible cell membrane.
      - May have smaller vacuoles.
- - - - Apparatus Setup: : : : :
      - Three test tubes with different conditions: one with air and water, one with boiled water/oil barrier, and one with calcium chloride as a drying agent.
      - Results:
      - Left nail rusts (contact with air and water).
      - Middle nail does not rust (not in contact with air).
      - Right nail does not rust (not in contact with water due to calcium chloride).
      - Conclusion:
      - Rusting requires both oxygen and water.
      - Rusting Speed:
      - Rusting is slower in water and air compared to water and pure oxygen (as air is only 21% oxygen).
    - - Nature of Rust:
      - Rust is a soft solid that easily flakes off, exposing fresh iron beneath.
      - Over time, all iron can rust, weakening the structure.
    - - Barrier Methods:
      - Coating iron with barriers prevents contact with water and oxygen.
      - Coatings can be compromised if washed away or scratched, exposing iron to rusting.
      - Galvanising / Sacrificial Protection:
      - Iron can be protected by using metals higher in reactivity.
      - Galvanising involves coating iron with a layer of zinc, acting as a barrier.
      - Even if the coating is damaged, zinc corrodes preferentially (higher reactivity than iron), protecting iron from rusting.
  - - - An ionic compound can only be broken down when it is molten or aqueous.
      - In liquid form, ions can move freely.
    - - Electrodes: Lead ions (Pb2+) to cathode, bromide ions (Br-) to anode.
      - Products: Lead and bromine are formed at the electrodes.
    - - Electrodes: Hydrogen ions (H+) to cathode, chloride ions (Cl-) to anode.
      - Products: Hydrogen and chlorine are produced.
    - - Electrodes: Hydrogen ions (H+) to cathode, hydroxide ions (OH-) to anode.
      - Products: Hydrogen and oxygen are formed.
    - - Anion: Negatively charged ion attracted to the anode.
      - Anode: Positive electrode.
      - Aqueous: Dissolved in water.
      - Cathode: Negative electrode.
      - Cation: Positively charged ion attracted to the cathode.
      - Electrode: Rod of metal or graphite conducting electric current.
      - Electrolyte: Ionic compound conducting electricity in molten or dissolved form.
      - Inert: Unreactive, e.g., carbon (graphite) or platinum electrodes.
      - Molten: Melted.
    - - Brine is a concentrated solution of aqueous sodium chloride (NaCl).
      - Electrolysis with inert electrodes produces chlorine, hydrogen, and sodium hydroxide solution.
      - Industrial uses: Chlorine for bleach, hydrogen for margarine, sodium hydroxide for soap and detergents.
    - - Product at the Negative Electrode (Cathode):
        
        H+ ions are discharged, forming hydrogen gas.
      - Product at the Positive Electrode (Anode):
        
        Na+ and OH– ions remain, forming sodium hydroxide solution.
        
        Cl– ions are discharged, forming chlorine gas (Cl2).
    - - Hydrogen (H2): Burns with a pop.
      - Oxygen (O2): Relights a glowing splint.
      - Chlorine (Cl2): Turns blue litmus paper red and then bleaches it white.
    - - Cathode: H+ to cathode, produces H2 (g).
      - Anode: OH- to anode, produces O2 (g).
      - Ratio of hydrogen to oxygen is 2:1 as in H2O (water).
  - - - Central Nucleus: Contains protons (positively charged) and neutrons (neutral).
      - Shells of Electrons: Electrons (negatively charged) orbit the nucleus in shells.
    - - Electrons fill inner shells first before outer shells.
      - Noble gas electronic structures are stable and significant in understanding electron configurations.
    - - The total number of protons and neutrons in the nucleus.
    - - Relative numbers of atoms in a compound determine its formula.
    - - The number of protons in the nucleus of an atom.
      - Defines the element.
    - - Definition: Breakdown of an ionic compound when molten or in aqueous solution by the passage of electricity.
      - Involves inert electrodes, electrolyte, anode, and cathode.
    - - Protons: Positive charge, relative mass of approximately 1.
      - Neutrons: Neutral charge, relative mass of approximately 1.
      - Electrons: Negative charge, negligible mass compared to protons and neutrons.
    - - Molten Lead(II) Bromide:
      - Electrode Products: Lead and bromine.
      - Observations: Grey solid forms (lead), reddish-orange liquid/vapour formed (bromine).
      - Concentrated Aqueous Sodium Chloride:
      - Electrode Products: Hydrogen gas and chlorine gas.
      - Observations: Bubbles of gas at both electrodes.
      - Dilute Sulfuric Acid:
      - Electrode Products: Hydrogen gas and oxygen gas.
      - Observations: Hydrogen at the cathode, oxygen at the anode.
    - - Mixtures of a metal with other elements.
      - Alloys are used for improved properties compared to pure metals.
    - - Solids with high melting and boiling points.
      - Malleable (can be hammered into thin sheets).
      - Good conductors of heat and electricity.
    - - Presence of oxygen and water.
    - - Coatings like paint act as a barrier to prevent contact with oxygen and water.
    - - Hydrogen Gas: Burns with a pop.
      - Oxygen Gas: Relights a glowing splint.
      - Carbon Dioxide Gas: Turns lime water milky.
      - Chlorine Gas: Bleaches damp blue litmus paper.
- - - - Melting: Solid to liquid.
      - Boiling: Liquid to gas.
      - Evaporation: Liquid to gas (surface molecules only).
      - Freezing: Liquid to solid.
      - Condensation: Gas to liquid.
    - - Use of Thermometers: Measure temperature on the Celsius scale.
      - Celsius Scale: Common temperature scale.
    - - Particle Separation: Far apart.
      - Particle Arrangement: Random; no fixed positions.
      - Particle Motion: Rapid and constant motion; fill the available space.
    - - Melting Point: Temperature at which a substance changes from solid to liquid.
      - Boiling Point: Temperature at which a substance changes from liquid to gas.
      - Water's Points: 0°C (melting) and 100°C (boiling).
    - - Particle Separation: More spaced out than solids.
      - Particle Arrangement: Less ordered; particles slide past each other.
      - Particle Motion: Particles move freely but stay close together.
    - - Escape of Molecules: More energetic molecules escape from the liquid surface.
      - Cooling Effect: Evaporation causes a cooling effect on the remaining liquid.
    - - Particle Separation: Close arrangement of particles.
      - Particle Arrangement: Fixed positions in a regular pattern.
      - Particle Motion: Vibrate in fixed positions.
    - - Conduction: Transfer of heat through direct contact.
      - Convection: Transfer of heat through the movement of fluids.
      - Radiation: Transfer of heat through electromagnetic waves.
    - - Main Method in Liquids and Gases: Fluid movement transfers heat.
      - Illustration: Heat rising, cool air sinking.
    - - Exothermic: Releases heat to the surroundings.
      - Endothermic: Absorbs heat from the surroundings.
    - - Medium Not Required: Heat transfer without a medium.
      - Infrared (IR) Radiation: Part of the electromagnetic spectrum involved in energy transfer.
    - - Conduction: Cooking on a hot stove.
      - Convection: Heating a room with a radiator.
      - Radiation: Feeling warmth from the sun.
    - - Insulation: Using materials that reduce heat transfer.
      - Double Glazing: Trapping air between layers for insulation.
      - Draft Exclusion: Sealing gaps to prevent heat escape.
  - - - Methane (CH4) is the main constituent of natural gas.
    - - Petroleum is a mixture of hydrocarbons.
      - Fractional distillation separates petroleum into useful fractions.
    - - Coal, natural gas, and petroleum are fossil fuels that produce CO2 upon combustion
    - - Refinery gas for bottled gas (heating and cooking).
      - Gasoline fraction for fuel in cars.
      - Naphtha fraction for chemical production.
      - Diesel oil/gas oil for diesel engines.
      - Bitumen for road surfaces.
    - - Recognize by molecular structures and reaction with aqueous bromine.
    - - Alkenes are unsaturated hydrocarbons with one double covalent bond.
      - Cracking is a reaction producing alkenes.
    - - Complete combustion of hydrocarbons yields carbon dioxide and water.
    - - Alkanes are saturated hydrocarbons with single covalent bonds.
      - Properties include general inertness, except for burning.
    - - Carbon dioxide gas (lime water test).
      - Water (cobalt chloride paper or anhydrous copper sulfate test).
    - - Poly(ethene) formation is an example of addition polymerization of monomer units.
- - - - Oxygen (O2): 21% (Inspired) / 16% (Expired)
      - Carbon dioxide (CO2): 0.04% (Inspired) / 4% (Expired)
      - Water vapour (H2O): Less in Inspired / More in Expired
      - Nitrogen (N): 78% (inspired) / 74.5% (Expired)
    - - Arteries: Carry blood away from the heart (high pressure).
      - Veins: Carry blood back to the heart (low pressure).
      - Capillaries: Tiny vessels for material exchange between blood and tissues.
    - - Red Blood Cells: Transport oxygen (contain hemoglobin).
      - White Blood Cells: Defend against infection.
      - Platelets: Assist in blood clotting.
      - Plasma: Transports cells, nutrients, CO2, and hormones.
    - - Blood pumped from heart to arteries, returns via veins.
      - Coronary arteries supply blood to heart muscles.
      - Blockage can lead to a heart attack.
    - - Exercise increases pulse rate due to increased demand for oxygen and energy.
      - Respiratory and circulatory systems respond to meet the elevated requirements.
    - - Lungs: Gas exchange surface.
      - Diaphragm: Controls thoracic volume for inhalation/exhalation.
      - Ribs: Protect heart and lungs.
      - Intercostal Muscles: Control rib movement for breathing.
      - Larynx: Voice box.
      - Trachea: Windpipe connecting mouth/nose to lungs.
      - Bronchi and Bronchioles: Air passages.
      - Alveoli: Tiny air sacs for gas exchange with capillaries.
    - - Exhalation:
        
        Intercostal muscles relax.
        
        Ribs move down and in.
        
        Diaphragm relaxes and 'domes up.'
        
        Thorax volume decreases, air is pushed out.
      - Inhalation:
        
        Intercostal muscles contract.
        
        Rib cage moves up and out.
        
        Diaphragm contracts and flattens.
        
        Thorax volume increases, air is drawn in.
    - - Release of energy from food in cells.
      - Uses oxygen to break down nutrients.
      - Key Equation: glucose + oxygen → carbon dioxide + water.
  - - - Blood vessels, heart, and valves ensure one-way blood flow.
      - Blood pumped from heart to arteries and returns via veins.
    - - Arteries carry oxygenated blood away; veins bring deoxygenated blood back.
      - Capillaries facilitate nutrient and gas exchange in tissues.
    - - Vena cava, aorta, pulmonary artery, and pulmonary vein connect to the heart.
    - - Red cells transport oxygen using hemoglobin.
      - White cells contribute to immunity, platelets clot blood.
      - Plasma transports various components in the blood.
    - - Muscular organ with septum, ventricles, and atria.
      - One-way valves and coronary arteries present.
    - - Exercise increases demand for oxygen, elevating heart rate.
    - - Lungs, diaphragm, trachea, bronchi, and alveoli facilitate breathing.
    - - Inspired air has more oxygen, less carbon dioxide, and water vapor.
      - Expired air contains higher CO2 levels, detectable with limewater.
    - - Increased physical activity raises both rate and depth of breathing.
    - - Aerobic respiration (glucose + oxygen → carbon dioxide + water) with abundant oxygen.
      - Anaerobic respiration (glucose → lactic acid or ethanol + carbon dioxide) in the absence of oxygen.