SCIENCE EOY

Chapter 1: Water and Life

• Learning Objectives:

  • Understanding water absorption by root hairs from the soil.

  • Water transport through plant xylem vessels.

  • The process of transpiration and replacement of evaporated water.

  • The role of mineral salts, specifically magnesium and nitrates, and how they are stored in plant cells.

  • The human renal system, urea removal, and the function of kidney machines (dialysis).

• The Watery Planet (Voyager 1 Perspective):

  • Launched in 1977, Voyager 1 sent a photo in 1990 from $6 \times 10^{9}\,km$ away showing Earth as a small blue spot the size of a full stop.

  • The blue appearance is due to water absorbing sunlight colors (Newton's spectrum), with blue being the last color absorbed and thus reflected.

  • Green reflected from land comes from plants, which survive via the water cycle.

• Earth Composition:

  • Approximately $29\,\%$ is land; $71\,\%$ is covered by water, primarily in oceans.

  • Outer-space water detection: Europa (moon of Jupiter) is thought to have a sub-ice ocean. K2-18b, an exoplanet $110\,\text{light years}$ away in Leo, has water in its atmosphere.

• Plant Organs and Water Transport:

  • Five main organs: root, stem, leaf, flower, bud.

  • Root Hairs: Projections from roots growing into soil spaces. There can be up to $500\,\text{root hairs}$ per $cm^{2}$. They increase surface area for water absorption without the plant using energy.

  • Xylem Tissue: Formed by columns of dead cells where walls break down into tubes. They conduct water from roots to leaves and form vascular bundles (seen as fibers in celery stalks).

• Transpiration:

  • Process: Water evaporates from leaf cells (lower layer), forming vapour which diffuses out via holes. This draws water up from the xylem tissue.

  • Transpiration Stream: The continuous movement of water from roots through stems to leaves.

• Minerals and Plant Health:

  • Nitrogen (Nitrates): Essential for leaf development, protein synthesis, and chlorophyll. Deficiency causes yellow leaves and poor growth.

  • Magnesium: Required to make chlorophyll. Deficiency causes yellowing around leaf veins.

  • Monitoring: Satellites provide artificially colored images to help farmers manage yield by observing soil water and nitrogen content.

• Human Renal System:

  • Function: Regulates water and removes urea (toxic poison from amino acid destruction in the liver) as urine.

  • Anatomy: Kidneys (approx. $12\,cm$ long), ureters, bladder, and urethra.

  • Mechanism: Blood filters through up to $1.5 \times 10^{6}\,nephrons$ in a kidney. Cells and vital substances remain in plasma; urea and water become urine.

  • Kidney Machines (Dialysis): Technology using diffusion and filtration to clean blood. Sessions typically take $4\,\text{hours}$, three times a week.

Chapter 2: Photosynthesis

• Definition: The process by which plants make carbohydrates (food) using light energy.

• Historical Research:

  • Joannes Baptista van Helmont (17th Century): Grew a willow sapling for $5\,\text{years}$ with only water. The tree gained $73\,kg$, while soil mass decreased by only $60\,g$. Conclusion (limited): $water \rightarrow \text{mass of plant}$.

  • Stephen Hales (18th Century): Discovered 'a portion of air' helps plants survive.

  • Jan Ingenhousz: Showed green plants take up $CO_2$ in light.

  • Joseph Priestley: Discovered plants produce oxygen (refreshes the air) in light.

• Starch Testing in Leaves:

  • Iodine Test: Brown iodine solution turns blue-black in the presence of starch.

  • Protocol:

    1. Boil leaf in water ($30\,\text{seconds}$) to kill cells.

    2. Cover leaf with ethanol and place in a hot water bath (flammable—Bunsen burner must be off). Ethanol dissolves chlorophyll.

    3. Soften the now-brittle leaf in hot water.

    4. Spread on a white tile and add iodine.

  • De-starching: Placing a plant in darkness for $2\text{--}3\,\text{days}$ to remove existing starch.

• Photosynthesis Requirements:

  • Carbon Dioxide: Absorbed by soda lime (mix of $NaOH$ and $Ca(OH)_2$); sodium hydrogencarbonate adds it to air.

  • Light: Proven by covering leaves with opaque foil.

  • Chlorophyll: Proven using variegated leaves (white parts lack chlorophyll/starch).

• Equations:

  • Word Equation: $water + carbon dioxide \frac{light}{chlorophyll} carbohydrate (starch) + oxygen$

• Science in Context: Greenhouse/Polytunnels control temperature, water, $CO_2$, and light for maximum yield.

Chapter 3: Genetics

• Variation:

  • Inter-species: Differences between species (ears of cat vs. rabbit).

  • Intra-species: Differences within a species (height, fingerprints).

  • Continuous Variation: A wide range of values (height, mass).

  • Discontinuous Variation: Distinct categories (male/female, free/attached ear lobes, hitchhiker's thumb).

• Pioneers of Genetics:

  • Gregor Mendel: Austrian monk who cross-pollinated pea plants. Identified 'factors' (genes) passed from parents to offspring.

  • Hugo de Vries: Supported Mendel's work; proposed pangenes (later 'genes' by Wilhelm Johannsen).

• Chromosomes and DNA:

  • Chromosomes: Found in the nucleus; visible during cell division. Humans have $46\,\text{chromosomes}$ ($23\,\text{pairs}$). Typical counts: Chicken ($78$), Elephant ($56$), Kangaroo ($16$).

  • DNA: Deoxyribonucleic acid. Discovered as a double helix by James Watson and Francis Crick using Rosalind Franklin's X-ray data.

  • Genes: Sections of DNA on chromosomes carrying characteristic instructions.

• Reproduction:

  • Gametes: Sex cells with half the chromosome number ($23$ in humans) produced by special cell division. Sperm (male) and Ovum/Egg (female).

  • Fertilization: Fusion of gametes into a zygote ($46\,\text{chromosomes}$).

  • Sex Inheritance: Female ($XX$), Male ($XY$). Punnett square shows a $50\,\%$ chance for either sex.

• Natural Selection (Charles Darwin):

  • The Beagle Voyage (1831): Five-year trip. Darwin observed finches and mockingbirds in the Galapagos Islands.

  • Mechanism: Struggle for survival due to limited resources; individuals with better-adapted features (e.g., specific beak shapes for seeds vs. insects) survive/breed. Termed 'Natural Selection'.

  • Contrast Theory: Jean-Baptiste Lamarck's 'acquired characteristics' (e.g., giraffe necks stretching over time) was disproven.

Chapter 4: Care in Fetal Development

• Gestation: Human pregnancy lasts approx. $9\,\text{months}$ in the uterus.

• Fetal Support: Nutrients/oxygen passed via the placenta.

• Impact of Diet/Substances:

  • Poverty/Diet: Malnutrition leads to smaller, disease-prone babies.

  • Specific Foods: Soft cheeses (Listeria micro-organisms); Caffeine (slows growth).

  • Smoking: Nicotine/poisons lower blood oxygen; increases heart rate in fetus, causes premature birth, low weight, or stillbirth.

  • Alcohol: Causes nerve damage, small head size, or Fetal Alcohol Syndrome (hyperactivity, poor memory).

  • Drugs: Cannabis, cocaine, etc., lead to addiction in the baby and inhibited growth.

• Diseases:

  • Malaria and Tuberculosis can be fatal.

  • Rubella (German measles) can cause deafness/blindness in the fetus.

  • STDs (Syphilis, Gonorrhea) cause sores, blindness, or liver issues. AIDS damages the baby's immune system.

• Neonatal Care: Period from birth to $28\,\text{days}$.

  • Incubators: Stéphane Tarnier (1870s) was inspired by zoo chicken incubators. Alexandre Lion (1889) added thermostats and fans. Modern units regulate temperature, humidity, and oxygen to prevent hypothermia.

Chapter 5: Environmental Change and Extinction

• Adaptation: Adjustments to survive in a habitat (e.g., Moss campion growing as a cushion to resist wind).

• Jane Goodall: Observed chimpanzees in Gombe. Discovered they use/make tools (poking termite mounds) and eat meat (colobus monkeys), disproving they were strictly herbivores.

• Population Change:

  • Ecological Models: Food chains and Food webs.

  • Monitoring: Charles Elton studied Snowshoe hare/Lynx pelt data over $90\text{--}years$. Fluctuations show predator-prey trends.

  • Birth/Death Rate: Populations increase if $\text{birth rate} > \text{death rate}$.

• Extinction:

  • IUCN Red List Categories: Endangered (EN), Critically Endangered (CR), Extinct in the Wild (EW), Extinct (EX).

  • Causes: Deforestation, climate change, bushfires, plastic pollution.

  • Assistance: Breeding programs in zoos.

  • Historical Snail Incident: William Perkin accidentally created purple aniline dye while seeking a malaria cure; this saved the 'purple dye murex' snail from over-harvesting.

• The Big Five Extinction Events:

  1. Late Ordovician: ($455 \text{--} 430\,\text{million years ago}$) - Ice age/volcanoes; $85\,\%$ marine loss.

  2. Late Devonian: ($376 \text{--} 360\,\text{mya}$) - Land plants/$CO_2$ reduction; $75\,\%$ species loss.

  3. Permian-Triassic ('The Great Dying'): ($252\,\text{mya}$) - Global warming; $96\,\%$ marine source loss.

  4. Triassic-Jurassic: ($201\,\text{mya}$) - Acidic oceans; $80\,\%$ loss.

  5. Cretaceous-Tertiary: ($66\,\text{mya}$) - Asteroid; $76\,\%$ loss (dinosaurs).

  6. Anthropocene: (Current) - Human activity; $40\,000+\,$ threatened species.

Chapter 6: The Periodic Table

• History:

  • John Dalton (1805): Measured atomic weights ($H=1, O=7$ - later corrected to $O=16$). First to use circle symbols.

  • Döbereiner's Triads (1829): Groups of three with similar properties (e.g., Li, Na, K).

  • John Newlands: Law of Octaves; properties repeated every eight places.

  • Dmitri Mendeleev: Arranged by atomic weight but left gaps for undiscovered elements. Predicted properties accurately.

• Modern Structure:

  • Atomic Number: Number of protons in the nucleus (used to arrange elements today).

  • Periods: Horizontal rows.

  • Groups: Vertical columns. Group 1 ($Li, Na, K$) are Alkali Metals.

• Group 1 Trends:

  • Physical: Moving down decreases melting/boiling points.

  • Reactivity: Increases down the group. Lithium fizzes; Potassium bursts into flame ($metal + H_2O \rightarrow \text{metal hydroxide} + H_2$).

Chapter 7: Bonds and Structures

• Electron Orbits: Shelves of electrons. Simple helium has $2$. Shells usually fill at $2, 8, 8$. Stability/Inertia occurs when the outer shell is full (Noble Gases: He, Ne, Ar).

• Covalent Bonding: Sharing electrons between non-metals.

  • Hydrogen ($H_2$): Shares $1\,\text{pair}$.

  • Water ($H_2O$): Oxygen shares with two Hydrogens.

  • Methane ($CH_4$): Carbon shares with four Hydrogens.

  • CPK Colouring: Hydrogen (white), Carbon (black), Oxygen (red).

  • Bucky-ball: $C_{60}$ molecule discovered by Harry Kroto using laser-ablated graphite; shaped like a soccer ball (geodesic dome).

• Ionic Bonding: Transfer of electrons between a metal and non-metal.

  • Sodium Chloride ($NaCl$): $Na$ loses an electron to become a Cation ($Na^{+}$); $Cl$ gains one to become an Anion ($Cl^{-}$).

• Structures:

  • Simple Molecular: Low melting/boiling points, non-conductors ($H_2, H_2O, CH_4$).

  • Giant Covalent: $lattice$ structure ($Diamond, Graphite, Silica$). Diamond is hard (4 bonds); Graphite conducts and is soft (3 bonds, 1 free electron).

  • Giant Ionic: Repeating lattice ($NaCl, MgO$). High melting points; conduct only when dissolved or molten.

Chapter 8: Density

• Formula: $\text{density} = \frac{\text{mass}}{\text{volume}}$

• Units: $kg/m^3$ (SI) or $g/cm^3$. Conversion: $g/cm^3 \times 1000 = kg/m^3$.

• Common Densities: Water ($1000\,kg/m^3$), Ice ($920\,kg/m^3$), Gold ($19\,320\,kg/m^3$), Iron/Steel ($7\,900\,kg/m^3$), Air ($1.29\,kg/m^3$).

• Measuring Techniques:

  • Regular Solid: Measuring dimensions ($L \times W \times H$) and weighing.

  • Irregular Solid (Pebble): Water displacement in a measuring cylinder.

  • Liquid: Calculating mass ($B - A$) of liquid in a cylinder of volume $V$.

  • Gas: Using a round-bottomed flask and a vacuum pump to find mass of removed air.

• Floating/Sinking: Less dense substances float on denser ones (Ice floats on water; Paraffin oil floats on water).

• Balloons: Montgolfier brothers used hot air ('levity'). Modern balloons use Helium (safer than Hydrogen).

Chapter 9: Displacement Reactions

• Definition: A more reactive element replaces a less reactive one in a compound.

• Reactivity Series: $K, Na, Ca, Mg, Zn, Fe, H, Cu, Ag, Au$ (Order of reactivity).

• Examples:

  • $Fe + CuSO_4 \rightarrow FeSO_4 + Cu$ (Iron nail in blue copper sulfate turns brown).

  • $Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$ (Magnesium displaces hydrogen in water; indicator Phenolphthalein turns pink).

  • Acid Reactions: $metal + acid \rightarrow \text{metal salt} + hydrogen$.

• Industrial Use: Thermite welding for railway tracks ($Al + \text{iron oxide} \rightarrow \text{iron} + \text{aluminium oxide}$).

Chapter 10: Preparing Common Salts

• Reactions:

  • $\text{acid} + \text{metal} \rightarrow \text{salt} + H_2$

  • $\text{acid} + \text{carbonate} \rightarrow \text{salt} + CO_2 + H_2O$

• Acids/Salts: Hydrochloric ($\rightarrow$ chlorides), Sulfuric ($\rightarrow$ sulfates), Nitric ($\rightarrow$ nitrates).

• Purification:

  • Filtration: Separating residue (solid) from filtrate (liquid).

  • Evaporation/Crystallization: Heating solution to saturation, then cooling until pure crystals form.

• Pioneer: Salimuzzaman Siddiqui extracted ajmaline (heart medicine) and neem tree chemicals as natural insecticides.

Chapter 11: Rates of Reaction

• Conservation Laws:

  • Mass: Conserved in closed systems. Non-closed systems lose mass if gas escapes (e.g., $CO_2$ from marble chips + acid).

  • Energy: Conserved. $E = mc^2$.

• Measuring Rates: Time taken for a certain volume of gas produced or mass lost.

• Factors Increasing Rate:

  1. Concentration: More particles per volume increase collision frequency.

  2. Surface Area (Particle Size): Smaller pieces (dust) increase contact points ($surface area \times 2$ when cube cut into $8$ pieces).

  3. Temperature: Increase of $10\,^\text{o}C$ can double reaction speed due to faster particles/harder collisions.

• Catalysts: Substances that speed up reactions without being consumed.

  • Elizabeth Fulhame (1794) studied catalysts.

  • Enzymes are biological catalysts.

  • Catalytic converters ($NO, CO \rightarrow N_2, CO_2$).

• Triangle of Fire: Fuel, Oxygen, Heat. Removing one extinguishes the fire.

Chapter 12: Energy

• Internal Energy: Measured as the total kinetic energy of particles.

• Temperature: Average kinetic energy ($^\text{o}C$).

• Thermodynamics: Energy flows from Hot to Cold (Dissipation).

• Heat Transfer:

  1. Conduction: Vibrational transfer in solids (Metals have a 'sea of electrons' and are best).

  2. Convection: Current-based transfer in liquids/gases (Hot fluid expands, becomes less dense, and rises).

  3. Radiation: Transfer via infrared waves; travels through a vacuum.

• Evaporation Cooling: High-energy particles escape, reducing the remaining liquid's temperature (Sweating, refrigerators).

• Fridges: Use refrigerant ($compaction \rightarrow condensation \rightarrow \text{expansion/evaporation}$).

• Thermal Imaging: William Herschel discovered infrared beyond red light ($1800$). Used in medicine and night vision.

Chapter 13: Waves

• Sound Waves: Produced by vibrations. Particles move to-and-fro, creating high pressure (Compression) and low pressure (Rarefaction).

• Waveform Features:

  • Amplitude: Maximum distance from rest position (Linked to Loudness in decibels, $dB$).

  • Wavelength: Distance between crests/troughs.

  • Frequency: Waves per second ($Hertz, Hz$) (Linked to Pitch).

• Interference:

  • Constructive: Waves align to increase amplitude.

  • Destructive: Waves cancel out (Dead spots).

  • Beats: Produced by two waves of different frequencies.

• Doppler Effect: Frequency increases as source moves towards listener, decreases as it moves away.

• Acoustics: Engineering to control sound and reduce echoes.

Chapter 14: Electrical Circuits

• Basic Measurements:

  • Current ($I$): Flow of electrons, measured in Amps ($A$) by an ammeter (in series).

  • Voltage ($V$): Potential difference, energy per electron, measured in Volts ($V$) by a voltmeter (in parallel).

  • Resistance ($R$): Opposition to current, measured in Ohms ($\Omega$).

• Ohm's Law: $V = I \times R$

• Circuit Types:

  • Series: Single loop. Adding bulbs increases resistance, dims light.

  • Parallel: Multiple branches. Voltage is the same in all branches; total current is sum of branch currents.

• Resistors:

  • Fixed: Maintain specific resistance.

  • Variable (Rheostat): Sliding contact changes wire length.

• Superconductors: Heike Kamerlingh-Onnes found Mercury has zero resistance at $-273\,^\text{o}C$. Used in MRI scanners.

Chapter 15: Planet Earth

• Tectonic Plates: Earth's crust is fragmented. Evidence by Alfred Wegener:

  • Rocks: Matching Cratons (shields) in Africa and South America ($2 \times 10^{9}\,years$ old).

  • Ocean Floor: Mid-Atlantic Ridge discovered via bathymetric mapping.

  • Fossils: Mesosaurus (freshwater reptile) and Glossopteris (plant) found on widely separated continents.

  • Magnetism: Patterns of magnetic 'stripes' (polarity reversals).

• Mantle Structure: Crust, Mantle (magma), Outer Core, Inner Core.

• Convection Currents: Heat from the core causes magma to rise/circulate, moving floating plates at approx. $2.5\,cm/year$.

• Seismology: P-waves (through solid/liquid) and S-waves (only solid) help map internal layers.

Chapter 16: Cycles on Earth

• The Carbon Cycle:

  • Photosynthesis: Plants fix carbon into glucose ($CO_2$ entry via stomata/guard cells).

  • Respiration: All living things release carbon ($glucose + O_2 \rightarrow CO_2 + H_2O + energy$).

  • Feeding: Carbon passes through primary/secondary consumers.

  • Decomposition: Decomposers (fungi/bacteria) respire, releasing $CO_2$.

  • Combustion: Burning fuels releases long-stored carbon.

• Greenhouse Effect: $CO_2$, Methane, and others trap heat (infrared) in the atmosphere.

• Climate Change: Long-term weather changes. Global temp has risen nearly $1\,^\text{o}C$ since $1880$.

• Impacts: Rising sea levels (flooding Maldives/deltas), extreme weather (hurricanes, droughts, blizzards).

Chapter 17: Earth in Space

• Solar System Objects:

  • Asteroids: Rocky objects found in the Asteroid Belt (Mars-Jupiter) or as Trojans.

  • Impacts: Collisions cause 'Impact Winter' (dust blocks sun). Chicxulub crater ($66\,mya$) killed Dinosaurs/Ammonites.

• Moon Formation: Big Splash theory—Earth collided with planet-sized Theia ($4.5 \times 10^{9}\,mya$).

• Stars: Born in Nebulae (stellar nurseries) when gravity compresses Hydrogen to fuse into Helium.

• Modern Astronomy: Uses observatories (Mauna Kea, Canary Islands space telescopes). Relies on Peer Review.

• Universe Mysteries: Dark Matter (holds galaxies together) and Dark Energy (causes faster expansion).