Year 9 Self-Testing Booklet - Double Science (Higher)
Year 9 Self-Testing Booklet (Double Science - Higher)
Units Covered
P1: Particle model of matter
B1: Cell biology
C1: Atomic structure & Periodic Table
P1: Energy
C1: Bonding, structure & properties of matter
B1: Organisation (organ systems)
P1: Electricity
Topic 1: Particle Model of Matter
PAGES: 191-194
4.3 Particle Model of Matter
Three Main States of Matter
Solid
Liquid
Gas
Particle Arrangement of the Three States
Solid: Fixed pattern, closely packed particles
Liquid: Particles can move over each other
Gas: Freely moving particles
Properties of Particles in a Solid
Strong force of attraction
Vibrate on the spot
Fixed pattern
Cannot be compressed
Cannot take the shape of a container
Properties of Particles in a Liquid
Weak force of attraction
Can move over each other
Cannot be compressed
Can take the shape of a container
Properties of Particles in a Gas
Very weak force of attraction
Can move freely
Can be compressed
Can take the shape of a container
4.3.1.1 Density of Materials
Definition of Density
Density is the amount of matter in a volume.
Density Equation
ho = rac{m}{V} , where:
ho = density (kg/m³)m = mass (kg)
V = volume (m³)
Required Practical: Measure Density of Regular and Irregular Solids and Liquids
Regular Shape Method
Measure length (l), width (w), height (h) of a steel cube.
Measure mass on a top pan balance.
Calculate volume using: V = l imes w imes h
Calculate density using:
ho = rac{m}{V}
Irregular Shape Method
Measure mass of stone on a top pan balance.
Fill displacement can until water is level with bottom of pipe.
Place measuring cylinder ready to collect displaced water.
Drop stone into can and collect displaced water in cylinder.
Measure volume of displaced water.
Calculate density using:
ho = rac{m}{V}
4.3.1.2 Changes of State
Label Changes in State: Evaporation, Condensation, Freezing, Melting, Deposition, Sublimation
Mass During Change in State
Mass is conserved during a change in state.
Definition of Physical Change
A physical change is when a material can recover its original properties if the change is reversed (e.g., change in state).
4.3.2 Internal Energy and Energy Transfers
Definition of Internal Energy
Total kinetic and potential energy of all particles (atoms/molecules) in a system.
Effects of Heating on a System
Increases kinetic energy
Increases internal energy
Particles move more
Temperature increases or there is a change in state
4.3.2.3 Changes of Heat and Specific Latent Heat
Definition of Latent Heat
Energy needed for a substance to change state.
Arrows representing changes in state: A (Evaporation), B (Condensation), C (Freezing), D (Melting), E (Deposition), F (Sublimation)
Temperature During Change in State
Temperature stays the same during a change in state.
Definition of Specific Latent Heat
The amount of energy required to change the state of one kilogram of a substance without a change in temperature.
Specific Latent Heat Equation
E = mL , where:
E = energy for change in state (J)
m = mass (kg)
L = specific latent heat (J/kg)
Specific Latent Heat of Fusion
Energy needed to change the state from solid to liquid.
Specific Latent Heat of Vaporization
Energy needed to change the state from liquid to gas.
4.3.3.1 Particle Motion in Gases
Definition of Gas Pressure
Gas pressure is the force exerted by particles in a gas in a given area.
Pressure Change in Gas at Constant Volume
Pressure changes by altering the temperature.
Why Heating Gas Increases Pressure
Kinetic energy increases
Internal energy increases
Increased particle movement results in more impacts on surfaces, hence increasing pressure.
Why Cooling Gas Decreases Pressure
Kinetic energy decreases
Internal energy decreases
Particles slow down leading to fewer impacts on surfaces, hence decreasing pressure.
Topic 2: Cells and Cell Transport
PAGES: 11-23
4.1.1.2 Animal Cells
Draw and Label an Animal Cell
Function of Organelles
Nucleus: Contains DNA; controls the cell.
Mitochondria: Site of respiration.
Cell Membrane: Controls what goes in and out of the cell.
Cytoplasm: Site where chemical reactions occur.
Ribosome: Site of protein synthesis.
4.1.1.2 Plant Cells
Draw and Label a Plant Cell
Function of Organelles
Chloroplast: Site of photosynthesis.
Cell Wall: Provides rigidity.
Vacuole: Stores cell sap.
Differences Between Animal and Plant Cells
Plant cells have chloroplasts, a cell wall, and a vacuole.
4.1.1.1 Bacterial Cells (Prokaryotic)
Draw and Label a Bacterial Cell
Differences from Animal or Plant Cells
No nucleus
Much smaller
DNA is in a loop and contains plasmids (smaller rings of DNA).
4.1.1.3 Specialized Cells
How is a Sperm Cell Specialized?
Long tail for swimming to the egg.
Numerous mitochondria for energy.
Enzymes in the head to penetrate the egg.
How is a Nerve Cell Adapted?
Carries electrical signals.
Very long structure.
Branched connections to connect to other nerves.
How are Muscle Cells Specialized?
Long structure for contraction.
Many mitochondria to provide energy.
Root Hair Cells Adaptation for Absorption
Large surface area for absorption of water and minerals.
Phloem and Xylem Adaptation for Transport
Long tubes joined together.
Xylem are hollow in the centre; phloem has minimal subcellular structures.
4.1.1.4 Cell Differentiation
Definition of Differentiation
The process where a cell becomes specialized for a specific function.
When Does Differentiation Occur in Animals?
Very early in development (e.g., in an embryo).
Where Does Differentiation Occur in Plants?
Meristem regions.
Differences Between Plant and Animal Cell Differentiation
Plant cells can become specialized at any time.
4.1.1.5 Microscopy and Magnification
Differences Between Electron and Light Microscopes
Electron microscopes use electrons; light microscopes use light.
Advantages of Electron Microscopes
Higher magnification and higher resolution.
Equation Linking Image Size, Actual Size, and Magnification
ext{Magnification} = rac{ ext{Image size}}{ ext{Actual size}}
Conversion from Millimetres to Micrometres
1000 µm = 1 mm.
How to Convert Millimetres into Micrometres
Multiply the measurement in mm by 1000.
Required Practical: Microscopy
Using a Light Microscope to Observe Specimens
Method:
Place the slide on the microscope stage.
Select the lowest power objective lens (usually ×4).
Adjust lens position to focus using coarse and fine knobs.
Switch to higher power and refocus.
Make clear, labelled drawings of cells and note magnification.
4.1.2.2 Mitosis
Definition of Chromosomes
Coiled lengths of DNA.
Chromosome Count in Human Cells
46 chromosomes (23 pairs).
Reasons for Cell Division
Growth and repair.
Pre-Division Cell Actions
Cells make copies of organelles (e.g., mitochondria).
Describe the Four Main Steps of the Cell Cycle.
[Details not provided in the transcript]
4.1.2.3 Stem Cells
Definition of Stem Cells
Unspecialized (not differentiated) cells.
Locations of Stem Cells in Humans
Bone marrow; embryos.
Locations of Stem Cells in Plants
Meristems.
Uses of Stem Cells
Can differentiate into many types of cells (e.g., treatment for diseases).
Potential Use of Stem Cells
Cure diseases like diabetes and repair damaged nerve cells.
Ethical Concerns Regarding Stem Cells
Some view embryonic stem cells as potential human life.
Use of Plant Stem Cells
To clone plants.
4.1.3.1 Diffusion
Definition of Diffusion
Movement of particles from high concentration to low concentration.
Factors Affecting the Rate of Diffusion
Temperature
Surface Area
Concentration Gradient
Distance
Examples of Diffusion in Humans
Gas exchange in the alveoli (lungs).
Nutrient absorption in the small intestine.
Example of Diffusion in Plants
Gas exchange through stomata (leaves).
Gas Exchange in Fish
Oxygen absorbed from water via gills through diffusion.
4.1.3.2 Osmosis
Definition of Osmosis
Movement of water molecules from high concentration to low concentration through a partially permeable membrane.
Definition of Partially Permeable Membrane
A membrane with small holes that allows the passage of certain molecules.
Required Practical: Osmosis
Investigate Effects of Concentrations of Salt or Sugar Solutions on Plant Tissue
Method:
Cut five potato cylinders of the same diameter.
Remove potato skin.
Accurately measure mass and length of each cylinder.
Measure concentrations of solutions in labelled tubes.
Add potato cylinders to boiling tubes.
Leave for over 30 minutes.
Measure new mass and length of cylinders.
Calculate percentage change in mass and length.
4.1.3.3 Active Transport
Definition of Active Transport
Movement of particles from low concentration to high concentration using energy.
Source of Energy for Active Transport
Respiration.
Example of Active Transport in Plants
Root hair cells pump minerals into the root against the concentration gradient.
Adaptations of Root Hair Cell for Diffusion, Osmosis, Active Transport
Large surface area for absorption.
Example of Active Transport in Humans
Small intestine pumps glucose against the concentration gradient.
Topic 3: Atomic Structure and the Periodic Table
PAGES: 96-110
4.1.1.1 Atoms, Elements, Compounds & Mixtures
Definitions
Atom: Smallest part of an element that can exist.
Element: Substance containing only one type of atom.
Compound: Two or more elements chemically bonded together.
Mixture: Two or more substances not chemically bonded.
Methods of Separation
Filtration: Separate insoluble solids from liquids.
Distillation: Separate soluble solids from solutions.
Crystallisation: Separate soluble solids from solutions.
Chromatography: Separate different solutes in a mixture.
Distillation
Gently heat the solution; lowest boiling liquid evaporates first; vapour condenses in the condenser.
Crystallisation
Heat solution in an evaporating dish until crystals form; filter and dry crystals.
Chromatography
Draw pencil line on chromatography paper; place sample on line; suspend paper in beaker; allow solvent to move up paper.
4.1.1.3 Model of the Atom
Plum Pudding Model
Atom as a ball of positive charge with negative electrons embedded.
Rejection of Plum Pudding Model
Rejected due to Rutherford’s alpha particle scattering experiment.
Rutherford’s Scattering Experiment
Positive alpha particles fired at gold; most pass through, some deflected.
Conclusion:
Most of atom is empty space.
Mass of atom concentrated at its centre (nucleus).
Nucleus has positive charge.
Niels Bohr's Discovery
Electrons orbit nucleus at set distances (in shells).
Rutherford's Additional Discovery
Nucleus contains positive protons.
James Chadwick's Discovery
Nucleus contains neutral particles (neutrons).
Atom Size
Approx. 0.1 nm (1 x 10⁻¹⁰ m).
Nucleus Size
Approx. 1 x 10⁻¹⁴ m (1/10,000 radius of atom).
4.1.1.4 Subatomic Particles
Relative Charges of Subatomic Particles
Proton: +1
Neutron: 0
Electron: -1
Why Atoms Have No Overall Charge
Equal number of protons and electrons.
Same Subatomic Particle Numbers in Same Element
Atoms of same element have the same number of protons.
4.1.1.5 Size and Mass of Atoms
Periodic Table Top Number
Mass number.
Mass Number in Terms of Particles
ext{Mass number} = ext{no. of protons} + ext{no. of neutrons}
Periodic Table Bottom Number
Atomic (proton) number.
Atomic Number Significance
Represents number of protons (and electrons).
Relative Masses of Subatomic Particles
Proton: 1
Neutron: 1
Electron: Very small (1/2000).
Isotopes
Atoms of the same element with different number of neutrons.
Difference between Carbon-12 and Carbon-14
Carbon-12 has 6 neutrons; Carbon-14 has 8 neutrons.
4.1.1.6 Relative Atomic Mass
Relative Atomic Mass Definition
Average mass number based on relative abundance of different isotopes.
Relative Atomic Mass Equation
Ar = rac{ ext{sum of (isotope abundance} imes ext{isotope mass number)}}{ ext{sum of abundances}}
4.1.1.7 Electronic Structure
Maximum Number of Electrons in First Four Shells
1st shell: up to 2
2nd shell: up to 8
3rd shell: up to 8
4th shell: up to 18
Electron Arrangement of Oxygen Atom (Atomic Number = 8)
4.1.2.2 Development of the Periodic Table
Arrangement of Elements in Periodic Table
Elements arranged by atomic (proton) number.
Reason for the Name 'Periodic Table'
Similar properties occur at regular intervals.
Horizontal Rows in Periodic Table
Periods (number of electron shells).
Vertical Columns in Periodic Table
Groups (number of outer shell electrons).
Early Periodic Table Arrangement
Ordered by atomic mass; led to misclassification.
Problems with Atomic Mass Ordering
Different isotopes with varying atomic masses.
Mendeleev's Innovation
Ordered primarily by atomic number; grouped similar properties and left gaps for undiscovered elements.
4.1.2.3 Periodic Table: Metals and Non-Metals
Most Elements in the Periodic Table
Metals.
Location of Non-Metals in Periodic Table
Top right hand side.
Properties of Metals
Strong, malleable, good conductors of heat and electricity, shiny.
Properties of Non-Metals
Dull, brittle, generally do not conduct electricity.
4.1.2.5 Group 1
Group 1 Metals Name
Alkali metals.
Electron Structure of Group 1 Metals
One electron in outer shells; similar properties.
Properties of Group 1 Metals
Soft, low density, low melting points, highly reactive with air and water.
Trend in Properties Down Group 1
Reactivity increases, lower melting and boiling points.
Explanation for Reactivity of Group 1 Metals
Losing one electron for full outer shell is easier as outer electron is further from the nucleus down the group.
4.1.2.6 Group 7
Group 7 Elements Name
The Halogens.
Charge of Halogen Ions
Form -1 ions as they gain an electron.
Trend in Properties Down Group 7
Reactivity decreases, higher melting and boiling points.
Explanation for Decreased Reactivity of Group 7 Elements
Difficulty in gaining an electron as the outer shell is further from the nucleus.
Properties of Halogens
Form diatomic molecules (e.g., F₂), non-metals, colored vapors, more reactive halogens displace less reactive ones.
4.1.2.4 Group 0
Properties of Group 0 Elements (Noble Gases)
Unreactive (inert), monatomic.
Reason for Inertness of Noble Gases
Full outer electron shell.
Boiling Point Trends in Noble Gases
Increase down the group due to larger atoms.
Topic 4: Energy
PAGES: 167-178
4.1.1.1 Energy Stores and Systems
Eight Energy Stores
Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear.
Four Ways Energy can be Transferred
Mechanically (work), electrically (moving charges), by heating, by radiation (sound or light).
Definition of a System
An object or group of objects involved in energy transfer.
Energy Changes in a System
Energy is transferred.
Definition of a Closed System
A system where energy cannot enter or leave.
Wasted Energy Concept
Energy that is stored in a less useful way.
Definition of Work Done
Energy transferred.
How Throwing a Ball Does Work
Chemical energy in the arm transferred to kinetic energy of the person and the ball.
How Dropping a Ball Does Work
Gravitational potential energy converted to kinetic energy.
Braking a Car and Work Done
Friction transfers kinetic energy to thermal energy.
Effect of Work Against Friction
Temperature of the object rises.
Work Done in Collisions
Kinetic energy transferred to elastic potential and thermal energy in the car.
Boiling a Kettle as Work Done
Energy transferred to water through heating.
4.1.1.2 Changes in Energy
Kinetic Energy Formula
E_k = rac{1}{2} m v^2 , where:
E_k = Kinetic energy (J)
m = mass (kg)
v = speed (m/s)
Symbols of Kinetic Energy Formula
E_k - Kinetic energy (J), rac{1}{2} - 0.5, m - mass (kg), v - speed (m/s)
Elastic Potential Energy Formula
E_e = rac{1}{2} k e^2 , where:
E_e = Elastic potential energy (J)
k = spring constant (N/m)
e = extension (m)
Limit of Proportionality in Elastic Potential Energy
Assumed that the limit has not been exceeded.
Definition of Gravitational Potential Energy
Energy gained by raising an object above ground level.
Gravitational Potential Energy Equation
E_p = m g h , where:
E_p = Gravitational potential energy (J)
m = mass (kg)
g = gravitational field strength (9.8 N/kg)
h = height (m)
Symbols in Gravitational Potential Energy Equation
E_p - Gravitational potential energy (J), m - mass (kg), g - gravitational field strength (9.8 N/kg), h - height (m)
4.1.1.3 Energy Changes in Systems (Specific Heat Capacity)
Definition of Specific Heat Capacity
Energy required to raise temperature of 1 kg of substance by 1°C.
Linking Energy Transfer to Specific Heat Capacity
E = m c heta , where:
E = Energy transferred (J)
m = mass (kg)
c = specific heat capacity (J/kg°C)
heta = temperature change (°C)
Required Practical: Specific Heat Capacity
Method
Step-by-step method for measuring the specific heat capacity of a sample material; includes equipment set-up and measurements.
Definition of Power
Rate at which energy is transferred or work is done.
Power Calculation Formulas
P = rac{E}{t} (energy transferred/time).
P = rac{W}{t} (work done/time).
Unit of Power
Watts (W).
Watt Equivalent
1 Watt = 1 Joule/second (1 J/s).
4.1.2 Conservation and Dissipation of Energy
Definition of Conservation of Energy
Energy can be transferred, stored, or dissipated but can never be created or destroyed.
Energy Transfers with Mobile Phones
Chemical energy of battery transferred usefully, some is wasted as thermal energy.
Ways to Reduce Unwanted Energy Transfers
Lubrication (reduces friction).
Thermal insulation (prevents thermal energy loss).
Thermal Energy Transfer in Solids
Conduction.
Thermal Energy Transfer in Fluids
Convection.
Thermal Conductivity Definition
Measure of how quickly energy is transferred through a material by conduction.
Factors Affecting Cooling Rate of Buildings
Thickness and thermal conductivity of walls.
4.1.2.2 Efficiency
Efficiency Calculation Formula
ext{Efficiency} = rac{ ext{Useful energy output}}{ ext{Total energy input}}
Ways to Increase Efficiency
Increase useful energy output; decrease wasted energy output.
Why Useful Energy Output is not Total Energy Output
Some energy is usually wasted as thermal energy.
Exception to Energy Output Rule
Electric heaters transfer all energy to useful thermal energy.
Non-Renewable Energy Resource Definition
Energy sources that will eventually deplete.
Types of Non-Renewable Energy
Crude oil, natural gas, coal (fossil fuels).
Other Non-Renewable Resource
Nuclear energy.
Renewable Energy Resource Definition
Sources that can be replenished while being used.
Types of Renewable Energy Resources
Solar, wind, water waves, hydroelectric, biofuel, tidal, geothermal.
Major Uses of Energy Resources
Transport, electricity generation, heating.
Evaluate Different Energy Resources
Energy Resource | Advantages | Disadvantages |
|---|---|---|
Fossil Fuels and Nuclear | Reliable, easy to obtain, cost-effective | Will deplete, cause pollution (acid rain, global warming, nuclear contamination) |
Geothermal | Reliable, minimal environmental damage | Limited to certain areas, high startup costs |
Solar | Renewable, low running costs | Maximum output limited, high initial costs |
Wind | Renewable, low running costs | Could be visually polluting, initial costs high |
Hydro | No pollution, reliable (unless drought) | Flooding, habitat loss, costly to set up |
Biofuel | Carbon neutral, reliable | Refining costs high, can conflict with food production |
Tidal | No pollution, reliable | Visual pollution, impacts boat navigation |
Topic 5: Bonding, Structure and Properties of Matter
PAGES: 112-121
4.1.1.2 Ionic Bonding
Elements Combining to Form Ionic Compounds
Metals combine with non-metals.
Ionic Bonding and Electrons
Metals lose electrons to form positive ions, non-metals gain electrons to form negative ions.
Visual Representation of Sodium to Sodium Ion
Visual Representation of Oxygen to Oxygen Ion
Force of Attraction Between Ions
Electrostatic attraction (ionic bond).
Groups That Form Ions Easily
Groups 1 and 7, then Groups 2 and 6.
4.2.2.3 Properties of Ionic Compounds
Structure of Ionic Compounds
Regular (giant ionic) structure.
Properties of Ionic Compounds
High melting/boiling points, conduct electricity in molten/solution, dissolve easily in water.
Description of Ionic Compound Structure
Giant lattice of opposing charged ions held by strong electrostatic forces.
Empirical Formula Definition
Simplest ratio of elements in a compound.
Working Out Empirical Formula from Dot-Cross Diagram
Count number of atoms of each element.
Example: Magnesium Chloride Empirical Formula
ext{Empirical Formula} = ext{MgCl}_2
Working Out Empirical Formula from 3D Ionic Lattice
Identify ions, balance charges for zero compound charge.
Example: Empirical Formula of Potassium Oxide
Potassium forms +1 ions, oxygen forms -2 ions; thus, ext{Empirical Formula} = ext{K}_2 ext{O}
4.2.1.4 Covalent Bonding
Types of Elements for Covalent Compounds
Non-metals with non-metals.
Formation of Covalent Bonds
Atoms share electrons.
Diagram of Water Molecule Bonding (H₂O)
Examples of Covalent Compounds
Water (H₂O), Methane (CH₄), Carbon Dioxide (CO₂).
Properties of Simple Molecular Compounds
Low melting/boiling points, liquids/gases at room temperature, do not conduct electricity.
Why Simple Molecular Compounds Have Low Melting/Boiling Points
Strong covalent bonds but weak intermolecular forces, requiring little energy to overcome.
4.2.3.1 Properties of Giant Covalent Structures
Examples of Giant Covalent Substances
Diamond, graphite, silicon dioxide, buckyballs.
Diamond Properties Related to Structure
Very hard, high melting point; each carbon atom forms 4 covalent bonds.
Why Diamond Cannot Conduct Electricity
No delocalised electrons present.
Graphite Properties Related to Structure
High melting point; conducts electricity (delocalised electrons), soft/slippery (weak intermolecular forces between layers).
Silicon Dioxide High Melting Point Explanation
A giant covalent compound; strong covalent bonds require significant energy to overcome.
4.2.3.3 Graphene and Fullerenes
What is a Fullerene?
Structures made from carbon in hexagonal arrangements forming hollow shapes (e.g., spheres, tubes).
First Discovered Fullerene
Buckminster fullerene (C₆₀); spherical shape.
What is Graphene?
A single layer of graphite.
What are Nanotubes?
Cylindrical fullerene shapes.
Uses of Nanotubes
High length-to-diameter ratios; useful in electronics.
4.2.1.5 Metallic Bonding
Metallic Bonding in Terms of Electrons
Positively charged metal ions surrounded by a sea of delocalised electrons; ions attracted to electrons.
High Melting Point of Most Metals Explanation
Strong electrostatic forces between positive ions and delocalised electrons require immense energy to overcome.
Why Metals are Good Conductors
Delocalised electrons can carry heat and charge.
Definition of Malleability in Pure Metals
Ability to be bent, hammered, or shaped.
Why Pure Metals are Malleable
Atoms arranged in layers can slide over one another.
Definition of Alloys
Mixtures of metals and/or non-metals.
Why Alloys are Harder Than Pure Metals
Larger atoms disrupt orderly layers, making it difficult for them to slide past each other.
4.2.2.5 Polymers
Nature of Plastics/Polymers
Large molecules formed from repeating monomer units via strong covalent bonds.
Structure of Polymers
Large and strong intermolecular forces result in solid state at room temperature.
Topic 6: Organisation (Organ Systems)
PAGES: 27-42
4.2.1 Principles of Organisation
Definitions
Cell: Basic building blocks of organisms.
Tissue: Group of similar cells.
Organ: Group of different tissues.
4.2.2.1 Digestive System
Function of Digestive System
Break down and absorb food.
Organs of the Digestive System and Their Functions
Salivary Gland: Produces amylase.
Stomach: Physically breaks down food, produces pepsin and hydrochloric acid.
Liver: Produces bile.
Pancreas: Produces protease, amylase, and lipase.
Gall Bladder: Stores bile.
Small Intestine: Produces enzymes and absorbs digested food.
Large Intestine: Absorbs excess water.
Rectum: Stores faeces.
Required Practical: Food Tests
Testing for Carbohydrates, Lipids, Proteins
Sugars: Use Benedict's solution, turn from blue to orange if sugar is present (heat).
Starch: Iodine turns from brown to blue-black.
Lipids: Form cloudy layer with ethanol and distilled water.
Protein: Biuret solution turns from blue to lilac.
4.2.2.1 Enzymes
Definition of Enzymes
Biological catalysts.
Factors Affecting Enzyme Activity
Temperature, pH.
Lock and Key Theory
Substrate fits into enzyme's active site; specific shape.
Effect of Extreme pH on Enzymes
Active site shape changes; enzyme denatures.
Effect of High Temperature on Enzymes
Active site changes; enzyme denatures.
Digestive Enzymes
Amylase: Produced in salivary glands, pancreas; acts on starch to produce glucose/maltose.
Protease (Pepsin): Stomach, pancreas; acts on proteins to produce amino acids.
Lipase: Pancreas; acts on lipids to produce fatty acids and glycerol.
Functions of Bile
Neutralizes stomach acid; emulsifies fat.
Required Practical: The Effect of pH on Enzymes
Investigating Amylase Reaction Rate with pH
Heat water to 35°C, prepare buffered solutions, mix with starch and amylase, monitor reaction with iodine solution.
4.2.2.2 Heart and Blood Vessels
Function of Heart
Pumps blood in a double circulatory system.
Double Circulatory System Definition
Blood travels twice through the heart to complete one circuit.
Heart Diagram with Labels
Function of Left Ventricle
Pumps oxygenated blood to the body.
Function of Right Ventricle
Pumps deoxygenated blood to the lungs.
Heart Rate Control
Pacemaker cells produce electrical impulses for rhythmic contraction.
What is an Artificial Pacemaker?
Device implanted to maintain heart rhythm.
Types of Blood Vessels
Arteries, veins, capillaries.
Structure and Function of Arteries
Strong, elastic walls; carry high-pressure blood away from heart.
Structure and Function of Veins
Carry low-pressure blood to heart; contain valves to prevent backflow.
Structure and Function of Capillaries
Thin walls (one cell thick) for substance diffusion.
Required Practical: Measuring Lung Structure
Lung Structure Diagram with Labels
4.2.2.3 Blood
Components of Blood
Red blood cells, white blood cells, platelets, plasma.
Components, Functions, and Adaptations
Red Blood Cells: Carry oxygen (no nucleus, large surface area, contains haemoglobin).
White Blood Cells: Defend against infection (produce antibodies, phagocytosis).
Platelets: Help clot blood (no nucleus, small fragments).
Plasma: Transports cells (pale straw-coloured liquid).
4.2.2.4 Coronary Heart Disease
What are Coronary Arteries?
Supply blood to heart muscle.
Causes of Coronary Heart Disease
Fatty material builds up in arteries, reducing blood flow and oxygen.
Treatment of Coronary Heart Disease
Stents (keep arteries open), statins (reduce blood cholesterol).
Consequence of Faulty Heart Valve
Blood flows backward when the heart is relaxed.
Types of Heart Valves
Mechanical and biological valves.
Heart Failure Treatments
Transplant or artificial hearts while waiting.
4.2.2.5 Health Issues
Definition of Health
Physical and mental well-being.
Definition of Communicable Diseases
Infectious diseases passed between individuals.
Definition of Non-Communicable Diseases
Non-infectious diseases.
Factors Affecting Physical and Mental Health
Diet, stress.
Defects to Immune System Effects
Increased susceptibility to infectious diseases.
Definition of Pathogen
Micro-organism causing disease.
Pathogen Type Triggering Cancers
Viruses.
Immune Reactions Causing Allergies
Rashes and asthma.
4.2.2.7 Cancer
Definition of Cancer
Uncontrolled cell division.
Definition of Benign Tumor
Growth of cells contained in one area.
Definition of Malignant Tumor
Growth that invades neighboring tissues and forms secondary tumors.
Lifestyle Impact on Non-Communicable Diseases
Definition of Risk Factor
Factor increasing disease likelihood.
Risk Factors for Cardiovascular Disease
Poor diet, smoking, lack of exercise.
Risk Factors for Cancer
Carcinogens including ionizing radiation.
Major Risk Factor for Type 2 Diabetes
Obesity.
Risk Factors Affecting Unborn Babies
Smoking and alcohol exposure.
Effects of Smoking on Lungs
Lung disease, lung cancer.
4.2.3 Plant Tissues
Leaf Structure and Function
Waxy Cuticle: Transparent; waterproof to prevent evaporation.
Upper Epidermis: Transparent; allows light through.
Palisade Mesophyll: Contains chloroplasts for photosynthesis; elongated for absorption.
Spongy Mesophyll: Air spaces for gas exchange.
Xylem: Transports water/minerals.
Phloem: Transports sugars.
Guard Cells: Open/close stomata.
4.2.3.2 Plant Organ Systems
Function of Root Hair Cell
Absorbs water/minerals from soil.
Adaptation of Root Hair Cell
Long projections increasing surface area for better absorption.
Adaptations of Xylem Vessels
Formed from dead cells; hollow tubes transport water; strengthened by lignin.
Adaptations of Phloem Cells
Living cells with small pores for sap movement; can transport sugar bi-directionally.
4.2.3.3 Transpiration
Definition of Transpiration
Loss of water from leaves through evaporation.
Factors Affecting Transpiration Rate
Light intensity, temperature, air flow, humidity.
Effect of Changes in Environmental Factors
More light opens stomata, higher temperatures increase evaporation, more airflow increases evaporation, lower humidity causes faster transpiration.
Measure Rate of Transpiration
Measure water uptake related to leaf evaporation.
Definition of Translocation
Transport of dissolved substances (e.g., sugars) in a plant.
Topic 7: Electricity
PAGES: 179-190
4.2.1 Current, Potential Difference, and Resistance
Standard Circuit Diagram Symbols
4.2.1.2 Electrical Charge and Current
Definition of Electric Current
Flow of electrical charge.
Factors Determining Electric Current Size
Rate of flow of electrical charge.
Equation for Electrical Charge Flow
Q = I imes t , where:
Q = charge flow (C)
I = current (A)
t = time (s)
Charge Flow Unit
Coulomb (C).
Necessity for Electrical Charge Flow
Source of potential difference.
Current Rule in Series Circuits
Current same at any point in loop.
4.2.1.3 Current, Resistance, and Potential Difference
Current Dependence Factors
Resistance (R) and potential difference (V).
Current Changes with Resistance
For constant potential difference, increasing resistance decreases current.
Potential Difference Calculation
V = I imes R
Required Practical: Investigating Resistance Changes
Method
Connect crocodile clips to resistance wire (100 cm apart).
Record ammeter and voltmeter readings.
Move one crocodile clip closer (90 cm).
Repeat reducing length down to 10 cm.
Calculate resistance using R = rac{V}{I} .
Graph resistance against length.
4.2.1.4 Resistors
Current-Voltage Graph for Ohmic Conductor
Current-Voltage Graph for Filament Lamp
Current-Voltage Graph for Diode
Resistance of Filament Lamp Changes
Resistance increases with temperature due to increased filament temperature.
Current Direction in Diodes
Current flows only in one direction due to high reverse resistance.
Resistance Changes in Ohmic Conductors
Resistance remains constant at a constant temperature; current proportional to potential difference.
Required Practical: Voltage and Current Characteristics
Voltage-Current Relationship Experiment Procedure
Alter potential difference in circuit setup; measure current and voltage.
4.2.2 Series and Parallel Circuits
Series Circuit Example
Parallel Circuit Example
Series Circuit Current Rule
Current is the same through each component.
Series Circuit Potential Difference Rule
Total potential difference is shared among components.
Series Circuit Resistance Rule
Total resistance is the sum of each component's resistance: R_{ ext{total}} = R_1 + R_2
Parallel Circuit Current Rule
Total current is the sum of currents through each loop.
Parallel Circuit Potential Difference Rule
Same potential difference across each component.
Parallel Circuit Resistance Rule
Total resistance is less than the smallest individual resistor.
4.2.3 Domestic Uses and Safety
Domestic Electricity Supply Characteristics (UK)
Frequency = 50 Hz, Potential difference = 230 V.
Direct vs. Alternating Current
Direct current flows one way (batteries); alternating current changes direction (mains).
Mains Connection Method
Appliances connected via three-core cable (three pin plug).
Wires in Three-Core Cable
Live (Brown): Carries alternating potential difference.
Neutral (Blue): Completes circuit, carries away current.
Earth (Green/Yellow): Safety wire.
Potential Differences of Wires
Live: 230 V
Neutral: 0 V
Earth: 0 V.
Electric Shock Risk When Plug is Off
Risk from live wire still present.
Danger of Live-Earth Connections
Low resistance links can cause high current flow, risk of fire.
4.2.4 Power
Power, Potential Difference, Current Relationship
P = V imes I
Power, Current, Resistance Relationship
P = I^2 imes R
Units of Power, Potential Difference, Current, and Resistance
Power (P) = Watts (W)
Potential Difference (V) = Volts (V)
Current (I) = Amperes (A)
Resistance (R) = Ohms (Ω)
Electrical Appliances Purpose
Bring about energy transfers.
Energy Transfer Dependence
Based on appliance power and duration of use.
Work Done in Circuits
Occurs when charge flows.
Unit of Charge Flow
Coulomb (C).
Energy Transfer Calculation
E = P imes t or E = Q imes V
Power Relationships with Charge Flow
Increasing potential difference increases charge flow, leading to increased current and power transferred.
What is the National Grid?
System of cables and transformers linking power stations to consumers.
Step Up Transformers Usage
Increase potential difference for reduced energy loss in transmission.
Step Down Transformers Usage
Decrease potential difference for safe domestic use.
National Grid Efficiency
Transmits high power at high potential difference, reducing energy loss due to low current flow.