Science Knowledge Organiser Binder by AssemblyTube

Atherosclerosis - A disease only affecting arteries  Arteries are at greater risk of damage than other blood vessels due to the rapid movement of blood under high pressure.  May lead to CHD or stroke.

Blood Clotting

Subject: Science Years: 12 Term: 1a Topic: 1 – Lifestyle, Health and Risk – Part One Lesson Sequence Topic: 1. Introduction to Case Studies 2. Importance of Circulation 3. Heart Structure and Function 4. Water as a Solvent 5. Structure and Function of Blood Vessels 6. Cardiac Cycle 7. Core Practical 1 8. Ethics of Using Small Invertebrates in Research 9. Atherosclerosis 10. Blood Clotting 11. Perception of Risk 12. Correlation, Causation and Conflicting Evidence 13. Evaluating Study Design 14. Factors affecting CVD Key Assessments EA Exam 1 Core Practical 1

Core Texts Salters Nuffield AS/A Level Biology Revise Salters-Nuffield AS/A Level Biology A Revision Guide

Structure and Function of Blood Vessels Vessel Structure Artery  Thick walls  Smooth muscles  Elastic Fibres  Lined by smooth endothelial cells  Narrow lumen Water As A Solvent  Water is a polar molecule (dipole) held together by covalent bonds. The oxygen atom has more protons, so attracts more than its fair share of electrons.  Water is liquid at room temperature. Hydrogen bonds form electrostatic interactions between polar molecules.  Water easily dissolves ionic (salt) and polar molecules (sugar, amino acids).

Capillaries



Veins

   

Very thin, one cell thick. Only have endothelium. Thin walls Little smooth muscle or elastic fibres Wide lumen Valves

Structure and Function of Blood Vessels



A number of factors must be present before blood clotting can begin.



This is essential to prevent blood clotting in the wrong place (such as blood vessels), which may lead to a blockage.

Function  Withstands high blood pressure.  Allow diameter to alter with blood flow.  Allows stretching and recoil, smooth blood flow.  Low friction, ease blood flow  To maintain blood pressure 

Rapid exchange (diffusion) between blood and tissue.

 

Blood under low pressure No pulse so no stretch and recoil needed.

 

Large volume acts as blood reservoir Stop backflow

Keywords

Anaerobically

Diastole

Angina

In the absence of oxygen. A widening or bulge in the wall of a blood vessel (or organ) that may weaken and rupture. Chest pain caused by reduced blood flow to the heart forcing heart muscle cells to respire anaerobically.

Arrhythmia

Mass Transport System Myocardial Infarction

Diffusion

The pressure in your blood vessels when your heart rests between beats - mmHg. Movement of atoms from a region of their high concentration to a region of their low concentration by slow random movement.

Irregular or abnormal heartbeat.

Dipole

A molecule containing opposite charges.

Plaque

Arterioles

Small arteries leading into capillaries.

Double Circulation

A circulatory system where blood passes twice through the heart on one trip around the body.

Polar Molecule

Atheroma

Degeneration of arterial walls leading to restriction and a risk of thrombosis.

Endothelium

The tissue that forms a single layer of cells lining the inside of blood vessels.

Positive Feedback Prothrombi n

Fibrinogen

The insoluble protein formed from fibrinogen by the action of thrombin during blood clotting. A soluble protein involved in blood clotting. It is converted into insoluble fibrin strands following activation of thrombin.

Heart Attack Hydrogen Bonding Hydrophilic

Also known as a myocardial infarction or coronary thrombosis. A weak electrostatic interaction between a proton and an electronegative atom. Water loving, easily mixed with water.

Single Circulation Sphygmom anometer Stroke

Hydrophobic

Repels water, or fails to mix with water.

Systemic

Hypertension Inflammatory Response

Abnormally high blood pressure. A response of the body to disease or injury (typically pain, heat, redness and swelling). An inadequate blood supply to an organ or body part, especially heart muscles.

Systole Systolic Pressure

Aneurysm

Atherosclerosis Atrioventricular Valves

Calories Cardiac Cycle Cardiac Muscle Cardiovascular Disease (CVD) Cascade Cholesterol Collagen Coronary Arteries Coronary Heart Disease (CHD) Correlation

The clogging of arteries with a fatty substance known as plaque (atheroma). Name given to the valves located between the atrium and ventricle. Prevents return of blood to the atrium. Unit for measuring heat. The amount of heat needed to raise the temperature of 1g of water by 1 oC. The sequence of events that occur when the heart beats. Specialised muscle found only in the heart. A class of diseases that involve the heart or blood vessels. An event or series of chemical reactions in response to a signal [signalling cascade]. A fat containing substance found in body tissue that may cause atherosclerosis. A fibrous protein that provides strength to connective tissue and blood vessels. A branch of the aorta that provides the heart with a blood supply. A disease caused by the build up of plaque (atherosclerosis) inside coronary arteries. A mutual relationship or connection between two or more things.

Diastolic Pressure

Phase of the heartbeat. Heart muscles relax and the heart refills with blood.

Fibrin

Ischaemia Kilocalories Kilojoule Mass Flow

1000 calories. 1000 joules, a measure of the energy value of foods. Movement of fluid in one direction through a system of tube-like vessels.

Oedema

Semilunar Valves

Thrombin Thrombopla stin Thrombosis Tissue Fluid

Movement of materials from an exchange surface or exchange surfaces of cells to the rest of the organism. Heart attack, when blood flow to the heart decreases causing tissue damage or death of part of a heart muscle. A condition whereby an excess of watery fluid collects in cells, cavities or body tissue. A patch of degenerative material on the inner lining of arterial walls in atherosclerosis. An asymmetric molecule where there is a partial positive charge on one part of the molecule. The enhancing or amplification of an effect by its own influence on the process which gives rise to it. A plasma protein produced in the liver (in the presence of vitamin k) that converts to thrombin during blood clotting. Pair of valves at the base of the aorta and the pulmonary artery, three cusps that prevent the flow of blood back into the heart. A circulatory system (e.g. Fish) where blood passes once through the heart in each complete circuit of the body. Instrument used to determine systolic and diastolic blood pressure. Death of brain cells due to a lack of oxygen. The part of the circulatory system that provides oxygen and removes carbon dioxide. Phase of the heartbeat whereby heart muscles contract. The maximum arterial pressure during contraction of the left ventricle â&#x20AC;&#x201C; mmHg. A protease made during blood clotting that catalyses conversion of fibrinogen into fibrin. An enzyme in blood platelets that converts prothrombin into thrombin as blood clots. The formation of a blood clot inside a blood vessel that obstructs the flow of blood. An extracellular fluid that bathes the cells of most tissues, arriving via blood capillaries.

Key Terms Eurakryotic cells Eukaryote Prokaryotic cells DNA Ribosome Respiration Diffusion Organelle Mitochondrion Chloroplast Cytoplasm Nucleus Cell membrane Vacuole Cell wall Photosynthesis Turgid Biconcave

Knowledge Organiser â&#x20AC;&#x201C; Cell Structure Cells that contain a nucleus An organism that is made of eukaryotic cells Single-celled organisms that do not contain a nucleus Deoxyribonucleic acid â&#x20AC;&#x201C; the genetic information found in all living orgnanisms A cell organelle that makes proteins The release of energy from glucose The net movement of particles form an area of high concentration to an area of lower concentration A part of a cell with a specific function A cell organelle in which respiration occurs A cell organelle in which photosynthesis occurs Jelly like substance in cells where chemical reactions occur A cell organelle found in eukaryotes containing their genetic material Structure surrounding the cell that controls what moves in and out of the cell Found in plant cells, filled with cell sap, keeps the cell turgid Made from cellulose and provides structural strength the some cells (not animal cells) Chemical reaction that happens in chloroplasts that stores energy in glucose Describes a swollen cell Describes a shape with a dip that curves inwards on both sides

Ova Axon Phloem Xylem Electron microscope Resolution

Diagrams

Eggs The extension of a nerve cell along which the electrical impulses travel Tubes of living cells that carry sugars to all cells in plants Tubes of dead plant cells through which water flows A microscope that uses electrons in place of light to give higher magnification The smallest distance between two seperate points

Key Terms Infectious Vector Antibiotic Chitin Hyphae Malaria Insecticide Lysozymes Cilia Antigen Antitoxin Vaccine Antiseptic Anaesthetic Efficacy

Knowledge Organiser â&#x20AC;&#x201C; Infection and Response

Describes a pathogen that can easily be transmitted, or an infected person who can pass on the disease. An animal that spreads a communicable disease. A group of medicines, first discovered by Alexander Fleming, that kill bacteria and fungi but not viruses. A polymer made from sugars that forms the cell walls of fungi and the exoskeleton of insects. Branching filaments of a fungus that spread out. A communicable disease, caused by a protest transmitted in mosquitos, which attacks red blood cells. A chemical that kills insects. Antibacterial enzymes found in your tears to prevent eye infections. Tiny hair-like projections from ciliated cells that waft mucus out of the gas exchange system. A protein on the surface of a pathogen that your antibodies can recognize as foreign. A protein produced by your body to neutralize harmful toxins produced by pathogens. A medicine containing an antigen from a pathogen that triggers a low level immune response so that if you become infected later your body can respond more quickly to the pathogen. A substance applied to the skin or another surface to destroy pathogens. A drug that stops all pain sensation and can be local or general. How effective a drug is.

Diagrams

A medical experiment in which the patient and doctors Double blind trials do not know who has been given the drug and who has been given the placebo. Placebo A medicine that has only psychological effects. Phagocytes A type of white blood cell that engulf pathogens. Lymphocytes A type of white blood cell that produce antibodies. Highly specific Y-shaped proteins that are produced by Antibodies the immune system to help stop intruders from harming the body.

Key Terms Endothermic reaction

Knowledge Organiser – Bioenergetics A reaction that requires energy to be absorbed to work

The process by which plants use sunlight to produce glucose. Happens in chloroplasts Limiting factor Anything that reduces or stops the rate of a reaction Yield The amount of an agricultural product produced The process by which living things release energy from Respiration glucose. Happens in mitochondria Aerobic In the presence of oxygen Oxidation A reaction that uses oxygen Exothermic A reaction that gives out thermal energy reaction Anaerobic In the absence of oxygen The amount of extra oxygen the body needs after exercise to Oxygen debt break down lactic acid The chemical breakdown of glucose into ethanol and carbon Fermentation dioxide by respiring micro-organisms such as yeast The sum of all the chemical reactions that happen in an Metabolism organism

Photosynthesis

+ energy + energy

Diagrams

Key Terms Atom Proton Neutron Electron

Knowledge Organiser â&#x20AC;&#x201C; Atomic Structure and the Periodic Table

A particle with no electric charge made up of a nucleus containing protons and neutrons and surrounded by electrons. A positively charged particle found in the nucleus of an atom. A neutral particle found in the nucleus of an atom. Negatively charged particles found on energy levels (shells) surrounding the nucleus inside atoms. Central part of an atom containing protons and neutrons. The region an electron occupies surrounding the nucleus inside an atom.

Nucleus Energy level (shell) Atomic Number of protons in an atom. number Mass number Number of protons plus neutrons in an atom. Atoms with the same number of protons but a different number Isotope of neutrons. The average mass of atoms of an element taking into account Relative the mass and amount of each isotope it contains. atomic mass RAM = Total mass of atoms / total number of atoms Electronic The arrangement of electrons in the energy levels of an atom. structure An electrically charged particle containing different numbers of Ion protons and electrons. Group The name given to each column in the periodic table. Element A substance containing only one type of atom. A substance made from different elements chemically bonded Compound together. Period The name given to a row in the periodic table. Alkali metals The elements in Group 1 of the periodic table. Noble gases The elements in Group 0 of the periodic table.

Diagrams

Halogens The elements in Group 7 of the periodic table. Diatomic molecule A molecule containing 2 atoms. Halides Compounds made from Group 7 elements. More than one substance that are not chemically Mixture bonded. Solvent The liquid that a solute dissolves in. Solution A solute dissolved in a solvent. Soluble A substance that will dissolve. Insoluble A substance that will not dissolve. Solute The solid that dissolves in a solvent.

Key Terms

Knowledge Organiser – Bonding, structures and the properties of matter

Ionic substances are made up of a giant lattice of positive and negative ions in a regular structure. Ionic bonding The electrostatic attraction between positive and negative ions Molecule Particle made from atoms joined together by covalent bonds Covalent bond Two shared electrons joining atoms together Intermolecular Weak forces between molecules forces Long chain molecule made from joining lots of small Polymer molecules together by covalent bonds Monomer The building block (molecule) of a polymer Delocalised Free to move around Metallic The attraction between the nucleus of metal atoms and bonding delocalized electrons Malleable Can be hammered into shape A mixture of a metal with small amounts of other elements, Alloy usually other metals States of These are solid, liquid and gas matter Family of carbon molecules each with carbon atoms linked in Fullerenes rings to form a hollow sphere or tube Substance that speeds up a chemical reaction but is not used Catalyst up in it Giant Lattice

Ionic bonding and structure

Metallic structure

Diagrams

Key Terms

Knowledge Organiser â&#x20AC;&#x201C; Quantitative Chemistry

Relative atomic mass Relative formula mass Mole Avogadro constant Thermal decomposition

The average mass of atoms of an element, taking into account the mass and the amount of each isotope it contains. The sum of the relative atomic masses of all the atoms in the formula. Measurement of the amount of a substance. The number of atoms, molecules or ions in one mole of a given substance (6.02x1023). Reaction where high temperature causes a substance to break down into simpler substances.

Excess

When the amount of a reactant is greater than the mount that can react.

Limiting reactant

The reactant in a reaction that determines the amount of products formed. Any other reagents are all in excess and will not react.

Diagrams

Key Terms

Knowledge Organiser – Chemical Changes

Reactivity An arrangement of metals in order of reactivity series Displacement Reaction where a more reactive element takes the reaction place of a less reactive element in a compound A reaction in which a substance loses electrons (gains Oxidation oxygen) Reaction in which a substance gains electrons (loses Reduction oxygen) Ore A rock from which a metal can be extracted for profit Acid

Solution with a pH less than 7; produces H+ ions in water

Aqueous

Solution with a pH more than 7; produces OH- ions in water Dissolved in water

Strong acid

Acid in which all the molecules break into ions in water

Alkali

Acid in which only a small fraction of the molecules break into ions in water A solution in which there is a small amount of solute Dilute dissolved Concentrated A solution in which there is a lot of solute dissolved A reaction that uses up some or all of the H+ ions from Neutralisation an acid Electrolysis Decomposition of ionic compounds using electricity Electrolyte A liquid that conducts electricity Discharge Gain or lose electrons to become electrically neutral Inert Electrodes that allow electrolysis to take place but do electrodes not react themselves Weak acid

Acid + Alkali ‐> salt + water Metal + acid ‐> salt + hydrogen Metal oxide + acid ‐> salt + water Metal carbonate + acid ‐> salt + water + carbon dioxide

Diagrams

Knowledge Organiser â&#x20AC;&#x201C; Energy Changes Reaction where thermal energy is transferred from the chemicals to the surroundings and so the temperature increases Reaction where thermal energy is transferred from the Endothermic surroundings to the chemicals and so the temperature reaction decreases Activation The minimum energy particles must have to react energy Exothermic reaction

Knowledge Organiser – Formulae and equations

Key Terms Diatomic molecule Spectator ions Ionic equation

A molecule containing two atoms Ions that do not take part in a reaction and do not appear in the ionic equation for the reaction Balanced equation for reaction that omits any spectator ions

Common Reactions Element + oxygen ‐> oxide of element Eg Calcium + oxygen ‐> calcium oxide Compound + oxygen ‐> oxides of each element in compound Eg Methane + oxygen ‐> carbon dioxide + water Water + metal ‐> metal hydroxide + hydrogen (for metals that react with water) Eg water + sodium ‐> sodium hydroxide + hydrogen Acid + metal ‐> salt + hydrogen Eg Hydrochloric acid + magnesium ‐> magnesium chloride + hydrogen Acid + metal oxide ‐> salt + water Eg Sulphuric acid + copper oxide ‐> copper sulphide + water Acid + metal hydroxide ‐> salt + water Eg nitric acid + potassium hydroxide ‐> potassium nitrate + water Acid + metal carbonate ‐> salt + water + carbon dioxide Eg hydrochloric acid + calcium carbonate ‐> calcium chloride + water + carbon dioxide Acid + ammonia ‐> ammonium salt Eg nitric acid + ammonia ‐> ammonium nitrate

Diagrams

Key Terms

Knowledge Organiser – Energy

Specific heat capacity

The energy needed to raise the temperature of 1kg of a substance by 1°C. To scatter in all directions or to use wastefully. When energy has Dissipate been dissipated it means we cannot get it back. The energy has spread out and heats up the surroundings. Non-renewable Energy resources which will run out, because they are finite energy resources reserves, and which cannot be replenished. Renewable Energy resources which will never run out and (or can be) energy resources replenished as they are used. Resources other than fossil fuels. The resources may or may not be renewable. Nuclear power is not a renewable energy resource, but Alternative energy resource tidal power is. Alternative energy resources do not contribute to global warming. Fuel produced from biological material. Biofuels are provided by Biofuel trees such as willow that can be grown specifically as energy resources.

Energy Equations Efficiency (%) = (useful energy out ÷ total energy in) x 100. GPE = mgh Gravitational Potential Energy = mass x gravity x height. Ee = ½ke2 Elastic potential energy = 0.5 x spring constant x extension2 KE = ½mv2 Kinetic Energy = 0∙5 x mass x velocity2. W = F x d work done = force x distance. W = E work done = energy transferred. P = E ÷ t power = energy ÷ time. E = c x m x θ energy = specific heat capacity x mass x change in temperature.

Diagrams

Knowledge Organiser – Electricity

Key Terms Potential difference (p.d.) Electric current Resistor

A measure of the electrical work done by a cell (or other power supply) as charge flows round the circuit. Potential difference is measured in volts (V). A flow of electrical charge. The size of the electric current is the rate at which electrical charge flows round the circuit. A component that acts to limit the current in a circuit. When a resistor has a high resistance, the current is low.

When two quantities are directly proportional, doubling one quantity will cause the other Directly quantity will cause the other quantity to double. When a graph is plotted, the graph line proportional will be straight and pass through the origin. Inversely When two quantities are inversely proportional, doubling one quantity will cause the other proportional quantity to halve Ohmic

The current flowing through an ohmic conductor is proportional to the potential difference across it. If the p.d. doubles, the current doubles. The resistance stays the same.

Non-ohmic

The current flowing through a non-ohmic resistor is not proportional to the potential difference across it. The resistance changes as the current flowing through it changes.

P = V x I V = I x R Q = I x t E = V x Q E = V x I x t

power = voltage x current. voltage = current x resistance. charge = current x time. energy = voltage x charge. energy = voltage x current x time.

Total cost = number of units x cost per unit.

Diagrams

Key Terms

Equations ρ = m/v ΔE = mc Δθ E = mL

Knowledge Organiser – Particle Model of Matter Density = Mass ÷ volume Change in thermal energy = mass x specific heat capacity x temperature change Energy required to change state = mass x specific latent heat

Diagrams

Key Terms

Knowledge Organiser â&#x20AC;&#x201C; Atomic Structure

Proton

A positively charged particle found in the nucleus of an atom.

Neutron

A neutral particle found in the nucleus of an atom.

Electron

Negatively charged particles found on energy levels (shells) surrounding the nucleus inside atoms.

Atomic number Mass number Isotope Alpha particle Beta particle Gamma ray GeigerMĎ&#x2039;ller (GM) tube Half-life

Number of protons in an atom. Number of protons plus neutrons in an atom. Atoms with the same number of protons but a different number of neutrons. A particle formed from two protons and two neutrons. A fast moving electron. An electromagnetic wave. A device which detects ionizing radiation. An electronic counter can record the number of particles entering the tube. The time taken for the number of nuclei in a radioactive isotope to halve. In one half-life the activity or count rate of a radioactive sample also halves.

1 Becquerel An emission of 1 particle per second (1Bq)

Diagrams

Key Terms Atom Proton Neutron Electron

Knowledge Organiser â&#x20AC;&#x201C; Atomic Structure and the Periodic Table

A particle with no electric charge made up of a nucleus Halogens containing protons and neutrons and surrounded by electrons. Diatomic molecule A positively charged particle found in the nucleus of an atom. Halides A neutral particle found in the nucleus of an atom. Mixture Negatively charged particles found on energy levels (shells) surrounding the nucleus inside atoms. Solvent Solution Central part of an atom containing protons and neutrons. The region an electron occupies surrounding the nucleus inside Soluble Insoluble an atom. Solute Number of protons in an atom.

Nucleus Energy level (shell) Atomic number Mass number Number of protons plus neutrons in an atom. Atoms with the same number of protons but a different number Isotope of neutrons. The average mass of atoms of an element taking into account Relative the mass and amount of each isotope it contains. atomic mass RAM = Total mass of atoms / total number of atoms Electronic The arrangement of electrons in the energy levels of an atom. structure An electrically charged particle containing different numbers of Ion protons and electrons. Group The name given to each column in the periodic table. Element A substance containing only one type of atom. A substance made from different elements chemically bonded Compound together. Period The name given to a row in the periodic table. Alkali metals The elements in Group 1 of the periodic table. Noble gases The elements in Group 0 of the periodic table.

Diagrams

The elements in Group 7 of the periodic table. A molecule containing 2 atoms. Compounds made from Group 7 elements. More than one substance that are not chemically bonded. The liquid that a solute dissolves in. A solute dissolved in a solvent. A substance that will dissolve. A substance that will not dissolve. The solid that dissolves in a solvent.

Key Terms

Knowledge Organiser â&#x20AC;&#x201C; Atomic Structure

Proton

A positively charged particle found in the nucleus of an atom.

Neutron

A neutral particle found in the nucleus of an atom.

Electron

Negatively charged particles found on energy levels (shells) surrounding the nucleus inside atoms.

Atomic number Mass number Isotope Alpha particle Beta particle Gamma ray GeigerMĎ&#x2039;ller (GM) tube Half-life

1 Becquerel An emission of 1 particle per second (1Bq)

Diagrams

Key Terms Endothermic reaction

Knowledge Organiser â&#x20AC;&#x201C; Bioenergetics

A reaction that requires energy to be absorbed to work

Aerobic Oxidation Exothermic reaction Anaerobic Oxygen debt Fermentation Metabolism

In the presence of oxygen A reaction that uses oxygen A reaction that gives out thermal energy In the absence of oxygen The amount of extra oxygen the body needs after exercise to break down lactic acid The chemical breakdown of glucose into ethanol and carbon dioxide by respiring micro-organisms such as yeast The sum of all the chemical reactions that happen in an organism

+ energy + energy

Diagrams

Key Terms Giant Lattice Ionic bonding Molecule Covalent bond Intermolecular forces Polymer Monomer Delocalised Metallic bonding Malleable Alloy States of matter Fullerenes Catalyst

Knowledge Organiser â&#x20AC;&#x201C; Bonding, structures and the properties of matter

Ionic substances are made up of a giant lattice of positive and negative ions in a regular structure.

The electrostatic attraction between positive and negative ions Particle made from atoms joined together by covalent bonds Two shared electrons joining atoms together Weak forces between molecules Long chain molecule made from joining lots of small molecules together by covalent bonds The building block (molecule) of a polymer Free to move around The attraction between the nucleus of metal atoms and delocalized electrons Can be hammered into shape A mixture of a metal with small amounts of other elements, usually other metals These are solid, liquid and gas Family of carbon molecules each with carbon atoms linked in rings to form a hollow sphere or tube Substance that speeds up a chemical reaction but is not used up in it

Ionic bonding and structure

Metallic structure

Diagrams

CB1a Microscopes What is the most common microscope used today? The most common light microscope used today contains 2 lenses and was invented at the end of the sixteenth century. Robert Hook used a microscope like this to discover cells in 1665.

CB1 - Key Concepts in Biology (Paper 1 and 2) What magnification did Hook’s microscope have? Hook’s microscope had a magnification of about x30 (it made things appear about 30 times bigger).

What is an electron microscope? Instead of light, beams of electrons pass through a specimen to build up an image. These microscopes can magnify up to x2,000,000 with resolutions down to 0.0000002 millimetres. They allow us to see cells with much greater detail and clarity than a normal light microscope.

What does the detail obtained by a microscope depend on? The detail obtained by a microscope depends on its resolution. This is the smallest distance between 2 points that can still be seen as 2 points. Van Leeuwenhoek’s best microscopes had a resolution of 0.0014 millimetres.

Why do bacteria release digestive enzymes? They release digestive enzymes into their environment and then absorb digested food into their cells.

CB1f Enzyme Action What is an enzyme made from? An enzyme is a 3D protein molecule formed from a chain of amino acids. The 3D contains a small pocket called the active site. What is an active site? An active site is where the substrate of the enzyme fits at the start of a reaction. Different substrates have 3D shapes, and different enzymes have active sites of different shapes. This explains why every enzyme can only work with specific substrates that fit the active site. E.g. each key only fits 1 specific lock.

CB1e Enzymes and Nutrition

How can enzymes be affected? Changes in pH or temperature can affect how the protein folds up and so can affect the shape of the active site. If the shape of the active site changes too much the substrate will no longer fit neatly in. We say that the enzymes has been denatured (key no longer fits in the lock).

How do digestive enzymes in humans work? Digestive enzymes turn the large molecules in our food into the smaller sub-units they are made of. The digested products are then small enough to be absorbed by the small intestine. What are proteins broken down into? Protein molecules are broken down into amino acids.

What are starch molecules broken down into? Starch molecules are broken down into glucose molecules.

CB1c Specialised Cells What is a specialised cell? A specialised cell has a specific function. There are about 200 specialised cells in humans. Specialised cells are adapted to their functions. E.g. nerve, small intestine, pancreas, gametes, epithelial cells.

CB1b Plant and Animal Cells What is an organelle? An organelle is a structure inside a cell with a specific function.

How are cells specialised for digestion? The cells that line the small intestine absorb small food molecules produced by digestion. They are adapted by having membranes with many tiny folds. These adaptations increase the surface area of the cell for faster absorption of digested food.

Where does fertilisation occur? Fertilisation occurs in the oviduct. The cells in the lining of the oviduct transport egg cells towards the uterus. The oviduct cells are adapted for this function by having hair like cilia. These wave from side to side sweeping the egg along.

CB1g Enzyme Activity How are enzymes affected by temperature? As the temperature increase, molecules move faster. Higher speeds increase the chance of substrate molecules bumping into enzyme molecules. However when the temperature gets too high, the shape of the enzyme molecule starts to change. The temperature which the enzyme works fastest is called its optimum temperature.

How does pH affect enzymes? At pHs below and above the optimum the active site’s shape is altered and so the enzymes does not work so well.

How is a human egg cell specialised? The cell membrane fuses with the sperm cell membrane. After fertilisation the cell membrane and jelly coat become hard to stop other sperm cells entering. The cytoplasm is packed with nutrients to supply the fertilised egg with energy and raw materials.

What is the optimal temperature of most human enzymes? The optimum temperature is around 37oC.

CB1d Inside Bacteria

What are lipid (oil and fat) molecules broken down into? Lipids are broken down into fatty acids and glycerol.

How do living plants and animals use enzymes to speed up reactions? Enzymes are biological catalysts that increase the rate of reactions. Enzymes are a special group of proteins found throughout the body. What does amylase do? It is found in the saliva and small intestine and breaks down starch to small sugars. E.g. maltose and glucose.

What does catalase do? Found most cells and especially in liver cells and breaks down hydrogen peroxide. What does starch synthase do? It is found in plant cells and makes starch from glucose. What is DNA polymerase? It is found in the nucleus and joins DNA strands from its monomers (building blocks).

Why are bacteria difficult to see? Bacteria are difficult to see with light microscopes because they are very small and mostly colourless.

CB1h Transporting Substances Explain the structure of a bacteria. Bacteria are prokaryotic, which mean that their cells do not have nuclei or chromosomes or mitochondria or chloroplasts. Instead the cytoplasm contains 1 large loop of chromosomal DNA, which controls most of the cells activities. Smaller loops of DNA are called plasmids. They have a cell wall and a cell membrane.

How are sperm cells specialised for reproduction?

What is active transport? Cells may need to transport molecules against a concentration gradient or transport molecules that are too big to diffuse through the cell membrane. They can do this using active transport. This process is carried out by transport proteins in the cell membrane. The transport proteins capture certain molecules and carry them across the cell membrane. This is an active process and so requires energy. What is osmosis? If there are more water molecules in a certain volume on one side of a membrane than the other, there will be an overall movement of water molecules from the side where there are more water molecules. This diffusion of small molecules of a solvent through a semi permeable membrane is called osmosis.

What is diffusion? Diffusion is the movement of gas and liquid particles from a high concentration to a low concentration. A difference between 2 concentrations forms a concentration gradient. Particles diffuse down a concentration gradient. The bigger the difference between concentrations, the steeper the concentration gradient and the faster diffusion occurs. How do small molecules move into and out of cells? Small molecules such as oxygen and carbon dioxide move into out of cells by diffusion.

What are passive processes? Osmosis and diffusion are passive processes so do not require an input of energy.

Key Vocabulary Definitions Adaptations – the features of an organism that enable it to do a certain function (job). Biological catalyst – a substance found in living organisms that speeds up reactions (an enzyme). Ciliated epithelial cells – a cell that lines certain tubes in the body and has cilia on it’s surface. Cilium – a small hair like structure on the surface of some cells. Plural is cilia. Concentration Gradient – the difference between 2 concentrations. Denatured – a denatured enzyme is one where the shape of the active has changed so much that its substrate no longer fits and the reaction can no longer happen. DNA – deoxyribonucleic acid. A polymer made of sugar and phosphate groups joined to bases. Epithelial cells – a cell found on the surfaces of parts of the body. Eukaryotic – a cell with a nucleus is eukaryotic. Eyepiece lens – organisms that have cells like this are also said to be eukaryotic organisms. Field of view – the circle of light you see looking down a microscope. Gametes – a haploid cell produced by meiosis used for sexual reproduction. Haploid – a cell or nucleus that has 1 set of chromosomes. Gametes are haploid. Magnification – the number of times larger an image is than the initial object that produced it. Objective lens – the part of the microscope that is closest to the specimen. Partially Permeable membrane – describes a membrane that will allow certain particles to pass through it but not others. Another term for this is semi permeable. Product – a substance formed in a reaction. Prokaryotic – a cell with no nucleus is prokaryotic. Organisms such as bacteria are said to be prokaryotic. Resolution – the smallest change that can be measured by an instrument. For example, in a microscope it is the smallest distance between 2 points that can be seen as 2 points and not blurred into 1 point. Scale bars – a line drawn on a magnified image that shows a certain distance at that magnification. Specialised cells – a cell that is adapted for a certain specific function (job). Substrate – a substance that is changed during a reaction. Synthesis – to build a large molecule from smaller sub units.

Calculations To work out a microscopes’ magnification, you multiply the magnifications of its 2 lenses together. So, the magnification of a microscope with a x5 eyepiece lens and a x10 objective lens is 5 x 10 = x50. To calculate mass change work out the difference between the mass of tissue at the start and at the end (final mass – initial mass) divide this difference by the initial mass and multiply by 100. Percentage change in mass = (Final mass – initial mass) ÷ initial mass x 100 A negative answer is a percentage loss in mass.

CB2a Mitosis

CB2 â&#x20AC;&#x201C; Cells and Control (paper 1)

What is the cell cycle? A sequence of growth and division that happens in cells. It includes interphase and mitosis and leads to the production of 2 daughter cells that are identical to the parent cell. How many chromosomes are found in the nuclei of human body cells? The nuclei of human body cells contain 2 copies of each of 23 types of chromosome, making 46 in all. Give an example of one animal and one plant that relies on asexual reproduction? Strawberry plants use stems that grow along the ground, called runners. Animals such an aphids also reproduce asexually.

What are the advantages and disadvantages of asexual reproduction? Asexual reproduction is much faster than sexual reproduction because organisms do not need each other for reproduction. However sexual reproduction produces variation.

Explain the growth of cancer tumours. Changes in cells can sometimes turn them into cancer cells, which means that they undergo uncontrollable cell division. This rapid cell division produces growing lumps of cells called tumours that can damage the body and cause death.

CB2d Stem Cells What are stem cells? Stem cells are cells that can divide repeatedly over a long period of time to produce cells that then differentiate. In plants these cells are found in meristems. How do cells become specialised in most animals? A fertilised egg cell divides to form an embryo. The cells of an early stage embryo are embryonic stems cells that can produce any type of specialised cell. As the cells divide the embryo develops different areas that will become the different organs. The stem cells then become more limited in the types of specialised cells they can produce.

Explain how plants grow? A group of cells near the end of each root and shoot allows the plant to grow. These groups of cells are called meristems. The cells in meristems divide rapidly by mitosis. The cells produced increase in length (elongation) and differentiate into specialised cells.

CB2b Growth in Animals What is growth? Growth in an increase in size as a result of an increase in number or size of cells.

What is asexual reproduction? Asexual reproduction produces offspring that are clones, which means that their cells have the same chromosomes as their parent (they are genetically identical).

How can growth be recorded? By measuring length or mass over time. What is a percentile growth curve? These charts were created by measuring a very large number of babies, the measurements were divided into 100 groups. When divided like this we can find out what percentage of readings are below a certain value or percentile. For example 25 percent of babies will have masses below the 25th percentile line.

What is cell differentiation? The process by which a less specialised cell becomes more specialised for a particular function. The cell normally changes shape to achieve this.

What do the curved lines show? The curved lines show the rate of growth of a baby who stays at exactly the same percentile within the population. Give some examples of specialised human cells A red blood cell has no nucleus, allowing more space for red haemoglobin molecules. Nerve cells have a long fibre that carries electrical impulses around the body. Muscle cells contain special contractile proteins that can shorten the cell.

Give examples of specialised plant cells. Examples of specialised plant cells are root hair cells and xylem cells. There are many different kinds of specialised cells in a plant, allowing the plant to carry out many different processes effectively.

CB2e The Nervous System What is the central nervous system? The brain and spinal cord form the central nervous system (CNS), which controls your body. Nerves make up the rest of the nervous system, this organ system allows all the parts of your body to communicate using electrical signals called nerve impulses.

What is a stimulus? Anything your body is sensitive to, including changes inside your body and in your surroundings. Sense organs (such as eyes, ears and skin) contains receptor cells that detect stimuli. For example skin contains receptor cells that detect the stimulus of temperature change.

What happens to stem cells in a fully developed animal? By the time the young animal is fully developed, the stem cells produce the type of specialised cell that is in the tissue. These are called adult stem cells. What is the function of an adult stem cell? The adult stem cells in humans allow the tissues to grow and to replace old or damaged cells.

CB2c Growth in Plants

What is neurotransmission? The travelling or transmission of impulses is called neurotransmission and happens in neurones. Neurones have a cell body and long extensions to carry impulses.

Why are dendrons and axons frequently long? They are long to allow fast neurotransmission over long distances.

What is a myelin sheath? It is a fatty layer surrounding dendrons and axons. They electrically insulate a neurone, stopping the signal losing energy. It also makes an impulse jump along the cell between the gaps in the myelin and speeds up neurotransmission.

CB2f Neurotransmission Speeds

Why are synapses useful? They are useful because neurotransmitters are only release from axon terminals and so impulse only flow in one direction. They also allow many fresh impulses to be generated in many neurones connected to one neurone.

What is an effector? When the brain coordinates a response to a stimulus, impulse are sent to effector and these carry out an action. Effector include muscles and glands. How can stem cells be used to treat diseases? Scientists have studied embryonic stem cells to treat diseases such as type 2 diabetes or to replace damaged cells. This is done by stimulating stem cells to produce specialised cells and injecting them into the places they are needed. What are the problems with using stem cells? If the stem cell continues to divide inside the body after they replace damaged cells, they can cause cancer. Also stem cells from one person are often killed by the immune system of the person they are put into. This is called rejection.

Explain the role of different neurones? Motor neurone carry impulse to effectors. Relay neurones are short neurones found in the spinal cord, where they link motor and sensory neurones. Neither of these types of neurone has a Dendron and the dendrites are on the cell body.

What is a reflex arc? A neurone pathway consisting of a sensory neurone passing impulses to a motor neurone via a relay neurone which allows a reflex action to occur.

What is a reflex action? Reflex actions are responses that are automatic, extremely quick and protect the body. For example moving your finger away from a hot candle.

What is a synapse? One neurone meets another at a synapse which contains a tiny gap. When an impulse reaches an axon terminal a neurotransmitter substance is release into the gap. This is detected by the next neuron which generates a new impulse.

Key Vocabulary Definitions Asexual reproduction – producing new organism from 1 parent only, these organisms are genetically identical to the parent. Axon – the long extension of a neurone that carries an impulse away from the dendron or dendrites towards other neurones. Axon terminals – the small button at the end of the branches that leave an axon. Cancer cells – a cell that continues dividing causing disease. Clones – the offspring from asexual reproduction, all the cells in a clone are genetically identical to each other and to the parents’ cells. Daughter cells - a new cell produced from the division of a parent cell. Dendrite – a fine extension from a neurone which carries impulse towards the cell body. Dendron – large long extension of a sensory neurone that carries impulse from a dendrite towards the axon. Differentiation – a process by which a less specialised becomes more specialised for a particular function. The cell normally changes shape to achieve this. Diploid – a cell or nucleus that has 2 sets of chromosomes. In humans, almost all cells except the sperms and egg cells are diploid. DNA – deoxyribonucleic acid. A polymer made of sugar and phosphate groups joined to bases. Elongation – when something gets longer such as a cell in a plant root or shoot before it differentiates into a specialised cell. Haploid – a cell or nucleus that has one set of chromosomes. Gametes are haploid. Impulses – an electrical signal transmitted along a neurone. Mitosis – the process of cells dividing to produce two diploid daughter cells that are genetically identical to the parent. Neurones – a cell that transmits electrical impulses in the nervous system. Neurotransmission – impulses passing from neurone to neurone. Neurotransmitter – a substance that diffuses across the gap between one neurone and the next at a synapse, and triggers an impulse to be generated. th

Percentile – the value of a variable below which a certain percentage of observations fall. For example, in an ordered set of data the 20 percentile is the value at which 20 percent of the data points are the same or lower. Rejection – when the immune system attacks and kills cells and tissue that come from another person such as blood cells or stem cells. Root hair cells – a cell found on the surface of plant roots that has a large surface area to absorb water and dissolved mineral salts quickly from the soil. Stem cells – an unspecialised cell that continues to divide by mitosis to produce more stem cells and other cells that differentiate into specialised cells. Synapse - the point at which 2 neurones meet. There is a tiny gap between neurones at a synapse. Tumour – a lump formed of cancer cells. Xylem cells – a long, thick-walled tube formed in plants, made from many dead xylem cells. The vessels carry water and dissolved mineral salts through the plant.

Calculations There are many different ways of measuring growth in plants, including height, leaf surface area and mass. Percentage changes are often worked out for these values and can be calculated using this formula: Final value – starting value ÷ starting value × 100%

CB3a Meiosis

CB3 – Genetics (paper 1)

What is a zygote? Humans start life as a single fertilised egg cell (a zygote). This is formed when 2 gametes fused during fertilisation. The zygote forms a ball of cells using a form of cell division called mitosis. What is DNA? The instructions controlling each individual cell are found as a code in a molecule called DNA. The DNA of an organism is its genome. What is the human genome? The human genome is found on 46 very long molecules of DNA and each molecule is inside a chromosome. Along the length of a DNA molecule are sections that contain a code for making a protein. The DNA sections are genes.

What is a protein? Proteins are polymers made by linking different amino acids together in a chain. Why do gametes have to be haploid? If you diploid cells joined in fertilisation, the zygote would have 4 sets of chromosomes, so gamete need to have just 1 set of chromosomes. They have to be haploid (the shorthand for a haploid cell is 1n).

How many chromosomes does a human have? There are 23 different chromosomes in humans and most nuclei contain 2 of each type. So a human body contains 2 sets of 23 chromosomes making 46 in total. A cell like this is diploid (written as 2n in shorthand).

CB3d Inheritance

CB3bi DNA Describe a molecule of DNA A molecule of DNA contains 2 strands, each of which forms a shape called a helix. The strands are joined together by pairs of substances called basesbases to form double helix. How many areathere in DNA? There are 4 bases in DNA: adenine, thymine, cytosine and guanine (A, T, C and G). A always pairs with T and C always pairs with G. These What are bases attached to? are complementary base pairs. Each base is attached to a sugar and each sugar is attached to a phosphate group. The sugars and phosphate groups form the backbone of the DNA strands. What do the curved lines show? Why do parts of DNA bases have a hydrogen The curved lines show the rate of growth of a baby who bond? stays at exactly the same percentile within the population. Parts of DNA bases have very slight electrical charges. A negatively charged part of one base attracts a positively charged part of another base. This weak force of attraction is called a hydrogen bond. Cytosine and guanine form 3 What is the DNA code? hydrogen bonds between them. Adenine and The order of bases in a gene contains the coded instructions for a protein. We all have slight difference in our thymine form 2 hydrogen bonds. This explains genes causes by different orders of bases in our DNA. Everyone except identical twins has different DNA. why C only pairs with G and A pairs with T.

CB3c Alleles What are your sex chromosomes? Two of your chromosomes determine what sex you are. They are your sex chromosomes and there are two types: X and Y. Females have two X sex chromosomes and males have one X and one Y.

What is the difference between an egg cell and a sperm cell? A woman’s gametes all contain an X sex chromosome. The male sperm cells may contain either an X or a Y (diagram A).

What is an allele? Genes for the same characteristic (e.g. eye colour) can contain slightly different instructions that create variations. Different forms of the same gene are called alleles.

CB3e Gene Mutation Why do we use Punnett squares? Punnett squares are used to work out the probability of different phenotypes caused by alleles.

How do mutations happen? Mutations happen when there is a mistake in copying DNA during cell division. For example one base in a DNA sequence might be replace by another. This can happen naturally of if there is damage to the DNA caused by radiation or other harmful substances.

What affect will a mutation have? Sometimes a mutation produces an allele that causes a big change in the protein that is produced. This will affect how the body works. Some mutations may only have a small effect on the protein that is produced, while some will not change the protein at all.

What is the human genome project? The human genome project mapped the bases pairs in the human genome. Mapping a person’s genome can indicate their risk of developing diseases that are caused by different alleles of genes. It can also help identify which medicines might be best to treat a persons’ illness.

CB3f Variation What is genetic variation? Genetic variation is caused by the different alleles inherited during sexual reproduction.

What produces genetic variations? There are 2 copies of every chromosome in a body cell nucleus, a body cell contains 2 copies of every gene. Each copy of a gene may be a different allele. The different combination of alleles in each person give us slightly different characteristics. Explain the term homozygous If both alleles for one genes are the same an organism is homozygous for that gene.

What is a Punnett square? Punnett squares (diagram B) demonstrate inheritance. The boxes show the possible genotypes. Two boxes contain XX and two contain XY. The probability of being male is 50%.

Why do we use Punnett squares? Punnett squares are used to work out the probability of different phenotypes caused by alleles.

What is the difference between a genotype and a phenotype? The alleles in an organism are its genotype. What the organism looks like is its phenotype.

What is a dominant characteristic? Characteristics from a dominant allele will always be expressed. A dominant allele is shown by a capital letter, the recessive allele has the lower case version of the same letter. The letter for the dominant allele is always written before the recessive one. What is a recessive characteristic? A recessive characteristic is only seen if both alleles are recessive (diagram D).

Explain the term heterozygous If the alleles are different an organism is heterozygous.

What is environmental variation? Many characteristics also show environmental variation because they are affected by their surroundings. For example how well a plant grows is affected by how much light, water and nutrients it gets.

In what two ways can variation be grouped? A discontinuous variation is where the data can only take a limited set of values e.g. the number of leaves on a plant. Continuous variation is where the data can be any value in a range e.g. the length of a leaf on a tree. Continuous data for variation often forms a bell-shaped curve known as a normal distribution.

Key Vocabulary Definitions Acquired characteristics Alleles – most genes come in different versions called alleles. Bases – a substance that helps make up DNA. There are four bases in DNA, shown by the letters A, C, G and T. Chromosome – a thread-like structure found in the nuclei of cells. Each chromosome contains one long DNA molecule packed with proteins. Complementary base pairs - two DNA bases that fit into each and link by hydrogen bonds Daughter cell – a new cell produced from the division of a parent cell. Diploid – a cell or nucleus that has two sets of chromosomes. Dominant – describes an allele that will always affect a phenotype as opposed to a recessive allele, whose effect will not be seen if a dominant allele is present. Double helix – the shape of a DNA molecule consisting of two helices. Family pedigree chart – a chart showing the phenotypes and sexes of several generations of the same family to track how characteristics have been inherited. Gametes – a haploid cell produced the meiosis used for sexual reproduction. Genes – A section of the long strand of DNA found in a chromosome which often contains instructions for a specific protein. Genetic diagram – a diagram showing how the alleles in two parents may form different combinations in offspring when the parents reproduce. Genome – all of the DNA in an organism. Each body cell contains a copy of the genome. Genotype – the alleles for a certain characteristic that are found in an organism. Haploid – a cell or nucleus that has one set of chromosomes. Gametes are haploid. Hydrogen bond – a weak force of attraction caused by differences in the electrical charge on different parts of different molecules. Meiosis – a form of cell division in which one parent cell produces four haploid daughter cells. Mutation – a change to a gene caused by a mistake in copying the DNA base pairs during cell division, or by the effects of radiation or certain chemicals. Normal distribution – when many individuals have a middle for a feature with fewer individuals having greater or lesser values. This sort of data forms a bell shape on charts and graphs. Phenotype – the characteristics produced by a certain set of alleles. Polymers – a long-chained molecule made by joining many smaller molecules (monomers) together. Punnett square – a diagram used to predict the characteristics of offspring produced by two organisms with known combinations of allele. Recessive – describes an allele that will only affect the phenotype if the other allele is also recessive. It has no effect if the other allele is dominant. Replicate – when DNA replicates, it makes a copy of itself. Sex chromosomes – a chromosome that determines the sex of an organism. Variation – difference in the characteristics of organisms. Zygote – a fertilised egg cell.

Calculations

Key Terms

Eurakryotic cells Eukaryote Prokaryotic cells DNA

Ribosome

A cell organelle that makes proteins

Respiration

The release of energy from glucose The net movement of particles form an area of high concentration to an area of lower concentration A part of a cell with a specific function A cell organelle in which respiration occurs A cell organelle in which photosynthesis occurs Jelly like substance in cells where chemical reactions occur A cell organelle found in eukaryotes containing their genetic material Structure surrounding the cell that controls what moves in and out of the cell Found in plant cells, filled with cell sap, keeps the cell turgid Made from cellulose and provides structural strength the some cells (not animal cells) Chemical reaction that happens in chloroplasts that stores energy in glucose Describes a swollen cell Describes a shape with a dip that curves inwards on both sides

Diffusion Organelle Mitochondrion Chloroplast Cytoplasm Nucleus Cell membrane Vacuole Cell wall Photosynthesis Turgid Biconcave

Ova Axon Phloem Xylem Electron microscope Resolution

Diagrams

SB2 â&#x20AC;&#x201C; Cells and Control (Paper 1) SB2e The Brain What cells are found in the brain? Once an embryo is 3three weeks old the stem cells in the brain differentiate to produce neurones, which make up most of the brain.

How many neurons does an adult brain have? An adult brain has about 86 billion neurones, which interconnect with one another to process information and control the body.

SB2f Brain and Spinal Cord Problems What is the spinal cord connected to? The mass of neurones in the medulla oblongata connect the brain to the spinal cord. The spinal cord consists of many nerves. These carry information between the brain and the rest of the body.

What is the role of the cerebral cortex? It is used for most of our sense, language, memory, behaviour and consciousness. What is the structure of the cerebral cortex? It is divided into two cerebral hemispheres. The right hemisphere communicates with the left side of the body and vice versa.

What is the cerebellum? At the base of the brain, it is divided into two halves and controls balance and posture.

What are cones? Cones are receptor cells that are sensitive to the colour of light. Cones detect red, green or blue light. Cones generate impulses in sensory neurones which lead to the brain through the optic nerve. This information is processed into full colour vision.

What is a PET scan? This shows brains activity. The patient is injected with radioactive glucose. The more active the cells the more glucose they use (for respiration). The radioactive cause gamma rays, which the scanner detects. More gamma rays come from the more active brain cells.

How can brain tumours be treated? Tumours can be cut out or the cells can be killed using radiotherapy and chemotherapy. All these methods can damage the body and brain, chemotherapy may not work due to the blood-brain barrier.

Why is it difficult for patients to regain full movement or feeling after spinal cord damage? There are no adult stem cells that can differentiate into neurones in the spinal cord, so new neurones cannot be made to repair damage.

What is the medulla oblongata? It controls your heart rate and your breathing rate. It is responsible for reflexes such as vomiting, sneezing and swallowing.

What is the eye? A sense organ that contains receptor cells found in a layer called the retina.

What is a CT scan? This shows the shape and structure in the brain. An X-ray beam moves in a circle around the head, and detectors measure the absorption of the X-rays. A computer used this information to build up a view of the inside of the body as a series of slices. Differences in the shapes in the brain can be linked to differences in the way people think and act.

What is spinal cord damage? Damage to the spinal cord reduces the flow of information between the brain and parts of the body. Nerve damage in the lower spinal cord can cause loss of feeling and use of the legs.

SB2f The Eye

What are rods? Are receptor cells that detect differences in light intensity. Rods work very well in very dim light situations.

What is a brain tumour? A brain tumour may squash parts of the brain and stop them working.

What is the pupil? The dark area in the middle of your eye where light enters. The amount of light entering the eye is controlled by muscles in the iris which can constrict the pupil or dilate it.

What is the role of the cornea? Light rays entering the eye need to be focused onto a point in the retina. Most focussing is done by the cornea which bends light rays to bring them together.

What is the role of the lens? The lens fine tunes and focuses the image. Ciliary muscles make the lens fatter to focus light from near objects and thinner to focus light from distant objects.

What is a cataract? Sometimes a protein builds up inside the lens and makes it cloudy. This is a cataract. Full vision can be restored by replacing the clouded lens with a plastic one.

What is colour-blindness? Where some cones do not work properly. The most common form is red-green colour-blindness. Cones that detect green light are faulty making it difficult to tell the difference between red, green and brown. Colour-blindness cannot be corrected.

Key Vocabulary Definitions Blood-brain barrier – a natural filter that only allows certain substances to get from the blood to the brain (mainly due to cells in the capillary wall in the brain fitting together very closely). Chemotherapy – use of drugs to treat a disease such as in the treatment of cancer. Ciliary muscles – a muscle that relaxes or contracts to change the shape of the lens in the eye. Converging lens – a lens that brings light rays together. Diverging lens – a lens that causes light rays to spread apart. Gamma rays – a high-frequency electromagnetic wave emitted from the nucleus of a radioactive atom. Gamma rays have the highest frequencies in the electromagnetic spectrum. Radioactive – a substance is radioactive if it emits ionising particles or radiation. Radiotherapy – use of ionising radiation to treat diseases, such as to kill cancer cells. Tumour – a lump formed of cancer cells.

CB2a Mitosis

CB2 â&#x20AC;&#x201C; Cells and Control (paper 1)

CB2b Growth in Animals What is growth? Growth in an increase in size as a result of an increase in number or size of cells.

What is asexual reproduction? Asexual reproduction produces offspring that are clones, which means that their cells have the same chromosomes as their parent (they are genetically identical).

What is cell differentiation? The process by which a less specialised cell becomes more specialised for a particular function. The cell normally changes shape to achieve this.

CB2c Growth in Plants

What is neurotransmission? The travelling or transmission of impulses is called neurotransmission and happens in neurones. Neurones have a cell body and long extensions to carry impulses.

Why are dendrons and axons frequently long? They are long to allow fast neurotransmission over long distances.

CB2f Neurotransmission Speeds

What is a reflex arc? A neurone pathway consisting of a sensory neurone passing impulses to a motor neurone via a relay neurone which allows a reflex action to occur.

What is a reflex action? Reflex actions are responses that are automatic, extremely quick and protect the body. For example moving your finger away from a hot candle.

Cell Biology

Bacterial Cell Section 1- Cell Structure

Structure 1. Nucleus 2. Cell Membrane 3 Cytoplasm 4 Mitochondria 5 Ribosomes 6 Chloroplast 7 Vacuole 8 Cell Wall 9 DNA Loop 10 Plasmid

Function Contains the genetic information that controls the functions of the cell.

Prokaryotic Cells Bacterial Plant Cells Cells

Eukaryotic Cells Animal Cells Y

Controls what enters & leaves the cell. Where many cell activities & reactions happen.

Provides energy from aerobic respiration.

Make proteins- site of protein synthesis.

Where photosynthesis occurs. Use to store water & other chemicals as cell sap. Strengthens & supports the cell (made of cellulose in plants) A loop of DNA NOT in a nucleus. A small circle of DNA, may contain genes associated with antibiotic resistance.

Section 3- Microscopy Y 17 Magnification

Y Y Y

18 Resolution Y Y Y

Tells you how many times bigger a microscope makes an object. Magnification = length of magnified object ÷ length of actual object The ability of a microscope to distinguish between 2 separate points.

19 Light Microscope

A basic microscope, using light. Can magnify objects ×1500

20 Electron Microscope

A microscope which uses electrons, to magnify images more than a light microscope. Gives greater detail. Can magnify objects ×2,000,000

Section 2- Specialised Cells Specialised Cell 11 Sperm Cell 12 Nerve Cell 13 Muscle Cell 14 Root Hair Cell 15 Xylem Cell 16 Phloem Cell

How structure relates to function Acrosome contains enzyme to break into egg, tail to swim. Many mitochondria to provide energy. Long to transmit electrical impulses across a distance. Contain protein fibres that contract when energy is available, making the cells shorter. Long extension to provide a large surface area for water & mineral absorption- thin cell wall. Waterproofed cell wall, cells are hollow to allow water through. Some cell shave a lot of mitochondria to give energy for active transport. Some cells have little cytoplasm for sugars to move through easily.

Section 4- Orders of Magnitude Unit Prefix Centimetre (cm) Millimetre (mm) Micrometre (µm) Nanometre (nm)

Size in Metres 0.01m 100 cm= 1m 0.001m 1000 mm= 1m 0.000001m 1000000 µm = 1m 0.000000001m 1000000000 nm = 1m

Key Terms

Knowledge Organiser â&#x20AC;&#x201C; Chemical Changes

Reactivity An arrangement of metals in order of reactivity series Displacement Reaction where a more reactive element takes the place reaction of a less reactive element in a compound A reaction in which a substance loses electrons (gains Oxidation oxygen) Reaction in which a substance gains electrons (loses Reduction oxygen) Ore

A rock from which a metal can be extracted for profit

Acid

Solution with a pH less than 7; produces H+ ions in water

Aqueous

Solution with a pH more than 7; produces OH- ions in water Dissolved in water

Strong acid

Acid in which all the molecules break into ions in water

Alkali

Diagrams

Weak acid

Acid + Alkali -> salt + water Metal + acid -> salt + hydrogen Metal oxide + acid -> salt + water Metal carbonate + acid -> salt + water + carbon dioxide

Links:

7A Part 1 States of Matter and Diffusion States of Matter –

SOLID LIQUID GAS

Density 1 kg of a gas has a larger volume than 1 kg of a solid. There is empty space between particles in a gas, but in a solid, they are tightly packed together.

Dissolving

Density = Mass / Volume

We call the solid the SOLUTE

When the particles in a solid spread out in a liquid. We call the liquid the SOLVENT

… so the density of the gas is much smaller than the density of the solid. The particles should be the same in all 3 diagrams. Changes of State

As a substance is heated it gains energy. When the particles gain enough energy they overcome the forces between them. Whilst a change of state is happening the temperature of the substance does not change. (flat line on graph)

Video link

Diffusion Particles in a liquid or a gas spread out from an area of high concentration to an area of low concentration until the concentrations are equal.

Video link

The higher the concentration gradient the faster the net diffusion. The higher the temperature the faster the net diffusion. If the particles that are spreading are water molecules we call this process osmosis. Video link

We call the mixture of the solid and the liquid a SOLUTION. A solid that will dissolve in a liquid is called SOLUBLE. A solid that will not dissolve in a liquid is called INSOLUBLE. Video link

Animation link

Links:

7A Part 2 Separation Techniques Filtration

Decanting Pour a liquid from the top of a settled solid or a more dense liquid.

Separates an insoluble solid from a liquid.

Distillation Separating substances with different boiling points. Video link

The solid pieces are too big too fit through the holes in the filter Paper.

Video link

Chromatography

Evaporation Separating a soluble solid from a liquid.

Method Draw pencil line. Put dot of colour on line. Hang bottom edge (below dot) in the water. Leave until water soak up to almost the top of the paper.. Compare with known substances.

Salt water mixture is heated. At 100oC water boils and the particles gain enough energy to become a gas (water vapour). Boiling point of salt is 1413oC so it does not boil and stays in the flask.

Different colours contain different mixtures of inks. The different inks move at different speeds up the paper. This is because of different solubility. Chromatogram

Video link

Crystallisation Heat until almost all the water has evaporated. Leave for the remaining water to evaporate slowly to form crystals. Video link

Water vapour rises and travels past the thermometer into the condenser. Thermometer checks the temperature to identify the gas. Condenser cools the water vapour so that it condenses back to liquid water.

Hydrocarbons Crude Oil is made from the remains of living sea creatures decayed in mud millions of years ago

Frac8onal Dis8lla8on

C9 Crude Oil and Fuels

How do we separate the mixture of hydrocarbons to use them? Works by evapora0on and then condensa0on.

It is a FINITE resource It is made of a mixture of Hydrocarbons. Hydrocarbons are made of Hydrogen and Carbon only.

Smaller molecules burn most easily

The main hydrocarbons in Crude Oil are alkanes

Combus8on

Combus0on (burning) is a reac8on with oxygen A reac8on with oxygen is called ‘oxida0on’

When hydrocarbons burn a lot of energy is released.

Complete combus0on of hydrocarbons the only products are carbon dioxide and water Complete combus8on only happens if there is plenty of oxygen

General equa8on

The general formula for an alkane is -

1.  Heat the crude oil to evaporate it. 2.  The gases rise up the column. 3.  The diﬀerent frac8ons condense at diﬀerent temperatures.

Complete combus8on of propane

Cracking The larger molecules from frac0onal dis0lla0on are less useful. We can break them down into smaller, more useful molecules. Cracking produces a mixture of alkanes and alkenes.

Alkenes have some double bonds. They turn bromine water colourless. They are used to make polymers. The apparatus for cracking

Cataly8c cracking – catalyst and 500oC Steam cracking – steam and 850oC

Key Terms Potential difference (p.d.) Electric current Resistor

Knowledge Organiser â&#x20AC;&#x201C; Electricity

The current flowing through an ohmic conductor is proportional to the potential difference across it. If the p.d. doubles, the current doubles. The resistance stays the same.

Non-ohmic

The current flowing through a non-ohmic resistor is not proportional to the potential difference across it. The resistance changes as the current flowing through it changes.

P = V x I power = voltage x current. V = I x R voltage = current x resistance. Q = I x t charge = current x time. E = V x Q energy = voltage x charge. E = V x I x t energy = voltage x current x time. Total cost = number of units x cost per unit.

Diagrams

Key Terms Specific heat capacity

Knowledge Organiser – Energy

The energy needed to raise the temperature of 1kg of a substance by 1°C. To scatter in all directions or to use wastefully. When energy has been dissipated it means we cannot get it back. The energy has Dissipate spread out and heats up the surroundings. Non-renewable Energy resources which will run out, because they are finite energy resources reserves, and which cannot be replenished. Renewable Energy resources which will never run out and (or can be) energy resources replenished as they are used. Resources other than fossil fuels. The resources may or may not be renewable. Nuclear power is not a renewable energy resource, but Alternative energy resource tidal power is. Alternative energy resources do not contribute to global warming. Fuel produced from biological material. Biofuels are provided by trees such as willow that can be grown specifically as energy Biofuel resources.

Energy Equations Efficiency (%) = (useful energy out ÷ total energy in) x 100. GPE = mgh Gravitational Potential Energy = mass x gravity x height. Ee = ½ke2 Elastic potential energy = 0.5 x spring constant x extension2 KE = ½mv2 Kinetic Energy = 0·5 x mass x velocity2. W = F x d work done = force x distance. W = E work done = energy transferred. P = E ÷ t power = energy ÷ time. E = c x m x θ energy = specific heat capacity x mass x change in temperature.

Diagrams

Key Terms

Diatomic molecule Spectator ions Ionic equation

Knowledge Organiser â&#x20AC;&#x201C; Formulae and equations

A molecule containing two atoms Ions that do not take part in a reaction and do not appear in the ionic equation for the reaction Balanced equation for reaction that omits any spectator ions

Common Reactions

Element + oxygen -> oxide of element Eg Calcium + oxygen -> calcium oxide Compound + oxygen -> oxides of each element in compound Eg Methane + oxygen -> carbon dioxide + water Water + metal -> metal hydroxide + hydrogen (for metals that react with water) Eg water + sodium -> sodium hydroxide + hydrogen Acid + metal -> salt + hydrogen Eg Hydrochloric acid + magnesium -> magnesium chloride + hydrogen Acid + metal oxide -> salt + water Eg Sulphuric acid + copper oxide -> copper sulphide + water Acid + metal hydroxide -> salt + water Eg nitric acid + potassium hydroxide -> potassium nitrate + water Acid + metal carbonate -> salt + water + carbon dioxide Eg hydrochloric acid + calcium carbonate -> calcium chloride + water + carbon dioxide Acid + ammonia -> ammonium salt Eg nitric acid + ammonia -> ammonium nitrate