Explain the difference between magnification and resolution.Magnification: Degree to which the size of the image is larger than the object.Resolution: Degree to which it is possible to distinguish between two points that are close together.

State the resolution and magnification that can be achieved by a light microscope, TEM and SEM and the need for staining samples. Type of MicroscopeMagnificationResolutionStainingExtra information

Light Microscope X1500200nmChemicals bind to allow it to be seen. Bind to specific structure.Wax stops distorting structure when cuttingLiving and non-living specimen.Lab, education and research.Eyepiece magnify by x10.

Scanning Electron MicroscopeX100 0000.1nmMetal salts used to scatter electrons = contrastElectrons dont pass through specimen, provide 3D image. Projected onto screen or photographic paper.

Transmission Electron MicroscopeX500 0000.1nmMetal salts used to scatter electrons = contrastElectrons pass through specimen, show denser parts of specimen. 2d image.

UndulipodiaCilia

Hair like structure on surface membrane.Use ATP

Longer, larger numbers.Protrude from cell surface and has membraneMicrotubules contract to move cell forward. Outer membrane, rind of 9 microtubules with one in the middleMicrotubules allow cilia to move and waft substances

Explain the importance of the cytoskeleton in providing mechanical strength to cells, aiding transport within cells and enabling cell movementCytoskeleton = network of protein fibres making up internal framework.Functions: 1) Strengthen cell shape. 2) Transport materials in cell. 3) Support organelle. 4) Move cell. Actin filaments: move against each other, move organelles inside cell.Microtubules: protein=tubulin. Move through liquid or waft past cell. Provide pathway for organelles. ATP used to drive movements Recognise structure Undulipodia and cilia and outline functions

Outline the interrelationship between the organelles involved in the production and secretion of proteins1. Instructions in DNA (gene on chromosome) in nucleus2. Instructions transcribed onto mRNA3. mRNA leaves nucleus through nuclear pore and attach to ribosome (ER or not)4. Ribosome read instructions and use codes to assemble amino acids (protein synthesis)5. Protein pinched off in vesicle6. Goes to Golgi apparatus7. Protein modified (add carbohydrate) and package in vesicle8. Move to cell surface membrane9. Vesicle fuse with surface membrane10. Cell surface membrane opens to release protein (secretion)

OrganelleStructureFunctionMem-branePlant CellsAnimal Cells

NucleusLargest organelle and has dark patches of chromatinHouses all genetic material. Chromatin made of DNA and proteins, instructions for making proteins. When cells divide. Chromatin condenses into chromosomes. XXX

NucleolusDense, spherical structure inside nucleusMakes RNA and ribosomes. N/AXX

Nuclear envelopeSurrounds Nucleus. Has two membranes with fluid between them Nuclear pores go through envelope, large enough for molecules to pass through, N/AXX

Rough ERER made of flattened membrane bound sacs (cisternae) and continuous with outer nuclear membrane. Rough ER has ribosomes. Smooth ER does not. Transport proteins made on attached ribosomes. Makes proteins that are excreted from cell.XXX

Smooth ERMake lipids needed by cells. XXX

LysosomeSpherical sacs surrounded by single membraneContain digestive enzymes to break down materials.XX

Golgi ApparatusStack of membrane-bound, flattened sacsReceives proteins from ER and modifies them then packages proteins into vesicles to be transported. XXX

Cell membraneN/AXX

Cell Wall-Outside cell membrane. Made of cellulose that forms sieve like network that makes wall strong. Held rigid by turgid pressure it supports plant.N/AX

VacuoleMaintains cell stability. Filled with water and solutes so pushes cytoplasm against cell wall = turgid. All plant cells turgid, helps support plant. Important in non woody plants. N/AX

MitochondriaTwo membranes separated by fluid filled space. Inner membrane folded to form cristae. Central part called matrix.Produce ATP during respiration.XXX

AmyloplastStores starch in plants.N/AX

RibosomesTiny organelles. Some free in cytoplasm and some bound to ER.Site of protein synthesis in cell where proteins made. Free Ribosomes make proteins that stay in the cell cytoplasm. Xx

ChloroplastsTwo membranes separated by fluid filled space. Inner membrane continuous with network of flattened sacs (thylakoids). Chlorophyll on thylakoid membranes and internal membranes. Site of photosynthesis. Xx

CentriolesSmall tubes of protein.Take part in cell division and form spindle which moves chromosomes during nuclear division. x

Eukaryote Prokaryote

Animal Cell Plant Cell Bacterial Cell

Plasma Membrane

Cell Wall Cellulose Peptidoglycan

Nucleus

Lysosome

Ribosome

Rough ER

Smooth ER

Vesicle

Golgi apparatus

Mitochondrion Mesosomes

Chloroplast

Centriole

Cilia

Undulipodia Flagella

Prokaryotes:-No membrane bound organelles-Cell wall of peptidoglycan-Capsule-Smaller ribosomes-Plasmids no nucleus, general area is nucleoid-ATP production in mesosomes-Flagella (different structure to Undulipodia)-Hair like pili-Resistance eon plasmids which can be passed on.

Roles of membranes: Internal membranesSurface membranes

Separate contentsOrganelle contents from cytoplasmSeparate DNA from cytoplasmProtect cell from lysosomesSeparate contents from environment

Cell recognition and signallingCell recognition and signallingCell to cell attachment

Hold components of metabolic pathways in placePrevent disruption of metabolic reactions in organelles

Regulate transport in or out of cellControl movement in or out of cell (Facilitated diffusion, active transport)

-Phosphate head is hydrophilic.-Fatty acid tails are hydrophobic. -Properties from way charges are distributed.-Molecules with evenly distributed charges dont mix with water. Unevenly distributed molecules can interact easily.-phospholipid molecules mixed with water form layer at surface. Phosphate head in water and fatty acid tail out of water. -Phospholipid molecules completely surrounded, bilayer forms. Phosphate heads on each side and fatty tails point towards each other so held away from water molecules. -Phospholipid molecules can move freely.-Phosphate head cant pass easily through hydrophobic region in middle of bilayer giving it stability. -Phospholipid bilayer is basic structural component of all biological membranes. -Hydrophobic layer creates barrier and separates contents.-Single phospholipid bilayer is incapable of performing al functions and would be too fragile to function as a barrier. It needs other components which varies according to the function of the membrane which is part of differentiation.

State that plasma (cell surface) membranes are partially permeable.-All membranes are permeable as water can diffuse through lipid bilayer.-aquaporin make membranes more permeable.-Partially permeable membranes are permeable to water and some solutes.-Plasma membranes are permeable to small polar and non-polar molecules.-Impermeable to large polar molecules, charged ionic molecules and water soluble molecules. Describe the fluid mosaic model of membrane structure-Main features: Phospholipid bilayer Protein molecules Carbohydrates--Fluid: phospholipid units not attached and constantly moving-Mosaic: plasma membrane comprised of many different componentsDescribe the roles of the components of the cell membrane, including phospholipids, cholesterol, glycolipids, proteins and glycoproteins. ComponentStructure/PlacementFunction/Role

PhospholipidsPhosphate head, Fatty acid tail. Form mirror image, fatty acid on inside, phosphate head on outside.Forms phospholipid bilayerHydrophobic layer creates barrier and separate contents.

CholesterolFits between fatty acid tails in bilayerType of lipid. Makes membrane more complete and stable, less permeable. Rigid at high temp. Fluid at low temp.

GlycolipidsPhospholipid molecules with carbohydrate attached. Stabilise membrane by forming hydrogen bonds

GlycoproteinsProtein molecule with carbohydrate attachedActs as receptorCell recognitionStabilise membrane by forming hydrogen bondsBind together in tissues

ProteinsChannel proteinCarrier proteinReceptors

Outline the effects of changing temperature on membrane structure and permeability. -Increase in temperature increases kinetic energy of molecules making them more fluid.-Temperature < 0oC =membrane rigid and components dont have much energy and dont move much. Channel and carrier proteins denature increasing permeability. - 0oC < Temperature < 45oC =phospholipid moves and not tight, membrane partially permeable.- Temperature >45oC =bilayer breaks down and membrane more permeable. Chanel and carrier proteins denature, increasing permeability.Explain the term cell signalling-Processes leading the communication and co-ordination between cells and can lead to identification/recognition which can trigger a response.-Communication via messenger molecule which has a complementary shape to the target receptor. Explain the role of membrane bound receptors as sites where hormones and drugs can bind-Cell with receptor for molecule is a target cell. -Different receptors for different molecules. Shape must be complementary. -Messenger molecules are drugs, neurotransmitters, hormones etc.-Drugs can bind to the receptor sites.-This can prevent the messenger molecule binding to the receptor (preventing normal molecule binding therefore preventing response) or can bind to receptor and produce a response. Describe and explain what is meant by passive transport (diffusion and facilitated diffusion)-Passive transport is when an input of energy is not require, and the movement of molecules is from the kinetic energy already possessed by the molecules. -Diffusion is the movement of molecule from a high concentration to a low concentration down a concentration gradient. -Living organisms maintain concentration gradient to prevent equilibrium. -Factors affecting diffusion: Concentration, Temperature, Surface area, Distance, Movement, Size.-Facilitated diffusion is the movement of small, charged particles or larger molecules through membranes by proteins. -Channel proteins form pores in membranes. Only allow one type of molecule through. May be gated.-Carrier proteins are shaped so a specific molecule fits in them at the membrane surface, change is shape allows it through to the other side. Describe the role of membrane proteins in passive transport-Membrane made of phospholipids, fat soluble molecules pass through (steroid).-Small molecules and ions small enough to pass through. (sometimes water).-Different membranes have different carrier/channel proteins.Substances moved by:Examples

Simple diffusionGases like oxygen and carbon dioxide. Lipid based molecules like steroid hormones.

Facilitated diffusion using channel proteinsIons like sodium and calcium

Facilitated diffusion using carrier proteinsLarge molecules like glucose and amino acids.

Describe and explain what is meant by active transport, endocytosis and exocytosis.-Active transport is the movement of molecules from a low concentration to a high concentration against a concentration gradient, using ATO to drive protein pumps. -Difference between protein pumps and carrier proteins: Molecules only go one way Faster Use ATP Molecules accumulate Opposite direction to concentration gradient-Endocytosis is the bulk movement of large molecules into a cell.-Exocytosis is the bulk movement of large molecules out of the cell. -Bulk transport possible because membranes easily fuse, separate and pinch off. ATP needed to form vesicle. endo inwards exo outwards phago solid material pino liquid materialExplain what is meant by osmosis, in terms of water potential-Osmosis is the movement of water molecules from a region of high water potential to a region of low water potential across a partially permeable membrane. -Water molecules are small enough to pass through bilayer aquaporin make it more permeable. -Movement of water affected be amount of water in cytoplasm and environment, solute concentration, aquaporin presence and pressure on cell wall.Type of cellHigh water potentialNegative water potential

AnimalWater moves inCell bursts = haemolysedWater moves outCell crenated

PlantWater moves in, cell turgidWater moves out. Cell plasmolysed.

Recognise and explain the effects that solutions of different water potentials can have upon plant and animal cells

State the mitosis occupies only a small percentage of the cell cycle and that the remaining percentage includes copying and checking of genetic information-DNA wrapped around histones make up chromatin.-DNA replicated before division, held together at centromere. Replicas = sister chromatids. -Interphase made up of: G1: Biosynthesis protein synthesis and organelle synthesis takes place. S: Semiconservative replication DNA replicated to form sister chromatids G2: Organelles grow, ATP store increases-Replicated DNA proofread by enzymes, if not copied properly may cause mutations and cells cant function properly. Explain the significance of mitosis, for growth, repair and asexual reproduction in animals and plants-Growth meristem cells in plants. Found in Cambium, and root and shoot apex. -Asexual reproduction-Repair/replace damaged cells.Describe, with the aid of diagrams, the stages of mitosis-Prophase: Chromosomes supercoil and condense to become visible. Nuclear envelope breaks down. Centriole divides and moves to opposite ends Spindle fibres being to form.-Metaphase: Spindle fibres completely formed. Chromosomes align on cell equator.Anaphase: Spindle fibres attach the centromere of chromosomes and pull them apart. Spindle fibres shorted and pull chromatids to opposite poles. -Telophase: Spindle fibres break down. Nuclear envelope and nucleolus reforms. Chromosomes uncondense and are no longer visible. -Cytokinesis: Cell divides by constriction in animal cells Cell plates form in plant cellsDefine the term stem cellUndifferentiated cells that are capable of becoming differentiated to a number of possible cell types (omnipotent, totipotent, pluripotent). Explain the meaning of the term homologous pair of chromosomes-Chromosomes that have the same genes at the same loci, -Members of a homologous pair up during meiosis.-Diploid organisms produced by sexual reproduction have homologous pair of chromosomes, one from each parent.Outline the process of cell division by budding in yeast-Yeast go through cytokinesis by producing a small bud that nips off the cell. Process called budding.State that cells produced as a result of meiosis are not genetically identical -Diploid = two sets of chromosomes-Daughter cells f meiosis are haploid.-Produce genetic variety.Define the term differentiation with respect to the production of erythrocytes and neutrophils derived from stem cells in bone marrow and the production of ylem vessels and phloem sieve tubes from cambium.-Differentiation = change occurring in cells of multicellular organism so each different type of cell becomes specialised to perform a special function. -Cell can differentiate by changing number of organelles, shape of cell and contents of cell. Describe and explain how cells become specialised for different functions, with reference to erythrocytes, neutrophils, epithelial cells, sperm cells, palisade cells and root hair cells. Define the term differentiation with reference to the production of xylem vessels and phloem sieve tubes from cambium.CellOriginHow differentiated to perform function

ErythrocytesProduced from undifferentiated stem cells in bone marrow. Lose nucleus, mitochondria, Golgi apparatus and rougher.Packed full of haemoglobin.Becomes biconcave.

NeutrophilsKeep nucleus. Flexible shape to engulf foreign bodiesCytoplasm appear granules due to lysosomes. Enzymes in lysosomes allow neutrophils to kill microorganisms

Epithelial cellsHave cilia to move particlesMicrovilli to increase surface area

Sperm CellsMitochondria produce energy for Undulipodia movementContains lysosome acrosome to allow head to penetrate eggSmall, long, thin shape to ease movement Tail propel up uterine tractHalf number of chromosomes

Palisade cellsChloroplasts to absorb light.Thin walls, co2 diffuse in

Root hair cellsEpidermal layer of plant rootsHair like projection from surface out into soil.Increase surface area

XylemMeristem cellsWas elongate and waterproofed by lignin which kills contents and ends break down forming long tubes with wide lumen. Transport water up pant and support

PhloemCells elongate, ends dont break down but form sieve plates. Next to sieve plates are companion cells, metabolically active and move photosynthesis products up and down plant

Guard cellsThin outer wall, thick inner wallIn light absorb water, become turgid. Allows gas exchange.

Explain the meaning of the terms tissue, organ and organ system.-A tissue is a collection of similar cells and perform a common function.-An organ is a collection of similar tissues working together to perform a particular function.-An organ system is made up of similar organs working together to perform an overall life function. Explain, with the aid of diagrams and photographs, how cells are organised into tissues, using squamous and ciliated epithelia xylem and phloem.- There are four main types of animal tissue: Epithelial tissue - Layers and linings Connective tissues - Hold structures together and provide support Muscle tissue - Cells specialised to contract and move parts of the body Nervous tissue - Cells that convert stimuli to electrical impulses and conduct those impulses.-Squamous epithelial tissue: flattened thin cells form a thing smooth flat surface Fluid pass easily over them. Provide short diffusion path for gas exchange. Held in place by basement membrane. : made of collage and glycoproteins secreted by epithelial cells

-Ciliated epithelial tissue: Column shaped cells Inner surface of tubes Part of cell surface always exposed Synchronised waves Waft mucus-Xylem: Made of xylem vessel cells and parenchyma cells Parenchyma cells fill gaps between xylem provide support-Phloem: Made of sieve tubes and companion cells Companion cells highly metabolically activeDiscuss the importance of cooperation between cells, tissues, organs and organ systems- Movement: the muscular and skeletal system must work together for movement to take place, but this can only happen if the nervous system instructs muscles to coordinate their actions. As muscles and nerves work, they use energy, so they require a supply of nutrients and oxygen from the circulatory system, which in turn receives the chemicals from the digestive and ventilation systems.Explain, in terms of surface area to volume ration, why multicellular organisms need specialised exchange surfaces and single celled organisms do not-Organisms need certain substances from environment and need to remove waste products.-As the size of an organism increases, its surface area to volume ratio decreases.-Required substances will not be able to get to core of body, only surface and will not exchange fast enough to keep cells alive. Describe the features of an efficient exchange surface with reference to diffusion of oxygen and carbon dioxide across and alveolus- Large surface area =more space for molecules to diffuse-Short diffusion path = reduce diffusion distance, faster-Maintain concentration gradient (fresh supply on one side, removal on other) =CO2 concentration higher in blood than alveoli, diffuses across. Oxygen concentration higher in alveolus than blood. -Removal = CO2 removed by breathing out. Oxygen removed by blood (red blood cells take to tissues)Describe the features of the mammalian lung that adapt it to efficient gas exchange-Alveoli have large surface area-Alveolus wall is one cell thick. Capillary wall is one cell thick. Both made of squamous cells, in close contact. -Narrow capillaries, red blood cells close to wall, close to air.Outline the mechanism of breathing (inspiration, expiration) in mammals, with reference to the function of the rib cage, intercostal muscles and diaphragm. InhalationExpiration

Diaphragm flattens digestive organs underneathIntercostal muscles contract to raise ribsVolume of chest cavity increasesPressure drops below atmosphericAir moves inDiaphragm pushed up by digestive organs underneathIntercostal muscles relax and ribs fallChest cavity volume decreasesPressure rises above atmosphericAir moves out

Describe the distribution of cartilage, ciliated epithelium, goblet cells and smooth muscles and elastic fibres in the trachea, bronchi and bronchioles and alveoli of the mammalian gaseous exchange systemDescribe the functions of cartilage, ciliated epithelium, goblet cells and smooth muscles and elastic fibres in the mammalian gaseous exchange systemDistributionFunction

Cartilage (Thick walls made of several layers of tissue).Found in C shaped/incomplete rings Trachea: widerBronchi: narrower, less regular-Structural role, hold trachea and bronchi open.-Prevent collapse when low pressure during inhalation.-Incomplete rings make it flexible to allow movement of neck and oesophagus.

Ciliated epitheliumEpitheliumTiny, hair like appendages which move in synchronised pattern to waft mucus up airway and to back of throat.

Goblet cellsUnder epitheliumSecrete mucus that traps particles in air. Traps bacteria so it can be removed without risk of infection

Smooth musclesLumenContract to constrict lumen, restricting air flow Used when allergic to airborne substances e.g. asthma

Elastic fibresSmooth muscle constriction cannot be reversed. Elastic fibres deformed during constriction. Smooth muscle relaxes, elastic fibres recoil, helps dilate airways

Explain the meanings of the terms tidal volume and vital capacity-Tidal volume volume of air moved in and out of the lungs with each breath when at rest (approx. 0.5dm)-Vital capacity the largest volume of air that can be moved into and out of the lungs in a single breath. Describe how a spirometer can be used to measureSpirometer is a chamber filled with oxygen floating on a tank of water.Person breaths through mouthpiece connected to oxygen.When they take in oxygen, the chamber sinks down. Breathe out, air pushed back in so chamber floats up. Vital capacity: breathe in and out as much as they canTidal volume: breathe normallyBreathing rate: ask person to breath normally. Divide number of breaths by time.Oxygen uptake: Difference in volumeExplain the need for transport systems in multicellular animal in terms of size, activity and surface are to volume ratioSize: The larger the animals, the smaller the surface area to volume ration, but the more cells, therefore more substances are needed Cells deeper in the body will not get any needed substances.Level of activity: The more active an animal, the more oxygen used in respiration which supplies the energy needed for movement. Surface area to volume ratio: large animals need tissues and structure support for strength so body gets thicker but surface area does not change. The surface area to volume ration decreases therefore a transport system is needed to supply all the oxygen and nutrients required.Explain the terms single and double circulatory system with references to the circulatory systems of fish and mammals-Single circulatory system= blood flows through heart once during each circulation e.g. fish ( heart gills body heart) Blood flows slower to rest of body after reduced to go through capillaries, limits rate of delivery. Dont need to maintain body temperature. -Double circulatory system= blood flows through heart twice during each complete circulation e.g. mammals (heart body heart --< lungs heart) heart increase pressure and fast delivery. Better for active animals to maintain body temperatures.Explain the meaning of the terms open and closed circulatory system with reference to the circulatory system of fish and insects-Open circulatory system = blood not always in vessels e.g. insects-Closed circulatory system = blood is always in vessels e.g. fish Describe the internal and external structure of the mammalian heartInternalExternal

-Four chambers-Atria receive blood from major veins -Ventricles separated by septum.-Atrium and ventricles separated by atrioventricular valves. -Valves attached to tendinous cords. -Coronary arteries lie over surface of heart (carry oxygenated blood)-Atria in the middle of cavity.-Firm red muscle = ventricles.

Found in C shaped/incomplete ringsExplain the difference in thickness of the walls of the different chambers of the heart in terms of their functions-Atria: thin wall, doesnt need to create pressure as blood goes to ventricles-Right Ventricle: thicker than atria, allows pump blood out heart. Thinner than left ventricle as pumps blood to lungs, doesnt need to go far, capillaries are thin so low pressure needed to prevent bursting.-Left Ventricle: 2 or 3 times thicker than right ventricle. Needs sufficient pressure to overcome resistance of systematic circulation. Describe the cardiac cycle with reference to the actions of the valves in the heart Step Contract/Relax/ValvesDirection of blood flowPart of cardiac cycleStage of heartbeat

1Atria and Ventricles relaxedMajor veins into atriumDiastole

2Open atrioventricular valvesAtrium to ventricles

3Atria contract simultaneously Ensure ventricles full of bloodAtrial systole

4Ventricles full, begin contractingBlood fills AV valves (snap shut)

5Pressure in arteries higher than ventricles, semi lunar valves shut.

6Ventricles contract (start at apex)Ventricles up to arteriesVentricular systole

7Ventricles >arteries, semilunar valves pushed open

8Ventricles relaxHeart starts to fill

-AV valves: open when ventriclesatria.-Semilunar valves: open when ventricles>arteries. Close when ventricles