A LEVEL BIOLOGY内部辅导讲义（1）：A cell structure

AAAA cellcellcellcell structurestructurestructurestructure Ⅰ SyllabusSyllabusSyllabusSyllabus ContentsContentsContentsContents 1 The microscope in cell studies 1) The differences between light microscopes and electron microscopes light microscopes electron microscopes Magnification 1,000 times 250,000 times Resolution 200 nm 0.5 nm Observation Living cells Dead cells Images Colorful Black and white sources Light electrons 2) Transmission and scanning electron microscopes differences Transmission electron microscopes scanning electron microscopes Electrons be seen transmitted reflected Resolution High low Observation Inside of specimen Surface of specimen common Their source are both electron beams. 2 Cells as the basic units of living organisms Cell theory states that the basic unit of structure and function of all living organisms is the cell. All cell arise from pre-existing cells by cell division. 3 Detailed structure of typical animal and plant cells, as seen under the electron microscope; Comparisons with structure of typical animal and plant cells seen under the electron microscope Animal cells Plant cells nucleus √ √ cytoplasm √ √ Plasma membrane √ √ Endoplasmic reticulum √ √ Golgi apparatus √ √ ribosome √ √ mitochondria √ √ vacuole √ √ Cell wall × √ chloroplast × √ centriole √ × Lysosome √ × √=present ×=absent 4 Outline functions of organelles in plant and animal cells Structure and functions of organelles Organelles Structure Function figure Nucleus Nucleolus,chromatin,nu clear pore and nuclear envelope(two membranes) Nucleus controls the cell's activities and division of nucleus precedes cell division. Centrioles A ring of microtubules Grow the spindle fibres for nuclear division. Endoplasmic reticulum (ER) An extensive system of membranes running through the cytoplasm.Smooth ER with ribosomes on its surface.Rought ER with no ribosomes on its surface. The proteins that are manufactured on the ribosomes are transported throughout the cell by the rough ER. The smooth ER makes lipids and steroids. ribosome A smaller and a larger subunit. Site of protein synthesis Golgi apparatus A stack of flattened sacs. Collects, processes and sorts molecules (particularly proteins from the rough ER), ready for transport in Golgi vesicles either to other parts of the cell or out of the cell. Lysosome Spherical sacs, surrounded by a single membrane. Break down of unwanted structures, e.g. Old organelles or even whole cells. Mitochondria Surrounded by two membranes. The inner of these is folded to form finger-like cristae. Site of the later stages of aerobic respiration Plasma membrane Phospholipid bilayer Transport some nutrients and ions, osmosis, recognition between two cells Cilia Contains microtubules that extend throughout its length. Movement of cells Chloroplast Surrounded by two membranes. Parallel flattened sacs(thylakoids) run through the stoma and are stacked in places to form grana. Site of photosynthesis. Cell wall cellulose Support plant Vacuole Surrounded by a single membrane(tonoplast) Controls the exchange between the vacuole and the cytoplasm. 此处隐去内容………………………………………… Ⅱ SamplesSamplesSamplesSamples ofofofofA-LEVELA-LEVELA-LEVELA-LEVELbiologybiologybiologybiology examinationexaminationexaminationexamination forforforfor analyinganalyinganalyinganalying 1111.... useuseuseuse anananan eyepieceeyepieceeyepieceeyepiece graticulegraticulegraticulegraticule andandandand stagestagestagestage micrometermicrometermicrometermicrometer scalescalescalescale totototo measuremeasuremeasuremeasure cellscellscellscells andandandand bebebebe familiarfamiliarfamiliarfamiliar withwithwithwith unitsunitsunitsunits (millimetre,(millimetre,(millimetre,(millimetre, micrometre,micrometre,micrometre,micrometre, nanometre)nanometre)nanometre)nanometre) usedusedusedused inininin cellcellcellcell studiesstudiesstudiesstudies;;;; Eye-pieceEye-pieceEye-pieceEye-piece graticulegraticulegraticulegraticule isisisis aaaa transparenttransparenttransparenttransparent scale,scale,scale,scale, usuallyusuallyusuallyusually withwithwithwith 100100100100 divisions,divisions,divisions,divisions, whichwhichwhichwhich isisisis placedplacedplacedplaced inininin thethethethe microscopemicroscopemicroscopemicroscope eye-piece.eye-piece.eye-piece.eye-piece. StageStageStageStage micrometermicrometermicrometermicrometer isisisis aaaa transparenttransparenttransparenttransparent ruler,ruler,ruler,ruler, whichwhichwhichwhich maymaymaymay bebebebe etchedetchedetchedetched ontoontoontoonto glassglassglassglass slideslideslideslide orororor printedprintedprintedprinted onononon aaaa transparenttransparenttransparenttransparent film.film.film.film. ItItItIt commonlycommonlycommonlycommonly hashashashas subdivisionssubdivisionssubdivisionssubdivisions ofofofof 0.10.10.10.1 andandandand 0.010.010.010.01 mm.mm.mm.mm. Samples: 1. (9700_w11_qp_11,5) The diagram shows a stage micrometer on which the small divisions are 0.1 mm. It is viewed through an eyepiece containing a graticule. The stage micrometer is replaced by a slide of a plant cell. What is the length of the nucleus? A 0.8 mm B 8 μm C 25 μm D 200 μm Key: C Interpretion: The diagram shows a stage micrometer on which the small divisions are 0.1 mm. It equals the length of 40 divisions in Eye-piece graticule, so each division represents ummm mm 5.20025.0 40 1.0 == . The length of nucleus is equal to 10 divisions of eye-piece graticule, so it is umum 25105.2 =× . 2.（ 9700_s10_qp_11,3) The diagram shows a stage micrometer, with divisions 0.1 mm apart, viewed through an eyepiece containing a graticule. What is the area of the field of view of the microscope at this magnification? (π = 3.14) A π × 12.5 × 12.5 = 4.9 × 102μm2 B π × 55 × 55 = 9.5 × 103μm2 C π × 125 × 125 = 4.9 × 104μm2 D π × 250 × 250 = 2.0 × 105μm2 Key: C Interpretion: The diagram shows a stage micrometer, with divisions 0.1 mm apart, which equals the length of 40 divisions in Eye-piece graticule, so each division represents ummm mm 5.20025.0 40 1.0 == . The radius of circle has 50 divisions, so its length is umum 125505.2 =× . The area is π r2=π × 125 × 125 = 4.9 × 104μm2 . unitsunitsunitsunits ofofofof measurementmeasurementmeasurementmeasurement inininin cellcellcellcell studiesstudiesstudiesstudies nmum ummm 3 3 101 101 = = SizeSizeSizeSize ofofofof somesomesomesome biologicalbiologicalbiologicalbiological structuresstructuresstructuresstructures 200um-50200um-50200um-50200um-50 000um:000um:000um:000um: somesomesomesome largelargelargelarge cellcellcellcell andandandand unicellularunicellularunicellularunicellular organism.organism.organism.organism. AlgalAlgalAlgalAlgal cellcellcellcell Av.Av.Av.Av. parameciumparameciumparameciumparamecium 50505050 000um000um000um000um 200um200um200um200um 0.5um-40um:0.5um-40um:0.5um-40um:0.5um-40um: somesomesomesome smallsmallsmallsmall cell,cell,cell,cell, largelargelargelarge organellorganellorganellorganell andandandand bacterium.bacterium.bacterium.bacterium. Av.Av.Av.Av. DiameterDiameterDiameterDiameter ofofofof plantplantplantplant cellcellcellcell Av.Av.Av.Av. DiameterDiameterDiameterDiameter ofofofof animalanimalanimalanimal cellcellcellcell Av.Av.Av.Av. DiameterDiameterDiameterDiameter ofofofof mitochondrionmitochondrionmitochondrionmitochondrion Av.Av.Av.Av. DiameterDiameterDiameterDiameter ofofofof bacteriumbacteriumbacteriumbacterium 40um40um40um40um 20um20um20um20um 1um1um1um1um 0.5-1um0.5-1um0.5-1um0.5-1um 0.002-0.02um:0.002-0.02um:0.002-0.02um:0.002-0.02um: somesomesomesome smallsmallsmallsmall organell.organell.organell.organell. Av.Av.Av.Av. DiameterDiameterDiameterDiameter ofofofof ribosomeribosomeribosomeribosome Av.Av.Av.Av. ThicknessThicknessThicknessThickness ofofofof membranemembranemembranemembrane DiameterDiameterDiameterDiameter ofofofof DNADNADNADNAmoleculemoleculemoleculemolecule 0.02um0.02um0.02um0.02um 0.007um0.007um0.007um0.007um 0.002um0.002um0.002um0.002um Samples: 3. (9700_w11_qp_11,1) What is the diameter of a typical prokaryote, such as Streptococcus? A 7.5 × 101nm B 7.5 × 102nm C 7.5 × 100μm D 7.5 × 101μm Key: B Interpretion: 7.5 × 102nm=0.75um. Av. Diameter of bacterium is 0.5-1um. 4. (9700_s10_qp_11,1) Which structures are measured using these units? 10-3m 10-6m 10-9m A B C D chloroplast nucleus ribosome xylem vessel Ribosome Chloroplast xylem vessel nucleus Nucleus xylem vessel Chloroplast Ribosome Key: D 2222.... explainexplainexplainexplain andandandand distinguishdistinguishdistinguishdistinguish betweenbetweenbetweenbetween resolutionresolutionresolutionresolution andandandand magnification,magnification,magnification,magnification, withwithwithwith referencereferencereferencereference totototo lightlightlightlight microscopymicroscopymicroscopymicroscopy andandandand electronelectronelectronelectron microscopy;microscopy;microscopy;microscopy; Magnification=Magnification=Magnification=Magnification= specimen of size actual image of size ResolutionResolutionResolutionResolution isisisis defineddefineddefineddefined asasasas thethethethe abilityabilityabilityability totototo distinguishdistinguishdistinguishdistinguish betweenbetweenbetweenbetween twotwotwotwo separateseparateseparateseparate points.points.points.points. Samples: 1. (9700_s11_qp_11. 2) In the following table, which is the correct comparison between light and electron microscopes? Light microscope Electron microscope Resolution Magnification Resolution Magnification A B C D High High Low low High Low High Low Low Low High High Low High Low High Key: D 2. (9700_s09_qp_1,3) What describes the features of an electron microscope? Maximum magnification Resolution/nm specimen A B C D 2.5 × 103 2.5 × 104 2.5 × 105 5.0 × 105 2.5 × 102 5.0 × 10–1 5.0 × 10–1 2.5 × 102 Dead Living Dead living Key:C 此处隐去内容………………………………………… Ⅲ PracticesPracticesPracticesPractices 1. (9700_w11_qp_11,3) Where would cristae be found in a cell? 1 endoplasmic reticulum 2 Golgi apparatus 3 mitochondrion A 1 and 2 B 1 and 3 C 2 and 3 D 3 only 2. (9700_w11_qp_11,4) Which cell components are present in all prokaryotic cells? cell surface membrane cell wall endoplasmic reticulum flagellum A B C D √ √ √ × √ × √ √ × √ × √ √ × × √ Key √=present ×=not present 此处隐去内容………………………………………… 9. (9700_s10_qp_22,1) Fig. 1.1 is a diagram of an electron micrograph of a plant cell. Fig. 1.2 is a diagram of an electron micrograph of an animal cell. Both diagrams are incomplete. (a)(a)(a)(a) Explain how Fig. 1.1 can be identified as a plant cell. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... .....................................................................................................................................[2] (b)(b)(b)(b) Some organelles are missing from Figs 1.1 and 1.2. Information about these organelles is shown in the shaded boxes in Table 1.1. Complete the empty boxes in Table 1.1 by adding the correct information below each column heading. name of organelle diagram of organelle(s) as seen under the electron microscope (not to scale) one function of organelle cell type(s) in which organelle is located mitochondrion animal and plant assemble microtubules to produce the mitotic spindle rough endoplasmic reticulum protein synthesis Golgi apparatus animal and plant photosynthesis plant only KeyKeyKeyKey andandandand interpretioninterpretioninterpretioninterpretion 1. D 2. C Interpretion: Flagellum is found in eukaryocytes. 此处隐去内容………………………………………… 9. Key: (a) Because there are cell wall outside the cell and plasmodesma exist in cell wall. Vacuole, which could be found in the cell, enclosed with tonoplast. (b) name of organelle diagram of organelle(s) as seen under the electron microscope (not to scale) one function of organelle cell type(s) in which organelle is located mitochondrion Aerobic respiration animal and plant centrioles assemble microtubules to produce the mitotic spindle animal rough endoplasmic reticulum protein synthesis animal and plant Golgi apparatus Processing, packaging and modifying proteins animal and plant chloroplast photosynthesis plant only Mark scheme: 需要完整资料请联系扣扣一九八七三五五五九三，讲义每一 章 10101010元。