Chapter 1: Cells and Microscopy Flashcards

Question

how is the structure of an erythrocyte related to its function?

Answer 1

* no nucleus * few organelles (incl. no mitochondria, GA) * biconcave (incr. SA) * production of haemoglobin (for oxygen transportation)

Answer 2

* lobed nucleus * granular cytoplasm * many lysosomes containing hydrolytic enzymes (phagocytosis)

Answer 3

* mixed (representative) * known dilution (accurate counting)

Answer 4

count number of cells in 3-line square using NW rule = \_\_\_find volume (0.2 x 0.2 x 0.1 = 0.004 mm3) in 1 mm3 = 1/0.004 x ___ = ~~~ cells account for dilution = ~~~ x dilution factor = ........ cells

Answer 5

analysis of physical and chemical characteristics of cells in heterogenous cell populations

Answer 6

flow cell (liquid stream carrying single file cells) measuring system detector amplification system computer + relevant analysis software

Answer 7

* specific antibodies can be tagged to different fluorochromes --\> recognise and target specific antigens inside cells/on CSM * fluorochromes can be attached to a chemical that binds to a specific of DNA/cell membrane/cells structure * each fluorochrome has its own peak of excitation and emission wavelengthslaser causes tagged cell to fluoresce so it can be counted * scattering occurs based on size and density

Answer 8

1. cell = basic unit of all life forms 2. organisms can be uni- or multi-cellular 3. metabolic processes take place inside the cell 4. new cells are derived from pre-existing cells 5. cells process genetic material which is passed to daughter cells 6. cell = smallest unit of an organism capable of surviving independently

Answer 9

* phospholipid bilayer - selective permeabilitycholesterol - strength and consistency * proteins - integral (channels) and peripheral (recognition) * carbohydrates - glycoproteins (recognition)

Answer 10

1. maintains physical integrity 2. maintains a chemical environment 3. selective permeability 4. marks and signals cell

Answer 11

* surrounded by double membrane called nuclear envelope * pores in nuclear envelope (allows exchange of molecules) * contains at least one nucleolus * large & spherical structure ~10-20um diameter * fluid within nucleus = nucleoplasm

Answer 12

* contains genetic, hereditary material in form of DNA * control of hereditary characteristics * replication of DNA for mitosis in S stage of cell cycle * controls of expression * chromosomes carry genes for production of polypeptide chains → and hence proteins

Answer 13

* granular and fibrillar * components ill-defined matrix * found within the nucleoplasm * small spherical structure

Answer 14

Produces rRNA Produces ribosomal subunits and assembles them into ribosomes

Answer 15

* Rod shaped organelles * Capable of changing shape and replicating * ~1-10nm length * Possess their own small loop of DNA (code for production of enzymes used in aerobic respiration) * Surrounded by mitochondrial envelope (double membrane * Filled with liquid called matrix * Matrix contains 70s ribosomes & small plasmids (circular loops of DNA)

Answer 16

ATP production through aerobic respiration * Main function = site of link reaction, Krebs cycle & oxidative phosphorylation (later stages of aerobic respiration) * Site of ATP production for the cell

Answer 17

* folding network of cisternae held together by cytoskeleton * RER also has attached ribosomes

Answer 18

* RER: protein production * SER: production, metabolism and storage of fats and steroid hormones * sarcoplasmic reticulum: storage and release of Ca²⁺ ions for muscle contraction

Answer 19

* Small, fluid filled membrane bag organelle formed by GA * Contain different types of hydrolytic enzymes (proteases & lipases) * ~1um diameter * Typical internal pH ~5

Answer 20

* breaking down macromolecules in hydrolysis * remove unwanted cell structures & organelles and chemicals within cell * important role in phagocytosis & apoptosis * enzymes usually formed on RER and then enclosed in vesicles which bud off the Golgi body

Answer 21

* Appear similar to SER but form convex shapes * Made from fluid-filled flattened sacs of cisternae held together by matrix proteins and cytoplasmic microtubules * Typically 40-100 stacks per GA & 3-6 cisternae per stack

Answer 22

* Assemble polypeptides into proteins * Package proteins and lipids made by RER and SER * Modify proteins and lipids * addition of glycocalyces (glycocalyx = singular) which are oligosaccharides → glycoproteins & glycolipids * addition of phosphate groups → phospholipids * Sort proteins into vesicles → ensures proteins/lipids are transported to correct place in cell * ost modification (glyco)proteins, (glyco)lipids and phospholipids packaged into golgi vesicles

Answer 23

* NOT membrane bound i.e. not true organelles * Actually cytoplasmic granules made from rRNA and protein * Found free in cytosol or bound to ER to form RER * Each ribosome contains 2 subunits: large & small subunit * Two types: * 80*s* * only found in eukaryotes (free or on RER) * 25-30 nm diameter * 1:1 ratio of rRNA:protein * Large subunit = 60*s*, small = 40*s* * 70*s* * found in cytosol of prokaryotes * 65%:35% ratio of rRNA:protein in prok. * also found in mitochondria & chloroplasts * Large subunit = 50*s*, small = 30*s*

Answer 24

synthesis of a polypeptide chain through translation of mRNA

Answer 25

* Cylindrical structure found in membrane bound vesicle → centrosome * Membrane of centrosome is continuous with nuclear envelope during interphase * Found in pairs * Composed mainly of protein called tubulin in structures called microtubules (see later) * Short cylinders of 9+0 arrangement (i.e. 9 microtubules arranged in circle around the circumference but none in the centre)

Answer 26

* Organise spindle fibres in nuclear division (mitosis & meiosis) * Centriole within centrosome duplicates itself during G2 phase of cell cycle: they are arranged at right angles to each other * Centrosomes migrate to poles during prophase * Impotant in increasing effectiveness of mitosis * Involved in the movement of cilia and flagella

Answer 27

* membrane-bound sacs * surrounded by a sinlge membrane called a tonoplast (selectively permeable membrane)

Answer 28

* Acts as reservoir for water (main content) * Also contain dissolved salts, sugars, organic acids * Provide support to the plant _cell_ * Contributes to cell turgidity i.e. provides _whole_ plant support * Surrounded by tonoplast

Answer 29

* nucleus contains gene for transcription of protein * nucleolus = site of ribosomal subunit production & assmebly * ribosomes = site of translation of mRNA to form ppc * RER is continuous with nuclear envelope * vesicles transport protein to golgi apparatus, which processes it (e.g. quaternary structure by adding prosthetic groups) * golgi vesicles transport protein to CSM

Answer 30

* no nucleus * no embrane-bound organelles * 70 Svedberg ribosomes * peptidoglycan cell wall * flagella * polysaccharide capsule * plasmid DNA

Answer 31

* amoeba * chlamydomonas * paramecium

Answer 32

* cell stability * support * movement of cilia and flagella * changing shape of cell during cytokinesis * phagocytosis * exocytosis * movement of organelles/vesicles

Answer 33

1. microfilaments 2. intermediate filaments (10nm) 3. microtubules (23nm)

Answer 34

* binding conformational change * filament release * conformational relaxation * filament rebinding

Answer 35

quantitative analysis of a solution to determine its quantity/quality

Answer 36

passive movement of molecules down the concentration gradient (until an equilibrium is reached) across a partially permeable membrane

Answer 37

* Concentration gradient * Size of molecule * Amount of kinetic energy the molecules posses (i.e. directly related to temperature) * Polarity of the molecule * Surface area * Diffusion distance

Answer 38

Passive movement of molecules down the concentration gradient through specialised proteins (until an equilibrium is reached) across a partially permeable membrane

Answer 39

Channel proteins * Form pores form aqueous channels which allows ions to cross * Can be **gated** which enables the channels to be open or closed depending on * A potential differences across the membrane * The presence of a specific molecule (a **ligand**) * Used to transport water soluble molecules and ions * Different channels are specific to specific ions i.e. some channels allow Na⁺ to cross whereas others allow Cl^- ions to cross etc Carrier proteins * each carrier protein has a complementary binding site to a specific molecule * carrier protein undergoes allostery i.e. a conformational change * The carrier protein changes between a ‘ping’ and ‘pong’ state * P**i**ng state = binding site exposed to **o**utside of the cell * P**o**ng state = binding site exposed to **i**nside of the cell * Used to transport larger molecules e.g. glucose, amino acids uptake in small intestine

Answer 40

* the movement of molecules against their concentration gradient * requires ATP * requires a carrier protein:- * with a specific binding site * to undergo a conformational change * have a binding site for ATP- ∴ can carry out hydrolysis

Answer 41

* carrier protein takes up molecule from outside * molecule binds to carrier protein * ATP attaches to membrane protein on inside * molecule causes conformational change to structure --\> access for molecule opened * molecules released to inside of membrane using E from hydrolysis of ATP * release of molecule causes carrier protein to revert to binding configuration

Answer 42

* intake of small quantitites of liquid by pinocytosis * intake of olid material by phagocytosis

Answer 43

* uptake of nutrients * engulfing bacteria

Answer 44

* insoluble waste material excreted from cell * e.g. * the **removal** of **waste products** or secretion of useful products (e.g. **secretion** of **pancreatic enzymes, secretion of insulin** from **-cells** of the **pancreas**) * plant cells use it to develop the cell wall which is outside of the cell surface membrane

Answer 45

Testing liquid smaples: * add ethanol * add equal volume of distilled water * shake gently * mixture turns cloudy/milky Testing solid samples * Place a small piece of each solid into test tube * Add 2 cm³ **ethanol** to test tube and shake thoroughly * Using the glass rod gently mash each sample: ensure rod is cleaned between samples to avoid cross-contamination * Shake each tube thoroughly * Allow the solid to settle to the bottom of the tube * Carefully pipette the ethanol from each sample into a fresh, labelled tube, leaving the solid sediment behind * Add 2 cm³**distilled water** and shake gently to **mix** * Observe the appearance of each sample

Answer 46

Both * contain glycerol * contain fatty acids * contain choline * contain ester bonds * contain C, H and O * formed by condensation reactions

Answer 47

* T: 3 fatty acids; P: 2 fatty acids * T: 3 ester bonds; P: 2 ester bonds * T: absence of phosphate group; P: presence of phosphate group

Answer 48

* To enable them to be cut into secrions to observe under a microscope * To enable them to be treated with different stains

Answer 49

1. Fixation: use 70% alcohol 2. Staining: use few drops of appropriate differential stain 3. Mounting: cover with coverslip to exclude dust and air

Answer 50

1. Rapid & simple procedure (no complex apparatus or skill required) 2. Can mount specimen in glycerine to prolong examination period

Answer 51

* specimen in life like condition * minimises distortion * chemicals such as or are added to make proteins and nucleic acids insoluble à fixing them in position

Answer 52

* traces of water from fixed material * Achieved by placing the specimen in increasing e.g. up to 70% ethanol

Answer 53

* Addition of xylol * Ensures material is made

Answer 54

* material so it is firm enough for sectioning * can be resin, plastic or wax

Answer 55

1. General adv = most biological specimens are colourless & almost transparent → easier to observe tissues/cells/chemicals 2. when observing animal tissue = allows observer to distinguish xylem vessels from other tissues etc 3. when observing plant tissue = allows observer to distinguish between **different types** of WBC

Answer 56

1. Low skill set needed by user 2. Can be transported to use in field work 3. Can observe living organisms 4. Relatively inexpensive so available for schools & colleges

Answer 57

1. Low resolution 2. Hence limited magnification 3. Many internal cellular structures can’t be seen e.g. ribosomes, cristae,

Answer 58

**Advantages of EM** * greater resolution (~0.1nm) * higher magnifications can be used * finer detail seen e.g. ribosomes **Disadvantages of EM** * specimen has to be placed in vacuum therefore must be dead (as essential specimen is completely dehydrated) * highly expensive so prohibits use in schools * high skill set required à need for training before use * must be used in specialist room due to electromagnets within the EM * more complex process to prepare specimen e.g. must be mounted on copper grid rather than glass slide * more prone to artefacts due to complex preparation procedure

Answer 59

Both * use e- beam * place specimen in vacuum * can only be used to observe dead specimens * produce images that can be colour enhanced * have higher resolution than LM * obtain higher magnifications than LM Differences * TEM = 2D image, SEM = 3D image * TEM higher resolution than SEM * TEM max mag = 100 000x, SEM 10 000x * TEM shows internal detail, SEM shows surface detail and contours *

Answer 60

1. ability to eliminate or reduce background information away from the focal plane to reduce to image degradation 2. capability to collect a series of optical sections from thick specimens ay various depths by optical sectioning 3. ability to obtain high resolution images 4. ability to obtain 3D reconstructions 5. ability to image living cells and tissues 6. any out-of-focus light is blocked à clearer image than standard LM

Answer 61

1. point source of light is detected on to the object plane 2. point of **emitted fluorescence** light or reflected light from the specimen is **directed** through **detector pinhole** 3. fluorescent/reflected light is enhanced using **photomultiplier** 4. fluorescent/reflected light displayed on computer screen as a pixel 5. specimen is scanned point by point & line by line à **very thin, blur-free optical** sections are recorded one pixel at a time 6. series of images then combined à **image stack →** **3D image**

Answer 62

* **fluorochromes** **attached** to **antibody** that is specific for one antigen on or in the cell * **fluorochromes** can also be **tagged** to a chemical that binds specifically to a component of the csm, DNA or other structure * each **fluorochrome** has its **own peak excitation** & **emission** **l** * **lasers** with **different** **l** are **used** depending on which fluorochromes are used * **laser** **excites** the **fluorochrome** causing the **tagged cells** to **fluoresce** * this **fluorescence** is **counted** by the **detector** * the specific light scattering and fluorescent characteristics of each cell as they pass the laser beam is **used for counting and sorting**

Answer 63

Calculating field of view: Field of view = area that can be seen when looking down through eyepiece Hence FOV = area of circle i.e. **πr²** (units = **mm²** *assuming radius measured in mm*)

Answer 64

* Role in blood clotting * Role in clot formation

Answer 65

* Defend against bacterial and fungal infections * Engulf bacteria by phagocytosis

Answer 66

Produce immunoglobulins (antibodies)

Answer 67

* Several types: * T helper cell – produces cytokines to coordinate the immune response * Cyotoxic T cell – binds to antigens on viral infected cells/tumour cells & destroys them * Natural killer cells – roles vary

Answer 68

* Carry out phagocytosis * Longer living than neutrophils * Can leave the blood stream by amoeboid movement & differentiate into macrophages in the liver, spleen & lungs

Answer 69

1. Neutrophils 2. Monocytes

Answer 70

* count all cells that lie completely within the triple lined 5x5 grid * also include any cell that lies on the middle line of the north triple boundary and the middle line of the west triple boundary * if a cell lies on the middle triple line on the south or east boundary do **not** count them

Answer 71

* analysing the activity of molecules found in the cell surface membrane and within the cell * characterising and defining different cell types in heterogeneous (mixed) cell populations * assessing the purity of samples * analysing cell size and volume

Answer 72

Larger and more granular granulocyte cells produce a large population with high SS and FS Monocytes are large cells, but not so granular, so these produce a separate population with high FS but lower SS Smaller lymphocytes and lymphoblasts produce a separate population with less FS. They are agranular cells so also have low SS.

Answer 73

* double membrane * that surrounds nucleus * outer membrane of NE is continuous with RER

Answer 74

* Gaps within the NE (usually ~3000 pores) * Each pore~40-100nm diamete * Enables cell to control what enters and exits the nucleoplasm from cytosol e.g. allows exit of mRNA after transcription to enable translation to occur in cytosol

Answer 75

* Series of flattened membrane sacks (cisternae) that form sheets in the cytosol * Tubular appearance

Answer 76

* Site of lipid synthesis, storage and transport * Site of carbohydrate synthesis, storage and transport * Site of steroid hormone synthesis, storage and transport

Answer 77

* Series of flattened membrane sacks (cisternae) that form sheets in the cytosol * Has ribosomes attached to outer surface of cisternae * Continuous with outer membrane of nuclear envelope

Answer 78

* Site of protein & glycoprotein synthesis * Site of folding of ppc into 20, 30 structure * Provides pathway to transport proteins & other materials through the cell

Answer 79

* Used in various processes * secretion e.g. release of insulin from β-cell in pancreas, secretion of antibodies from B-lymphocyte by exocytosis * phagocytosis * endocytosis * transports phospholipids to csm for cell growth * Also used in cell metabolism and enzyme storage

Answer 80

* Cell to cell connections between adjacent plant cells * Enables materials and chemicals to be transferred between cells

Answer 81

**Structure:** * Very small circular pieces of DNA * Separate from main DNA within cytosol * Capable of replicating independently of main DNA **Role:** * Carry genes that increase survival chances of prokaryote e.g. genes to produce enzymes that breakdown antibiotics (i.e. antibiotic resistance genes)

Answer 82

* Formed by invaginations of cell surface membrane (csm) * Site of aerobic respiration

Answer 83

* Hair-like structures * Extend through cell wall * Enable bacteria to adhere to each other (important in sexual reproduction in bacteria) or other surfaces * NB Not found in all species of bacteria

Answer 84

**Structure** * Specialist extension of csm and cytosol **Role** * Enables motility and movement of bacteria * Rotation unit at base of flagellum (motor protein) * Some bacteria have multiple flagella

Answer 85

* made from a specialised protein = **actin** * **thinnest** cytoskeletal filaments * consist of **2 intertwined strands** * **7nm width**

Answer 86

* maintain the cell shape * enable motility e.g. pseudopodia * enable muscle contraction e.g. skeletal muscle * enable cytokinesis of cell division

Answer 87

* ~**10nm** **diameter** * more stable than microfilaments * made specialised protein called **keratin** * consist of **fibres wound together**

Answer 88

* maintain the cell shape * anchor the nucleus & organelles in the cytosol

Answer 89

* ~**23 nm diameter** * made of specialised protein called **tubulin** * arranged in **hollow** cylinders

Answer 90

* maintain the cell shape * enable motility e.g. cilia & flagella * enable movement of chromosomes * enable movement of organelles

Answer 91

* help to maintain the cell’s **shape** & **structure** * enable the movement of **organelles** within the cytosol * enable the **intracellular transport** of molecules & materials * enable the **movement of chromosomes** to occur during mitosis & meiosis

Answer 92

1. Motor protein **binds** **strongly** **to** a **cytoskeleton** **filament** 2. Motor protein undergoes a **conformational change** (allostery) 3. **Motor protein** is **released** from the filament (unbound) 4. Motor protein undergoes conformational relaxation (i.e. returns to original shape) 5. Motor protein **rebinds** to the cytoskeletal filament i.e. process repeats 6. This cyclical process à motor protein & associated organelle/molecule moves few nm at a time along filament

Answer 93

1. control entry & exist of molecules within organelles 2. isolate organelles to enable specialisation of chemical reactions 3. provide internal transport system 4. concentrate enzymes & substrates to increase efficiency and productivity of organelle 5. isolate enzymes to prevent cellular damage 6. maintain internal specific conditions at optimal level 7. can be moved within cell to where they are needed 8. provide surfaces for chemical reactions

Answer 94

1. phospholipids 2. proteins 3. cholesterol

Answer 95

* 7nm wide * Allow lipid soluble molecules to cross bilayer * Prevent water soluble molecules from crossing bilayer * Allows membrane to be flexible * Allows membrane to be stable

Answer 96

* span across both monolayers

Answer 97

1. Carrier proteins for specific molecules 2. Channel proteins for water-soluble molecules & ions 3. Electron carriers 4. Structural role 5. Receptor proteins 6. Membrane-bound enzymes

Answer 98

Proteins that only exist within one monolayer

Answer 99

* Glycoproteins receptors * Membrane-bound organelles * Electron carriers * Structural role * Cell to cell recognition * Antigens that trigger an immune response * Cell to cell adhesion

Answer 100

* Have a polar head * Which consists of glycerol, choline & phosphate group * Is hydrophilic * And a non-polar tail * which consists of 2 fatty acid tails * is hydrophobic * PPL molecules are arranged as a bilayer (upper & lower monolayer) * PPL bilayer acts as a barrier to water-soluble molecules

Answer 101

* Provide mechanical strength to the cell membrane * Regulate fluidity of the membrane * Prevent water & water-soluble ions leaking out * Reduce lateral movement of PPL within the monolayer

Answer 102

* It is a specialised lipid (steroid) * It is mostly hydrophobic but one part is hydrophilic (this area is attracted to the phosphate head of the PPL molecules) * The amount of cholesterol within different membranes varies

Answer 103

State: * carbohydrate chain which can be added to a protein or a PPL Function * Act as antigens * Act as recognition sites for the attachment of other molecules

Answer 104

**Glycolipid = lipid + glycocalyx** * Acts as recognition sites * E.g. cholera toxin **Glycoprotein = protein + glycocalyx** * Acts as recognition site for molecules * E.g. Hormones & neurotransmitters

Answer 105

* **polar** * **hydrophilic** * because it can **form** **hydrogen bonds** with **water** * this property **stabilises** the **membrane**

Answer 106

* **non-polar** * **hydrophobic** * unsaturated fatty acids **contribute to fluidity** of the membrane * fatty acid core forms **barrier to hydrophilic substances** and ions * fatty acid core **allows movement of non-polar substances & fat-soluble molecules**

Answer 107

1 glycerol + 1 choline + 1 phosphate group + 2 fatty acids

Answer 108

* Requires **3 condensation reactions** (one between each FA and glycerol) * **3 water** molecules removed (and released as waste product) * **3 ester bonds** formed (one between each FA & glycerol)

Answer 109

* Formed by **2 condensation reactions** * One condensation reaction between 1 FA and glycerol molecule

Answer 110

* at ***_low***_ temp it _***increases_*** fluidity * at ***_high***_ temp it _*****dec**_r_eases_*** fluidity

Answer 111

1. Antigens and cell markers 2. Cell adhesion 3. Satabilises the membrane by interacting with water 4. Acts as a receptor molecule for cell signalling 5. Cell recognition

Answer 112

both * use **intrinsic** proteins * posses a **binding site** * have a binding site which is **specific** for a particular molecule * have a bindings site which is **complementary** to the molecule to be transported * undergo a **conformational change** (i.e. **allostery**) to move the molecules

Answer 113

Carrier proteins involves in AT also * Have an **additional** **binding site** for **ATP** * Requires the **hydrolysis** of ATP to release the molecule form the binding site * Only work in **one direction** * Allow the **accumulation** of molecules within the cell (i.e. do not stop at the point of equilibrium) * Work **against** the **concentration gradient**

Answer 114

* This is when cells **take in solid** material in **large quantities** * The cells are called phagocytes * They produce phagocytic vesicles * E.g. bacteria being engulfed by a phagocyte

Answer 115

* This is when cells **take in liquid** material in **large quantities** * **Very small vesicles** are formed in a process called **micropinocytosis** * E.g. the uptake of nutrients by an ovum from follicle cells

Answer 116

**Qualitative test** * Only tells of presence or absence of substance **Semi-quantitative test** * Gives an indication of the **relative** amounts of a substance * Resulting positive result should be scaled low/medium/high **Quantitative test** * provides information on absolute quantity of substance present

Answer 117

**Qulaitative:** * Emulsion test: cloudy /colurless = lipids present/absent **Semi-quantitative:** * Emulsion test - degree of cloudines can indicate relative amounts of lipid present (more cloudy = mpre lipid present) **Quantitative :** * Emulsion test: use colorimeter to measure transmission and then use a calibration curve to determine an absolute concentration of lipid

Answer 118

* Higher temperatures (for example, from 55 °C) increased the permeability of the tonoplast and plasma membrane, which have the same structure. * Membrane (cell surface membrane and tonoplast) proteins become denatured. * Both these create spaces for pigment leakage by diffusion. * This occurs faster i.e. more pigment leaks out at higher temperatures. * Non linear trend

Answer 119

* Ethanol will cause membrane disintegration as it forms temporary bonds with the phospholipid heads in the membrane. * Causes the phospholipids to move out of place so large gaps form in the membrane allowing pigment to leak out. * Ethanol also affects bonding in the membrane proteins leading to denaturation causing further gaps in the membrane. * Cholesterol, important in membrane structure, is soluble in ethanol, and so once it is removed, larger gaps allow increased permeability of molecules such as betalin.

Answer 120

* Cutting cylinders will damage some cell walls and tonoplasts → this will potentially vary between different cylinders * Differences between blotting techniques (more blotting → removes more pigment) * Cylinders sit on top of each other /next to each other in some tubes →decreases SA exposed to water (i.e. varies between tubes) * Degree of swirling will vary between tubes * Some beetroot loose tissue may be transferred to the cuvette * Fluctuations in waterbaths → temperature not fully stable & takes longer for cells in centre of cylinder to reach higher temperatures * Use of forceps to remove cylinder may squeeze tissue and damage cell walls & tonoplasts releasing more pigment * Insufficient intermediate temperatures → unable to see data between temperatures tested * No replicates → unable to determine if result is anomalous → can’t calculate SD to determine reliability * Lack of stirring of solution after removal of cylinder → more densely coloured liquid may not be poured into cuvette

Answer 121

1. Accuracy of cutting cylinders → differences in SA 2. Accuracy of timing period

Answer 122

* Carry out at least 3 replicates at each temperature * Ensure all cylinders cut from same area of the same beetroot * Standardise blotting mechanism e.g. place on towel and roll once * Stir coloured liquid after removing cylinder before decanting * Decant coloured liquid through sieve into cuvette to remove any tissue debris

Answer 123

* The kinetic energy of the PPL molecules increases * Causing the PPL molecules to move more within their monolayer * This causes the PPL molecules to become more spaced out * This causes spaces to occur between the PPL molecules within the cell membranes * This causes the cell surface membrane and the tonoplast to become disrupted

Answer 124

* The kinetic energy of the protein molecules increases * Causing the protein molecules to move more within their monolayer * This causes the protein molecules to become denatured * This causes spaces to occur between the protein and PPL molecules within the cell membranes * This causes the cell surface membrane and the tonoplast to become more disrupted