What is a Lab Practical What is a Lab Practical In lab learning is very hands on Designed to allow students to practice and develop a wide range of discipline based techniques Lab Practical test designed to assess this type of learning Timed Required to use techniques learned during lab classes 1107 Lab Practical 2 Parts PowerPoint Section 1 2 questions per slide 1 minute 10 seconds per slide Questions are short answer format Practice Question Is the cell under the microscope prokaryotic or eukaryotic Eukaryotic What is the structure identified by the pointer Chloroplast 1107 Lab Practical 2 Parts Lab Skills 8 9 questions actions Will require skills learned throughout your labs Using a microscope Using a scale Using a graduated cylinder Using a thermometer Using a ruler Using a pipette correctly Practice Question How much water is in the graduated cylinder in microliters 11 500 l Write the previous answer in scientific notation 1 15 x 104 Answer Sheet No Word Bank Print no cursive Pencil is preferred Make sure to include your section e g M V XXC Make sure to include units for measurements Practice Question Which pipette would you use to pipette 0 05 ml of solution How many grams is 500 l of water P 200 0 5 g Practice Question What is the part of the microscope identified by the arrow Fine Adjustment Knob What objectives can you use this knob on ALL scanning low power high power and oil Practice Question What is the total magnification of the scanning objective lens 40x What is the approximate size of the cell in m if the field of view is 1 mm 250 m Practice Question Name one dye used to measure diffusion through a semi solid agar gel Methylene Blue or Potassium Permanganate Why did one dye move further through the agar than the other Molecular Weight larger particles move slower than smaller particles Practice Question If a potato slice was placed in a hypotonic solution should the weight of the slice increase or decrease Increase Weight Define hypothesis Tentative explanation for an observed phenomenon that is both testable and falsifiable Final Comment Be able to read graphs Scientific Method Review Hypothesis Tentative explanation to an observed phenomena Needs to be Testable Falsifiable Statement SHOULD END IN PERIOD Specific offer only one explanation Leads to predictions Never proven true just supported Experimental Designs A Good Experiment Tests one variable at a time Fair and Unbiased Outside factors should not affect the outcome of the experiment Appropriate comparisons Experimental group vs control group Variables Independent variables are manipulated cause of Dependent variables are observed and measured effect what is affected Constants are conditions that are kept the same Metric Units based on powers of 10 one decimal point Prefixes 1 meter Giga G 1 000 000 000 0 000000001 Mega M 1 000 000 0 000001 Kilo k 1 000 of basic unit Basic Unit meters liters or grams Centi c 1 100 of basic unit Milli m 1 1 000 of basic unit Micro 1 1 000 000 of basic unit Nano n 1 1 000 000 000 of basic unit 1 000 000 000 nm 0 001 km 1 m 100 cm 1 000 mm 1 000 000 m Metric Units 10 units apart thus one decimal apart Scientific Notation Exponent of 10 the number of places to shift the decimal point Big numbers 1 0 have positive exponent Very small numbers 1 0 have negative exponent Don t have zeros in front of decimal Only one whole number in front of decimal 453 600 000 4 536 x 108 0 00007568 7 568 x 10 5 Temperature Celsius C is considered the scientific unit Temperatures Important in Science Boiling Point 100 C 212 F Freezing Point 0 C 32 F Room Temperature 22 C 71 6 F Human Body Temperature 37 C 98 6 F Mechanical Pipettes Used for pipetting small volumes 1ml or less Each pipette has certain volume range do NOT set them outside this range Name of Pipettor P 20 P 200 P 1000 Range of Liquid Dispensed 2 20 l 20 200 l 100 1000 l Decimal point is the line on smaller ranges Only move the plunger SLOWLY Mechanical Pipettes To pipet 1 Go to 1st stop and place in liquid 2 Release SLOWLY drawing liquid up 3 To dispense liquid go to 1st stop SLOWLY then push the last bit out by going to the 2nd stop 4 Release SLOWLY 5 Eject tip back into tip box or waste Parts of a Microscope Arm Condenser Knob Coarse Adjustment Knob Fine Adjustment Knob Oculars Rotating Nose Piece Objective Lens Iris Diaphragm Lever Light Source Control Knob Parts of a Microscope Mechanical Stage Stage Base Stage Control Knob Light Intensity Control Knob How to Focus Start with 4X short scanning lens Center specimen directly over light Move stage all the way up Looking through oculars slowly lower stage until specimen comes in focus using coarse adjustment knob Use fine adjustment knob to make optimize focus Move to next objective lens 10x should only need to use fine adjustment knob Diffusion Diffusion Process where molecules move from an area of high concentration to an area of low concentration Requires no energy Diffusion occurs in all states of matter solid liquid gas Diffusion How quickly diffusion occurs is affected by Temperature Particle size molecular weight Concentration Diffusion through Semi Solid Look at the effect of temperature and molecular weight on diffusion through semi solid Agar gel is made from polysaccharides and water 98 Dye molecules will diffuse through the gel Use two dyes Methylene Blue MW 319 85 g mol Potassium Permanganate MW 158 03 g mol Use same amount of dye in precut holes use 3 drops Let diffuse for approximately 45 minutes Osmosis and Tonicity Osmosis Diffusion involving water passing through a Isotonic semipermeable membrane moving from low solute concentration to high concentration Hypotonic Hypertonic Enzymes Enzymes proteins that act as biological catalysts Increasing speed of chemical reactions by lowering activation energy Each enzyme has an active site that temporarily binds the substrates reactants forming an enzyme complex The catalytic action of the enzyme converts the substrate s to a product s Optimum Performance Enzymes have an optimum environment in which they perform at their maximum potential Temperature Humans 37 C pH Humans varies blood pH 7 35 7 45 Sucrase Sucrase enzyme that hydrolyses sucrose disaccharide to form glucose and fructose monosaccharides ase identifies it as an enzyme Benedict s Reagent In the presence of a reducing sugars a redox reaction occurs in which copper II ions Cu 2 are reduced to copper I ions Cu 1 This results in an orange red precipitate Controls