Lab Exam
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Compound microscopes (2 lenses)
Transmits focused light through a specimen fixed to a glass slide • 2D image • 2000X • Small objects (Cells, Bacteria)
Stereoscope or Dissecting Microscope
Can be used to view “live” organs ●Reflects light from the surface of a specimen ●3D image ●300X magnification ●Parts of or entire organisms (butterfly’s wings), (dissected cat’s beating heart), etc.
Scanning (SEM)
Electron beam bounced off specimen coated with gold to provide 3D image • Specimen/organism is sacrificed (i.e dead) • Image usually in Black and White • Magnifies up to 100,000X; 1 nm • View external features of small objects or part of objects (fly’s eyes, bacteria, virus) • >$50,000
Transmission (TEM)
Electron beam sent through thin slice of specimen to create a 2D image of an internal structure • Magnifies up to 100,000X; resolution 0.2 nm • View internal features of small objects or thin sections of objects (nucleus, DNA) • >$50,000
Hypothesis
proposed explanation or prediction based on limited evidence, serving as a starting point for further investigation
Null
No effect or no difference
Alternate
Some effect
Independent variable
is the factor that is manipulated or controlled in an experiment to test its effects on a dependent variable.
Dependent variable
factor that is measured or observed in an experiment to assess the effect of changes in the independent variable.
controlled/standardized variables
are factors that are kept constant throughout an experiment to ensure that any changes in the dependent variable can be attributed solely to the manipulation of the independent variable.
Control group
is a group in an experiment that does not receive the treatment or intervention being tested.
Protein
Biuret solution (purple) Monomer - amino acids; function - structure, enzymes.
Sugar glucose
Chem strips or Benedict’s test (red/orange = positive).
Starch
Gram iodine lugols or lk (blue/ black = positive).
Lipids
Sudan 4 or Sudan red Red film Monomer - fatty acids; function - energy storage, membranes.
Carbohydrates:
Monomer - monosaccharides; function - energy.
Nucleic Acids:
Monomer - nucleotides; function - genetic information.
Selectively Permeable:
Membrane allows certain substances to pass.
Dialysis Tubing:
Simulates a cell membrane for diffusion studies.
Diffusion:
Movement of molecules from high to low concentration.
Osmosis:
Movement of water across a membrane.
Hypertonic:
Higher solute concentration outside cell.
Hypotonic:
Lower solute concentration outside cell.
Isotonic:
Equal solute concentration.