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biology ~ definitions > Required Practical Techniques > Flashcards

Required Practical Techniques Flashcards

(54 cards)

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1
Q

what apparatus do you use to record mass

A

use a top-pan balance

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2
Q

how do you measure time

A

use a stopwatch or digital timer

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3
Q

how do you measure volume

A

-measuring cylinder ( but is less precise)
-volumetric pipette (very precise usually for volumes of 10/25 cm3)
-graduated pipette for flexible volumes
-burette (for titrations or when precise control is needed)
-micropipette (very small volumes)

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4
Q

how to measure temperature

A

-digital thermometer which is more accurate
-alcohol or mercury thermometer
-temperature probe (used with data loggers or for continuous monitoring)

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5
Q

apparatus for measuring distance

A

-ruler
-vernier calipers
-measuring tape

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6
Q

how to measure pH

A

-pH meter (most accurate but needs calibration)
-pH probe with datalogger (for continuous or digital readings)
-universal indicator and pH chart (less accurate used for approximate values

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7
Q

how to use a colorimeter

A

-set the filter (contrast to the colour of the solution)
-zero using a cuvette of distilled water should read 0
-place each sample in cuvette and measure the absorbance (or transmission)
-plot calibration curve of absorbance against known concentration

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8
Q

how to use a potometer

A

preparation of sample:
-cut shoot underwater (prevents air entering the xylem)
-dry leaves of shoot as any moisture present will affect rate of transpiration

using potometer:
-place shoot in tube
-ensure that equipment is airtight (use vaseline to seal any gaps)
-remove capillary tube from the beaker of water to allow a single air bubble to form and place tube back into the water
-record starting location of the air bubble
-leave for a set period of time
-record end location of the air bubble
-remove/reset bubble by opening the tap below the reservoir

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9
Q

equation for finding concentration in serial dilution

A

final concentration = initial concentration / dilution factor

the dilution factor is how much the concentration is diluted at each step (how much greater the final volume is then the initial)

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10
Q

when can serial dilutions be used

A

-courting bacteria or yeast populations, determining unknown glucose, starch, protein concentrations

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11
Q

how can comparisons of serial dilutions to standard done

A

-visual
-measured through a calibration curve
-measured through a colourimeter

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12
Q

what is a serial dilution

A

created by taking a series of dilutions of a stock solution, the concentration decreases by the same quantity between each test tube

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13
Q

how can the volume of stock solution (concentrated thing) be measured

A

desired concentration / concentration of stock x volume wanted

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14
Q

how to focus (use) a light microscope

A

-set objective lense to the lowest magnification
-use the coarse adjustment knob to move the lense down to just above the slide
-use the fine adjustment knob to carefully readjust the focus until the image is clear (a higher magnification be used if needed)

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15
Q

comparison of when to use a light microscope at a high or low power - field of view

A

lower- larger field of view as more of the specimen is available
higher- smaller field of view as less of the specimen is available

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16
Q

comparison of when to use a light microscope at a high or low power - detail

A

-lower if less detail is available
-higher - is more detail is available (such as individual cells, nuclei)

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17
Q

comparison of when to use a light microscope at a high or low power - depth of field

A

-lower - greater (more layers in focus at once)
-higher- shallower (as only one layer is in focus)

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18
Q

comparison of when to use a light microscope at a high or low power - focusing

A

-lower - easier to focus
-higher - harder to focus as needs to the fine adjustment

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19
Q

comparison of when to use a light microscope at a high or low power - use

A

-lower - good of scanning, locating structures, viewing tissue layout
-higher- good for examining cell structures closely

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20
Q

why should an eyepiece graticule be used

A

measure size of cells or structures, does need to be calibrated using a stage micrometer first

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21
Q

how to calibrate an eyepiece graticule with a stage micrometer

A

-place the stage micrometer on the microscope slide
-align the graticule with the stage micrometer, using the chosen objective lense
-calculate the value of one graticule unit
-repeat calibration for each objective lense (such as low, medium and high power) as the magnification changes the scale

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22
Q

how to use a calibrated eyepiece graticule to calculate size

Study These Flashcards
A

-place the specimen under the microscope
-count how many graticule divisions span the structure
-multiply by the value of each graticule unit at the magnification to calculate the actual size

23
Q

Benedict’s test for reducing sugars

Study These Flashcards
A

-add benedict’s reagent and heat in boiling water baths
-if reducing sugar is present, a brick-red precipitate will form

24
Q

what is benedict’s reagent

Study These Flashcards
A

contains copper (II) sulfate ions

25
benedict's test for non-reducing sugars (sucrose)
-add dilute acid (HCl) and heat in boiling water bath -add alkali (sodium hydrogen carbonate) -add benedict's reagent and heat in water bath that has been brought to the boil and brick red precipitate will form
26
how to test for starch
-add iodine solution -colour change from brown to blue-black
27
what is iodine solution made of
iodine and potassium iodide
28
how to test for protein
-add a few drops of NaOH solution (to make alkali) -add copper (II) sulfate solution -colour change from blue to purple
29
how to test for lipids
-add ethanol and shake -pour into water -lipid will show as a milky white emulsion layer (the more lipid present, the more noticable the colour will be)
30
quantitative Benedict's test
-carry out standard Benedict's test -remove precipitate by filtration -place sample (not filtrate) in colourimeter and measure absorbance -plot calibration curve of glucose concentration v absorbance
31
chromatography (example of amino acids)
-can identify as each amino acid will be more or less soluble -each amino acid will be more or less soluble in the mobile phase so will separate out the mixture travelling with the solvent at different times and distance -this depends on charge or size
32
gel electrophoresis
-molecules separated due to size and overall charge -positively charged molecules will go to cathode (negative pole) -negative molecules will go to anode (positive pole) (DNA negative so moves to this) -smaller molecules move quicker as can move through the pores in the gel more quickly -larger molecules move more slowly
33
safety considerations for measuring plant or animal responses
-avoid harmful conditions such as heat -handle to organisms gently and minimally -clean and disinfect equipment -avoid allergens such as pollen
34
what are ethical considerations of measuring plant or animal responses
-minimise stress and discomfort to animals -ise invertebrates where possible to avoid high suffering -return organisms to habitat or dispose of ethically -gain the appropriate consent if testing on humans
35
safety considerations where measuring physiological functions
-avoid harm to test organisms (such as in the daphnia study only use a low concentration of alcohol) -ensure there is good ventilation especially when using chemicals -monitor the heart rate safely (such as human volunteers being healthy) -wash hands after handling organisms)
36
ethical considerations when measuring physiological functions
-limit time exposure and return of organisms afterwards -replace animal models with simulations where possible -obtain informed constant if using human participants -respect the privacy and data of human subjects
37
aseptic techniques
-wash hands thoroughly with soap and water -disinfect work surfaces with disinfectant or alcohol -do not grow microorganisms at room temperature -flame inoculating loop or use a sterile pipette to transfer cultures -flame bottleneck to avoid contamination -sterilise and dispose of equipment immediately -light bunsen as convection currents draw air up and bring air through flame -remove petri dish lid at an angle
38
how to minimise risks when doing a dissection
-sharp tool (such as scalpels and scissors) --> cut away from the body, so not attempt to change the blade, keep away from the edge of the desk -mounted needle --> hold with the pointed end downwards, keep away from the edge of the desk -biohazard --> cover any cuts and wear gloves, wash hands after handling and dispose in a specific (designated) bin bag, use disinfectant to clean surfaces where heart was -the disinfectant is flammable so esure no naked flames are in the room
39
what are the sampling techniques used in fieldwork
-random sampling -systematic sampling -stratified sampling -mark-release recapture
40
what are quadrats and transects used to sample
non-motile organisms
41
how are motile organisms collected
traps or nets, for flying organisms a sweep net is used, for aquatic organisms a net is used
42
quadrats- how is species frequency found
number of individuals recorded in each quadrat
43
quadrat- how is percentage cover found
counting how much of the quadrat is covered by a species. a square is counted if more than half of the square is covered
44
when are transects used
to find how organisms are distributed across an area
45
what are the 2 types of transects
-belt transects -interrupted belt transects
46
what is a belt transect
quadrats are placed next to each other along the transect to work out how species frequency and percentage cover along the transect
47
what is an interrupted belt transect
instead of investigating the whole transect you can take measurements using a quadrat placed at regular intervals (such as every 2m). this makes it easier to cover a large distance
48
how is mark-release recapture done
1- capture a sample by using the appropriate technique 2-mark them in a way that is harmless and does not affect survival 3- release them back into their habitat 4- wait some time (such as a week), take a second sample from the same population 5-count how many of second sample are marked 6- use equation total population size+ (number caught in 1st sample x number in second sample) / number marked in 2nd sample
49
when is computer modeling used
-when scenarios are difficult or unethical to test in real-life, example include... -when modelling a population growth using exponential models (or logs) -simulating enzyme activity at different temp of pH -predicting effects of environmental change on ecosystems
50
what are data loggers
electronic devices that automatically record measurements over time
51
when are data loggers used
-measuring light intensity, temperature, CO2 levels, pH, oxygen concentration -often used in fieldwork or investigations that involve photosynthesis, respiration or enzyme activity
52
what is the advantage of using data loggers
they are more precise and continuous than manual readings, minimise human error
53
what software is used process data
spreadsheet programmes such as excel or google sheets
54
when is software to process data used
-calculate means, standard deviation, and percentage change -create graphs (such as bar charts, line graphs, scatter plots) -perform statistical tests -graphing and analysis software can be used on school labs for more complex processing

biology ~ definitions (2 decks)

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