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BTEC Unit 2 Applied Science Questions And Answers
Suggest why laboratory technicians must complete health and safety training before they are allowed to work in the laboratory
to ensure that they are aware of the risk and hazards in laboratories and how to deal with them.
Information that must be recorded for samples taken
date
name of person handling samples
location (where sample is from and where it is transported to)
Flame test colours
Barium (Ba2+)= Pale Green
Copper= Green Blue
Lithium= Crimson Red
Sodium (Na+)= Yellow
Potassium (K+)= Lilac
Calcium (Ca2+)= Orange-red
Properties of a suitable internal standard
Internal standard is chemically related to the compounds that are being analysed but it should not be naturally present in the sample.
Compounds which have the same functional groups.
Why are tubes containing blood samples enclosed in plastic watertight containers
Prevents degradation by water.
Two containers limits possibility of loss sample if one container is broken.
2 ways of reducing risks associated with hazards in labs
Carry out risk assessment
Use PPE for protection
ā¢Look through graticule at a calibration slide to find number of divisions on calibration slide corresponding to divisions on graticule.
ā¢Calculate the true distance corresponding to divisions.
ā¢Calculate width of hair.
Explain how Gel Electrophoresis can be carried out in a school or college laboratory
ā¢Prepare the agarose gel tray, place this tray into Electrophoresis chamber.
ā¢Submerge gel using diluted electrophoresis buffer.
ā¢Load wells with dye samples and place safety cover.
ā¢Connect wires to the power source and begin electrophoresis by loading current through the gel.
ā¢Use a timer to observe time taken for dyes to travel.
ā¢Once completed remove gel and casting tray from chamber.
DNA samples are loaded into wells at one end of the gel. DNA fragments are negatively charged so they are attracted to positive electrode. Small fragments move through gel faster than larger ones. DNA-binding dyes will show same sized DNA fragments.
Types of Chromatography
High Performace Liquid Chromatography- HPLC
Thin Layer Chromatography (similar to Paper Chromatography)
Gas-Liquid Chromatography
Polymerase Chain Reaction (PCR)
- Solution is heated allowing DNA strand to separate- Denaturation
- Solution is cooled allowing DNA primers to bind- Annealing
- DNA polymerase binds and synthesizes new DNA strand- Extension
PCR is used for DNA mapping, Genetic testing and personal DNA tests.
External Ultrasound
External Ultrasounds are often used to examine the heart or an unborn baby. A transducer is used to examine the parts of the body. Lubricating gel allows transducer to move smoothly. Pulses of Ultrasound are sent from a probe into the transducer.
Calibration Method
Mix ice and water and leave it for a few minutes, thermometer should be 0Ā°C.
when carrying out a random sample it is important to consider that the statistical significance is adequate and that the investigation can and will be carried out in a timely manner and cost effective manner.
However, when conducting an investigation on random sampling it is important to analyse whether there could be any bias occurring and how it can be prevented.
Representative Sample
Representative sampling is a sample taken from a subset of the population.
Representative sampling may take place when it may not be suitable to sample randomly in a natural delicate environment, as this may cause wider damage compared to taking a small representative sample in one area.
Rf Value
Distance travelled by substance divided by distance travelled by solvent
Paper Chromatography method
- A pencil line is drawn about 1cm from the origin.
- The sample(s) are applied in solution at points on the origin and allowed to dry.
- The paper is placed vertically in the container with a shallow layer of solvent, so that the origin is above the level of the solvent.
- The container is covered or sealed to prevent evaporation and the solvent will be drawn up to the paper.
- When the solvent reaches the origin, substances in the sample will dissolve and begin to move.
- Once the solvent has moved far enough up the paper, the sheet is removed from the container.
- The position that the solvent reached is marked.
The use of electrophoresis for the separation of the components of a mixture that are charged in the DNA analysis
DNA molecules have a negative charge due to all the phosphate groups in the sugar-phosphate backbone. if they are placed in an electrical field they will be attracted to the positive terminal(anode). This is usually carried out in a gel made of agarose. The gel forms a matrix that allows the DNA molecules to pass through, but shorter molecules can move more easily through the matrix and so move faster.
DNA samples are loaded into wells at one end of the gel. DNA fragments are negatively charged so they are attracted to positive electrode. Small fragments move through gel faster than larger ones. DNA-binding dyes will show same sized DNA fragments.
Mass Spectrometry
MS can be used to identify the amount of types of compounds by ionising the sample and then masuring the ratio of mass to charge of the ions produced. This can be done is various ways,
- By measuring how far the ions were deflected by a magnetic field, more massive ions are deflected less.
Controlled airflow cabinets
Controlled airflow cabinets serve to protect the culture from contamination as well as protecting the user from the culture. They incorporate filters and directed airflow which helps to contain any hazard within the cabinet. If you do not follow recommended procedures there is a great risk increase in contamination.
Gas Chromatography Method
- Small sample injected into one end of heated column, where it turns to vapour.
- Carrier gas carries sample through stationary phase. Substances separate as they travel through column at different speeds.
- Detector records arrival of each chemical from column. Number of peaks on the output of gas Chromatograph shows number of compounds present.
Cauliflower Cloning
- Place forceps into a pot of sterilising solution, such as SDICN.
- Clean the bench and wipe surface with a small amount of 70% ethanol.
- Collect small 'mini floret' or cauliflower and place in a petri dish.
- Use a scalpel and cut mini floret into micro florets, 'explants'.
- Use forceps to pick up your explants and place in jar of SDICN. Cover and swirl for 5 seconds, put forceps back in the pot.
- Every few minutes, swirl jar for 5 seconds. Repeat for 15 minutes.
- Carefully strain liquid from jar into waste beaker. Use forceps to stop explants from falling out.
- Take lid off vial of agar growth medium.
- Use forceps to put an explant into the pot of agar medium. Press lightly and replace lid.
Hazards likely to be encountered in a lab
Harmful chemicals
Harmful bacteria
Flames
Broken glassware
Blood
Radioactive material
Spillage and tripping
Explain how the solution of sodium carbonate can be used to find concentration of hydrochloric acid solution by titration
- Use pipette to put 25cmĀ³ of sodium hydroxide solution in a conical flask.
- Use appropriate indicator, place flask on white tile/paper so colour change is visible.
- Fill burette with hydrochloric acid and put it on a stand above the flask. Take initial reading.
X-Rays (XRF and XRD)
XRF- X-Ray Fluroscence, XRD- X-Ray Diffraction, both non-destructive techniques
X-Ray collides with an atom disturbing its stability. An electron is ejected from a low energy level and a space is created. XRF is used for material analysis.
XRD is used for determining the atomic and molecular structure of a crystal in which crystalline atoms cause a beam of X-Rays to diffract to many specific directions.
X-Rays in Health
X-Rays are a type of radiation.
As X-Rays pass through the body, photons are absorbed at different rates.
Dense parts of the body i.e bones show up white, softer material i.e lungs show up dark.
Procedure to carry out a flame test on a sample
Clean flame test wire, place metal loop in the hottest part of the Bunsen Burner flame, if there is a colour change place wire in concentrated acid solution and put in flame again.
Place flame test loop into test solution and then hold metal loop at the edge of the flame. Create flame test chart and note colours shown.
Units of measurement ( Microscopy )
metres to millimetres= Ć·
millimetres to micrometer= Ć·
micrometer to nanometer= Ć·
Advantages and Disadvantages of Atomic Emission Spectroscopy
Advantages
- Quick automated process
- Only requires small sample
Disadvantages
- Destructive, sample will burned
- Does not identify compounds
Differences between images generated by X-Ray scanners and ultrasounds
Uses of Thin Layer Chromatography
Determine number of components in a mixture.
Verify a substance identity.
Analyse fractions obtained from column chromatography.
Thin Layer Chromatography and Paper Chromatography stationary and mobile phases
TLC
Stationary Phase
Polar absorbent- Alumina or silica particles
Mobile Phase
A single solvent or a combination of solvents
PC
Stationary Phase
Cellulose paper
Mobile Phase
Water/alcohol
Steps involved in producing a risk assessment
HSA (Health and Safety Authority)
- Identify hazards in workplace.
- Assess risks presented by these hazards.
- Implement control measures to reduce hazards caused by identified risks.
HSE (Health and Safety Executive)
Step 1- Identify the hazard(s).
Step 2- Evaluate who might be harmed and why.
Step 3- Analyse the risks and decide on precautions.
Step 4- Record findings and implement them.
Step 5- Review risk assessment and make updates if necessary.
Control measures to minimise risks (HSA)
- Eliminate the hazard (not always practical and achievable).
- Substitute the hazard with a lesser risk (overall negative harm or health effects will be lessened, for example in laboratory research toluene is used as substitute for benzene as it is less toxic).
Waste disposal
Hazardous Waste Regulations
Chemical waste needs to be dealt with accordingly by identifying and dealing with their hazardous waste to ensure that it is stored and transported safely. Waste centres also need to ensure that they are properly disposing waste as some substances are incompatible and therefore cannot be disposed in the same manner.
Biological waste is any material that contains or has been contaminated by a bio hazardous agent, these can include petri dishes, culture tubes, syringes, surgical wraps, needles, blood vials, PPE and more.
There are two tiers for biological waste- 1 and 2. Tier 1 should be treated with autoclave or disinfectant prior to pickup.
Tier 2 biological waste is non infectious and does not require treatment (examples of tier 2 Biological waste is animal tissue, cell cultures etc).
Once personnel have completed all prior necessary steps, the final step to remove waste from your laboratory is to sign a Biological Waste Treatment and Certification Form and call REM to schedule a pickup.
Standard procedures for breakages
-Reporting
-Safe cleaning up
-Disposal using an appropriate container
-Review cause of breakage
-Appropriately modify protocol
Stages of Mass Spectroscopy
(Ionisation, Acceleration, Deflection, Detection)
Ionisation
1.Samples becomes vapourised then it gets passed into the ionisation chamber. In this chamber an electrically heated coil gives off a stream of electrons (in some cases, the collision causes a positively charged ion as the electron gets knocked off). At this stage most of the ions have formed a +1 charge.
Acceleration
Positively charged ions are repelled from ionisation chamber (as it is positively charged) and pass through negatively charged holes which focus and accelerate this into a beam.
Deflection
The stream of prositvely charged ions are deflected by a magnetic field. Amount of deflected ions is dependant on the mass of the ion and the charge of the ion. (Mass/charge ratio).
Detection
By varying the strength of the magnetic field, the different ion streams can be focused on the ion detector in order of increasing mass/charge ratio.
A mass spectrum is generated and the different mass/charge ratio values of ions present and their relative abundance is shown.
