Tools
5. Tools — IB Biology SL Revision Notes & Topical Questions
5 min read 13 parts Lesson 1 of 10
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Lesson summary
5. Tools — IB BIOLOGY SL notes: Apply safe and ethical practice, choose measuring tools, use sensors and data loggers, and draw and analyse graphs from biological data.Hazard = a feature of a procedure that can cause harmA chemical may be an irritant to the skin.Slippery rocks on…
- Risk assessment
- Justified precautions
- Chemicals used in biology
- Hazard warning symbols
- Human participants
- Field work
Section 1 of 13Hazard, risk and risk assessment
Hazard
Hazard a feature of a procedure that can cause harm
- A chemical may be an irritant to the skin.
- Slippery rocks on a shore are a hazard.
- A Bunsen burner flame can cause burns.
Risk
Risk how dangerous the hazard is, which depends on the likelihood and the severity of harm
Risk assessment
- Risk assessment identifies hazards, judges the risk and changes the procedure to reduce it
- In a rocky-shore quadrat study slippery rocks are a hazard and a fall is quite likely.
- A fall could cause bruises or twisted ankles.
- Reduce the risk by requiring shoes with good grip, avoiding rocks covered in seaweed and walking slowly.
Justified precautions
- Justified precautions name the hazard and justify the precaution
- Iodine is an irritant, so wear goggles and wash any skin contact immediately.
Section 2 of 13Hazard symbols
1Chemicals used in biology
- Chemicals used in biology stains, enzyme-reaction reagents and chromatography solvents
2Hazard warning symbols
- Hazard warning symbols nine standardised symbols in a red diamond on labels and safety data sheets
| Symbol | Meaning |
|---|---|
| Health hazard | Can cause skin rashes, eye damage or harm if swallowed |
| Corrosive | Skin burns and permanent eye damage |
| Flammable | Catches fire if heated or near a flame |
| Acute toxicity | Life-threatening effects even in small amounts |
| Hazardous to the environment | Threat to aquatic life and the environment |
| Oxidising | Can cause fire or explosions |
Section 3 of 13Ethics and environment
Ethics and environment
Animals
- IB policy allows animals to be used only when there is no alternative
- Experiments must not be cruel and must minimise distress.
- Keep experiments short, handle animals as little as possible and release them at the end.
Human participants
- Human participants they must give fully informed consent, for example when using a spirometer
Laboratory waste
- Do not pour toxic waste down the sink.
- Use sharps bins.
- Dispose of biological waste such as bacterial plates and dissected organs correctly.
Field work
- Field work avoid sensitive habitats, work in small groups and take litter away
Section 4 of 13Measuring mass and volume
1Mass
- Mass a digital balance, usually to two decimal places, tared before use so the container is not included
- 1 kg = 1000 g.
2Volume
- Volume units cm3, dm3, ml and l, with 1 ml = 1 cm3
- A measuring cylinder gives approximate volumes from 10 cm3 to 1 dm3.
- A volumetric pipette is the most accurate way to measure a fixed volume, usually 10 or 25 cm3, with the bottom of the meniscus on the mark.
- A burette is the most accurate for variable volumes from 0 to 50 cm3 and is read from top to bottom because 0.00 is at the top.
3Gases
- Gases a gas syringe, or an inverted cylinder of water if the gas is insoluble
4Time, temperature and length
- Time, temperature and length a stopwatch, a thermometer or probe, and a ruler, with human reaction time affecting short times
Section 5 of 13Counting, observing and required techniques
Counting populations
- Counting populations accurate counts are rare, so sampling is used
- Errors arise from large populations, missed individuals, misidentification and miscounting large groups.
- Cell counts use a haemocytometer or counting chamber.
Observation
- Labelled biological drawings are line drawings of observed features that follow drawing conventions.
- Qualitative observations such as sex, fur colour or number of limbs cannot be measured numerically.
Required techniques
- Required techniques paper or thin-layer chromatography, colorimetry and serial dilutions, physical and digital molecular modelling
- Light microscopy with an eyepiece graticule and preparation of temporary mounts.
- Identifying and classifying organisms and random and systematic sampling.
- Karyotyping and cladogram analysis.
Section 6 of 13Sensors and data loggers
Sensor
- Sensor detects changes in the surroundings and converts them to electrical signals that a data logger stores
- A computer then tabulates the data, calculates averages and gradients and plots graphs faster and more accurately than by hand.
pH meter
- pH meter measures H+ concentration as a pH value, which is useful for enzyme investigations
Temperature probe
- Temperature probe replaces a thermometer for experiments needing specific temperatures
Other sensors
- Other sensors gas, light, heart rate and lung volume monitors, and abiotic measurements in ecology
Section 7 of 13Databases and models
Database
- Database a structured collection of data, such as DNA and chromosome sequences, that can be searched, sorted and filtered
Spreadsheets
- Spreadsheets they record and process data, draw graphs and perform statistical analyses
Models and simulations
- Population growth curves predict real populations.
- Mesocosms are model ecosystems used to test the effect of changing one variable.
Section 8 of 13Drawing graphs
Choice of graph
- Choice of graph a line graph for continuous data over time and a bar chart for grouped data
Axes
- Axes the independent variable goes on the x-axis and the dependent variable on the y-axis
- Label both axes with units.
- Choose a scale that fits all the points.
Plotting
- Plotting plot points accurately in pencil so corrections are easy
Line of best fit
- Line of best fit a straight line or curve that shows the trend
- It passes through the majority of points with points evenly spread on both sides.
- It is not a join-the-dots line.
Section 9 of 13Reading graphs
Reading graphs
Interpolation
- Interpolation reading between plotted points
Extrapolation
- Extrapolation extending the line beyond the points, which is less reliable
Origin
- Origin decide whether (0,0) is a true data point, and if so it is a useful anchor
Intercepts
- Intercepts where the line crosses an axis
Maxima and minima
- Maxima and minima peaks and troughs where the gradient changes sign
Uncertainty bars
- Uncertainty bars show the uncertainty or variability of each measurement
Biology-specific diagrams
- Biology-specific diagrams dichotomous keys, food chains, webs and energy pyramids, and pedigree charts
Section 10 of 13Gradient and tangent
Gradient
- Gradient for a straight line it is change in y divided by change in x, and it is constant
Curved graphs
- Curved graphs many enzyme graphs are curves, so draw a tangent, a straight line touching the curve at one point, and find its gradient
1
Extrapolate the curve back to time 0.
2
Draw the tangent at t = 0 using a ruler.
3
Find the gradient as change in y divided by change in x.
4
State the initial rate, for example 72 cm3 in 20 s gives 72 / 20 = 3.6 cm3 s-1.
- Initial rate
- the gradient of the tangent at time 0
Section 11 of 13More from the specification
More from the specification
Laboratory Safety Considerations
- Carrying out biological investigations involves evaluating risks such as handling pathogenic bacterial cells, hazardous liquid chemicals,
- and sharp apparatus.
Ethical Considerations in Biological Inquiries
- Designing experiments with living organisms involves minimizing animal discomfort, ensuring appropriate culture disposal,
- and obtaining informed consent in human trials.
Environmental Issues and Waste Management
- Disposing of biological and chemical waste safely requires using dedicated autoclaves and chemical neutralization rather than discharging liquids into aquatic environments.
Valid Experimental Controls
- Setting up appropriate control apparatus ensures that observed changes in living tissue are genuinely caused by the experimental variable under test.
Laboratory Safety Considerations
- Carrying out biological investigations involves evaluating risks such as handling pathogenic bacterial cells, hazardous liquid chemicals,
- and sharp apparatus.
Ethical Considerations in Biological Inquiries
- Designing experiments with living organisms involves minimizing animal discomfort, ensuring appropriate culture disposal,
- and obtaining informed consent in human trials.
Environmental Issues and Waste Management
- Disposing of biological and chemical waste safely requires using dedicated autoclaves and chemical neutralization rather than discharging liquids into aquatic environments.
Valid Experimental Controls
- Setting up appropriate control apparatus ensures that observed changes in living tissue are genuinely caused by the experimental variable under test.
Safe disposal apparatus
- Safe disposal apparatus hazardous chemical waste and biological liquid cultures must never enter municipal sinks without proper decontamination.
Laboratory safety considerations
- Laboratory safety considerations using eye protection and specialized sharps containers prevents injury when handling biological apparatus.
Environmental issues
- Environmental issues proper containment and waste segregation reduce negative ecological impacts from discarded laboratory solutions.
Section 12 of 13Key terms
| Term | Meaning |
|---|---|
| Hazard | A feature of a procedure that can cause harm. |
| Risk | The likelihood and severity of harm from a hazard. |
| Tare | To set a balance to zero with the empty container on it. |
| Data logger | An electronic device that records sensor readings over time. |
| Tangent | A straight line touching a curve at one point whose gradient gives the rate there. |
| Line of best fit | A line or curve showing the trend with points evenly on both sides. |
| Uncertainty bar | A graph bar showing the uncertainty or variability in a value. |
| Interpolation | Reading values between plotted points. |
Section 13 of 13Exam technique
1
Joining the points on a graph instead of drawing a best-fit line — draw a smooth line or straight line through the trend
2
Writing wear goggles with no hazard identified or justification given — name the hazard and justify the precaution
3
Reading a burette from the bottom up — zero is at the top
4
Extrapolating a trend beyond the data and treating it as a measurement — extrapolation is less reliable
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