SL path
Unit 1 Body Systems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| B3.1 (Animal) | Who decides what counts as normal? | Reference values for lung function were long adjusted by race, a practice now widely challenged. Standards that look objective can carry social assumptions. |
| B3.2 (Animal) | Can we be justified in believing something we cannot yet observe? | Harvey's theory predicted vessels nobody had seen. Compare how much confidence a prediction deserves before and after direct observation. |
| C2.2 | How far can findings from one species be applied to others? | Much of what we know about human neurons began with squid. What must be true for that extrapolation to be reasonable? |
| C3.1 | Can a whole system be understood by studying its parts? | Biologists often isolate one organ or signal. Consider what integration between systems might be missed when studied that way. |
| D3.3 | What limits should there be on how knowledge is obtained? | The insulin work relied on experiments on dogs. Consider how the benefits of knowledge should be weighed against the way it was gained. |
| C3.2 | Why might good evidence be rejected? | Semmelweis's data were strong, but they conflicted with accepted medical ideas and he had no mechanism to offer. What makes a community ready to accept new knowledge? |
| D3.1 (Human) | Should what we can do decide what we should do? | Reproductive technology raises questions that data alone cannot answer. Consider how science and ethics each contribute to these decisions. |
Unit 2 Plant Systems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| B3.1 (Plant) | How reliably can we know about a past nobody observed? | Fossil stomata are indirect evidence. Consider what assumptions link a modern pattern to a time millions of years ago. |
| B3.2 (Plant) | How does the act of measuring affect what is measured? | Probing xylem can break the water column. Consider other areas of knowledge where observing something changes it. |
| D3.1 (Plant) | How much does a successful prediction strengthen a theory? | Compare a prediction made in advance with an explanation offered afterwards. Why might the first count for more? |
Unit 3 Genetics
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| D1.1 | What makes an experiment elegant? | The design made each hypothesis predict a different result. Consider whether a simple, decisive design is a kind of beauty, and whether beauty matters. |
| D1.2 | How does language shape understanding? | We say the genetic code is read, copied and translated. Consider where these metaphors help, and where they may mislead. |
| D1.3 | What does it mean to call an event random? | Mutation is called random, yet some sites mutate more often and mutagens raise the rate. Is randomness a feature of nature, or a statement about what we can predict? |
| D2.1 | Do our tools reveal reality or shape it? | Stains and fixatives alter cells before we see them, and cells on a slide are dead. How do we know that what we see is not an artefact? |
| D3.2 | What should we do with results that look too good? | Statistician R. A. Fisher argued that Mendel's data fit the ratios suspiciously well. Consider what this means for trust, and for how data are recorded. |
Unit 4 Biomolecules
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A1.1 | How does science correct its own mistakes? | Researchers around the world tested the claim and rejected it. Consider what this says about the value of replication. |
| A1.2 | Who gets the credit in collaborative knowledge? | Franklin's contribution was long under-recognised. Consider how credit is assigned, and who may be left out. |
| B1.1 | How should we act when evidence is uncertain? | Public advice must be given before science is settled. Consider how confidence should be communicated when evidence may change. |
| B1.2 | How can new techniques change the questions we ask? | Before sequencing, some doubted that proteins had a defined order. Consider how methods decide which questions can be answered. |
| C1.1 | Is a simpler model ever better than a more accurate one? | Lock and key is still taught first. Consider when usefulness and accuracy pull in different directions. |
| C1.2 | How do comparisons help us to know something new? | The experiment treated life as chemistry. Consider what a comparison can show, and where it can mislead. |
| C1.3 | How can careful experiments lead to wrong conclusions? | He could not test for what he had not thought of. Consider how existing ideas limit how we interpret results. |
Unit 5 Cells
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A2.2 | Is seeing through an instrument really seeing? | We trust a microscope image without seeing the object directly. What gives instruments that authority? |
| B2.1 | If models get replaced, in what sense are they knowledge? | A model can be useful and later be shown to be wrong. Consider whether today's fluid mosaic model is true, or simply the best available. |
| B2.2 | Why is it stronger when independent methods agree? | Seeing a structure and isolating its function are different kinds of evidence. Consider why agreement between methods increases confidence. |
| B2.3 | Can ethics change when technology changes? | New methods removed one objection while raising other questions. Consider whether ethical conclusions should depend on what is technically possible. |
| D2.3 | How do we justify claims about things we cannot observe? | Mass changes are the data, and osmosis is the explanation. Consider how far an inference goes beyond what was measured. |
Unit 6 Biodiversity
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A3.1 | How can expertise make errors last? | Some researchers doubted their own counts because 48 was the accepted number. Consider how authority can affect what people report. |
| A4.1 | What does theory mean in science? | In everyday speech, a theory is a guess. Consider how scientific usage differs, and why that matters for public understanding. |
| A4.2 | Can science tell us what is worth saving? | Prioritising species combines data with values. Consider which parts of the decision science can and cannot settle. |
| D4.1 | How do we test theories about long-term processes? | Evolution usually acts over long periods. Consider how far short-term observations can support claims about deep time. |
| B4.2 | How well do laboratory results apply to the natural world? | A flask is far simpler than an ecosystem. Consider what is gained and lost by simplifying a system to study it. |
Unit 7 Ecosystems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| B4.1 | Are categories discovered or invented? | Nature has no sharp borders between biomes. Consider whether our categories describe nature or simply help us to think about it. |
| C4.1 | Can an estimate count as knowledge? | A population estimate is never exact. Consider how stating uncertainty affects the strength of a claim. |
| C4.2 | Why does long-term data have special value? | Nobody could know in advance how much the record would matter. Consider how knowledge depends on funding work with no immediate payoff. |
| D4.2 | Is removing part of a system a fair way to learn about it? | Manipulating nature can reveal hidden links, but it also interferes. Consider when knowledge justifies that interference. |
| D4.3 | What role does consensus play in knowledge? | Consensus is not proof, yet it is meaningful. Consider how non-experts should decide whom to trust on complex issues. |
AHL path
Unit H1 Body Systems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| B3.3 | What does independent discovery tell us about knowledge? | Two teams reached the same idea at the same time. Consider what this suggests about how knowledge develops. |
| C2.1 | How do metaphors help and limit explanation? | We describe signalling using messengers and receptors. Consider what these human images add, and what they might hide. |
| B3.1 | How does naming shape what we remember? | Discoveries are often credited to one person. Consider how this affects our picture of how science works. |
| B3.2 | How do we learn to read data from an instrument? | An ECG trace is meaningless without training. Consider what makes expert interpretation reliable, and when experts might disagree. |
| C2.2 | What is the role of intuition in science? | The idea may have come from a dream, but the evidence came from an experiment. Consider how discovery and justification differ. |
| D3.3 | How should scarce medical resources be allocated? | Dialysis and transplants are not available to all who need them. Consider which kinds of knowledge should inform these decisions. |
| D3.1 | Why can correlation mislead us? | Women who chose HRT may have differed in other ways. Consider why the design of a study affects how far we can trust its conclusions. |
Unit H2 Plant Systems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| C3.1 | How does knowledge build across generations? | Each step depended on the one before. Consider how a question can stay productive for decades. |
| D2.3 | What does it mean to measure something abstract? | Water potential is a concept defined by a calculation. Consider whether it is a real property or a useful construct. |
Unit H3 Genetics
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| D2.2 | What can natural experiments tell us? | Researchers cannot ethically create a famine. Consider the strengths and limits of evidence from events that were never designed as experiments. |
| D1.1 | What is the role of puzzles in science? | A contradiction between models can lead to discovery. Consider why anomalies can be more useful than confirming results. |
| D1.2 | What happens when a simple rule meets its exceptions? | Consider when an exception should change a rule, and when it should only qualify it. |
| D1.3 | Who should decide how powerful knowledge is used? | Consider the roles of scientists, governments and the public in setting limits on technology. |
| D2.1 | Does the value of knowledge justify how it was obtained? | HeLa cells have brought huge benefits, but consent was never given. Consider who should benefit from research and who should decide. |
| D3.2 | Why is a significance level of 5% used? | The chi-squared cut-off is a convention. Consider how an agreed threshold shapes what counts as a real result. |
Unit H4 Biomolecules
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A1.1 | How do we reason from a small sample to a whole? | One comet cannot represent them all. Consider how much a single striking measurement should change our view. |
| A1.2 | Why is some evidence believed more readily than other evidence? | Many expected the genetic material to be protein. Consider how prior expectations affect the weight given to results. |
| B1.2 | Is predicting the same as understanding? | An AI system can predict a structure without giving a human explanation. Consider whether that counts as knowing why. |
| C1.1 | How do simplified mathematical models produce knowledge? | The model assumes conditions rarely found in cells. Consider how something known to be simplified can still be reliable. |
| C1.2 | How do paradigm shifts happen in science? | Researchers had been searching for a chemical intermediate. Consider how an expected answer can make a different one harder to accept. |
| C1.3 | How do new technologies create new knowledge? | Radioactive tracers made a hidden pathway visible. Consider how much scientific knowledge depends on the tools available. |
Unit H5 Cells
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A2.1 | How can we know about events that cannot be repeated? | No experiment can replay the origin of life. Consider the difference between showing something could happen and showing it did. |
| A2.3 | Is the boundary of life a discovery or a decision? | Whether viruses are alive depends on how we define life. Consider what kind of question this is. |
| A2.2 | What helps an unpopular idea to gain acceptance? | Consider the roles of new evidence, new methods and the persistence of individuals when knowledge changes. |
| B2.1 | Can one result settle a question? | A single clear experiment can be very persuasive. Consider what else would be needed before a scientific community accepts a claim. |
| B2.2 | How do we separate reality from artefact? | Consider what kinds of evidence persuade us that a structure is real, and not a product of the method used to see it. |
| B2.3 | Can observation be free from theory? | What we expect can influence what we see. Consider what safeguards help scientists to observe more objectively. |
Unit H6 Biodiversity
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| A3.2 | Do classifications describe nature or organize our thinking? | The tree of life changed when the data changed. Consider what this implies about taxonomy as knowledge. |
| A3.1 | Is a species a natural kind or a human label? | Different species concepts can give different answers. Consider what this means for the claim that a new species has been found. |
| A4.1 | How can historical sciences be tested? | Most speciation happened long before anyone could watch. Consider how evolutionary biology's methods compare with those of history. |
| D4.1 | How can a model known to be unrealistic be useful? | Its assumptions are almost never met in nature. Consider how departures from an ideal can themselves be informative. |
Unit H7 Ecosystems
| Subtopic | Question about knowledge | Where it connects |
|---|---|---|
| D4.2 | What happens when experts interpret the same evidence differently? | Both drew on real plant communities. Consider how scientists decide between competing interpretations. |
| D4.3 | How reliable are knowledge sources from outside science? | Old diaries were never meant to be scientific data. Consider how they can be checked before being used as evidence. |