Free HSC Year 11 Investigating Science Flashcard Review
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What is the difference between an observation and an inference?
An observation is what is directly detected by senses or instruments; an inference is an interpretation of what the observation means or what caused it.
Give one advantage and one drawback of qualitative data.
Advantage: quickly captures features that are hard to measure. Drawback: depends on the observer and is hard to compare or process mathematically.
Give one advantage and one drawback of quantitative data.
Advantage: allows calculation, graphing and objective comparison. Drawback: records only the variables chosen and may miss unexpected features.
What did Fleming observe, and what did he infer?
Bacteria failed to grow in a zone around a contaminating mould; he inferred the mould released a substance that inhibited bacteria, later identified as penicillin.
How did Galileo's observation of Jupiter challenge an existing idea?
Points of light that moved around Jupiter night to night were inferred to be orbiting moons, showing that not every body orbits Earth.
What observations guide cultural burning (firestick farming)?
The condition of Country is read, such as how far the land has dried out, how cured the grass is and the weather, to time small, cool, patchy fires that reduce fuel and renew habitat.
Define independent, dependent and controlled variables.
Independent: deliberately changed. Dependent: measured in response. Controlled: kept the same so the test is valid.
What five things should a primary-data method describe?
How the independent variable changes, what is measured, how data is collected, how controls are kept constant and how risks are minimised.
How do you calculate actual size from a micrograph or drawing?
Actual size = image size ÷ magnification, with both lengths in the same unit.
How much more acidic is a pH 2 solution than a pH 4 solution?
100 times, because each pH unit is a tenfold change in hydrogen-ion concentration.
How can you estimate the uncertainty of repeated readings?
Take half the range of the readings as the absolute uncertainty, then divide by the mean and multiply by 100 for percentage uncertainty.
Name two limits of an analogue liquid-in-glass thermometer compared with a digital probe.
It must be read by eye (parallax and reading error) and cannot log readings automatically or continuously.
How does leaching toxins from bush foods show observation and inference?
Observing that raw seeds cause illness led to inferring a harmful substance that could be washed out; washing in running water was tested and refined over generations.
Why can fresh water be found beneath sand near the sea?
Fresh water is less dense than salt water, so it can sit as a lens above seawater; long-term observation of where fresh water seeps and flows tells knowledge holders where to find it.
Name two biases that affected settlers' view of Aboriginal land management.
Ethnocentric bias (judging by European farming models) and confirmation bias (ignoring evidence of fire management, aquaculture and harvesting).
How can secondary data validate a primary-data inference?
It shows whether the same pattern holds over a wider range, with better equipment, larger samples or longer time spans.
Give three reasons to do secondary research before collecting primary data.
To form hypotheses, choose a sensible range and method, identify hazards, and avoid repeating work whose answer is already known.
What is the difference between a regular and an irregular pattern?
A regular pattern repeats predictably (e.g. Halley's Comet on average about every 76 years); an irregular pattern varies in timing or form (e.g. aurora displays).
What is pareidolia, and why does it matter for data?
Seeing meaningful shapes in random stimuli; the same tendency can make investigators see trends that are not real.
How should an outlier be handled?
Check records, repeat if possible, exclude from calculations only with a stated reason, and always report it.