CAEC Science Preparation Course: Inquiry: error, reliability and conclusions

1. Pytanie 1 z 16

   In science, what does it mean if results are reliable?

   • AThe results were shared online and many people liked them
   • BThe results match what the scientist hoped to find
   • CRepeated tests give similar results
   • DThe test was done only once, but very slowly and carefully
   Pokaż odpowiedź

   Odpowiedź: C. Repeated tests give similar results

   Reliability is about consistency: repeating the test should give similar results.

2. Pytanie 2 z 16

   What does it mean if an investigation is valid?

   • AIt was carried out by a famous scientist at a large university
   • BIts results were surprising and made the news headlines
   • CIt used the newest and most expensive equipment available
   • DIt really measures what it claims to
   Pokaż odpowiedź

   Odpowiedź: D. It really measures what it claims to

   A valid test measures the right thing in a fair way, with other variables controlled.

3. Pytanie 3 z 16

   Which trial is most likely an error and should be checked?

   Trial	1	2	3	4
   Reaction time (s)	0.31	0.29	0.30	0.52

   • ATrial 2
   • BTrial 3
   • CTrial 4
   • DTrial 1
   Pokaż odpowiedź

   Odpowiedź: C. Trial 4

   Trials 1–3 are all close to 0.30 s. Trial 4 (0.52 s) is far from the others, so it is an outlier, perhaps caused by a distraction.

4. Pytanie 4 z 16

   A kitchen scale shows 2 g even when nothing is on it. Every mass measured on it will be 2 g too high. What kind of error is this?

   • ARandom error
   • BSystematic error
   • CSelective reporting
   • DA controlled variable
   Pokaż odpowiedź

   Odpowiedź: B. Systematic error

   A systematic error pushes every measurement the same way by the same amount. Zeroing (taring) the scale fixes it.

5. Pytanie 5 z 16

   Different students start and stop a stopwatch slightly early or late each time. What is the best way to reduce this kind of error?

   • AStop recording times and estimate them instead
   • BKeep only the fastest time and ignore the rest
   • CUse a bigger stopwatch with a larger screen
   • DRepeat the timing and use the average
   Pokaż odpowiedź

   Odpowiedź: D. Repeat the timing and use the average

   Human reaction time causes random error. Repeating trials and averaging reduces its effect.

6. Pytanie 6 z 16

   Which conclusion is supported by the data?

   Each jar started with 300 mL of water at 80 °C. All jars were the same size and sat on the same table for 30 minutes.

   Wrap around jar	Water temperature after 30 min (°C)
   No wrap	52
   Aluminum foil	58
   Newspaper	61
   Wool sock	67

   • AAluminum foil is the best insulator for every possible use
   • BThe newspaper wrap added heat to the water in its jar
   • CAll four wraps kept the water warm equally well
   • DIn this test, the wool sock kept the water warmest
   Pokaż odpowiedź

   Odpowiedź: D. In this test, the wool sock kept the water warmest

   The wool-wrapped jar stayed warmest (67 °C). The data is about this test only, so broad claims like "every use" go too far.

7. Pytanie 7 z 16

   How many degrees did the water with no wrap cool down in 30 minutes?

   Each jar started with 300 mL of water at 80 °C. All jars were the same size and sat on the same table for 30 minutes.

   Wrap around jar	Water temperature after 30 min (°C)
   No wrap	52
   Aluminum foil	58
   Newspaper	61
   Wool sock	67

   • A52 °C
   • B22 °C
   • C13 °C
   • D28 °C
   Pokaż odpowiedź

   Odpowiedź: D. 28 °C

   It started at 80 °C and ended at 52 °C: 80 − 52 = 28 °C.

8. Pytanie 8 z 16

   You want to keep soup hot in a jar for a field trip. How can you best apply the results of this investigation?

   Each jar started with 300 mL of water at 80 °C. All jars were the same size and sat on the same table for 30 minutes.

   Wrap around jar	Water temperature after 30 min (°C)
   No wrap	52
   Aluminum foil	58
   Newspaper	61
   Wool sock	67

   • APut the jar in a newspaper bag and leave the lid off
   • BWrap the jar in a wool sock
   • CWrap the jar in foil because it is shiny
   • DLeave the jar unwrapped
   Pokaż odpowiedź

   Odpowiedź: B. Wrap the jar in a wool sock

   The investigation showed wool kept water hottest, so it is the best choice from the materials tested.

9. Pytanie 9 z 16

   Which study's results are more reliable and credible, and why?

   Study	People tested	How people were chosen	Published
   A	18	Volunteers who answered an online ad	Company website
   B	1,200	Chosen at random from several cities	Peer-reviewed journal

   • AStudy A, because it was posted online faster than Study B
   • BStudy B: large random sample, peer-reviewed
   • CBoth are equal, because both studies tested real people
   • DStudy A, because volunteers who answer ads are more honest
   Pokaż odpowiedź

   Odpowiedź: B. Study B: large random sample, peer-reviewed

   Study B used many people chosen at random and passed peer review. Study A had few self-selected volunteers and no independent check.

10. Pytanie 10 z 16

    A study found that towns with more ice cream sales also have more drownings. What is the best explanation?

    • AHot weather raises both; one need not cause the other
    • BEating ice cream causes people to drown while swimming
    • CDrowning accidents make people go out and buy ice cream
    • DThe data must have been made up, so ignore the study
    Pokaż odpowiedź

    Odpowiedź: A. Hot weather raises both; one need not cause the other

    Two things that change together are correlated, but that does not prove one causes the other. A third factor, hot weather, can explain both.

11. Pytanie 11 z 16

    A new hand cream helped the skin of 10 mice in one lab. The company says it "works for everyone." What is wrong with this claim?

    • AMice can never be used in any kind of science research
    • BHand creams are cosmetics, so they cannot be tested at all
    • CIt overgeneralizes from a small test on animals
    • DTen mice is far too many animals for a skin cream test
    Pokaż odpowiedź

    Odpowiedź: C. It overgeneralizes from a small test on animals

    A small test on mice does not show what will happen in all people. More testing in people is needed.

12. Pytanie 12 z 16

    A friend says, "My cousin drank celery juice and her cold went away, so celery juice cures colds." Why is this weak evidence?

    • ACelery juice was not measured in litres or millilitres
    • BColds are caused by viruses, which cannot be studied
    • CIt is one story with no comparison group
    • DYour friend is not a trained scientist with a degree
    Pokaż odpowiedź

    Odpowiedź: C. It is one story with no comparison group

    One personal story (an anecdote) has no control group. The cold might have ended without the juice.

13. Pytanie 13 z 16

    In an experiment on how temperature affects how fast sugar dissolves, a student stirred some cups but not others. How does this affect the results?

    • ALess valid: stirring was not controlled
    • BMore reliable, because stirring always helps sugar mix
    • CNo effect, because stirring is not related to temperature
    • DIt proves that stirring was the independent variable
    Pokaż odpowiedź

    Odpowiedź: A. Less valid: stirring was not controlled

    Stirring also speeds up dissolving. Because it was not kept the same, you cannot tell whether temperature or stirring caused the differences.

14. Pytanie 14 z 16

    A student found that seeds sprouted fastest at 25 °C out of the temperatures 5, 15 and 25 °C. What is a sensible next investigation?

    • AStop, because 25 °C must be the best temperature there is
    • BRepeat only the 5 °C test several more times
    • CTest temperatures above 25 °C
    • DChange the seed type and the temperature at the same time
    Pokaż odpowiedź

    Odpowiedź: C. Test temperatures above 25 °C

    The best temperature might be higher than 25 °C. Testing beyond the range, while changing one variable at a time, extends the conclusion.

15. Pytanie 15 z 16

    Which source is usually the most credible for a claim about a new medicine?

    • AAn advertisement from the company that sells the medicine
    • BA comment on a forum from an anonymous user who tried it
    • CA social media post that has thousands of likes and shares
    • DA peer-reviewed study by independent researchers
    Pokaż odpowiedź

    Odpowiedź: D. A peer-reviewed study by independent researchers

    Peer-reviewed research by independent scientists is checked by experts and less likely to be biased.

16. Pytanie 16 z 16

    A student measured the temperature of a cup of water once, with the bulb of the thermometer not fully in the water. What is the best way to improve the investigation?

    • AUse the same method but write the answer more neatly
    • BGuess the temperature by touching the water with a finger
    • CPut the bulb fully in the water and take several readings
    • DRound the reading to the nearest 10 °C to hide small errors
    Pokaż odpowiedź

    Odpowiedź: C. Put the bulb fully in the water and take several readings

    Using the tool correctly fixes a source of error, and repeated readings make the result more reliable.

Klawiatura: 1–4, aby odpowiedzieć, Enter – następne pytanie.

Prawdziwy egzamin: 55% on each CAEC test