How Science Works

Question 1

🔴️Importance of a large number of results

Answer 1

• Anomalies can be identified
• Results are more reliable and representative
• Can use of statistical tests

Question 2

🔴️Why should a location be selected randomly

Answer 2

• Reduces bias
• Statistical tests can be carried
• More representative data as choice of (x) not influencing data

Question 3

🔴️Why is it important to check the repeatability of measurements?

Answer 3

• Increases the reliability of measurements
• Anomalies and personal error can be identified

Question 4

🔴️A scatter diagram can be used to check the repeatability of a test. How?

Answer 4

• Plot appropriate graph
• Points should lie close to the line of best fit

Question 5

🔴️Why is a statistical test needed?

Answer 5

• The statistical test determines the probability that the results are due to chance
• It allows the null hypothesis to be accepted/rejected
• It determined whether the results are significant

Question 6

🔴️A statistical test showed that the difference between 2 frequencies of the t allele was significant at the P=0.05 level. Explain

Answer 6

• There’s a 5% probability that the difference in results are due to chance

Question 7

Explain the advantage of presenting the results as a ratio or ‘Per unit’

Answer 7

• Easier to have a valid comparison
• the sample size may vary

Question 8

Explain why it was important to grow the ‘plants’ under the same conditions up to ten days before the experiment.

Answer 8

So any difference is due to XYZ

Question 9

2 advantages of measuring the conc needed to kill 50% of the population in order to determine the effect of a pesticide.

Answer 9

• Provides a standard for comparison of the efficacy of different pesticides
• Does not kill all the tadpoles

Question 10

Suggest two advantages of carrying out investigations in natural habitats

Answer 10

• Can see effect of other biotic factors e.g predators
• Can see effect of abiotic factors e.g temperature

Question 11

Advantage of research being conducted by the government’s scientists.

Answer 11

• No bias so it’s trustworthy;
• Non-profit making;
• Focused on advancing environment

Question 12

How do we treat control groups?

Answer 12

• treat exactly the same but do not give the drug
• give a placebo
• this is done to compare the effect of treatment
• makes sure change in dependent variable is only due to independent variable

Question 13

What is null hypothesis?

Answer 13

• There is no difference between x and y
• Any difference is due to chance

Question 14

Reasons why the results of a study may be flawed?

Answer 14

• Small sample size
• Not sure of long-term ramifications
• No repeats
• Bias, not representative
• Not quantifiable results e.g ‘improvement’

Question 15

Why should the species of animals be kept the same in an experiment

Answer 15

• Similar alleles;
• Controls so genes not a factor
• Only indepents variable affects results

Question 16

other than cost which factors should be considered when selecting an antibiotic to treat a bacterial disease.

Answer 16

• side effects e.g allergic reactions
• interaction with other drugs
• should only act on the problem bacteria
• how much resistance the bacteria have built up;

Question 18

Why is measuring rectal temp better than measuring skin temp to find core temp?

Answer 18

• Skin temperature fluctuates more
• As more affected by environment

Question 19

Why do women outlive men?

Answer 19

• male risk of CVD
• more males smoke and drink to excess
• males involved in war;

Question 20

why may specific populationsshow very low levels of genetic diversity.

Answer 20

• Population might have been very small (genetic bottleneck)
• Population might have started with small number of individuals (founder effect)
• Inbreeding;

Question 22

Why is a statistical test important in analysing results

Answer 22

• Statistical test determines the probability of results being due to chance;
• Enables null hypothesis accepted/rejected;
• Determines whether correlation in result is significant;

Question 23

Explain what accurate and reliable mean

Answer 23

• Accurate means close to the true value
• Reliable means that measurements can be reproduced when repeated to give similar readings