Biology

Question 1

Why do you have controls in an experiment

Answer 1

to compare the results from an experiment to something else

to determine that any change in the DV is caused by changes to the IV.

Question 2

how are the groups controlled

Answer 2

treated the same
drug administered the same
but given a dummy/fake drug/saline

Question 3

what must you do to the variables

Answer 3

keep all the same to ensure an accurate result

Question 4

whats the independent variable

Answer 4

thing you change x axis

Question 5

whats the dependent variable

Answer 5

the thing you measure

y axis

Question 6

whats a control variable

Answer 6

something you keep the same e.g sex age temperature

Question 7

whats the use of percentages ratios rates

Answer 7

allows a comparison between two things that have different starting points e.g populations, starting masses, birth rates etc.

Question 8

what is the link between correlation and causation on a graph

Answer 8

say if graph shows a positive or negative correlation
it may show a correlation doesn’t mean causation
could be due to another factor (give example)
state the points that don’t fit the pattern

Question 9

what is bias

Answer 9

important to avoid so that everything is random
no professional or personal investment in the conclusion
random choice of sample/people so it is more representative

Question 10

what do you do when it says evaluate

Answer 10

positives and negatives
say what data supports the conclusion
say what doesn’t support the conclusion
quote data

Question 11

what do you do when it says describe

Answer 11

say what you see

quote figures

Question 12

what do you do when it says explain

Answer 12

say why something has happened in detail with key terms and phrases

Question 13

what do you do when it says suggest

Answer 13

give a sensible answer based on the info provided. no definitive answer
not been taught it specifically
use info to give sensible reason why

Question 14

what is the use of a mean

Answer 14

allow comparison with different sample sizes

Question 15

how do you find unknowns

Answer 15

say what variables you would plot
draw a line of best fit
state where you would extrapolate the answer on the graph

Question 16

what is standard deviation

Answer 16

spread of data around the mean
check if they overlap
if they do no real difference between the results
if they don’t STILL MENTION

Question 17

what to say about probability and chance

Answer 17

tells if theres a real or significant difference
there is a less than 5% probability the results are down to chance or there is a 95% prob the results aren’t down to chance
p means probability use a 0.05 or 0.01 most likely 0.05

Question 18

what is uncertainty

Answer 18

every measurement has some kind of uncertainty

no smaller than plus or minus half of the smallest division

Question 19

what to do with anomalous results

Answer 19

ignore them if they are one set of a repeated results

otherwise include to reduce the possibility that a key point is being overlooked

Question 20

what is precision

Answer 20

little spread about the mean value
depends only on the extent of random errors
it gives no indication of how close results are to the true value

Question 21

what does it mean for results to be repeatable

Answer 21

original experimenter repeats the investigation using the same method and equipment and gets the same results

Question 22

what does it mean for results to be reproducible

Answer 22

if the investigation is repeated by another person or by using different equipment or techniques and the same result is achieved

Question 23

how do you work out % change

Answer 23

change/original

x 100

Question 24

how to calculate rate from a graph

Answer 24

draw a tangent to the curve or if its a straight line use that
pick two points on the line to give coordinates
y2-y1 divided by x2-x1 = rate

Question 25

when are logarithmic scales used

Answer 25

can be used to deal with really big scales/ranges

that would be hard to plot on a graph

Question 26

what are the stats test for biology

Answer 26

t test
spearmans rank correlation
chi squared

Question 27

what does t test do

Answer 27

looking for difference between two means
difference is significant
the probability is less than 0.05 that the results are due to chance

Question 28

what do spearmans rank correlation do

Answer 28

looking for correlation between two sets of continuous data
1= perfect correlation
0= no correlation
+ shows a positive correlation
- shows a negative correlation
correlation will be significant or not significant

Question 29

what is chi squared used for

Answer 29

used when looking at frequencies e.g number
categoric data same dependent variable
expected and observed compared
difference will be significant or not

Question 30

what do you do when drawing graphs

Answer 30

join the points instead of line of best fit

as we don’t know the intermediate values

Question 31

what is accuracy

Answer 31

if something is accurate its close to the true value

Question 32

how to increase accuracy

Answer 32

carry out more tests around the estimated value to make the interval smaller
repetitions of each

Question 33

when evaluating a conclusion from a table what must you do

Answer 33

say why it does support say why it doesn’t

Question 34

why wouldn’t the results from a study support the results

Answer 34

small sample size
may be other variable causing results
no stats test may not be significant