Paper 5

Question 1

what does standard deviation do

Answer 1

evaluates reliability of the data by showing spread of data around the mean
the smaller the value of s the more reliable the data as they are more closely related to the mean

Question 2

what does standard error show

Answer 2

shows reliability of mean

the smaller the value of Sm the more reliable the mean is

Question 3

how is 95% confidence limit calculated and what are they used for

Answer 3

plus and minus 2sm
or plus and minus tsm
they are used to plot error bars to show if difference between 2 means is significant or not
if they overlap then diff is of no significance

Question 4

what is t test used for

Answer 4

to show if difference between 2 means is significant or due to chance

Question 5

how do u calculate degree of freedom for t test

Answer 5

n1+n2-2

Question 6

how is t test used

Answer 6

probability table at 0.05 at row of calculated degree of freedom to determine critical value t
if calculated t value is greater than critical value then there is significant difference

Question 7

what is the critical value

Answer 7

value under probability 0.05

sometimes known as 95% confidence level

Question 8

what is chi squared test used for

Answer 8

tests for differences between obtained observed and expected frequencies of nominal data in genetics and ecology

Question 9

what is hardy weinberg used for

Answer 9

estimates allele frequencies in a population and chances of passing on a particular genotype

Question 10

pearson’s linear correlation

Answer 10

tests for correlation between 2 sets of normally distributed data

Question 11

spearman’s rank correlation

Answer 11

tests for correlation between 2 sets of normally distributed data
the closer the value to 1 the stronger the correlation

Question 12

peterson or lincoln index

Answer 12

measures species richness and evenness from number of diff species in habitat

Question 13

how are immobilized enzymes made

Answer 13

add sodium alginate using dropper in calcium chloride solution and mix

Question 14

why is chi squared used

Answer 14

data is categoric

Question 15

variables and how they are controlled

Answer 15

humidity:by humidifier
temp:temp controlled room or thermostatically controlled WB
PH:using buffer solution
CO2:soda lime to absorb/CO2 meter/sodium hydrogen carbonate as source
light intensity:by fixing bulb at distances

Question 16

how is a haemocytometer used

Answer 16

calculate vol of smaple
(lengthxwidthxheight)
divide number of(object/sample ex sperm)by volume
+method of converting to cm
count number of object(sperm)filly inside square
include those touching the line
dilution of sample
repeat in diff fields of vision to calculate a mean

Question 17

explain how light microscope is used to calculate actual diameter of object

Answer 17

using an eye piece graticule
calibrate using stage micrometer
use formula: number of stage micrometer divisions x value of one micrometer division ➗ number of eye piece units

Question 18

describe how student could dilute 250mmoldm3 sol to make 100cm3 by reducing conc by 50mmol each time

Answer 18

simple dilution
c1v1=c2v2
200=20cm3 from water and 80cm3 stock
150=40cm3 water and 60cm3 stock
100=60cm3 water and 40cm3 stock
50=80cm3 water and 20cm3 stock
measure vol using measuring cylinder and stir

Question 19

systemic sampling investigation

Answer 19

transect lines with starting point at beginning of(area)
use measuring tape to measure 10m away from area
get quadrats of known size and dimensions
place quadrats 2m apart
identify each species in quadrats using pictures
calculate species frequency
calculate% coverage
replicate transect lines at diff edges from area parallel
to each other
risk of getting injured so wear thick gloves and boots
risk of getting lost so stay with group

Question 20

mark release recapture

Answer 20

catch as many individuals as possible
each is marked in a way that wont affect its survival
marked are counted and returned back to their habitat to mix
after a large time another sample is collected
no of marked and unmarked are counted
estimate no of population:
no of caught in first sample x number caught in 2nd sample/no marked in second sample

Question 21

when is random sampling used

Answer 21

when area looks uniform and there is no clear pattern to the way species are distributed

Question 22

state what is needed to calculate simpons index of diveristy

Answer 22

count number of all species