bio p3

how to calculate the initial rate of reaction

• measure mass/volume qs thing broken down at intervals over time

why initial rates determined for comparison

• rate slows down as (q spesific substance) is used up

• so rates can not be compared

describe how to make dilution out of given values

description of method (1) • calculation of dilution factor / use of C1V1=C2V2 to calculate sucrose solution volume as 2 (cm3) (1) • stating the volume of sucrose solution and calcium ion solution to be used to make 10cm3 (1)

vitamin c concentration formula

mass of vitamin C to decolourise 1cm³ of DCPIP = 10 mg × volume of vitamin C used

concentration = mass/volume

how to meassure zone of inhibition

place dish on {gridded / graph} paper (1) • count squares (1)

biodiverity

the {number of different / variety of} species (of living organisms) in an area / stated area (1)

• the genetic differences within species of living organisms (1)

describe how to modify to allow sd to be obtained

experiment repeated (1)

under the same conditions / described (1)

why eg ph is kept the same

because it might affect {(pollen grain) germination / enzymes (involved in germination)} (1)

• it is (thought to be) the optimum for {(pollen grain) germination / enzymes (involved in pollen germination)} (1)

protein test

ddition of {biuret reagent / base and copper sulfate} (1)  purple colour (1)

why initial rate of reaction is better

{the rate of the reaction slows down / gelatine is used up (over time)} (1)

 so rates can be validly compared / compared only if they are all initial rates (1

how to calculare initioal rate of reaction 2021 oct

measure transparency of film over time (1)  plot transparency against time (1)  calculate (initial rate from) gradient of straight part o

bond between amino acids and how broken

peptide bonds broken by hydrolosis

vitamin c q

because (antioxidants / vitamin C) reduce (the quantity of) free radicals (1) • that cause damage to {cells / tissues / blood vessels / endothelium} (1) • reducing {plaque / atheroma} formation (1)

how to make a solution remoing phosphates from the given thhe given table 2

remove potassium hydrogen phosphate (1) - NOT PHOSPHATE IONS

• replace potassium removed / add extra of named salt to adjust balance (1)

because this is the highest (uptake) of all mineral ions • {below 6.5 / at 8.0-8.5} phosphate in short supply / {above 8.0 / below 5.5} nitrate in short supply (1) • needed for appropriate {substance /process} (1) • pH {above / below} this range will denature enzymes (1)

how to use pipete accuratly

take readings at the (bottom of the) meniscus (1) • hold the pipette at eye level when taking the readings

Explain two safety precautions that must be taken when preparing bacterial plates.

{aseptic technique / description of aseptic technique} to avoid contamination of {cultures with other bacteria / ourselves with bacteria (which could be pathogenic)} (1)

• {leave the lid loose / only partially seal lid} (of Petri dish onto base) so that {conditions are aerobic / anaerobic bacteria (which could be pathogenic) do not grow} (1)

• growing bacteria at temperatures {slightly below 37°C / no higher than 35°C / body temperature} to decrease growth of pathogenic bacteria