Unit 1 pracs

Question 1

Caffeine on Daphnia

Answer 1

Effect of caffeine of the heart rate of Daphnia

Question 2

Caffeine on Daphnia: IV + DV

Answer 2

IV: caffeine concentration
DV: heart rate of Daphnia

Question 3

Caffeine on Daphnia: controls - V + how

Answer 3

CV: temperature - temp controlled room + beaker in ice / volume of solution (pond water, caffeine) - measuring beaker + pipette / sample of Daphnia - same - collect from same batch (age/size) / time - stop watch

Question 4

Caffeine on Daphnia: Control group

Answer 4

CG: Daphnia exposed to no caffeine - heart rate recorded / data can be compared to experimental group

Question 5

Caffeine on Daphnia: procedure

Answer 5

beaker (Daphnia in pond water) into ice - 30 mins / collect Daphnia from beaker - kept at a constant 25 degrees / using pipette put Daphnia on cotton wool on slide / add two drops of pond water / add volume+concentration of caffeine to the slide / use dissecting microscope observe + record results per minute / repeat experiment

Question 6

Caffeine on Daphnia: evaluation

Answer 6

Daphnia were same - validity / heat from microscope lamp - increase heart rate / enough data collected / high concentration = dead Daphnia /counting heart beats - stroboscope / reliability

Question 7

Vitamin C

Answer 7

The Vitamin C content of fruit juice

Question 8

Vitamin C: IV + DV

Answer 8

IV: type of fruit
DV: amount of vit C

Question 9

Vitamin C: IV + DV

Answer 9

IV: type of fruit
DV: amount of vit C in juice

Question 10

Vitamin C: CV + how

Answer 10

CV: temperature - controlled room - water bath / volume (1cm3) of DCPIP - pipette / sample of vit c - same source / shaking tubes - count / end result - blue to clear colouring

Question 11

Vitamin C: control group

Answer 11

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Question 12

Vitamin C: procedure

Answer 12

1cm3 DCPIP in test tube / using burette add 1% vit c soln drop by drop / shake tube / keep adding until blue turns clear / record volume of solution needed to decolourise / repeat - calculate mean - on other fruit

Question 13

Vitamin C: evaluation

Answer 13

difficult controlling temp / amount of shaking - adds oxygen = restores DCPIP / end point - hard to judge / loss of solution when transferring

Question 14

Temp on membranes

Answer 14

The effect of temperature of cell membranes

Question 15

Temp on membranes: IV+DV

Answer 15

IV: temperature of water
DV: % transmission of light through resulting solution

Question 16

Temp on membranes: CV + how

Answer 16

CV: volume distilled water - measuring beaker+pipette / time - stop watch / size of beetroot piece - measured then cut / same sample - same beetroot - batch

Question 17

Temp on membranes: procedure

Answer 17

using cork borer + knife cut beetroot 1cm / place in distilled water overnight /

Question 18

Temp on membranes: procedure

Answer 18

using cork borer + knife cut beetroot 1cm / place in distilled water overnight / wash + blot dry / place boiling tubes with distilled water in water baths / when at temp add beetroot pieces- 30 mins / remove beetroot - shake tube / set colorimeter 100% absorbance - blue+green filter / calibrate using cuvette

Question 19

Temp on membranes: procedure

Answer 19

using cork borer + knife cut beetroot 1cm / place in distilled water overnight / wash + blot dry / place boiling tubes with distilled water in water baths / when at temp add beetroot pieces- 30 mins / remove beetroot - shake tube / set colorimeter % absorbance - blue+green filter-cuvette+ distilled water - reads 0 absorbance / 2cm3 of beetroot soln into cuvette - colorimeter / record results / repeat for other pieces

Question 20

Temp on membranes: evaluation

Answer 20

beetroot has skin - affecting S.A. / maintaining temp / accurate reading on colorimeter / accurate size of beetroot / different parts of roots / same time at all temps

Question 21

Enzyme effect

Answer 21

Effect of changing the enzyme concentration on the rate of reaction

Question 22

Enzyme effect IV+DV

Answer 22

IV: concentration of enzyme
DV: time taken for enzyme to break down a substrate

Question 23

Enzyme effect CV + how

Answer 23

CV: temperature / volume of enzyme / volume of substrate / concentration of substrate / pH

Question 24

Enzyme effect procedures

Answer 24

5cm3 of protein suspension (