PAG's Flashcards
effect of exercise(or other effects too) on heart rate
1) measure + record resting pulse (15s x 4), use of electrical heart rate monitor is valid
2) gentle exercise for 5mins + immediate measuring of heart rate
3) resume to resting position and record how long it takes to return to normal
4) use of student’s t-test to analyse results between 2 sets of data
investigating muscle contraction via electromyography
1) attach 2 electrodes to places on the muscle to record from(use of inactive bony wrist area as a control)
2) switch off any electrical equipment which may interfere with the eletrical signal from the muscle
3) connect electrodes to an amplifier(increases strength of electrical signals) and computer
4) relax then contract muscle (amplitude varies depending on contraction intensity)
5) more aplicatude = more fatigue as electromygram records more activated motor units to generate the force required to hold the weight up
Phototropism
1) 9 wheat shoots cut roughly equal in height planted in individual pots of same soil
2) tips of 3 shoots covered with foil cap / 3 without / 3 at base coverage
3) set up shoots in front of light source and leave them for 2 days (same distance + intensity of light + alongside other controlled variables such as temp exposure to moisture)
4) the results show reflect the effect of covering with tin (norm - bend - slight shoot bend)
5) record growth (mm) as well as direction of growth to acquire quantitative results
geotropism
1) line 3 petri dishes with moist(no soaking wet) cotton wool(same volume of water/amount of cotton wool in each dish)
2) space + push 10 cress seeds into cotton wool on each dish
3) tape a lid onto each dish and wrap each one in foil(this prevents any light reaching the seeds and affecting results) and place into contant environment
4) flat 45’ 90’ angled dishes labelled
5) leave seeds for 4 days then observe shoot/root growth - shoot = neg phototropism root = pos phototropism
6) record growth(mm) of roots/shoots as well as angle of growth to acquire quantitative results
apical dominance
1) plant 30 plants(similar age,height and weight)
2) count/record number of side shoots growing from main stem of each plant
3) 10 plants = removed tip of shoot and paste containing auxins applied to top of stem
10 plants = removed with no paste applied
10 plants = untreated/affected as these are controls
4)each group is grown for 6 days each under the same conditions so that results are valid
5) after 6 days count the number of side shoots growing from main stem of each plant
the results should show that auxins inhibit the growth of side shoots and promote apical dominance
TLC can separate photosynthetic pigments
1) grind up several leaves with anhydrous sodium sulfate and propanone
2) transfer to liquid to a test tube, addd petroleum ether and gently shake the tube. 2 layers form, the top layer os the pigments mixed with petroleum ether
3) transfer the top layer into second test tube with some anhydrous sodium sulfate
4) horizontal pencil line + concentrated spot of the liquid from step 3 = point of origin
5) once point of origin is completely dry place into glass beaker wiht prepared solvent(mixture of propanone/cyclohexane/petroleum ether) - fill to point of origin above solvent,put lid and leave plate to develop - as solvent moves up the plate, different pigments move too, but at different rates, so they separate
6) when solvent nearly reaches top, remove plate and mark solvent front with pencil and leave to dry in fume cupboard/ventilated space
7) calculate rF values and compare to database
photosynthesis limiting factors investigation
1) test tube containing pondweed and water is connected to a capillary tube fullof water
2) tube of water is connected to a syringe
3) source of white light placed at a specific distance from the pondweed
4) pondweed left to photosynthesise for set amount of time -oxygen released is collected in capillary tube
5) at the end, the syringe is used to draw the gas bubble along the test tube whilst using ruler to measue the gas bubble + radius of capillary tube to calc volume of O2(this value is proportional to the volume of O2 released)
6) repeat to achieve average length of gas bubble - different distanes of light source
controls - temp duration
aerobic respiration rates of yeast
) put known volume/conc of substrate solution(glucose) in a test tube (conical flask traps more oxygen)
2) add known volume of buffer solution to maintain pH constant(opt for yeast is 4-6)
3) place test tube in water bath set at 25’ for 10min to allow temp and substrate to stabilise, this ensure constant temp throughout experiment
4) add known mass of dried yeast(Saccharomyces cerevisiae) to test tube and stir for 2 mins
5) once yeast has dissolved in solution, place bung set at 0 with tube attached to a gas syringe in top of the test tube
6) stopwatch ASA bung attached
7) gas syringe measures volume of CO2 released
8) regular time intervals record volume of CO2 present in gas syringe(every 10 min)
9) repeat 3 times using data to calc mean rate of CO2 production
control - no yeast with 0 CO2 production
anaerobic respiration
1) same setup as aerobic respiration
2) after yeast dissolves in substrate solution, trickle liquid paraffin down inside of test tube so it settles on and completely covers the surface of the solution(stops oxygen)
3) place bung with gas syringe set at zero
4) same performance as aerobic respiration of yeast
the rate of respiration using respirometer
1) respirometer set up
2) each tube contains potassium hydroxide solution(or soda lime) which absorbs carbon dioxide
3) control tube is identical but without woodlice
4) coloured fluid added to manometer by dipping end of capillary tube into beaker of fluid (capillary action)
5) appartus left for set time(20 minutes)
6) due to oxygen consumption by woodlice, volume of air decreases(Co2 absorbed by potassium hydroxide/soda lime)
7) decrease in volume reduces pressure and coloured liquid moves towards test tube in manometer
8) distance moved is measured then used to calculate volume of oxygen consumption per min + diameter of capillary tube
9) repeated to get more precise results and mean volume of O2 is calculated
controls - temp vol of KOH
electrnic oxygen sensors are used to measure oxygen concentration inside respirometer chamber and data loggers which reduces human error and data collected can be input into data analysis software in order to aid drawn conclusion
