NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Biology
Skills of Scientific
Experimentation, Investigation
and Enquiry
[HIGHER]
The Scottish Qualifications Authority regularly
reviews the arrangements for National
Qualifications. Users of all NQ support materials,
whether published by Learning and Teaching
Scotland or others, are reminded that it is their
responsibility to check that the support materials
correspond to the requirements of the current
arrangements.
Acknowledgement
Learning and Teaching Scotland gratefully acknowledges this contribution to the
National Qualifications support programme for Biology.
© Learning and Teaching Scotland 2011
This resource may be reproduced in whole or in part for educational purposes by
educational establishments in Scotland provided that no profit accrues at any stage.
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
Contents
Introduction
4
Teacher’s guide
Planning, designing and carrying out
Evaluating
Drawing conclusions
Making predictions and generalisations
6
7
8
8
Student’s guide
Planning, designing and carrying out
Evaluating
Drawing conclusions
Making predictions and generalisations
Experimental procedure for investigating respiration rate in
germinating peas
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
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INTRODUCTION
Introduction
This resource is intended to develop the skills of scientific experimentation,
investigation and enquiry. It is based around a simple experimental procedure
(measuring the respiration rate of peas) as this illustrates the principles and
ideas that can be applied to all scientific investigations or procedures.
There are three parts to this resource:
1.
2.
3.
4
Teacher’s guide to using this resource.
Student’s guide to the skills of scientific experimentation , investigation
and enquiry.
Experimental procedure for investigating respiration rate in germinating
peas.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
TEACHER’S GUIDE
Teacher’s guide
Please refer to the SQA document Guidance on learning and teaching
approaches for this course (Biology.)
The example of cell respiration was chosen for two reasons:
1.
2.
A high-tech approach places an established experiment in a more
modern setting, yet it still allows for the possibility of reverting to
simpler technology.
A sample set of data has been provided for centres that do not have time
to carry out the experimental work but wish to use this as a paper
exercise to develop the follow-up skills.
Cell respiration provides the framework for students to explore skills of
scientific experimentation, investigation and enquiry.
Students are most likely to be familiar with the conventional layout of an
experiment and this is an opportunity to develop these skills. Following on
from Standard Grade investigations, it is likely that small groups will work
together to generate aims and hypotheses.
Students should be made aware of the basic protocol and use of the carbon
dioxide (CO 2 ) probe, if it is going to be used. If probes are not available then
a simple respirometer could be used instead.
The main object is for students to generate an aim and a hypothesis, and then
evaluate their results, draw conclusions, and make predictions and
generalisations. For this it is probably best to use one of the suggested
extension experiments, which will be at a level more closely related to their
current studies.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
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TEACHER’S GUIDE
Planning, designing and carrying out
Suggested experiments
The basic protocol described on page 14 of this document could be extended
to:
1.
2.
3.
4.
5.
compare the rate of respiration of various types of germinating seeds
compare the rate of germination of seeds at different temperatures
compare the rate of respiration of yeast suspensions with different
sugars
compare the rate of respiration of yeast suspensions at different
temperatures
compare the rate of respiration of various organisms such as plants,
bacteria or invertebrates.
Some points to consider
 The original aim related to non-germinating and germinating peas serves
as an introduction to the experimental protocol, but is too simplistic for
work at this level; the experiment should be extended to reflect one of the
above aims.
 The rate of gas production and thus the rate of respiration vary with mass
of peas rather than the number of peas. Use of equal numbers of peas leads
to a variation in the mass of peas used in each experiment and thus
invalidates the procedure.
 Does every centre have a CO 2 gas sensor?
 How many gas sensors would be required for a class of 20 students?
 In the case of a shortage, this experiment could be included within a
‘stations’ set-up.
 Alternative methods are much more low tech.
(One example is from Higher Biology 2002, winter diet using a simple
respirometer.)
 Students may need to be reminded of the different variables, such as mass
of peas, temperature, oxygen availability etc.
 Students may need reminding of the need to write in the past imperfect
tense and passive voice.
 While students may plan and work in groups their report writing should be
as an individual.
Note
 Students could work in small groups to plan and carry out the experiment .
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
TEACHER’S GUIDE
 Any CO 2 probe could be used although the procedure described here u ses a
Vernier probe. (A class set of these can be borrowed from SSERC in
Dunfermline (http://www.sserc.org.uk).)
 Vernier sells either a specific booklet for each experiment or a complete
advanced biology laboratory manual.
Purchase at http://www.vernier.com/cmat/bioa.html.
Evaluating
A possible way to display data and calculate the average rate of respiration
(ppm/min) is as follows.
Change in CO 2 concentration (ppm)
over 5 minutes
Nongerminating
peas
Germinating
peas
Average
change
over 5
minutes
Average
rate of
respiration
(ppm/min)
Run 1
Run 2
Run 3
Run 4
5
–4
52
34
21.8
4.4
3662
4389
2811
2713
3393.8
678.8
Students should consider:
 the effect of variables that are not controlled in t he experiment
 sources of error
 how reliable the results are (ie how much variation/deviation from the
calculated average is there).
It could also be suggested that due to inbuilt flaws/errors within the gas
sensor:
 the accuracy of the average rate of respiration obtained has to be reviewed
 results within a range of –10 to +10 ppm/min are viewed as being zero, ie
no respiration has taken place.
How could the experiment be modified to eliminate identified errors, increase
accuracy, increase reliability etc?
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
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TEACHER’S GUIDE
Drawing conclusions
 What conclusions can be drawn? Are conclusions based on the student’s
own results?
 Has the student made reference to the aim, observations and trends?
 Has comment been made on the use of controls and between the different
variables?
Making predictions and generalisations
 Predictions will depend on which experiment has been undertaken.
 Having worked on one material students might hazard a guess as to what
might happen if another were used.
 Would their predictions be valid?
 What other factors might they have to consider?
 Have they given due consideration to safety issues?
 Have they given due consideration to ethical issues?
References
http://www.flashlearning.co.uk/RP_Planning/RP_Planning.html
http://www.unc.edu/depts/wcweb/handouts/lab_report_complete.html
http://ublib.buffalo.edu/libraries/projects/cases/teaching/teaching.html
http://ublib.buffalo.edu/libraries/projects/cases/teaching/novel.html
Delpech, Rodger, School Science Review, March, 87(320).
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
STUDENT’S GUIDE
Student’s guide
Studying biology involves learning biology facts and concepts. It also
involves developing particular skills.
There are four skills you should become competent in:
1.
2.
3.
4.
planning, designing and carrying out
evaluating
drawing conclusions
making predictions and generalisations.
These will all come together when you are being assessed for LO3 or in
Biology Investigations (DO34 13) at Advanced Higher.
Science advances by raising questions that have usually been prompted by
observations. This in turn is usually communicated with others in the
particular field, generating discussion and reasoned argument.
Report writing therefore becomes very important in the sciences as this is the
accepted, standardised method of communication between scientists.
Study the instructions in ‘Experimental procedure for investigating
respiration rate in germinating peas’ (see page 14).
You are given a very simple problem:
Do peas respire before germination?
Your prior knowledge will tell you that a sign of respiration is the evolution
of carbon dioxide (CO 2 ). This apparatus described on page 14 is used to allow
you to become familiar with more advanced technology and data logging , and
also should enable you to work in small groups, pooling results.
The apparatus should also give more accurate sampling and readings.
However, if this is not available a simple respirometer could be used.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
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STUDENT’S GUIDE
Every experiment starts with a question – this is turned into the aim. From
this a hypothesis is formed (ie what do you expect to happen?) .
In the first part of this experiment, the question may be :
‘Are the peas alive’?
or
‘Can we show respiration is taking place?’
This is at a level below that which you are stud ying.
Can you develop a new and more challenging aim, ie investigate some further
aspect of respiration?
Planning, designing and carrying out
A simple experimental procedure to investigate cell respiration is described
on page 6. This uses a CO 2 probe.
The experiment described is at a level below that which you are now
working.
Look at the method that is described and plan an experiment of your own that
is an extension of this:
 Try to form an aim for yourself by discussing with others.
 Now try to form a hypothesis (what do you expect to happen?)
In designing an experiment remember to give due attention to:





variables (both dependent and independent)
controls
accuracy
reliability
safety.
Some points to consider:
 In the original experiment the number of peas was used as a measurement
of biomass. Could this be improved?
 Respiration is a collection of enzyme -driven reactions. What factors affect
enzymes?
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
STUDENT’S GUIDE
 The dependent variable here is the production of CO 2 .What independent
variable can you think of?
 If the apparatus is limited or unavailable how might you overcome this?
 How are you going to make reliable comparisons?
 Consider the apparatus and materials under use.
 Can you see any dangers or the need for any specific safety measures?
Capture of results:
 If you are working in groups, has each member of the group got a clear
idea of their responsibility?
 What has each person got to do?
 How are results going to be recorded?
 Who is going to do that?
 Who cleans up?
 Who coordinates results?
Look at the data provided:
 This raw data needs to be analysed.
 If you are using the Vernier datalogger the programme will give a graph
and gradient.
 What do these tell you?
 Are you happy to accept all raw data?
 What pitfalls might you find?
Evaluating
In this section you are effectively being asked if your results are trustworthy.
In any experiment many things can go wrong.
 Have you thought through where errors may occur and what you have done
to eliminate them?
 Was your aim achievable?
 Did you select the correct variables?
 Did you select the correct controls?
 Did you select sufficient replicates?
If after discussion and comparison with others you feel confident you should
analysis your results.
 You may wish to discard some results but you must explain why.
 You may also combine replicates to develop averages.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
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STUDENT’S GUIDE
 If suggesting improvements, think about the design and limitations of
equipment or the use of living material.
 Consider how this experiment could be further developed.
In this experiment a lot will depend on how well the hardware performed.
 Did you set it up correctly?
 Did you check it was working before the experiment started?
 How could you improve in this area?
Results could be displayed in this form.
Change in CO 2 concentration (ppm)
over 5 minutes
Run 1
Run 2
Run 3
Run 4
Average
change
over 5
minutes
(ppm)
Average
rate of
respiration
(ppm/min)
Nongerminating
peas
Germinating
peas




Can you comment on any variations or reliability?
Should a range around an average be considered?
What graphs have you obtained?
If you are plotting data on your own, have you described the axis
correctly?
 Are the scales of each axis appropriate?
 Are the points plotted accurately?
 Can you find a trend or make a generalised statement?
Drawing conclusions
 Remember any conclusions must only be based on the results in front of
you.
 Results should be explained in terms of the independent and dependent
variables.
 Have you been selective with any of the data?
 Can you explain why you may have excluded any materi al?
 Did the controls act in the way intended? If not exactly can you give
reasons?
 Have you been able to identify any trends or patterns?
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
STUDENT’S GUIDE
Making predictions and generalisations
 Always take great care in making predictions, for example never assume
that what works for one species, works for another.
 Have you got sufficient evidence to support your prediction?
 Several of the experiments around cell respiration involve enzymes. Use
your knowledge of enzyme action to predict what might happen if other
environmental factors were changed.
 In what way is the enzyme affected? Explain your answer in terms of
enzyme configuration (shape), effect on active site and inhibition.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
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STUDENT’S GUIDE
Experimental procedure for investigating respiration rate in
germinating peas
Cell respiration refers to the process of converting the chemical energy of
organic molecules into a form immediately usable by organisms. Glucose
may be oxidized completely if sufficient oxygen is available by the following
equation:
C 6 H 12 O 6 + 6O 2 (g)  6H 2 O + 6CO 2 (g) + energy
All organisms, including plants and animals, oxidi se glucose for energy.
Often, this energy is used to convert ADP and inorganic phosphate into ATP.
It is known that peas undergo cell respiration during germination.
Aim
Do peas undergo cell respiration before germination?
Method
Using the CO 2 gas sensor you will monitor the CO 2 produced by peas during
cell respiration. Both germinating and non -germinating peas will be tested.
Procedure
1.
Set the sensor to the low (0–10,000 ppm) setting. Connect the CO 2
sensor to the Go!Link interface and connect to the computer.
2.
Prepare the computer for data collection by
opening the 11B Cell Resp file in the Biology
with Vernier folder.
3.
Obtain 20 germinating peas and blot them dry
between two pieces of paper towel. Use the
thermometer to measure the room
temperature. Record the temperature in Table
1.
4.
Place the germinating peas in the respiration
chamber.
5.
Place the shaft of the CO 2 gas sensor in the
opening of the respiration chamber.
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
STUDENT’S GUIDE
6.
Wait 1 minute, then begin measuring CO 2 concentration by clicking
. Data will be collected for 5 minutes.
7.
Remove the CO 2 gas sensor from the respiration chamber. Place the
peas in a 100-mL beaker filled with cold water and an ice cube. The
cold water will prepare the peas for part II of the experiment.
8.
Use a notebook or notepad to fan air across the openings in the probe
shaft of the CO 2 gas sensor for 1 minute.
9.
Fill the respiration chamber with water and then empty it. Thoroughly
dry the inside of the respiration chamber with a paper towel.
10.
When data collection has finished, determine the rate of respiration .
 Move the mouse pointer to the point where the data values begin to
increase. Hold down the left mouse button. Drag the pointe r to the
point where the data cease to rise and release the mouse button.
 From the Analyze menu select Linear Fit to perform a linear
regression. A floating box will appear with the formula for a best -fit
line.
 Record the slope of the line, m, as the rate of respiration in Table 1.
11.
Move your data to a stored run. To do this, choose Store Latest Run
from the Experiment menu.
12.
Obtain 20 non-germinating peas and place them in the respiration
chamber
13.
Repeat steps 5–11 for the non-germinating peas.
Results
A sample set of results is shown overleaf.
14.
To print a graph showing all three data runs:
(a)
(b)
Label both curves by choosing Text Annotation from the Insert
menu, and typing ‘Room Temp Germinated’ (or ‘Room Temp
Non-germinated’, as appropriate) in the edit box. Then drag each
box to a position near its respective curve. Adjust the position of
the arrowhead.
Print a copy of the graph, with all three data sets and the
regression lines displayed. Enter your name(s) and the number of
copies of the graph you want.
SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
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STUDENT’S GUIDE
Data
Table 1
Condition of peas
Rate of respiration (ppm/min)
Germinating, room temperature
Non-germinating, room temperature
Table 1 might represent the data from one student and would need to be
expanded to record class results.
Table(s) of results may alter depending on which area of investigation has
been undertaken.
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SKILLS OF SCIENTIFIC EXPERIMENTATION, INVESTIGATION AND ENQUIRY (H, BIOLOGY)
© Learning and Teaching Scotland 2011
STUDENT’S GUIDE
DRIED PEAS
SOAKED PEAS
CO 2 concentration (ppm)
CO 2 concentration (ppm)
Time(s) RUN1 RUN2 RUN3 RUN4
Time (s) RUN1 RUN2 RUN3 RUN4
0
314
378 420 325
0
405
477 359 397
4
311
377 433 322
4
447
505 367 408
8
311
378 436 327
8
482
527 378 413
12
314
378 443 330
12
511
554 385 423
16
311
377 454 335
16
538
576 389 430
20
311
378 456 337
20
558
595 394 435
24
311
378 457 338
24
583
615 404 440
28
311
378 459 340
28
614
632 414 451
32
312
378 462 337
32
648
655 427 454
36
308
378 463 341
36
686
676 439 466
40
309
378 462 347
40
721
698 452 478
44
312
378 462 350
44
755
721 471 493
48
313
377 466 350
48
795
748 486 505
52
314
378 468 349
52
835
783 511 527
56
312
377 469 350
56
881
813 534 547
60
315
377 465 350
60
926
848 560 567
64
314
378 470 349
64
980
884 591 592
68
316
376 470 349
68
1027 925 620 616
72
315
374 467 349
72
1071 962 648 643
76
315
374 462 349
76
1115 1005 677 664
80
311
378 463 350
80
1162 1054 710 691
84
311
377 465 352
84
1205 1103 746 722
88
314
374 466 350
88
1250 1155 779 750
92
312
374 467 350
92
1305 1211 813 784
96
314
374 470 356
96
1352 1280 848 820
100
313
375 475 359
100
1400 1339 887 850
104
314
374 476 359
104
1451 1395 925 886
108
317
374 469 356
108
1492 1457 966 920
112
316
374 472 359
112
1535 1518 1000 956
116
317
374 475 359
116
1586 1582 1041 989
120
315
373 476 360
120
1633 1645 1081 1028
124
315
375 475 360
124
1685 1719 1124 1074
128
312
373 475 360
128
1738 1786 1170 1117
132
313
375 475 359
132
1795 1858 1216 1158
136
313
374 475 359
136
1846 1926 1264 1207
140
314
373 475 360
140
1896 1995 1309 1247
144
315
372 475 360
144
1943 2065 1355 1293
148
318
372 475 362
148
1989 2138 1403 1334
152
319
374 475 362
152
2037 2214 1451 1385
156
319
375 476 362
156
2087 2285 1492 1427
160
315
375 476 362
160
2147 2360 1530 1466
164
319
374 475 359
164
2217 2430 1567 1514
168
319
374 475 359
168
2282 2503 1616 1553
172
319
374 476 359
172
2336 2589 1660 1594
176
318
374 475 362
176
2393 2662 1705 1638
180
318
374 475 362
180
2447 2739 1760 1678
184
319
371 478 363
184
2503 2824 1810 1728
188
318
370 478 362
188
2559 2903 1857 1772
192
319
374 478 361
192
2629 2987 1900 1823
196
319
373 475 361
196
2689 3071 1954 1865
200
318
374 476 361
200
2752 3142 2002 1906
204
320
374 475 364
204
2825 3224 2046 1954
SKILLS OF
SCIENTIFIC
INVESTIGATION
AND ENQUIRY
(H, BIOLOGY)
208
318
371 EXPERIMENTATION,
475 359
208
2887
3294 2091
1995
212
315
374
475
361
212
2951
3364
2139
2045
© Learning and Teaching Scotland 2011
216
319
374 475 360
216
3016 3428 2189 2096
220
320
374 473 359
220
3070 3499 2239 2144
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