The purpose of this practical is to investigate how the pulse rate of humans changes when they exercise. Someone who is physically fit can supply their muscles with enough blood, carrying glucose and oxygen, for an activity at a lower heart and breathing rate. The fitter you are the lower your resting heart rate. You and your classmates will be the humans investigated.
SAFETY: If you know you have any condition that affects you doing exercise, please make sure your teacher knows before you start the investigation. In the investigation you are going to measure and record your pulse rate, before and after doing some physical activity. Work in pairs and decide who will be the ‘exerciser’ and who will be the ‘pulse-taker and recorder’. The pulse-taker takes the resting pulse of the exerciser. The exerciser should be sitting down and holding their left hand out with their palm facing up and their elbow straight. The pulse-taker puts the index and middle fingers of their right (or left) hand together, and presses the pads of their fingers lightly on the underside of the exerciser’s left wrist, just at the base of their thumb. With their fingers in this position, they should be able to feel a pulse. Once the pulse has been found, the pulse-taker starts the stopwatch and counts the number of beats in 15 seconds. To find the heart rate in beats per minute, the pulse count for 15 seconds is multiplied by 4. The exerciser exercises (jog on the spot, do jumping jacks, step up and down on the platform at the front of the room at a rate of 30 steps per minute) for 3 minutes. The pulse-taker counts the number of beats in 15 seconds immediately after exercise has stopped, then 2 minutes after exercise stopped and then 4, 6 and 8 minutes after exercise stopped. These rates should be taken with the exerciser sitting down. Recovery is to be assessed by calculating the ‘4 minutes after exercise’ value as a percentage of resting rates and comparing the percentage with the measure of fitness. This should give an inverse relationship i.e. the fitter the subject, the lower the percentage.
Materials and apparatus:
* Independent (changed):
* Dependent (measured):
* Controlled (held constant):
Method: numbered steps
Observations and results:
* Table neatly ruled up, units in header column; ensure the title is descriptive. * Graph of data summarised in table.
* A concise description of other observations made, that are not given in table. * Calculation of the ‘4 minutes after exercise’ value as a percentage of resting rate. Discussion: examine the rubric in the table below closely; sequence your discussion as shown in the rubric; do not describe again how the experiment was carried out or restate the result; that is done in the ‘Method’. You will need to refer to the results in the process of explaining them. Focus on ‘Why’ i.e. the ‘Aim’ and ‘What the results indicated’ i.e. explain or account for the results; identify and explain sources of error and limitations in the experiment. Did the procedure and materials provided allow for the collection of sufficient data? Did the procedure and materials provided allow for the collection of accurate data? * Error – identify error(s) made in obtaining the results; explain how the error(s) affected the results and the objectives (Aim) of the investigation; describe how the error(s) could be reduced or eliminated. * Limitations – (consider – conditions, time, materials) explain how the limitation identified affected the accuracy of results, describe how limitation identified could be eliminated or reduced. * Conclusion: – answer the question using the results
Criteria| 2| 1| 0|
Background knowledge| Theory or problem being investigated is fully explained; the expected results are stated| Theory or problem being investigated is not quite fully explained; the expected results are not stated| Theory or problem being investigated is not explained; the expected results are not stated| Explanation of results| Results are thoroughly
interpreted| Results are fairly well interpreted| No interpretation of the results is provided; results are poorly interpreted| Sources of error| At least one well explained and valid source of error is provided| A valid source of error is provided but it is not well explained| No source of error is provided; that which is offered is invalid | Limitations | Limitations of the procedure are valid and well explained – at least one limitation | At least one limitation is presented but it is poorly explained| No limitation is presented; that which is presented is invalid| Conclusion| Conclusion is related to the ‘Aim’ and makes reference to the observations (results)| Conclusion is related to the ‘Aim’ but makes no reference to the observations (results)| Conclusion is not related to the ‘Aim’; makes no reference to the observations (results)|
OBSERVATION/REPORTING/RECORDING – Data table – 12 marks scaled to 10 Criteria| Complete| Partial| Not at all|
Title – a concise statement identifying the variables included in the table is printed and underlined with a single line| 2| 1| 0| A pencil and ruler are used to construct table – rows and columns ruled up so that items are distinguished from each other; table has an outer border | 2| 1| 0| Table is large enough so that all the entries can be neatly written in the available space; table is not broken| 2| 1| 0| First column is independent variable (chosen by the experimenter); second and subsequent columns the dependent variables (readings taken by the experimenter)| 2| 1| 0| Column headings include the quantity and the unit (as appropriate); accepted scientific conventions e.g. if the quantity being measured is length in millimeters column heading is to be written as ‘length / mm’; ‘length in mm’ or ‘length (mm)’| 2| 1| 0| Numerical values are inserted into the body of table no units| 2| 1| 0|
OBSERVATION/REPORTING/RECORDING – Line graph – 16 marks scaled to 10 Criteria| Complete| Partial| Not at all|
A pencil is used for drawings in lines on graphs, labeling the axes and writing the title| 2| 1| 0| The independent variable is plotted on the X axis and the dependent variable on the Y axis| 2| 1| 0| The scales chosen for the graph axes makes it easy to read the graph, such as 1, 2 or 5
units to a 20 mm square and make the best use of the space available – half or more of the length and width of the grid| 2| 1| 0| Each axis is labeled and the relevant quantity and units stated e.g. Temperature of solution/0C| 2| 1| 0| Points are lightly drawn (but are visible on the grid) with a sharp pencil using a fine cross or an encircled dot; points are no larger than one of the smallest squares on the grid| 2| 1| 0| Where data falls on a straight line or smooth curve, and then a line of best fit or an appropriate curve is drawn in on the graph; when a straight line or smooth curve is not formed neighboring points are joined by straight ruled lines; lines of best fit show an even distribution of points on either side of the line along its whole length| 2| 1| 0| Lines are thin, drawn without kinks or breaks| 2| 1| 0| Title – a concise statement identifying the variables included in the graph is printed and underlined with a single line| 2| 1| 0|