# Welcome to FLIS Biology 12 Module 0. Bubble experiments Identify your: Hypothesis Independent variable Dependent variable Control Variables you controlled.

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Welcome to FLIS Biology 12 Module 0

Bubble experiments Identify your: Hypothesis Independent variable Dependent variable Control Variables you controlled

Bubble experiments Identify your: Hypothesis statement that links independent and dependent variables eg the greater the detergent, the more bubbles produced Independent variable what you change eg amount of detergent, size of loop, type of water Dependent variable what you measure eg size of bubbles, number of bubbles, duration of bubbles Control what you use to compare to the experimental group Variables you controlled what you keep the same between both groups

Measurement

Use measuring cylinders not beakers Read from the bottom of the meniscus Tare button sets the scale to 0 If you hit it twice by accident you may not be able to get a reading Keep bulb in the material to be measured Don’t hold on to the bulb Read from 0, read over the top to avoid distortion Move 100’s, then 10’s, then units and then add them all up Read minutes, seconds and 100ths of seconds 13 mL 3 min 53.17 sec 15.4 g 1.9 mm 37 o C 43.6 g Humidity = 68% Temperature = 25.8 o C

Scientific method 1 A researcher working for a pharmaceutical company had developed an adrenaline related compound ("drug X") which showed promise as a bronchodilator in the treatment of asthma. Bronchodilators are substances which cause the muscular walls of the airways to relax during an asthma attack thus making breathing easier. Since one of the side-effects of adrenalin can be to increase the heart rate and blood pressure, it was decided to try-out the new drug on a group of volunteers. Identify the hypothesis being tested. Describe how you could test this hypothesis by identifying: The independent variable The dependent variable What you could use as a control Variables that would have to be controlled How to increase reliability

Scientific method 1 A researcher working for a pharmaceutical company had developed an adrenaline related compound ("drug X") which showed promise as a bronchodilator in the treatment of asthma. Bronchodilators are substances which cause the muscular walls of the airways to relax during an asthma attack thus making breathing easier. Since one of the side-effects of adrenalin can be to increase the heart rate and blood pressure, it was decided to try-out the new drug on a group of volunteers. Identify the hypothesis being tested. Drug X will not cause an increase in heart rate or blood pressure Describe how you could test this hypothesis by identifying: The independent variable drug X The dependent variable heart rate and blood pressure What you could use as a control a group not given the drug/ heart rate & blood pressure before drug given Variables that would have to be controlled anything that could affect heart rate or blood pressure eg exercise, drugs, temperature, food, drink, etc How to increase reliability large sample size, mixed sample – age, sex, health, etc, repetition, replication, increased measurement etc

Scientific method 2 This is how the drug was tested: Fifteen volunteers were selected from physical education students attending a local college. On day one, the volunteers assembled at the college and were asked to rest for half an hour. Their pulse was then measured. The average pulse rate for the group was 72 pulses per minute. Three days later the group reassembled. Each member of the group received an intravenous injection of the drug. They then rested for half an hour before their pulse was checked. This time the average pulse rate for the group was 73.5 pulses per minute. The researcher concluded that at this dosage drug X produced no significant increase in heart rate. When the pharmaceutical company finally marketed the drug in the form of an aerosol it was claimed in their advertising that it had been scientifically proven that the drug had no adverse affect on cardiac function. Was the drug tested effectively? How justified were their results? How could their testing be improved?

Scientific method 2 This is how the drug was tested: Fifteen volunteers were selected from physical education students attending a local college. On day one, the volunteers assembled at the college and were asked to rest for half an hour. Their pulse was then measured. The average pulse rate for the group was 72 pulses per minute. Three days later the group reassembled. Each member of the group received an intravenous injection of the drug. They then rested for half an hour before their pulse was checked. This time the average pulse rate for the group was 73.5 pulses per minute. The researcher concluded that at this dosage drug X produced no significant increase in heart rate. When the pharmaceutical company finally marketed the drug in the form of an aerosol it was claimed in their advertising that it had been scientifically proven that the drug had no adverse affect on cardiac function. Was the drug tested effectively? No – sample size too small, too biased – all fit, all young, averaging group pulse rates – no individual comparison before and after, drug given intravenously not by aerosol, heart rate not measured for 30 minutes – any changes may have been missed, blood pressure not measured How justified were their results? Not at all How could their testing be improved? larger sample size, more mixed sample – age, sex, health, etc, repetition, replication, increased measurement etc

Sample TEE multiple choice questions 1. Which is the sequence of steps most commonly followed when carrying out a biological investigation? (a) question, observation, hypothesis, prediction, experiment (b) question, hypothesis, prediction, experiment, observation (c) prediction, hypothesis, question, experiment, observation (d) observation, question, hypothesis, prediction, experiment 2. Why are controls used in experiments? (a) to compare with an experimental group (b) to increase sample sizes (c) to ensure that the experiment could be replicated (d) to test the experimental hypothesis 3. Which of the following statements is the best example of an observation? (a) The birds went to drink water at the same time each day. (b) The spider burrowed to avoid the heat. (c) The dolphin jumped out of the water to see the people in the boat. (d) The rat chewed each of the three balls to find if they were edible.

Sample TEE multiple choice questions 1. Which is the sequence of steps most commonly followed when carrying out a biological investigation? (a) question, observation, hypothesis, prediction, experiment (b) question, hypothesis, prediction, experiment, observation (c) prediction, hypothesis, question, experiment, observation (d) observation, question, hypothesis, prediction, experiment 2. Why are controls used in experiments? (a) to compare with an experimental group (b) to increase sample sizes (c) to ensure that the experiment could be replicated (d) to test the experimental hypothesis 3. Which of the following statements is the best example of an observation? (a) The birds went to drink water at the same time each day. (b) The spider burrowed to avoid the heat. (c) The dolphin jumped out of the water to see the people in the boat. (d) The rat chewed each of the three balls to find if they were edible.

Sample TEE multiple choice questions 4. One of the following options would not improve the design of this investigation significantly. Which one is it? (a) repeat the investigation in a range of plant species (b) repeat the investigation on another day (c) use a larger number of cuttings for each container (d)draw a graph of the results 5. Which two cuttings would best test the hypothesis that the cuttings take in water through the cut end? (a) cuttings W and X (b) cuttings Y and Z (c) cuttings X and Y (d) cuttings X and Z W latex covering the base and a small part of the stem of the cutting X latex covering the stem except for the cut base Y latex covering the stem and the cut base Z no latex covering

Sample TEE multiple choice questions 4. One of the following options would not improve the design of this investigation significantly. Which one is it? (a) repeat the investigation in a range of plant species (b) repeat the investigation on another day (c) use a larger number of cuttings for each container (d)draw a graph of the results 5. Which two cuttings would best test the hypothesis that the cuttings take in water through the cut end? (a) cuttings W and X (b) cuttings Y and Z (c) cuttings X and Y (d) cuttings X and Z W latex covering the base and a small part of the stem of the cutting X latex covering the stem except for the cut base Y latex covering the stem and the cut base Z no latex covering

Sample TEE short answer question (a) For this experiment, name the following: (i) The dependent variable (ii) The independent variable (iii) What is the control for this experiment? Give a reason for your answer. (b) Name four variables that the biologist would need to control in this experiment. Trays of 100 seedlings of a species of Eucalyptus (gum tree) were watered with various concentrations of salt water. The percentages of the seedlings that survived in each tray are recorded in the table below.

Sample TEE short answer question (a) For this experiment, name the following: (i) The dependent variable survival of seedlings (ii) The independent variable concentration of salt (iii) What is the control for this experiment? Give a reason for your answer. tray 1 – no salt (b) Name four variables that the biologist would need to control in this experiment. Same size trays, same soil, same amount of water, humidity, light, wind, same temperature, same variety of seedlings, same size/age of seedlings Trays of 100 seedlings of a species of Eucalyptus (gum tree) were watered with various concentrations of salt water. The percentages of the seedlings that survived in each tray are recorded in the table below.

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