Introduction to Science
Exercise 1 Questions
1. What patterns do you observe based on the information in Table 4?
The closer the pH is too neutral (7pH) the higher the number of colonies that are present.
2. Develop a hypothesis relating to the pH level of the culture media and the number of
microbial colonies observed in each culture.
The number of colonies increase when pH scale is closer to neutral.
3. What would your experimental approach be to test this hypothesis?
Analyse the number of colonies in different pH levels.
4. What would be the independent and dependent variables?
IV: pH of the solution DV: Number of colonies
5. What would be your control?
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H2O will be the control group
6. What type of graph would be appropriate for this data set? Why?
A bell curve to show the distribution of colonies based on the ph.
7. Graph the data from Table 4.
THE NUMBER OF COLONIES
350
300
250
200
150
100
50
0
0 2 4 6 8 10 12
8. Interpret the data from the graph you made in Question 7.
The farther from neutral (7 pH) the less colonies that will appear.
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Exercise 2 Questions
1. Fresh-baked bread develops mold more quickly than bread bought from the store.
Determine if the observation is qualitative or quantitative.
•Quantitative
Write a hypothesis and a null hypothesis.
• The less preservatives in bread will mold more quickly
The less preservatives in bread will not mold more quickly
What would be your experimental approach?
• Set two breads (fresh and store bought) in open air and monitor
them on a set time table (example: every 2 hours).
variables?
• DV: rate of mold.
IV: amount of preservatives.
What are your controls - both positive and negative?
• amount of light
Temperature of surrounding
Number of germs and toxins in the air.
How will you collect your data?
•Monitor the breads until mold appears on one. Then observe
until the other bread appears and compare rates. Then continue
to analyses both breads amount of mold.
What are the dependent and independent
How will you present your data (e.g., chart, graph)?
• Graph of the two different breads by amount of mold as X and
time it takes for the mold to develop.
How will you analyze your data?
• Observe the both data and analyze which took less time to start
molding and the rate of molding.
2. Sally comes to work sick; two days later, three of her coworkers are also sick.
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Determine if the observation is qualitative or quantitative.
• quantitative
Write a hypothesis and a null hypothesis.
• The more individuals that interaction with a sick individual, the
more likely individuals will get sick.
The more individuals that interaction with a sick individual, the
more likely individuals will not get sick.
What would be your experimental approach?
•To take many individuals (ex. 5 healthy people) and interact for
a set amount of time with an infected individual and see if they
develop an infection.
What are the dependent and independent variables?
• DV: The amount sick
IV: The amount of individuals
What are your controls - both positive and negative?
• Amount of time spent with infected
The environment
The infection
The health history of the individuals
Other exposers the healthy individuals have during the day
How will you collect your data?
• Will check the healthy individuals in a few days to see if they
were infected.
How will you present your data (e.g., chart, graph)?
• a graph
How will you analyze your data?
• by checking how many are affected by the disease will tell how
infectious the illness is.
3. You accidentally left a carton of milk on the counter all night, and you notice that the milk
tastes worse than it usually does when it is stored in the refrigerator.
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Determine if the observation is qualitative or quantitative.
• qualitative
Write a hypothesis and a null hypothesis.
• The temperature milk is stored in affects the taste of milk (i.e.
sours).
The temperature milk is stored in does not affects the taste of
milk (i.e. sours).
What would be your experimental approach?
• Leave glasses of milk in specific temperatures and determine
how fast each sour.
What are the dependent and independent variables?
• DV: The taste of the milk
IV: The temperatures the milk is stored in
What are your controls - both positive and negative?
• The container the milk is stored in
The amount of milk
The type of milk (ex:2%)
The same milk used in each cup
The same type of cup
How will you collect your data?
• Watch the milk and measure how long it takes to sour.
How will you present your data (e.g., chart, graph)?
• A chart for each cup on how long till milk sours.
How will you analyze your data?
• By analyze which takes the longest to sour will be the one to to
taste the best.
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Exercise 3 Questions
1. Four new students are learning how to count bacteria colonies. They all count the same
plate, and the first student counts 98 colonies, the second counts 115 colonies, the third
counts 103 colonies, and the fourth counts 93 colonies. The professor tells them there are
actually 107 colonies on the plate.
Accurate Precise Neither Both
2. You want to make sure your incubator is operating at the correct temperature of 37˚C, so
you place a thermometer inside the incubator and check it every hour for five hours. You
record readings of 36.9˚C, 36.9˚C, 37.1˚C, 37.0˚C, and 37.1˚C.
Accurate Precise Neither Both
3. You aren’t sure whether or not your pH meter needs to be calibrated, so you put it in a
solution that you know has a pH of 7. Take four separate readings, which are reported as
5.5, 8.6, 7.2, and 9.4.
Accurate Precise Neither Both
4. Your lab is working on sequencing a new plasmid. Before starting, you all decide to guess
how many base pairs you think the new plasmid has. The lab members’ guesses are
4,005; 4,006; 4,007; and 4,010. It turns out the plasmid has 7,968 base pairs.
Accurate Precise Neither Both
5. You try to measure out exactly 5.0 mL of water by eye into five different test tubes. When
you go back and check, you find the amount of water in each tube is 4.8 mL, 5.3 mL, 5.2
mL, 4.8 mL, and 4.7 mL.
Accurate Precise Neither Both
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Exercise 4 Questions
Part 1
Determine the number of significant digits in each number, and write the specific significant digits.
1. 405001
6 sigfig
2. 0.0098
2 sigfig
3. 39.999999
8 sigfig
4. 13.00
4 sigfig
5. 80,000,089
8 sigfig
6. 55,430.00
7 sigfig
7. 0.000033
2 sigfig
8. 620.03080
8 sigfig
Part 2
Convert each regular number into scientific notation.
1. 70,000,000,000
7.0x1010
2. 0.000000048
4.8x10-8
3. 67,890,000
6.789x107
4. 70,500
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7.05x104
5. 450,900,800
4.509008x108
6. 0.009045
9.045x10-3
7. 0.023
2.3x10-2
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Experiment 1 Data Tables
Table 5: Experiment Variables
Variables
1.amount of yeast
2.amount of water
3.amount of sugar
4.tempeture of water
5.height of fermentation
6.speed of fermentation
7.contence of the air surrounding the yeast
8.nutrinal value of the yeast
9.type of sugar used
10.hight of the cups
PROCEDURE
1. Identify ten variables that may affect aerobic fermentation in yeast. Record the variables in
Table 5.
2. From your list of variables, select three to test. Form a hypothesis regarding how each variable
may affect aerobic respiration in yeast.
The more sugar added to the cup the faster and higher the yeast will ferment.
3.amount of sugar
5.height of fermentation
6.speed of fermentation
3. Determine the positive and negative controls for your experiment.
The size of cups
The type of sugar
The type of yeast
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The amount and temperature of water
Introduction
This report discusses an experiment conducted to see if the amount of sugar added to a
cup of yeast would increase the speed and height of fermentation.
Procedures
The experiment involved 4 cups each had 120mL of water and 1tsp of yeast. The
experiment then started with adding no sugar to the first cup as a control for 15 min then
measure height of the bubbles. Then clean cup and replace its water and yeast in the cup.
Then added sugar in increasing amount of sugar to each cup by ½ tsp increments.
Results and Discussion
Height of bubbles (in)
2.5
2
Amount
1.5
of
Sugar 1
(tsp)
0.5
0
0 1/16 in 3/16 in 5/16 in 6/16 in
1 2 3 4 5
Cup 1 was the control with 0 sugar. cup 2 had ½ tsp of sugar with cup 3 having 1 tsp, cup
4 had 1 ½ tsp and 5 had 2 tsp.
Conclusion
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The conclusion of the experiment is the more sugar the faster the growth and the larger
the growth.
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