Name________________________ J#_____
Nature of Science Practice- Answers
1. An investigation was conducted using chicken eggs to represent cells with membranes. The mass of each egg
was measured to determine how much water diffused into or out of the eggs. The eggs were first soaked in
vinegar to dissolve the shell. Each egg was then placed in one of three different solutions for 24 hours. The table
shows the results of the investigation.
How cells absorb water (solutions vs. egg)
Solution Type
Mass of Egg
before Soaking
(grams)
71.2
65
64.5
Vinegar (95% water)
Alcohol (80% water)
Distilled Water (100% water)
What is the TEST Variable?
Mass of Egg
after soaking
(grams)
98.6
95
105.3
Amount of mass
gained (grams)
27.4
20
40.8
Type of Solution
What is the Outcome Variable?
Amount of mass gained by the egg
What are TWO constants that this experimenter must have? Amount of solution Type of Egg Condition of Egg
Is this data DISCRETE or CONTINUOUS? Discrete
How did you know? Amounts, Finite answer
What type of graph would you make? BAR why? Because Bar Graphs show actual amounts with data that has no
change over time.
Set up the graph below: *You do not need to MAKE the graph, but write in the x axis title, y axis title and a MORE
informative title than is given on the data table (How test affects outcome….).
How soaking an egg in different solutions affects the mass of an egg
Amount of
*There would be a bar for before and after for each solution type.
Mass (g) gained
Solution Type
2. Keesha did an experiment to study the rate of photosynthesis in the water plant Elodea. She placed a piece of
Elodea in a beaker of water and set the beaker 10 centimeters (cm) from a light source. Keesha counted the
bubbles released from the plant every minute for five minutes (min). She repeated the process two more times.
First, she moved the light to 20 cm from the beaker, and then she moved the light to 30 cm from the beaker.
Keesha’s setup and data are shown:
What is Keesha’s TEST Variable?
What is her Outcome Variable?
Distance of beaker from light source
Number of Bubbles released from Elodea Plant
What are TWO constants that she must have? Type of Plant Type of light
Size of Beaker Amount of water
Is this data DISCRETE or CONTINUOUS? Continuous
How did you know? Because it shows a change over time.
What type of graph would you make? Line why? Because time is being monitored while looking for changes in data.
Set up the graph below: *You do not need to MAKE the graph, but write in the x axis title, y axis title and a MORE
informative title than is given on the data table (How test affects outcome….). Careful….this one is more tricky!!!
How the distance a plant is from the light source affects photosynthesis
(or the amount of bubbles produced)
# of Bubbles
*Triple Line graph with a key for the 3 distances (test v.)
released by plant
Time (minutes)
3. Explain: Using this experiment above as an example, what would need to be done to say this is a repeatable
experiment?
This experiment in full (from hypothesis to conclusion) would need to be able to be repeated by the
same scientist with SIMILAR results each time.
Replicable?
This experiment in full (from hypothesis to conclusion) would need to be able to be
repeated by A DIFFERENT scientist with SIMILAR results each time.