1. 1. Independent Variable? ___________________
Students at DHS wanted to test if paper weight affects the distance paper airplanes fly. The same type of paper airplanes were folded from three different weight papers. The planes were thrown in the mall area to measure the distance they would fly. What are the following variables?
Weight of paper
1. Independent Variable? ___________________
2. Dependent Variable? ____________________
Distance the plane flew

2. 1. Independent Variable? ___________________
A group of students was asked to compare the taste of lemonade. One glass was from a pitcher made with one cup of sugar. The second glass was made from a pitcher with two cups of sugar. Both pitchers used the same amount of water, lemon juice, and ice. What are the following variables?
Amount of Sugar
1. Independent Variable? ___________________
2. Dependent Variable? ____________________
Taste

3. Squidward loves playing his clarinet and believes it attracts more jellyfish than any other instrument he has played. In order to test his hypothesis, Squidward played a song on 3 instruments for a total of 5 minutes and counted the number of jellyfish he saw in his front yard. He also recorded the number of jellyfish he observed when he was not playing an instrument.
3 trials with no music
1. What is the control group? _____________________________
2. What is the independent variable? _______________________
3. What is the dependent variable? ________________________
Instrument
Number of jellyfish

4. Observations vs. Inferences Tools & Procedures
What Scientists Do
Observations vs. Inferences
Tools & Procedures

5. Observations vs. Inferences
Scientists use observations to gather data (using the 5 senses).
Scientists use known data to make inferences (a logical interpretation of the data based on past experiences).

6. There are 2 doors.
Observation
Inference

7. They’re fighting, because someone ate their cookies.
Observation
Inference

8. They’re hitting each other hard.
Observation
Inference

9. Let’s test your observation skills. Take a good look at this picture:

11. Are there cars parked on the side of the road?
What color is the pickup truck driving in the road?
Are there any minivans around?
What does the blue sign say?
What’s the speed limit?
Are there pedestrians on the road?

12. How many did you get correct?
Yes
Blue
Yard Sale
35 mph No

14. Observations vs. Inferences
During labs, record your observations not your inferences.
Your inferences may be used when writing your conclusion.
Your observations can be qualitative or quantitative.
The petals are pink.
The flower has 5 petals.

15. Making Observations & Collecting Data
Biologists use metric measurements (the SI system) to gather & interpret data.

16. Some Metric Units used in Biology

17. The Metric System
The metric system is the universal measurement system based on the number 10.
The meter is the distance value.
The gram is the mass value.
The liter is the volume value.

18. Conversions
If you want to change a larger unit into a smaller unit, move the decimal point to the right.
If you want to change a smaller unit to a larger unit, move the decimal point to the left.
100 g = _____ kg
kL = _____ L .1
7.4

20. Scientific Notation
Used to make very large or very small numbers easier to read
Numbers that are very small have negative exponents.
Numbers that are very large have positive exponents.

21. Scientific Notation
The goal is to have a single non-zero number (1-9) to the left of the decimal & the exponent at the end tells you how many decimal places over & in which direction you would move to get to the original number.

22. Scientific Notation
It is really only useful if it will make the number shorter.
If the number does not have several zeros in front or behind the number taking up space, SN will only make the number longer.
Keep this in mind when converting.

23. Scientific Notation
kg is easier to read as 1.0 x kg
cm is easier to read as x 109 cm
g = _____________________
cm = _______________________
14698 g = _____________________________
x 1012
x 10-4
14698

24. Graphing How a scientist shows patterns in data
Several types of graphs – not all of them useful for data communication
Line Graphs
Bar Graphs
Pie Chart

25. Graphing
Line Graph: compares 2 things in which items on 1 axis affect the items on the other axis
If you’re comparing anything to time, it is usually a line graph.
Example: amount of CO2 in the atmosphere over the last 6 decades

26. Graphing Bar Graph: compares 2 or more values
Example: number of students with red hair in each class

27. Graphing
Pie Chart: effective in showing proportions or percentages of a whole thing
Example: comparing the percentage vote that each candidate received in an election

28. Graphing
Always draw lines with a ruler, use pencil, & use colored pencils when necessary.
Graphs must include:
Title: tell what you are comparing or displaying
X-axis: label & give scale
Y-axis: label & give scale
Key: give meanings of symbols & colors used
Data points: clearly marked & label them if there are no grid lines

29. Tools Used to Collect Data & Make Observations

30. Microscopes
Biologists use microscopes to see living things that are too small for the unaided eye.
2 basic types:
Light Microscopes
Electron Microscopes

31. Light Microscopes
Produce magnified images by focusing visible light rays
Magnifies up to 1000x

32. Electron Microscopes
Produce magnified images by focusing beams of electrons
Used to magnify tens & hundreds of thousands of times for extremely small objects like viruses

33. The hair on the leg of a fly (magnified by a factor of 1000)
Electron Microscopes
Salt crystals on the antennae of an insect (magnified by a factor of 5000)
The hair on the leg of a fly (magnified by a factor of 1000)

34. Other Techniques & Tools
Cell Cultures: in order to study cells under a controlled condition, a biologist can take a single cell & place it in a Petri dish with nutrient solution to help the cell regenerate & fill the whole dish!
This cell culture can be used to isolate a single type of cell, or study interactions between cells & chemicals!

35. Other Techniques & Tools
Cell Fractionation: in order to study a single part of a cell, the cells can be lysed (burst open) & the broken cells can be added to a liquid & placed in a tube.
This tube can be placed in a centrifuge, which spins the tubes at high speeds.
This causes cell parts to settle at different levels based on their density.

36. Other Techniques & Tools
Autoclave: in order to sterilize tools & kill anything a scientist may have been growing to test
The large steel machine uses heat & pressure to raise the temperature to a temperature in which no bacteria, viruses, or spore can survive.