1. Which statement best describes a controlled experiment?
(1) It eliminates the need for dependent variables.
(2) It shows the effect of a dependent variable on
an independent variable.
(3) It avoids the use of variables.
(4) It tests the effect of a single independent
variable.

2. Scientific Method Information– What is known (RESEARCH).
Hypothesis- What you THINK (NOT question)
Experiment- Design, perform, and collect data to test hypothesis. (Controlled!)
Analysis-Compare data between groups.
Conclusion- Is hypothesis correct?
Scientific Method

3. Which are bad hypothesis?
Will a seed germinate faster with less light? Increased soil acidity will make flowers red. How many sperm are required to fertilize an egg? Studying for 1 hour before an exam can increase scores by 10%

4. 2 groups to COMPARE results.
Controlled Experiment
2 groups to COMPARE results.
CONTROL GROUP EXPERIMENTAL GROUP
ONE change, ALL ELSE THE SAME
No change, “normal”

5. Two types of variables!!!!

6. Independent Dependent
You “control” this. Known BEFORE experiment starts.
Independent
Dependent
Measured during experiment. UNKNOWN until the experiment occurs.
We think that the amount of water will determine how quickly a plant grows
Amount of water
Plant Growth
The salinity of water determines the percentage of fish eggs that hatch
Salt in water
How many eggs hatch

7. New York State Required Labs – Review
Diffusion Through A Membrane
Making Connections
Beaks of Finches
Relationships and Biodiversity

8. Diffusion Through A Membrane
diffusion – movement of molecules from a region of high to a region of low concentration. No energy is needed (passive transport)

9. 24 hr Iodine & Starch & water Glucose &
Iodine = amber starch indicator solution
Benedict’s solution = blue glucose indicator solution (must be heated)
Iodine &
water
Starch &
Glucose &
24 hr

11. osmosis – diffusion of water across cell membrane.
NaCl

12. cytoplasm
red onion cells
in tap water
cell membrane
cell wall

13. cytoplasm
red onion cells in
salt water
cell membrane
cell wall

14. red onion cells in distilled water – returned to normal cytoplasm
cell membrane
cell wall

15. Which is in distilled water and
which is in salt water?

16. Applications –
salt on roads to melt snow
intravenous saline solutions
salty foods make you thirsty
salt on slugs to kill them
salty foods do not spoil as easily
gargling with salt water
digestion of starch to glucose

17. Part A: Looking for Patterns A1. What Is Your Pulse Rate?
Making Connections
Part A: Looking for Patterns A1. What Is Your Pulse Rate?
Measured three times and found average pulse rate.
Took class average totals.
Why speeds up with exercise?

18. A2. How Does Fatigue Affect Muscle Performance?
Squeezed clothespin for one minute.
Second time number lower due to muscle fatigue.
WHY?

19. Part B: Investigating Claims
Experimental Design
Problem: Can you squeeze a clothespin more times in one
minute if you exercise or rest beforehand?
Hypothesis: You can squeeze a clothespin more times in
one minute if you rest first.

20. Controlled experiment
Dependent variable: (what you measure) number of times
the clothespin can be squeezed in one minute
Independent variable: (the one we vary) amount of exercise
Variables that must be controlled (kept constant):
type of clothespin fingers used
time of exercise/rest time of squeezing
same hand for each trial
* use maximum sample size and number of trials in experiment *

21. Data Collected – includes data tables and graphs
Conclusions – does data support hypothesis?
Suggestions for improvement and future research; and publish research

22. Beaks of Finches Darwin’s finches show great variation in beak
adaptations .

23. seeds (small and large) represent food plate represents the island
different tools represent different beaks
seeds (small and large) represent food
plate represents the island
petri dish represents finch stomach

24. variation – different beak types and seed sizes
competition – more than one bird feeding at a time
struggle for survival – each bird trying to get enough
to survive
adaptation – particular characteristics of each beak
environment – the birds, food and island
selecting agent – the size of seed available 24

25. Relationships and Biodiversity
Botana curus – hypothetical plant used to
make Curol – for treating cancer
Botana curus – endangered, grows slowly
related species: X, Y and Z
Which is most closely related using structural
and molecular evidence
Decide which species (X, Y or Z) is most likely
to produce Curol

26. Structural Characteristics of Plants

27. Paper Chromatography to Separate Plant Pigments27

28. Test for Enzyme M Botana curus enzyme M present Species X
enzyme M absent
Species Y
enzyme M present
Species Z
enzyme M present 28

29. Simulated Gel Electrophoresis To Compare DNA
Translating the DNA Code to Make a Protein 29

30. 30

31. Which variables are THE SAME between the groups?
An experiment tested whether water plants make less Oxygen with less light. The bubbles of Oxygen were measured.
Which variables are THE SAME between the groups?
The plants, the water, the glass beakers…

32. Which single variable was changed?
An experiment tested whether water plants make less Oxygen with less light. The bubbles of Oxygen were measured.
Which single variable was changed?
The constant light for 24 hours

33. Which is the INDEPENDENT VARIABLE?
An experiment tested whether water plants make less Oxygen with less light. The bubbles of Oxygen were measured.
Which is the INDEPENDENT VARIABLE?
The light!
(YOU change this on purpose)

34. Which is the DEPENDENT VARIABLE?
An experiment tested whether water plants make less Oxygen with less light. The bubbles of Oxygen were measured.
Which is the DEPENDENT VARIABLE?
The Oxygen bubbles.
(THE LIGHT changes this.)

35. The graph might look like this…
Amount of Light
# of Oxygen Bubbles
Which is the INDEPENDENT VARIABLE?
The Light.
Which is the DEPENDENT VARIABLE?
The Oxygen bubbles.

36. (1) diameter of the field of view decreases
A student observes a red onion cell with a compound light microscope using low, then high power. The two views are represented below.
The best explanation for the changes observed by the student is that, when switching from low to high
power, the
(1) diameter of the field of view decreases
(2) slide was accidentally moved
(3) diameter of the field of view increases
(4) image is inverted and reversed

37. A student observes a red onion cell with a compound light microscope using low, then high power. The two views are represented below.
Which diagram represents the best cell location in the low-power field of view to be sure the entire cell will be visible after switching to high power?

38. Which statement best describes a controlled experiment?
(1) It eliminates the need for dependent variables.
(2) It shows the effect of a dependent variable on
an independent variable.
(3) It avoids the use of variables.
(4) It tests the effect of a single independent
variable.

39. There are two types of variables!!!!
Independent
You “control” this. It is what you are testing. It comes from your hypothesis. You know it BEFORE the experiment even starts.
Dependent
You measure this during the experiment. It is what you want to know. It is what you compare. You DO NOT KNOW THIS until the experiment occurs.

40. Other scientists check your work.
Reasons for conducting peer review include all of the following except
(1) analyzing the experimental design
(2) pointing out possible bias
(3) identifying an illogical conclusion
(4) changing data to support the hypothesis

41. What was the sample size?
Insecticides are used by farmers to destroy crop-eating insects.
Recently, scientists tested several insecticides to see if they caused damage to chromosomes. Six groups of about 200 cells each were examined to determine the extent of chromosome damage after each group was exposed to a different concentration of one of two insecticides. The results are shown:
What was the sample size?
Which insecticide has a more
damaging effect on chromosomes?
HOW DO YOU KNOW?

42. What was the sample size?
Insecticides are used by farmers to destroy crop-eating insects.
Recently, scientists tested several insecticides to see if they caused damage to chromosomes. Six groups of about 200 cells each were examined to determine the extent of chromosome damage after each group was exposed to a different concentration of one of two insecticides. The results are shown:
What was the sample size?
Which insecticide has a more damaging effect on chromosomes? Support your answer.

43. A scientist is planning to carry out an experiment on the effect of heat on the function of a certain enzyme. Which would not be an appropriate first step?
(1) doing research in a library
(2) having discussions with other scientists
(3) completing a data table of expected results
(4) using what is already known about the enzyme

44. An experimental design included references
from prior experiments, materials and equipment ,and step-by-step procedures. What else should be included before the experiment can be started?
(1) a set of data
(2) a conclusion based on data
(3) safety precautions to be used
(4) an inference based on results

45. What is the independent variable here?
A student squeezed a clothespin as many times as possible in a 30-second time period. The student repeated this procedure nine more times in quick succession. The data are in the chart below.
What is a possible hypothesis that was being tested?
Squeezing a clothespin for 30 seconds is not
as easy as squeezing for 15 seconds.
(2) The number of times I squeeze a clothespin will decrease with multiple tries.
(3) The number of clothespin squeezes will cause the number of trials to increase.
(4) I wonder how many times in 30 seconds I can squeeze a clothespin?
What is the independent variable here?

46. A technique used to
analyze pigments in
spinach leaves is shown
in the this diagram.
This technique is known as
(1) paper chromatography
(2) gene manipulation
(3) Dissection
(4) staining

47. Same number of chromosomes, leaf shape, and enzymes.
A valuable medicine is obtained from a certain rare species of plant. Scientists are anxious to find another more abundant species of plant that is closely related to the rare one, and also produces the medicine.
Two newly discovered plant species, A and B, were studied and compared
to the rare one. The results of the study are shown in the table.
Which newly discovered species is more closely related to the rare species?
Support your answer. B
Species:_____________
______________________________________________________________________
Same number of chromosomes, leaf shape, and enzymes.

48. species is most closely related to the rare species?
A valuable medicine is obtained from a certain rare species of plant. Scientists are anxious to find another more abundant species of plant that is closely related to the rare one, and also produces the medicine.
Two newly discovered plant species, A and B, were studied and compared
to the rare one. The results of the study are shown in the table.
Which procedure could also be carried out to help determine which newly discovered
species is most closely related to the rare species?
(1) measurement of respiration rate in the plants
(2) chromatography of pigment extracts from the plants
(3) determination of the type of gas released by photosynthesis in the
plants
(4) analysis of chemical bonds present in glucose in the plants

49. Child B & Child D have the same size bands
DNA samples were collected from four children.
The diagram represents the results of a
procedure that separated the DNA in each sample.
Gel electrophoresis
Band X represents the
(1) largest fragment of DNA that traveled the fastest
(2) smallest fragment of DNA that traveled the fastest
(3) largest fragment of DNA that traveled the slowest
(4) smallest fragment of DNA that traveled the slowest
The DNA is most similar in which two children? Support your answer.
______________________________________________________________________
Child B & Child D have the same size bands

50. What is the independent variable here?
A student squeezed a clothespin as many times as possible in a 30-second time period. The student repeated this procedure nine more times in quick succession. The data are in the chart below.
What is a possible hypothesis that was being tested?
Squeezing a clothespin for 30 seconds is not
as easy as squeezing for 15 seconds.
(2) The number of times I squeeze a clothespin will decrease with multiple tries.
(3) The number of clothespin squeezes will cause the number of trials to increase.
(4) I wonder how many times in 30 seconds I can squeeze a clothespin?
What is the independent variable here?

52. Which statement best describes a controlled experiment?
(1) It eliminates the need for dependent variables.
(2) It shows the effect of a dependent variable on
an independent variable.
(3) It avoids the use of variables.
(4) It tests the effect of a single independent
variable.

53. Fill in the missing mRNA bases and the amino acid sequence that corresponds to the DNA base sequence below.
DNA
RNA T A C G U
GUG
CAC
CUG
ACU
VAL
HIS
LEU
THR

54. Which statement best describes a controlled experiment?
(1) It eliminates the need for dependent variables.
(2) It shows the effect of a dependent variable on
an independent variable.
(3) It avoids the use of variables.
(4) It tests the effect of a single independent
variable.

55. What is the independent variable here?
A student squeezed a clothespin as many times as possible in a 30-second time period. The student repeated this procedure nine more times in quick succession. The data are in the chart below.
What is a possible hypothesis that was being tested?
Squeezing a clothespin for 30 seconds is not
as easy as squeezing for 15 seconds.
(2) The number of times I squeeze a clothespin will decrease with multiple tries.
(3) The number of clothespin squeezes will cause the number of trials to increase.
(4) I wonder how many times in 30 seconds I can squeeze a clothespin?
What is the independent variable here?

56. The diagram shows a laboratory set-up used by students in a biology class.
After a day, what is a likely observation a student may make?
The solution outside the membrane will change to white
The solution outside the membrane will change to yellow
The solution inside the membrane will change to yellow
The solution inside the membrane will change to black

57. The cactus finch, warbler finch, and woodpecker finch all live on one island. Based on the information in the diagram below, which one of these finches is least likely to compete with the other two for food? Support your answer with an explanation.

58. (1) AGC-UCU-CCU (2) AGU-UCC-CCG (3) AGC-UCA-CUU (4) AGU-UCG-CCC
Which three codons would code for a different amino acid sequence from that coded for by the mRNA base sequence AGU-UCA-CCA?
(1) AGC-UCU-CCU
(2) AGU-UCC-CCG
(3) AGC-UCA-CUU
(4) AGU-UCG-CCC