1. Students will review laboratory techniques and four required labs, including lab safety, measurements, use of microscopes, and diffusion through a membrane. 2. The diffusion through a membrane lab models how cells use diffusion to maintain homeostasis. Starch remained inside dialysis tubing while glucose diffused out, demonstrating molecule size affects diffusion. 3. Gel electrophoresis and DNA evidence are over 99% accurate and can determine evolutionary relationships between species, identify criminals, and solve paternity cases.

1. L.O: students will review laboratory
techniques and the four required labs.

2. First lab safety:
You should know what to do in a
lab…and……

3. You should know what NOT to do!

4. You will have ONE question on lab
techniques and lab safety!
Are you being safe?

5. Be able toexplain why any one of these
kids is not being safe”!
Are you being safe?

6. Measurements: when
one makes an observation
using numbers & a measuring
instrument.
There will be one measurement
question on the regents!

7. Example: what is the exact
measurement of this worm?

8. 9.0 centimeters

9. Example 2: how much water is in the
graduated cylinder?

10. 13.0 mL.

11. Example 3: how much water is in the
graduated cylinder?

12. 24.0 mL

13. Now answer 1-6.

14. Microscopes:
• You should know the
basic parts of a
microscope.
• There may be one
question.

15. Microscopes are use to make small
objects look bigger.

16. Objects under a microscope are always
upside down and backwards.

17. Because objects are upside down and
backwards, one has to move a slide
the OPPOSITE of where one wants to
move an object.
I must move the
slide this way
If i want to move the
organism this way

18. When wet-mounting a specimen on a
slide, the cover-slip must be lowered
at an angle to prevent air bubbles.

19. To stain a specimen, place a paper towel at
one side of the slip cover. Add the dye stain
at the opposite end. Capillary action will
“pull” the dye through, staining the
specimen.

20. A microscope’s field of view is the diameter
of the microscope’s circle. Knowing the
field of view can be used to determine the
size of microorganisms.

21. If this microscope’s field of view under low
power is 1000um, what is the size of the
organism?
1000um

22. If this microscope’s field of view under low
power is 1000um, what is the size of the
organism? ~200um
1000um

23. Now answer 7-14.

24. And now the four required labs.

25. We did a diffusion through a membrane
lab

26. We did a making connections lab

27. We did a relationships & biodiversity lab

28. We did a beaks of finches lab

29. First the diffusion through a membrane
lab>>>

30. The goal of the lab is to model how a cell
uses diffusion to maintain homeostasis.

31. 1. We put starch and
What we did: glucose inside a piece of
plastic called dialysis
tubing.
2. We tied both ends tight
with string.
3. We place several drops
of iodine starch indicato
into a cup of water.

32. We placed the dialysis tube in cup to
see what happens:

33. • The will
Our predictions: of the
dialysis tube because
the
.
• The will
the tube because
the
.
• The will stay
inside the tube because
the .
.

34. Results:

35. The starch molecules were too large to diffuse out. Inside
dialysis tube turned blue-black (purple-black) because the
starch indicator (iodine) diffused into tube & change the
starches’ color.

36. A sample of the liquid from outside the
tubing turned glucose indicator orange
because the small glucose diffuse out.

37. Indicators:

38. Indicators are used to determine if a
substance (ex. Starch or glucose) is present
(is there).

39. Starch indicator (iodine) turns purple-black
if Starch is present (is there).

40. Glucose indicator turns orange if glucose is
present (is there).

41. Diffusion: the movement of molecules
from areas of high concentration to
areas of low concentration without
using energy.

42. Diffusion: the movement of molecules
from areas of high concentration to areas
of low concentration without using energy.
More Less
sugar sugar
More
sugar Less sugar
97%
Cell has Surrounding has
97% 92% water
water
Cell has inside
surrounding
94%
Area has
water
96% water
inside

43. Diffusion: molecules move from high
concentration to low concentration
without using energy.
More Less
sugar sugar
More
sugar Less sugar
97%
Cell has Surrounding has
97% 92% water
water
Cell has inside
surrounding
94%
Area has
water
96% water
inside

44. Diffusion: molecules move from high
concentration to low concentration
without using energy.
Cell has Surrounding has
100% 6% water
water
surrounding Cell has inside
Area has 6% salt
100% water inside

45. Diffusion molecules move from areas
of high concentration to areas of low
concentration.

46. Diffusion molecules move from areas
of high concentration to areas of low
concentration.

47. Why will easy for molecule B diffuse
into the cell but hard for molecule A?

49. Another part of the diffusion through
a membrane dealt with red onion
cells.

50. What you did:
we looked at slices of red onions, then….
Salt water was added to the onion slices.
Salt
water

51. First we saw view A: normal red onion
cells.
After the salt solution: the onion cells
shriveled.

52. Then we put distilled (zero salt) water
on the shriveled cells… they swelled

53. Remember: salt solutions cause cells to
shrivel. Distilled water causes cells to
swell.

55. Now the beaks of finches lab:
Darwin’s
finches

56. Know how to read and use this chart:

57. The outer circle has the names and
drawings of the bills.

58. The next two circles describe the type
of the bills each species has.

59. The inner circle shows the type of the
food each species eats.

60. This is another finch chart that has
appeared on previous regents exams.

61. Now answer 15-23.

62. Gel
electrophoresis:

63. Gel electrophoresis is a method of
analyzing DNA (also RNA & proteins)

64. The DNA (or RNA & proteins) are cut
using enzymes…

65. The DNA (or RNA & proteins) samples are
put into wells on the gel and an electric
current is run. The electricity makes the
DNA bands more

69. Uses of gel electrophoresis:

70. 1. Evolutionary relationships: if organisms
are related.
Bands of
DNA

71. 2. Gel electrophoresis can be
used to determine paternity
Who the parent or who the relative
is.

72. 3. Gel electrophoresis can be used for
genetic testing. For genetic disorders

73. 4. To solve crimes using DNA

74. Gel electrophoresis separates the DNA
bands by size. The smallest move fastest
through the gel.
Bands of
DNA

75. The DNA results from gel
electrophoresis is often used to make
claudogram trees!

76. Gel electrophoresis is 99% or more
accurate…. It is how we know humans
are related to the other great apes.

77. Gel electrophoresis is 99% or more
accurate…. It is how we know humans
are related to the other great apes

78. It is how we know if someone is guilty
or innocent of a crime….

79. It is how we know who the “baby
daddy” is on Maury or Jerry Springer!
You ARE
the
father!

80. In the Relationships and Biodiversity lab we
were looking for which plant was related to
BotanaCurus, a hypothetical cancer
treatment.

81. The plants has similar appearance, seeds & microscope slides…

82. We used gel electrophoresis (DNA &
Amino acids) to determine which plant was
related to BotanaCurus.

83. We used gel electrophoresis (DNA &
Amino acids) to determine which plant was
related to BotanaCurus.

84. Remember: DNA (gel electrophoresis) &
amino acids are the most accurate way to
identify or determine relationships.

85. Which the most closely related to A,
according the the DNA bands?

86. Which the most closely related to A,
according the the DNA bands?

87. Which organisms are the most closely
related according to their amino acids?

88. Now answer: 24- 46.

89. Paper chromatography:

90. Chromatography: a method of
separating different molecules in a
mixture.

92. The final mandatory lab is the
making connections lab

93. The human body is like a machine
with many complicated systems.
All the systems must work together
to maintain homeostasis.

94. All of our organ systems work together
to maintain our homeostasis.
Examples:
• Our muscular system moves our body. It gets
Oxygen from our respiratory system in order
to produce ATP. The circulatory system brings
the oxygen to the muscles. Our excretory
system sweats to keep the muscles cool (from
over heating).

96. When we’re very active. All of our
systems speed-up to keep up with the
increased activity.

97. Why does running cause more exhaled
air than sitting?

98. Sample regents question

99. Sample regents question

100. Sample regents question

101. Sample regents question

102. Sample regents question

103. Now complete all the remaining
questions.