1. Introduction: The
Scientific Study Of Life
Biology 1

2. Scientific Method
2

3. Beginnings
• Aristotle (384 BCE-322 BCE or BC)
• ancient Greek philosopher
3

4. Aristotle
• Aristotle, more than any other thinker,
determined the orientation and the content of
Western intellectual history. He was the author
of a philosophical and scientific system that
through the centuries became the support and
vehicle for both medieval Christian and Islamic
scholastic thought: until the end of the 17 th
century, Western culture was Aristotelian. And,
even after the intellectual revolutions of
centuries to follow, Aristotelian concepts and
ideas remained embedded in Western thinking.
4

5. • In other words, Aristotle was so famous
that his work influenced thinking in the
Western world from his time to the
present.
• This was fine when he was right. But
he was so influential that his mistakes
were never noticed.
5

6. • Aristotle and his contemporaries believed
that all problems could be solved by
thinking about them.
• Sometimes this worked, other times it did
not.
• For example, Aristotle thought that heavy
objects would fall faster than lighter ones.
6

7. • Now that does seem reasonable at first.
And this is how “science” was done in
ancient times.
• But what did Aristotle not do?
• He never tested his ideas!
• The world would have to wait almost
2000 years for that to happen.
7

8. Galileo Galilei
•1564-1642 AD or CE
•Lived in what is today Italy
•Is considered to be the
first true scientist.
•Why????
•Because he actually did
the experiment.
8

9. • Aristotle said that heavy objects fall faster
than lighter ones.
• So Galileo asked, “How much faster?”
• So he sent students up to the top of a
building and had them drop a heavy ball
and a lighter one off at the same time. He
had other students waiting below to
measure the difference in time between
the two hitting the ground.
9

10. • Today of course we know what
happened. Much to everyone’s surprise
both balls hit the ground at about the
same time!
• This shows that it is much preferred to
test your ideas rather than merely think
about them.
• One test is worth a thousand expert
opinions. Bill Nye
10

11. Key Idea
• When conducting an experiment, change
one factor and keep everything else
exactly the same.
• The one thing you change is called the
variable.
• All the things you keep the same are called
controls.
11

12. Galileo’s Experiment
• What was the variable in Galileo’s
experiment?
• The weight of the balls.
• What were some controls?
• Dropped from same height.
• Dropped at same time.
• Balls had same shape/size.
12

13. Scientific Method Steps
• Make an observation
• State the problem.
• Make a hypothesis.
• Conduct the experiment.
• Record/analyze data.
• Make a conclusion.
• Report findings to others so they can repeat
the experiment.
13

14. How is biological research done?
The Scientific Method
Based on Hypothetic-deductive method
Step to scientific method
1. Making observations about the natural world
2. Asking a question about what you have observed
3. Construct hypotheses that may answer your
question
14

15. 4. Test the hypothesis by conducting
experiments or making extensive observations
in nature
Organize and collect the data. (charts, graphs,
and tables)
a. quantitative data- numeric
values from counting or
measuring
b. qualitative data- descriptive
characteristics
Your experiment will have one independent
variable and one dependent variable
15

16. Testing your Hypothesis:
Experiment
• A procedure to test the hypothesis.
16

17. Experiment
Variable – factor in the experiment that is
being tested
17

18. Experiment
A good or “valid” experiment will only have
ONE variable!
18

19. Controls and Variables
19

20. What is the Purpose of a
Control?
• Controls are NOT being tested
• Controls are used for COMPARISON
• The factor that is changed is known as
the independent variable .
• The factor that is measured or observed
is called the dependent variable .
20

21. Independent variable is the variable that is varied or
manipulated by the researcher, and the dependent variable
is the response that is measured.
For example: the independent variable how much
vitamin C you take can influence life expectancy (dependent
variable).
• The experiment
Group One get high doses of vitamin C
Group Two goes without vitamin C
The scientists will investigate if there is any statistically
significant difference in the life span of the people who took
the high dose and those who took no dose.
21

22. 5. Draw a conclusion each hypothesis
based on the results of the experiments/
observations. Once done you analyze your
results and state a conclusion
6. If you did not answer you original question
you…
Formulate new questions based on what
you have learned
7. Repeat, repeat, repeat...
22

23. Review
Variable: the Data: the Controls: the
one thing you information you parts of the
change in an get when you experiment that
experiment. test the stay the same.
variable.
Manipulated Responding Controlling
variable: you variable: variables
change this responds to the
yourself. change you
made.
Independent Dependant Controlling
variable: on its variable: variables
own. depends on the
change you
made.
23

24. Introduction
• Biology is the scientific study of life
In Latin:
• ‘Bios’ = life
• ‘Logos’ = study of
24

25. THE
CHARACTERISTICS
OF LIFE
How we’re different from rocks.
25

26. What makes something alive?
• Biologists sometimes say that living things are
“organic”. Before we go further, let’s define this
word.
• The word “organic” sometimes means. . .
– Raised/grown without pesticides or chemical alterations
– Containing Carbon
In biology, it primarily means that
something is living, or was once living!
26

27. Scientists have
found living
things share
common
characteristics,
no matter
what the
species. . .
27

28. 1) Cells: All living things are made of cells
• Unicellular =
made of one cell
• Multicellular =
made of 2 or
more cells
28

29. 29

30. 2) Organization:
• This organization contributes to their function.
For instance: A stomach is made of. .
atoms -> molecules -> cells -> tissues -> organ (stomach)
• All of the things that come together to form a stomach
contribute their own functions to the stomach’s function
• Organs (like the stomach) are organized into organ systems
(like the digestive system).
• Organ systems work together to form an organism (like you!).
• So…the whole story is this:
atoms -> molecules -> cells -> tissues ->
organs (stomach) -> organ systems -> organism
I’m an
organ!
30

31. 3) Metabolism: All living things use energy
• Together, all of the chemical reactions that happen
in a living organisms make up its METABOLISM.
METABOLISM
• People take chemical energy (food) and change it
to heat and mechanical energy
• Plants take light energy (sun), and change it to
chemical energy (sugars)
31

32. 4) Homeostasis: Living things
expend energy to maintain a stable
internal environment.
• Some examples:
– Goosebumps
– Sweating
– Thirst Sensation
32

33. 5) Growth and Development
All living things undergo stages of growth and
development, which are determined by their own
genetic codes (DNA).
33

34. 6) Reproduction: All living things reproduce
• Asexual : Reproduction by splitting or
budding (1)
• Sexual : Reproduction involving a male
and female species(2) 34

35. To be considered alive, a
thing must possess ALL of
these 6 characteristics, not
just some. . . .
35

36. For instance, a
For instance. . .
computer. . . .
HAS: organization, uses
energy, maintains
homeostasis
but. . .
DOESN’T HAVE: cells,
growth or development, or
reproduction
36

37. Eight General Life Functions
The processes used to maintain life.
37

38. 1. Respiration
• the process of releasing stored chemical energy
stored in nutrients, that can be converted to a form
that can be used directly by the living things.
38

39. 2. Reproduction
• is the process by which living things create a
new organisms.
• Two Types:
• Asexual reproduction: single individual
produces an offspring that is identical to
the parent.
• Sexual reproduction: reproduction
involving two parents producing and off
spring that is not identical to either parent.
39

40. • 3. Regulation A response to changes within
and around the organism.
• 4. Synthesis is the process in which simple
substances are combined to make complex
substance needed by the organism. The
substance can then become part of the body.
The incorporation of these substances by an
organism is called assimilation.
* Metabolism: is the process that builds up
and breaks down complex substances (all
chemical reaction occurring within the cells of
an organism are called its metabolism.
40

41. 5. Growth the process by which living
organisms increase cell numbers and cell
size. With increasing cell number comes
cell specialization.
6. Excretion the removal of the waste
products produced by the organism.
7. Transport the exchange of materials
form the surrounding environment. In
small organisms this exchange occurs
directly with the environment. In large
organism it occurs within a system
(example: circulatory)
41

42. • 8. Nutrition the taking in of material from
the external environment and turns it into
substances that can be used by the
organism for growth and repair.
• Two types:
•Organisms that produce their own
complex substances.
•Organisms that take complex
substances from the environment.
Mnemonic device
Running, Resting and Recreation Seldom
Gave Energy To Nancy
42

43. Hierarchical organization of Life
Atom molecule cell tissue
Organism organ system organ
Population community
Ecosystem
43

44. Hierarchical organization of Life
44

45. 45

46. Classification
46

47. Classifying life
KINGS PLAY CHESS ON FAT GREEN STOOLS
47

48. The Study of Microbial
Structure: Microscopy
and Specimen
Preparation
48

49. Scale
1mm = 1,000um
49

50. Discovery of Microorganisms
Antony van Leeuwenhoek (1632-1723)
first person to
observe and
describe
micro-organisms
accurately
50

51. Types of Microscopes
• Light (compound)
• Electron Microscope
• Scanning Electron Microscope
51

52. I. Light Microscope
• compound microscopes image formed by
action of 2 lenses
Magnification: the ability to make an
object look larger then actual size.
On a light microscope this can be up
to 100X – 100 times larger
Resolution the measure of clarity of an
image.
• The ability to separate two points that
are close together.
52

53. Ocular lens
(Eyepiece)
Body Tube
Nosepiece
Arm
Objectives
Stage
Stage Clips
Coarse Adjustment
Diaphragm
Fine Adjustment
Light
Base
Always carry a microscope with one hand
holding the arm and one hand under the base. 53

54. 54

55. What’s my power?
To calculate the power of magnification, multiply the power of
the ocular lens by the power of the objective.
What are the powers of
magnification for each of
the objectives we have on
our microscopes?
55

56. Lenses
• focus light rays at a specific place called
the focal point
• distance between center of lens and
focal point is the focal length
– short focal length ⇒more magnification
56

57. focal point
57

58. Comparing Powers of Magnification
We can see better details with higher
the powers of magnification, but we
cannot see as much of the image.
Which of these images
would be viewed at a
higher power of
magnification?
58

59. Let’s give it a try ...
1 – Turn on the microscope and then rotate the nosepiece to
click the red-banded objective into place.
2 – Place a slide on the stage and secure it using the stage
clips. Use the coarse adjustment knob (large knob) to get it
the image into view and then use the fine adjustment knob
(small knob) to make it clearer.
3 – Once you have the image in view, rotate the nosepiece to
view it under different powers.
Be careful with the largest objective! Sometimes there is
not enough room and you will not be able to use it!
59

60. 4 – When you are done, turn off the
microscope and put up the slides
you used.
60

61. 61

62. Preparation and Staining of Specimens
•increases visibility of specimen
•making the internal and external
structures of cell more visible by
increasing contrast with background that
have two common features
*We will use a wet mount technique to
stain our specimens
62

63. Example: of a Staining
techniques
• Gram stain divides microorganisms into groups based on
their staining properties
63

64. primary
stain
mordant
decolorization
counterstain
positive
negative
64

65. How to make a wet-mount slide …
1 – Get a clean slide and coverslip from your teacher.
2 – Place ONE drop of water in the middle of the slide.
Don’t use too much or the water will run off the edge and
make a mess!
3 – Place the edge of the cover slip on one side of the water
drop.
65

66. 4 - Slowly lower the cover slip on top of the drop .
Cover Lower slowly
Slip
5 – Place the slide on the stage and view it first with the
red-banded objective. Once you see the image, you can
rotate the nosepiece to view the slide with the different
objectives.
You do not need to use the stage clips when
viewing wet-mount slides!
66

67. II. Electron Microscopy
• beams of electrons
are used to produce
images
• wavelength of
electron beam is
much shorter than
light, resulting in
much higher
resolution
67

68. a. An image is formed by passing a beam of
electrons (-) over the surface or through a
specimen.
b. Can be magnified over 200,000X
c. Cannot view living specimens.
• Operates in a vacuum
• Specimen are dehydrated and/ or coated
in metal.
68

69. Electron Microscope
69

70. Fly head
70

71. Surface of a fruit fly eye
71

72. III. Scanning Electron Microscope
• uses electrons reflected from the
surface of a specimen to create image
• produces a 3-dimensional image of
specimen’s surface features
72

73. Fly head
73