Biology, 7e

1
SHE'S NEW TO FOOTBALL A guy took his
girlfriend to her first football game. Afterward
he asked her how she liked the game. "I
liked it, but I couldn't understand why they were
killing each other for 25 cents," she said.
"What do you mean?" he asked. "Well,
everyone kept yelling, 'Get the quarter back!'"
2
A. Science Helps Human Beings Understand the
Natural World.

• 1. Scientific investigation is limited to
  questions that can be studied objectively.

3
The Process of Science

• Observation defining the problem you wish to
  explain.
• Hypothesis one or more falsifiable explanations
  for the observation.
• Experimentation Controlled attempts to test one
  or more hypotheses.
• Conclusion was the hypothesis supported or not?
  After this step the hypothesis is either modified
  or rejected, which causes a repeat of the steps
  above.
•  

4
History Hippocrates
5
(No Transcript)
6
A. Science Helps Human Beings Understand the
Natural World.

• 2. Scientific conclusions are subject to change
  when new techniques and equipment are available.

7
A. Science Helps Human Beings Understand the
Natural World.

• 3. Ultimate goal of science is to understand
  natural world in terms of theories.

8
Important Theories

• Cell - All organism are composed of cells
• Biogenisis Life comes only from life
• Evolution common ancestors
• Gene DNA contains all lifes information

9
B. Scientists Have a Method

• 1. Scientific method is an approach employed by
  biologists for gathering information.
• 2. Based on observations, or data in the
  scientific literature, scientists formulate a
  hypothesis.

10
B. Scientists Have a Method

• 3. Formulating a hypothesis involves inductive
  reasoning (i.e., isolated facts are used to
  generalize about an observed phenomenon).

11
The Best Hypothesis

• Scientists never say that the data prove the
  hypothesis to be true.
• The best hypothesis is the one left after
  alternative hypotheses have been rejected.

12
(No Transcript)
13
B. Scientists Have a Method

• f. Reporting the findings in a scientific journal
  allows for repeatability.

14
B. Scientists Have a Method

• 6. Some investigations are controlled
  experiments.
• a. Controlled experiments have a control group
  that does not experience the tested variable.

15
B. Scientists Have a Method

• b. Experimental variable is the step that is
  deliberately manipulated.
• c. Dependent variable is component of an
  experiment that changes due to the experimental
  variable.

16
(No Transcript)
17
(No Transcript)
18
Assumptions

• Nature is real and understandable
• Nature is orderly and uniform
• Measurements yield information
• Natural laws are consistent over space and time

19
Chapter 2

• Biology
• 6th Edition
• Campbell Reece

20
Why learn Chemistry? Who Cares?

• Understanding the mechanisms of a system allows
  one to model the details, make predictions and
  exert CONTROL.

21
Living Things are composed of Chemicals
22
The Vital Force

• Hundreds of years ago, scientists believed that
  only non-living things consisted of chemicals.
• Living Things contained a Vital Force.
• Currently, it has been shown that living and
  non-living things have the same physical and
  chemical basis.
• Although, living things contain chemicals not
  found in inanimate objects, these chemicals can
  be understood by studying their basic chemical
  properties.

23
Chemistry Achemy
24
Basic Chemical Properties

• The Universe is composed of Matter and Energy
• Matter refers to anything that takes up space and
  has mass (solid, liquid and gas).
• Matter Is Composed of Elements
• All matter (living and nonliving) is composed of
  basic elements.
• a. Elements cannot be broken down to
  substances chemical or physical properties.
• b. Six elements (C, H, N, O, P, S) are
  commonly found in living things.

25
(No Transcript)
26
Chemistry Periodic Chart
27
(No Transcript)
28
(No Transcript)
29
Elements Contain Atoms

• Chemical and physical properties of atoms (e.g.,
  mass) depend on the subatomic particles.
• Different atoms contain specific numbers of
  protons, neutrons, and electrons.

30
Chemistry Atom
31
Protons and Neutrons
Video

• Protons and neutrons are in nucleus of atoms
  electrons move around nucleus.
• Protons are positively charged particles
  neutrons have no charge both have about 1
  atomic mass unit of weight.
• Electrons are negatively charged particles
  weight about 1/1800 atomic mass unit.

32
(No Transcript)
33
Subatomic Particles of Hydrogen

• Particle Charge Mass
  Location
• Proton 1 1 Nucleus
• Neutron 0 1 Nucleus
• Electron -1 0 Shell
• Total 0 2

34
(No Transcript)
35
Isotopes have different mass

• Isotopes are atoms with the same number of
  protons but differ in number of neutrons
• e.g., a carbon atom has six protons but may
  have more or less than usual six neutrons.

36
Chemistry Atoms Isotopes
37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
Isotopes have many uses

• 1) determine diet of ancient peoples by
  determining proportions of isotopes in
  mummified or fossilized human tissues
• 2) tracers of biochemical pathways
• 3) determine age of fossils using radioactive
  isotopes and
• 4) source of radiation used in medical diagnostic
  and treatment procedures.

41
Inductively Coupled PlasmaMass Spectrometer
42
Electrons
43
Atoms have Chemical Properties

• 1. Protons are positively charged
  electrons are negatively charged. Oppositely
  charged protons and electrons are attracted to
  each other.
• 2. Atom's proton number determines
  atom's number of electrons and its chemical
  properties.
• 3. Arrangement of atom's electrons is
  determined by total number of electrons and
  electron shell they occupy.

44
Chemistry Electrons
45
(No Transcript)
46
Chemistry Bohr
47
Chemistry Bohr Nuclear Power
48
(No Transcript)
49
(No Transcript)
50
How atoms react is based on number of electrons
in outer shell.

• 1) Atoms with filled outer shells do not react
  with other atoms.
• 2) In atoms with one shell, outer shell is
  filled when it contains two electrons.

51
(No Transcript)
52
(No Transcript)
53
Chemical Bonds
54
Atoms, Molecules Compounds
Video

• 1. Molecules are atoms held together by chemical
  bonds.
• 2. Molecules form when two or more atoms of same
  element react with one another (e.g., O2).
• 3. Two or more different elements react or bond
  together to form a compound (e.g., H2O).
• 4. Electrons possess energy bonds that exist
  between atoms in molecules contain energy.

55
(No Transcript)
56
(No Transcript)
57
Ancient Global Pollution

• The first "pollution crisis" hit the Earth about
  2.2 billion years ago.
• The presence of iron oxides in fossil soils, the
  appearance of "red beds" containing metal oxides
• Points to a fairly rapid increase in levels of
  oxygen in the atmosphere at about this time.
• Oxygen levels in the Archaean -
• 1.8 billion years ago, oxygen levels 15

58
Chemistry Bonds
59
Ionic Bonding (Losing or gaining electrons)

• 1. Ionic bonds form when electrons are
  transferred from one atom to another.
• 2. Losing or gaining electrons, atoms
  participating in ionic reactions fill outer
  shells, and are more stable.

60
(No Transcript)
61
Opposite Charges in Ionic Bonding

• 3. Example sodium with one less electron has
  positive charge chlorine has extra electron that
  has negative charge. Such charged particles are
  called ions.
• 4. Attraction of oppositely charged ions holds
  the two atoms together in an ionic bond.

62
Covalent Bonding (Sharing of Electrons)

• 1. Covalent bond results when two atoms share
  electrons so each atom has octet of electrons in
  outer shell.
• 2. Hydrogen can give up electron to become
  hydrogen ion (H) or share with another atom to
  complete its outer shell of two electrons.

63
(No Transcript)
64
(No Transcript)
65
(No Transcript)
66
(No Transcript)
67
Some Covalent Bonds Are Polar

• 1. Polar covalent bonds, the sharing of electrons
  is unequal.
• a. In water molecule (H2O), sharing of
  electrons by oxygen and hydrogen is not equal
  the oxygen atom with more protons dominates the
  H2O association.

68
Oxidation Is the Opposite of Reduction

• 1. Oxidation merely means the loss of electrons
  (or loss of hydrogen atoms).
• 2. Reduction merely means the gain of electrons
  (or gain of hydrogen atoms).
• 3. In ionic reaction Na Cl NaCl-, sodium has
  been oxidized, chlorine has been reduced.

69
Water (H2O)
70
Water Is Essential to Life

• Life Evolved in Water
• 1. All living things are 70-90.
• 2. Because water is a polar molecule,
  water molecules are hydrogen bonded to each
  other.
• 3. With hydrogen bonding, water is liquid
  between 0 C and 100 C which is critical for
  life.

71
(No Transcript)
72
(No Transcript)
73
Hydrogen Bonding

• Hydrogen bond is weak attractive force between
  slightly positive hydrogen atom of one molecule
  and slightly negative atom in another or the same
  molecule.
• 1) Many hydrogen bonds taken together are
  relatively strong.
• 2) Hydrogen bonds between complex molecules
  of cells help maintain structure and function.

74
(No Transcript)
75
Water Has Unique Properties

• 1. The temperature of liquid water rises and
  falls more slowly than that of most other
  liquids.
• a. Calorie is amount of heat energy required to
  raise temperature of one gram of water 1 C.
• b. Because water holds heat, its temperature
  falls more slowly than other liquids this
  protects organisms from rapid temperature changes
  and helps them maintain normal temperatures.

76
Water has a high heat of vaporization.

• a. Hydrogen bonds between water molecules require
  a large amount of heat to break.
• b. This property moderates earth's surface
  temperature permits living systems to exist
  here.
• c. When animals sweat, evaporation of the sweat
  takes away body heat, thus cooling the animal.

77
Frozen water is less dense than liquid water.

• a. Below 4 C, hydrogen bonding becomes more
  rigid but open, causing expansion
• b. Because ice is less dense, it floats
  therefore bodies of water freeze
  from the top down.
• c. If ice was heavier than water, ice would sink
  and ponds would freeze solid.

78
(No Transcript)
79
Water is universal solvent

• Water is universal solvent, facilitates chemical
  reactions both outside of and within living
  systems.
• a. Water is a universal solvent because it
  dissolves a great number of solutes.
• b. Ionized or polar molecules attracted to
  water are hydrophilic.
• c. Nonionized and nonpolar molecules that
  cannot attract water are hydrophobic.

80
(No Transcript)
81
Water molecules are cohesive and adhesive

• a. Cohesion allows water to flow freely without
  molecules separating, due to hydrogen bonding.
• b. Adhesion is ability to adhere to polar
  surfaces water molecules have positive,
  negative poles.
• c. Water rises up tree from roots to leaves
  through small tubes.
• 1) Adhesion of water to walls of vessels
  prevents water column from breaking apart.
• 2) Cohesion allows evaporation from leaves
  to pull water column from roots

82
(No Transcript)
83
Water has a high surface tension

• Water has a high surface tension measured by how
  difficult it is to break the surface of a liquid.
• a. As with cohesion, hydrogen bonding
  causes water to have high surface tension.
• b. Permits a rock to be skipped across
  pond surface supports insect walking on water
  surface.

84
(No Transcript)
85
Chemistry pH
86
Buffers keep pH steady

• a. Buffers stabilize pH of a solution by taking
  up excess hydrogen or hydroxide ions.
• b. Carbonic acid helps keep blood pH within
  normal limits H2CO3 H HCO3-.

87
(No Transcript)
88
The End.