Chapter 1 Flashcards
1
Q
What is an organism
A
An organism is a life-form—a living entity made up of one or
more cells
2
Q
Three of the greatest unifying ideas in all of science, which
depend on the five characteristics just listed, laid the groundwork for modern biology, are
A
the cell theory, the theory of evolution,
and the chromosome theory of inheritance
3
Q
An explanation for a very general class of phenomena or observations that is supported by a wide body of
evidence is a
A
Theory
4
Q
All living organisms share 5 characteristics, which are:
A
- Cells (Cell Theory - Robert Hooke and Anton van Leeuwenhoek, late 1660s). All organisms are made of membrane-bound cells
- Replication. All organisms are capable of reproduction
- Evolution (Theory of evolution by natural selection -
Charles Darwin and Alfred Russel Wallace, 1850s). Populations of organisms are continually evolving. - Information. All organisms process hereditary information encoded in
genes as well as information from the environment (The chromosome theory of inheritance - Walter Sutton
and Theodor Boveri, 1902) - Energy. All organisms acquire and use energy
5
Q
A hypothesis is a
A
Testable statement that explains
something observed
6
Q
A prediction is a
A
Measurable or observable result that
must be correct if a hypothesis is valid
7
Q
What allows researchers to test the effect of a factor on a particular phenomenon
A
An experiment
8
Q
Louis Pasteur’s hypothesis (fundamental to Cell Theory) states that
A
– Cells arise from cells
– Cells do not arise by spontaneous generation
9
Q
How did Louis Pasteur test his hypothesis
A
He placed the broth in a straight necked flask and a swan necked flask. He boiled to sterilize the flask. In the straight necked flask, preexisting cells enters from the air. In the swan necked flask, pre-existing cells were trapped in neck so no new cells enter the flask. In the swan-necked flask, no new cells were created.
10
Q
In 1858, which two scientists made the following claims:
1. All species are related by common ancestry. A species is a distinct, identifiable type of organism
2. Characteristics of species can be modified from generation to generation. This was referred to by one of the scientists as called this descent with modification
A
Charles Darwin and Alfred Russel
Wallace
11
Q
What is defined as:
– is a change in the characteristics of a population over
time.
– It means that species are related to one another and
can change through time.
A
Evolution
12
Q
A population is
A
– A group of individuals of the same species
– Living in the same area
– At the same time
13
Q
What is used to explain how evolution occurs
A
Natural selection
14
Q
Two conditions must be met for natural selection to occur in a population:
A
- Individuals must vary in characteristics that are
heritable—can be passed on - In a particular environment, certain versions of these
heritable traits help individuals reproduce more than
other versions
15
Q
If certain heritable traits lead to increased success in producing offspring, what happens
A
These traits become more common in the population over time. In this way, the population’s characteristics change as a result of natural selection acting on individuals
16
Q
Natural selection acts on
A
Individuals
17
Q
Evolutionary change occurs in
A
Populations
18
Q
Speciation occurs when
A
populations diverge to form new
species
19
Q
What is defined as:
– The ability of an individual to produce offspring.
– Individuals with high fitness produce many surviving
offspring
A
Fitness
20
Q
Adaptation is
A
A trait that increases the fitness of an individual in a
particular environment
21
Q
The chromosome theory of inheritance explains
A
- What is the source of heritable variation in traits?
- How is information stored and transmitted from
one generation to the next? - third unifying idea of biology
22
Q
Chromosomal theory of inheritance proposed in 1902 by
A
Walter Sutton and Theodor Boveri
23
Q
Chromosomal theory states
A
– Hereditary or genetic information is encoded in genes
– Genes are units located on chromosomes
24
Q
In the 1950s, what information was added to the chromosomal theory
A
- chromosomes are molecules of
deoxyribonucleic acid, or DNA
– DNA is the hereditary material
– Genes are segments of DNA that code for cell products
25
Each strand of the double helix is made up of four building blocks:
A, T, C, and G
26
DNA carries, or encodes, information needed for an organism’s
growth and reproduction
27
The two strands of the double helix are
held together by connections between the building blocks. The pairings are
– A pairs with T
– C pairs with G
28
The pairings in DNA allows
DNA to be copied, and preserves the information encoded in the
DNA
29
Who proposed that DNA is a double-stranded helix
James Watson and Francis Crick
30
What is the central dogma
- Describes the flow of
information in cells
- DNA codes for ribonucleic
acid, or RNA, which codes
for proteins
31
RNA copy is made of
the DNA’s information
32
The RNA copy is read to
determine
what building blocks to use to make a
protein
33
Why is DNA copied
to pass genetic information from
cell to cell or from one organism to its offspring
34
Copying DNA is highly
Accurate
35
What happens when a mistake is made in copying DNA?
– DNA sequence changes may lead to changes in
proteins
– Outward appearance is a product of proteins produced
– DNA sequence changes may cause changes in
outward appearance
36
At an individual level, what may increase or decrease fitness
Changes in DNA sequence
37
At population level, changes in DNA sequence may
– Lead to heritable variations that underlie diversity of life
– Make evolution possible
38
Where do the chemical reactions that sustain the diversity of life take place
inside cells and requires energy
39
Organisms have two fundamental nutritional needs:
1. Acquiring chemical energy in the form of adenosine
triphosphate (ATP)
2. Obtaining molecules that can be used as building
blocks to make DNA, RNA, proteins, etc
40
What is central to the diversification of life
How organisms acquire energy
41
What is a family tree of organisms that describes the
genealogical relationships among species with a single
ancestral species at its base
The Tree of Life
42
Phylogeny is
the actual genealogical relationships among all organisms
43
Biologists study RNA and DNA from different organisms to
– Compare sequences of the building blocks (A,T,C,G)
– Fewer sequence variations between two species may
indicate a closer relationship
44
A phylogenetic tree is used to
– Is used to show the relationships between species
– Branches that share a recent common ancestor
represent species that are closely related
– Branches that do not share recent common ancestors
represent species that are more distantly related
45
A phylogenetic tree is constructed using
- sophisticated computer programs
– arrangement of branches that is most consistent with
the similarities and differences observed in the genetic
data
46
The universal tree or tree of life includes
- a diverse array of species
- tree’s main node is the common ancestor of all living
species
47
The Three Domains of Life
proposed by Carl Woese (1990) are
1. bacteria
2. Archaea
3. Eukaryota
48
The tree of life shows
Fungi and animals are more closely related to each
other than either is to plants
49
Traditional classification schemes were often
Inaccurate
50
The location of certain branches on the tree of life is
hotly debated, and the shape of the tree will
continue to change as databases expand
51
The effort to name and classify organisms
Taxonomy
52
A taxon is
A named group
53
Who established the classification system in 1735 that is still in use today
Carolus Linnaeus
54
Each organism is given a unique two-part scientific name consisting of
the
genus and the species
55
What is made up of a closely related group of species.
Genus
56
What is made up of individuals that regularly breed together or have
characteristics that are distinct from those of other species
Species
57
Covalent bonds result from
electron sharing
58
When two hydrogen atoms form a covalent bond
their unpaired valence electrons are shared by each nucleus
59
What are substances held together by covalent bonds
Molecules
60
What are molecules in which atoms of different elements are held together
Compounds
61
Atoms may have different electronegativities, which is
the strength with which they pull electrons toward themselves
62
Electronegativity is determined by
- number of protons and the distance of the valence shell from the nucleus
- In general, moving up and to the right on the periodic table = higher electronegativity
- O > N > S,C,H,P
63
Differences in electronegativity dictate how
electrons are distributed in covalent bonds
64
What type of bond is this:
Electrons are evenly shared between two atoms
The bond is symmetrical
Example: C–H bond
Non-polar covalent
65
What type of bond is this:
Electrons are shared unevenly
Example: O–H bond
Polar covalent bond
66
Water is polar (electrons are pulled towards oxygen), so which bonds form between water molecules
Hydrogen bonds
67
Polarity (and, hence, water
solubility) is a function of
molecular shape and the
relative electronegativities
of atoms within the
molecule
68
Ionic bonds result when
electrons are transferred from
one atom to another to give both atoms full valence shells
69
An ion is an atom or molecule that
carries a charge
70
An atom that loses an electron and becomes
positively charged
Cation
71
An atom that gains an electron and becomes
negatively charged
Anion
72
Ionic bonds are the attraction between
oppositely charged ions
73
What is the electron sharing continuum
- the degree of electron sharing in chemical bonds can be thought as a continuum, from equal sharing in nonpolar covalent bonds to complete electron transfer in ionic bonds.
- Nonpolar covalent bonds (atoms have no charge), polar covalent bonds (atoms have partial charge), ionic bonds (atoms have full charge).
74
Describe how water participates in hydrogen bonds
- Water is polar
- The polar covalent bonds in water give the oxygen a partial negative charge and each hydrogen atom a partial positive charge
- The partial charges on water molecules can form up to four hydrogen bonds. The oxygen can form two; each hydrogen can form one.
75
Hydrogen bonds can also form between a water molecule
and
Any other polar molecule
76
Hydrophilic (“water-loving”) atoms and molecules
– Are ions and polar molecules that stay in solution
– They interact with water’s partial charges
77
What makes it possible for almost any
charged or polar molecule to dissolve in water
Hydrogen bonding
78
Polar molecules and ionic compounds dissolve regularly in
water
79
Hydrophobic (“water-fearing”) molecules are
– Are uncharged and non-polar compounds
– They do not dissolve in water
80
Hydrophobic molecules interact with each other through
hydrophobic interactions
81
Which molecules do not dissolve in water
- Nonpolar molecules
- In aqueous solution, nonpolar molecules are forced to interact with themselves
- This occurs because water is much more stable when it interacts with itself rather than with the nonpolar molecules
82
In terms of solubility in water, carbohydrates
vary
83
Water has several remarkable properties, largely due
to its ability to form hydrogen bonds, they include
1. Cohesive
2. Adhesive
3. Denser as a liquid than a solid
4. Able to absorb large amounts of energy
84
Cohesion is
- binding between like
molecules
– Water binds to itself by hydrogen
bonding
– Results in high surface tension
85
Adhesion is
- binding between unlike
molecules
– Water binds to plastic or glass
– Results in capillary action and
meniscus formation
86
Why does water in a glass form a dip in the middle
- water moleucles in a glass at the surface form hydrogen bonds with nearby water molecules and resist the upward pull of adhesion
- water molecules that adhere to the glass pull upward at the perimeter
87
Why do light objects not fall through the waters surface
Surface tension
88
Water resists forces that
increase its surface area
89
In ice water molecules form a
Crystal lattice due to bonding
90
In liquid water, no lattice develops because
As a liquid, bonds are continually breaking
91
Why does ice float
Liquid water is less dense than ice
92
Water molecules dissociate into
a hydrogen ion (H+) and
a hydroxide ion (OH−)
93
chemical equilibrium is when
Reaction happens in both directions at approximately the same
rate (e.g dissociation of water)
94
Since protons (H+) don’t exist by themselves, the reaction
actually produces
hydronium ions (H3O+)
95
Which substances give up protons during chemical reactions and raise the hydronium ion concentration [H3O+]
Acids
96
Adding an acid to a solution increases the concentration what in the solution
Proton concentration increases
97
What are substances that acquire protons during chemical reactions and lower [H3O+]
Bases
98
Adding a base to a solution decreases what concentration in a solution
Proton
99
The molecular weight of a molecule is
the sum of the atomic weights of all the atoms in the molecule
100
Which unit of measurement:
– Equals 6.022 × 1023 molecules
– Has a mass equal to the molecular weight expressed in
grams
A mole
101
The concentration of a substance in a solution is typically
expressed as
Molarity (moles/liter)
102
What determines how acid base reactions occur
Number of protons
103
The pH scale expresses
- proton concentration [H+] in a
solution
– Negative base 10 logarithmic scale
– pH of water is 7
104
What is the role of a buffer
- Buffers protect against changes in pH
– Life is sensitive to pH
105
Buffers allow for relatively constant conditions, this is known as
Homeostasis
106
Changes in proton concentration affect the structure and
function of
- polar or charged substances
– As well as the tendency of acid–base reactions to
occur
107
What works as a buffer in blood
Carbonic acid. Disassociation of carbonic acid in an aqueous
solution to form bicarbonate ions and protons
108
The capacity to do work or supply heat is known as
Energy
109
What are the two types of energy
1. Potential energy—stored potential to do work
2. Kinetic energy—active energy of movement
110
In molecules, potential energy is related to the position of
- shared electrons in covalent bonds
111
If the shared electrons are far from the atoms’ nuclei, the bonds are
the bonds are long and weak
112
If the electrons are shifted closer to one or both nuclei, the bonds are
the bond becomes shorter and stronger
113
A molecule’s potential to form stronger bonds is a type of
potential energy called
Chemical energy
114
Do highly electronegative particles such as oxygen increase or decrease potential energy
Highly electronegative atoms pull shared electrons closer to their own nuclei, increasing bond strength and decreasing potential energy
115
Do less electronegative particles such as carbon and hydrogen increase or decrease potential energy
They share electrons more equally, decreasing bond strength and increasing potential energy
116
The kinetic energy of molecular motion is called
Thermal energy
117
What is a measure of the thermal energy in a molecule
Temperature
118
If an object has a low temperature, its molecules are
moving
Slowly
119
If an object has a high temperature, its molecules are
moving
rapidly
120
What is a measure of thermal energy being transferred
between two objects
heat
121
What is the first law of thermodynamics
– Energy is conserved
– It cannot be created or destroyed
– It can be transferred or transformed
122
Chemical reactions are spontaneous if
– They proceed without any continuous external
influence
– No added energy is needed
123
Spontaneity of a reaction is determined by two factors
1. Products are less ordered than the reactants
Entropy (disorder) increases
2. Products have lower potential energy than the reactants (shared electrons are held more tightly than in the reactants)
124
When hydrogen and oxygen has react, the products have
Lower potential energy than the reactants. In the products, electrons are held loosely in bonds between atoms of equal electronegativities. For the reactants, electrons are held tightly by highly electronegative atoms, such as the oxygen. As a result, potential energy drops
125
The second law of thermodynamics states that
– Entropy always increases
– Chemical reactions result in products with
Less ordered energy
Less usable energy
126
Physical and chemical processes proceed in the direction that results in
lower potential energy and increased disorder
127
Why is carbon is the most versatile atom on Earth
– Because of its four valence electrons
– Because it can form many covalent bonds
128
Organic compounds are molecules that contain
- carbon bonded to other elements
– An almost limitless array of molecular shapes
– With different combinations of single and double bonds
129
The formation of carbon–carbon bonds was an important event in
Chemical evolution
130
functional groups are
important H-, N-, O-, P-, and S-containing groups found in organic compounds
131
Which functional group attracts a proton and act as bases
Amino (amines) group
132
Which functional group drops a proton, and act as acids
carboxyl (carboxylic acids)
133
Which functional group has sites that link molecules into larger, more-complex compounds
Carbonyl groups (aldehydes and ketones). Aldehydes especially react with certain compounds to form larger compounds.
134
Which functional group acts as weak acids
hydroxyl (alcohols)
135
Which functional group has two negative charges
Phosphate groups (organic phosphates)
136
Which functional group links together via disulphide bonds
Sulfhydryl groups (thiols)
