Week 1 wednesday: Bio-chem Flashcards
1
Q
chemicals are the stuff that make up: (3 parts)
A
our bodies, the bodies of other organisms and the physical environment
2
Q
life’s chemistry is tied to water, what are they? (3 parts)
A
a)life first evolved in water. b)all living organisms require water. c)the chemical reactions of your body occur in cells consisting of 70-95% water.
3
Q
organisms are composed of elements in combinations called compounds. living organisms are composed of __, which is anything that occupies space and has __ (weight).
A
weight, mass
4
Q
matter is composed of chemical __.
A
elements
5
Q
an __ is a substance that cannot be broken down to other substances.
A
element
6
Q
there are __ elements in nature and only a few exist in a pure state
A
92
7
Q
a __ is a substance consisting of two or more different elements in a fixed ratio.
A
compound
8
Q
sodium chloride is a compound of __ + __?
A
equal parts sodium Na and equal parts chlorine Cl
9
Q
how many elements are essential to life?
A
25
10
Q
what 4 elements make up about 90% of the weight of most living organisms?
A
oxygen, carbon, hydrogen, and nitrogen
11
Q
what are trace elements?
A
common additives to food and water and are only necessary in minute quantities and can prevent disease
12
Q
without __ your body cannot transport oxygen.
A
iron
13
Q
an __ deficiency prevents production of thyroid hormones resulting in goiter.
A
iodine
14
Q
__ is added to municipal water and dental products to help reduce tooth decay
A
fluoride
15
Q
several chemicals are added to food to: (3 parts)
A
a)help preserve it. b)make it more nutritious. c)make it look better
16
Q
atoms consist of what 3 things?
A
protons, neutrons, and electrons
17
Q
an __ is the smallest unit of matter that still retains the properties of an element.
A
atom
18
Q
protons are __ charged
A
positively charged
19
Q
electrons are __ charged
A
negatively charged
20
Q
neutrons are electrically __
A
neutral
21
Q
neutrons and protons are packed into an atom’s __?
A
nucleus
22
Q
what orbits the nucleus?
A
electrons
23
Q
the negative charge of electrons and the positive charge of protons keep electrons near the __.
A
nucleus
24
Q
the number of __ is the atom’s atomic number
A
protons
25
an atom's __ __ is the sum of the number of protons and neutrons in the nucleus
mass number
26
the __ __ is approximately equal to its mass number
atomic mass
27
although all atoms of an element have the same atomic number, some differ in __ number
mass
28
different isotopes of an element have (2 parts)
a)the same number of protons. b)but different number of neutrons
29
different isotopes of an element behave __ in chemical reactions
identically
30
in radioactive isotopes, the nucleus decays spontaneously giving off __ and __
particles and energy
31
radioactive isotopes can __ or __ us
help or harm
32
living cells cannot distinguish between isotopes of the same elements, therefore radioactive compounds in metabolic processes can act as __
tracers
33
instruments can detect radioactivity, leaving the fate of radioactive tracers can be monitored in __ __
living organisms
34
a radioactive imaging instrument that uses position-emission tomography (PET) detects the __ of injected radioactive materials
location
35
PET scans are useful for diagnosing __ __ and __
heart disorders, cancer, and brain research
36
radioactivity can also be dangerous (2 parts)
a)uncontrolled exposure can cause damage to some molecules in a living cell, especially DNA. b)chemical bonds are broken by the emitted energy which causes abnormal bonds to form
37
the distribution of __ determines an __ chemical properties
electrons, atom's
38
of the 3 subatomic particles -protons, neutrons, electrons - only __ are directly involved in chemical activity
electrons
39
electrons occur in energy levels called __ __
electron shells
40
information about the distribution of electrons can be found?
in the periodic table of elements
41
an atom may have 1,2, or 3 electron shells surrounding the nucleus. explain this process
the # of electrons in the outermost shell determines the chemical properties of the atom. Atoms whose outer shells are not full tend to interact with the other atoms, participating in chemical reactions.
42
atoms with incomplete outer shells tend to react so that both atoms end up with __ __ __
completed outer shells
43
these atoms may react with each other by __, __ or __ electrons
sharing, donating or receiving electrons
44
these atom reactions usually result by staying together held by attractions called __ __
chemical bonds
45
covalent bonds join atoms into __ through electron sharing
molecules
46
the strongest kind of chemical bond is a __ __ in which two atoms share one or more outer-shell electrons
covalent bond
47
two or more atoms help together by covalent bonds form a __
molecule
48
a covalent bond connects two hydrogen atoms in a molecule of the gas __
H2
49
there are # different ways to represent common molecules
4
50
atoms in a covalent bonded molecule continually compete for shared electrons (2 parts)
a)the attraction (pull) for shared electrons is called electronegativity. b)more electronegative atoms pull harder.
51
in molecules of only one element, the pull toward each atom is equal because each atom has the same __
electronegativity
52
the bonds formed are called __ covalent bonds
nonpolar
53
water has atoms with different electronegativities (5 parts)
a)oxygen attracts the shred electrons more strongly than hydrogen. b)so the shared electrons spend more time near oxygen. c)the oxygen atom has a slightly negative charge and the hydrogen atoms have a slightly positive charge. d)the result is a polar covalent bond. e)because of these polr covalent bonds, water is a polar molecule.
54
ionic bonds are attractions between ions of __ charge
opposite
55
an __ is an atom or molecule with an electrical charge resulting from gain or loss of electrons
ion
56
when an electron is lost a __ charge results
positive
57
when an electron is gained a __ charge results
negative
58
when the attraction of opposite charges holds the ions together it is called an __ __
ionic bond
59
__ is a synonym for an ionic compound
salt
60
hydrogen bonds are __ bonds important in the chemistry of life
weak
61
most large molecules are held in their three-dimensional functional shape by __
bonds
weak
62
hydrogen, as part of a polar covalent bond, has a partial __ charge
positive
63
the charged regions on molecules are electrically attracted to __ charged
regions on neighboring molecules
oppositely
64
because the positively charged region is always a hydrogen atom, the bond is called a
__ bond
hydrogen
65
chemical reactions make and break chemical bonds: (3 parts)
a)the structure of atoms and molecules determines the way they behave. b)atoms combine to form molecules. c)hydrogen and oxygen can react to form water
66
the formation of water from hydrogen and oxygen is an example of a __ __
chemical reaction
67
the reactants are converted to the __
product
68
chemical reactions do not create or destroy matter they only __ it
rearrange
69
photosynthesis is a chemical reaction that is essential to life on earth (explain)
carbon dioxide (from the air) reacts with water. sunlight powers the conversion to produce the products glucose and oxygen
70
hydrogen bonds make liquid water __
cohesive
71
the tendency of molecules of the same kind to stick together is cohesion. (explain)
cohesion is much stronger for water than other liquids. most plants depend upon cohesion to help transport water and nutrients from their roots to their leaves.
72
the tendency of 2 kinds of molecules to stick together is __
adhesion
73
cohesion is related to __ __ - a measure of how difficult it is to break the surface of a liquid
surface tension
74
__ __ give water high surface tension making it behave as if it were coated with an invisible film
hydrogen bonds. water striders can stand on water without breaking the surface
75
water's hydrogen bonds moderate __
temperature
76
because of hydrogen bonding, water has a greater ability to resist temperature change than any other liquids. (heat and temperature explain)
a)heat is the energy associated with movement of atoms and molecules in matter. b)temperature measures the intensity of heat.
77
heat is __ when hydrogen bonds form
released
78
heat must be __ to break hydrogen bonds
absorbed
79
when a substance evaporates, the surface of the liquid that remains behind cools down in the process of __ __
evaporative cooling. this cooling occurs because the molecules with the greatest energy leave the surface
80
ice is __ dense than liquid water
less
81
water can exist as 3 things
gas, liquid, solid
82
water is less dense as a solid than a liquid because of __ __
hydrogen bonding
83
when water freeze each molecule forms a stable hydrogen bond with its neighbours (2 parts)
a)as ice crystals form the molecules are less densely packed than in a liquid water. b)because ice is less dense than water it floats
84
water is the solvent of life. a __ is a liquid consisting of a uniform mixture of 2 or more substances
solution
85
the dissolving agent is the __
solvent
86
the substance that is dissolved is the __
solute
87
an __ solution is one in which water is the solvent
aqueous
88
water's versatility as a solvent results from the __ of its molecules
polarity
89
polar or charged solutes __ when water molecules surround them, forming aqueous solutions
dissolve
90
__ is an example of a solute that will go into solution in water
salt
91
the chemistry of life is sensitive to __ and __ conditions
acidic and basic
92
a compound that release H+ to a solution is an __
acid
93
a compound that accepts H+ is a __
base
94
the pH scale describe how acidic or basic a solution is. the scale ranges from #-# and each pH unit represents a tenfold change in the concentration of H+
0-14
95
a __ is a substance that minimizes changes in pH
buffer. a buffer accept H+ when it is in excess and it donte H+ when it is depleted
96
acid __ and ocean __ threaten the environment
precipitation and acidification
97
when we burn fossil fuels (coal, oil, gas) air polluting compounds and __are released into the atmosphere
CO2
98
sulfur ad nitrous oxides react with __ in the air to form acids
water. these acids fall to earth as acid precipitation which is rain, snow, fog with a pH lower than 5.2
99
CO2 dissolving in seawater lowers ocean pH in a process known as __
ocean acidification
100
the search for extraterrestrial life centres on the search for water. the emergent properties of water support life on earth
when astrobiologists search for signs of e.t. life on distant planets they look for water. NASA has found evidence that water was once abundant on mars
