UNIT 1 EXAM Flashcards
A(n) __________ refers to 2 or more atoms held together by covalent bonds.
Molecule
The core, or overarching theme of biology is
Evolution
All of the organisms on your campus make up
a community
Ecosystem dynamics include two major processes. What are they?
- chemical nutrients recycle. (chemicals cycle)
- energy flows
Nutrients are always recycled. Energy flows through the system, typically entering as solar energy and leaving as heat.
This kind of reasoning flows from specific observations to important generalizations
inductive reasoning
An ionic bond involves
an attraction between ions of an opposite charge
Trace elements are those required by an organism in only minute quantities. What is a trace element that is required by humans and other vertebrates?
Iodine
A water sample from a hot thermal vent contained a single-celled organism that had a cell wall but lacked a nucleus. What is its likely classification?
Archaea
Which of the following best describes the logic of scientific inquiry?
If my hypothesis is correct, i can expect certain test results
Which kingdom within the domain Eukarya is composed of organisms that are generally unicellular (single-celled)?
Protista
Which series of terms is in the correct sequence of biological organization, from the simplest to the most complex?
(simplest is the smallest, then most complex is the bigger ones)
cell, tissue, organ, population, community
Emergent properties of living systems are defined as properties that
are due to the arrangement and interactions of parts as complexity increases.
Emergent properties
are novel properties not present at the level of biological organization just below.
Emergent properties arise from the arrangement and interactions of parts as complexity increases.
Which of the following is an example of qualitative data?
The fish swam in a zigzag motion
Which of the following statements is most clearly inductively derived?
If the animals observed require organic molecules as nutrients, then it can be concluded that all animals require organic molecules as nutrients.
Induction moves from a set of
specific observations (humans require organic molecules, fish require organic molecules, etc) to reach a general conclusion (all animals require organic molecules).
Eukaryotic organisms that decompose dead organisms and absorb nutrients are generally found in which kingdom?
Fungi
Kingdom Fungi are
eukaryotic decomposers that obtain their nutrients by breaking down dead organisms and organic wastes.
Protists and bacteria are grouped into different domains because
protists have a membrane-bounded nucleus, which bacterial cells lack
At which point is a scientific investigator most likely to use deductive reasoning?
in establishing a test of a hypothesis.
In deduction, reasoning flows from
the general to the specific.
Deductive testing would take the form of “if…then” logic.
The best method for determining whether bean plants require sodium is to
grow bean plants with and without sodium.
In hypothesis-based scientific inquiry,
the experiment must have an experimental group and a control group.
In the case of whether the bean plants require sodium, growing bean plants with sodium would constitute the experimental group, and growing bean plants without the addition of sodium would constitute the control group.
A company was testing a new drug it thought would help decrease the risk of transmission of viruses from mother to fetus. In an experiment to test the compound, an investigator gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with a type of virus known to cause disease in rats. At the same time, 400 other pregnant rats were given only the virus. Of the rat pups born to the females that received both the virus and the drug, 203 showed no symptoms of the disease; 205 rat pups born to the virus only females showed symptoms. From these data, we can best conclude
that the drug seems to have little effect on viral transmission at the dosage given.
Approximately equal numbers of pups were affected in both groups (experimental group 400-203=197, control group=205), suggesting that the drug was probably not effective at the dosage given.
A theory is
a well-supported concept that has broad explanatory power.
Theories are
comprehensive and become widely accepted if they are supported by a large body of evidence
Which of the following is outside the realm of scientific inquiry?
addressing ethical dilemmas.
Questions of ethics are not amenable to solution by experiments or observations.
Which of the following can be considered a biological system?
a pond, the biosphere, a single liver cell, and a salmon’s cardiovascular system.
A (Biological) system is a
combination of components that function together. It can be defined at any scale.
Two garden plots were planted with corn. The soil was similar in each, and equal amounts of water were applied to each plot. One plot was fertilized, and the other was not. The experimenters measured the yield as bushels of corn from each plot. The plot that did not receive the fertilizer was the
control plot.
The control refers to the plot that does not receive experimental treatment or the variable being test, in this case, the fertilizer.
What is the fundamental unit of structure and function in living organisms?
cell
The cell is the
fundamental structural and functional unit of both single-celled and multicellular organisms.
Natural selection tends to act at which level?
Population.
Natural selection selects for
organisms within a population that are best adapted to their local environment.
Which of the following statements best describes what is meant by “emergence”?
The whole is greater than the sum of the parts.
In experimental procedures, repetition of the procedures
is necessary before concluding that a given set of results is correct.
Repetition of tests is
crucial to the process of science. Only when a result is repeatable can it be considered correct.
What are some observations or inferences on which Darwin’s theory of natural selection is based?
- A population can become adapted to its environment over time.
- There is heritable variation among individuals.
- Because of the overproduction of offspring, there is competition for limited resources.
- Individuals whose inherited characteristics best fit them to the environment will generally produce more offspring.
Which is NOT an observation or inference on which Darwin’s theory of natural selection is based?
Poorly adapted individuals never produce offspring.
A controlled experiment is one that
tests experimental and control groups in parallel
A hypothesis must be testable and falsifiable to be scientifically valid. Being testable and falsifiable means that
some conceivable observation or experiment could reveal whether a given hypothesis is incorrect.
Hypotheses should be phrased
in a way that enables one to make predictions that can be tested and falsified by experiments or observations.
With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of ______ and traits that differ among organisms as evidence of _______.
descent from a common ancestor . . . adaptation through natural selection.
Many shared traits have been
derived from common ancestry. The modifications to those shared traits can usually be attributed to adaption evolution by natural selection.
Which of the following domains is prokaryotic?
Archaea.
Domain Archaea are
among the simplest kinds of organisms, the prokaryotes.
How is the information encoded in DNA actually used by organisms?
The information in DNA is transcribed to RNA and then translated into protein.
What is the appropriate term for an interacting group of individuals of a single type occupying a defined area?
a population.
Only the organisms of a given species that have the opportunity to interact with one another are considered to be
within the same population
Radon is a radioactive gas that seeps into homes from the soil. It is thought to be a cause of lung cancer. A research team investigates this theory. They gather large amounts of data on basement radon concentrations and lung cancer rates and conclude that the more radon there is in a home, the more likely are people living in those homes to develop lung cancer. After the study is published, other researches criticize it by asserting that the studied neighborhoods with higher radon concentrations also have a higher percentage of older people and a higher percentage of cigarette smokers than the low-radon neighborhoods. Both advanced age and cigarette smoking increase the risk of lung cancer. This criticism, if correct, shows that the radon study suffered from
uncontrolled variables.
An important feature of the scientific process is the
controlled experiment in which two groups are established and treated exactly alike, except for the one variable that the experiment is designed to test.
Which of the following best describes the unity among all organisms?
the structure and function of DNA
Systems biology is mainly an attempt to
understand the behavior of entire biological systems
Experimentation is only one part of the process of scientific inquiry, but it is a very important step because it
allows rejection of a hypotheses
Experimentation is important because
hypotheses can be rejected if contradictory evidence emergences
Which of the following is an attribute of living things?
They must be able to evolve and adapt.
The energy used by most organisms for metabolism and growth ultimately comes from
the sun.
Energy for most life ultimately comes from
the light energy of the sun, trapped in the chemical bonds of molecules synthesized by photosynthetic organisms.
What is the molecule that can account for both the unity and the diversity of life?
DNA
The uniformity of coding in DNA is
virtually universal. Life’s variety arises from variations in the nucleotide sequences of inherited DNA molecules, the substance of genes.
What are some attributes of living things?
- All living things maintain complexity of order.
- Populations of living things evolve.
- All living things use DNA as their genetic material.
- They convert energy from one form to another.
Which is NOT an attribute of living things?
All living things require oxygen
There are many species of bacteria that live in the absence of
oxygen.
So, all living things do NOT require oxygen.
What are some examples of emergence?
- A calculator
- An organ
- Bees making a beehive
- Water’s high specific heat
Emergence is not restricted to
biological systems
Which of the following statements best distinguishes hypotheses from theories in science?
Hypotheses usually are relatively narrow in scope; theories have broad explanatory power.
Should an experiment test only one variable at a time?
Yes, an experiment should only test one variable at a time. This ensures that the experimental outcome is clearly due to one identifiable factor.
Treatment of an experimental group should differ from treatment of a
control group by only a single variable so that the researcher can determine what causes the observed effect.
A particular carbon isotope has an atomic number of 6 and an atomic mass of 14. The respective number of neutrons, protons, and electrons that this carbon isotope has is
8, 6, and 6
Evaluate the following statement: Oxygen is not a greenhouse gas; therefore, gases containing oxygen, such as ozone, nitrous oxide, and carbon dioxide, are not greenhouse gases either.
False. Compounds can have emergent properties that are very different from the elements that form them.
Emergent properties of compounds are
more than simply the sum of their parts.
Compounds represent a higher level of organization than
elements and can have characteristics that are different than the elements that compose them.
For most atoms, a stable configuration of electrons is attained when the atom
has eight electrons in its outermost shell
An atom with a complete valence shell is
unreactive
Which of the following four statements, if any, is true regarding essential elements and living organisms?
Although all forms of life require iron, other elements are required only by certain species.
Humans and other vertebrates require small amounts of
iodine in their diets to maintain thyroid function. This is a requirement not observed among invertebrates.
The most common form of calcium has 20 protons, 20 neutrons, and 20 electrons. Which of the following elements would be an isotope of calcium?
an atom with 20 protons, 21 neutrons, and 20 electrons
Isotopes of an element have the same number of protons but different numbers of
neutrons
Pharmaceutical researches are often interested in blocking particular receptor proteins on cell surfaces. What chemical property of a molecule would be most important for this type of application?
the molecule’s shape.
The molecule would have to have te correct shape to bind to the receptor protein and block it.
Ionic bonds form as a result of
attraction between ions that have opposite charges
Oppositely charged ions attract each other electrically, forming an
ionic bond.
Isotopes of an element will always differ in
atomic mass
Atomic mass refers to the number of
protons and neutrons in an atom.
Atomic forms of an element with the same number of protons (atomic number) but different number of neutrons are
isotopes of that element
A sodium atom has a mass number of 23. Its atomic number is 11. How many electrons doe it have it if is not an ion?
11
The number of electrons will equal the number of
protons in an electrically neutral atom
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
The rates of the forward and reverse reactions are equal.
What are the four most abundant elements found in living systems?
Hydrogen, oxygen, nitrogen, and carbon
Hydrogen, oxygen, nitrogen, and carbon make up about
96% of living matter
Compared with 31P, the radioactive isotope 32P has
one more neutron
How many electrons would be present in the valence shell of a sulfur atom (atomic number 16, mass number 32)?
six electrons
We can represent atoms by listing the number of protons, neutrons, and electrons-for example, 2p+. 2n0, 2e- for helium. Which of the following represents the 18O isotope of oxygen?
8p+, 10n0, 8e-
What coefficients must be placed in the following blanks so that all atoms are accounted for in the products?
C6H12O6 S _______ C2H6O + _________CO2
2;2
Evaluate the following statement: Concentrations of trace elements in the environment above what is required by organisms generally has no effect on those organisms.
False. Elevated concentrations of some trace elements such as cobalt and chromium can be toxic.
Some nonessential elements are known to be toxic to organisms.
What is the role of van der Waals interactions in biological molecules?
Although they are weak bonds, van der Waals interactions help to reinforce the three-dimensional shapes of large molecules.
Weak bonds are important in the three-dimensional structure of
most large biological molecules, and they play a role in molecular interactions.
In the term trace element, the adjective trace means that
the element is required in very small amounts.
Some groups of elements react chemically in similar ways. For example, the chemistry of sodium and the chemistry of lithium are similar. The chemistry of chlorine and the chemistry of iodine are also similar. These similarities in chemistry result when different elements hace similar
numbers of outer-shell electrons
Atoms with the same number of electrons in their valence shells
exhibit similar chemical behavior or reactivity
Which of the following subatomic particles has appreciable mass and lacks a charge?
Neutron
A neutron weighs about
1.7 x 10-24 grams (has a mass close to 1 dalton), and it is electrically neutral
A covalent bond is likely to be polar if
one of the atoms sharing electrons is much more electronegative
If one atom is more electronegative than the other,
electrons of the bond will not be shared equally, resulting in a polar covalent bond.
Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two electrons?
The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a 2+ charge.
The loss or gain of an electron(s) does not influence the
atomic number (number of protons) or the mass number (number of protons plus neutrons) of an atom.
What is an example of a trace element?
Copper
The number of protons in an uncharged atom
equals the number of electrons
An uncharged atom has an equal number of
protons and electrons
An element has 8 protons, 9 neutrons, and 8 electrons, Its atomic number and atomic mass, respectively, are
8 and 17
A polar covalent bond is a bond that
has shared electrons pulled closer to the more electronegative atom
Polar covalent bonds share electrons
unequally, so that one part of the molecule has a partial negative region and one part a partial positive region.
There are ____ naturally occurring elements.
92.
About 25 of the 92 are essential to life.
WHen the proton number and electron number are unequal, the atom or molecule
is an ion
WHen the proton number and electron number are unequal,
the atom or molecule has a net positive (cation) or negative charge (anion).
Which of the following molecules has the shape of a completed tetrahedron?
methane (CH4).
The nucleus of the carbon atom is at the center of the tetrahedron, with its four covalent bonds radiating to the hydrogen nuclei at the corners of the tetrahedron.
Which statement is true of all atoms that are anions?
The atom has more electrons than protons.
A hydrogen bond
is a weak chemical bond
Hydrogen bonds are
weak chemical bonds that are very important in the chemistry of life
The chemical characteristics or reactivity of an element depend mostly on the
number of electrons in its outermost shell
Only electrons are directly involved in the
interactions between atoms, and the number of electrons in the outermost shell determines the chemical behavior or reactivity of an atom.
An atom that normally has ____ in its outer shell would not tend to form chemical bonds with other atoms.
eight electrons
Eight electrons in the outer shell will leave
no unpaired electrons in the valence shell. IN this configuration atoms are chemically unreactive or inert.
The reactivity of an atom arises from
the existence of unpaired electrons in the valence shell
The compound CaSO4 ionizes into a calcium ion and a sulfate ion (SO4). Calcium has two electrons in its outer shell. Upon ionization, what would you expect the charge on the sulfate ion to be?
-2.
By gaining two electrons from calcium, the sulfate ion now has a charge of -2 and calcium has a charge of +2.
Which of the following has negligible mass?
electron.
The mass of an electron is only about 1/2000 that of a proton or neutron, electrons are not considered when computing atomic mass.
An uncharged atom of nitrogen (atomic number=7_ has
seven protons and seven electrons.
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.
H2S
Which of the following states describes a reversible reaction that has reached chemical equilibrium.
The rate of the reverse reaction equals the rate of the forward reaction
When one or more pairs of valence electrons are shared by two neutral atoms, what type of bond is formed?
a covalent bond
Covalent bonds are formed between atoms that
share one or more pairs of valence electrons
What is the strongest type of bond?
A covalent bond
Water is a polar molecule. This means that
the opposite ends of the molecule have opposite electrical charges
In the case of water, oxygen is slightly negative and the hydrogen atoms are slightly
positive
Why is the increasing amount of carbon dioxide being taken up by the oceans a cause for concern?
More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to a decrease in the concentration of carbonate ion (CO32).
As seawater becomes more acidic,
carbonate ion concentration decreases. The decrease in the availability of carbonate ion makes it more difficult for marine organisms to secrete calcium carbonate shells.
Most of water’s unique features (for example, its versatility as a solvent, ability to moderate temperature, and cohesive behavior) result from the fact that
oxygen attracts electrons more than hydrogen does
Because oxygen is more electronegative than hydrogen,
water molecules are polar and form hydrogen bonds that give water its extraordinary properties
A glass of grapefruit juice, at pH 3, contains _____ H+ as a glass of a tomato juice, at pH4.
ten times as much
The pH scale is a base-10 logarithmic scale. The change from any pH value to the next smaller value represents a
tenfold increase in the hydrogen ion concentration
A solution at pH 6 contains ______ than the same amount of solution at pH 8.
100 times more H+
Pure water has a pH of 7. Why does uncontaminated rainwater have a pH of 5.6?
formation of carbonic acid from carbon dioxide and water.
The presence of carbonic acid in rainwater causes it to have a
lower pH that pure water.
Which of the following accurately relates the emergent properties of water to the effects of global warming in the Arctic?
The significant increase in Arctic air temperature over the past 50 years is causing sea ice to form later in the year, to melt earlier, and to cover a smaller area each year.
The warming that has occurred in the Arctic has significantly affected the seasonal balance between ice and liquid water to the degree that sea ice communities are in danger.
Sweating has a cooling effect because of water’s high
heat of vaporization.
Water’s high heat of vaporization results in
evaporative cooling because when water evaporates, the surface of the water cools down.
Which of the following statements is true about acid precipitation?
It washes away some minerals that are plant nutrients, and causes some toxic minerals to accumulate.
Important plant nutrients such as calcium and magnesium may be washed away from the soil, and aluminum may build up to dangerous levels.
Water molecules have _______ than molecules of similar size, such as ammonia and methane, reflecting its capacity to absorb large amounts of heat.
a higher boiling point.
More heat is needed to vaporize 1 g of water than most other liquids.
The phenomenon responsible for maintaining the upward movement of water through a vessel is
cohesion
Cohesion is a consequence of
hydrogen bonding between water molecules
Because molecules of water are farther apart in ice than in liquid water,
ice floats
Because water molecules in ice are farther apart than in liquid water,
ice is less dense, and therefore, it floats
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules
An acid is
a compound that donates hydrogen ions to a solution
Hydrophobic molecules are ____ water
repelled by
Substances that are nonionic and nonpolar
repel water and are termed hydrophobic
The bonds that are broken when water vaporizes are
hydrogen bonds between water molecules
The absorption of human-generated CO2 by the oceans
increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for calcifying organisms
Thee absorption of CO2 by the oceans causes an increase in the carbonic acid, and hydrogen ion concentration (lower pH). The extra hydrogen ions bind wit the carbonate ion to form
bicarbonate. This reduces the amount of carbonate ions available for calcification, the production of calcium carbonate (CaCO3) by many marine organisms, including reef-building corals and animals that build shells.
If water were not a polar molecule, how would the effects of global warming differ from what are currently observed or predicted to occur in the future?
The effects would be drastically worse because the loss of the polar nature of water would greatly reduce its specific heat and its ability to moderate temperature.
A loss of the polar nature of water would equate to a loss in the ability to form
hydrogen bonds. Breaking hydrogen bonds absorbs energy, which accounts for water’s high specific heat and its ability to influence and moderate climate.
Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?
10-4 M
10^-4 M
Why are cell membranes composed primarily of hydrophobic molecules?
In order to perform their function of separating the aqueous solutions outside of cells from the aqueous solutions inside of cells, cell membranes cannot be soluble in water.
If cell membranes were hydrophilic,
they would break down and dissolve in the presence of water, rendering them useless as a barrier.
Nonpolar molecules that cluster away from water molecules are called ______ molecules
hydrophobic
Substances that are nonionic and nonpolar
repel water
The tendency of water molecules to stay close to each other as a result of hydrogen bonding
- acts to moderate temperature
- keeps water moving through the vessels in a tree trunk
- is called cohesion
- and provides the surface tension that allows leaves to float on water
A molecule that has all nonpolar covalent bonds would be
hydrophobic
The hydrophobic behavior of oil molecules results from a
prevalence of nonpolar covalent bonds. Nonpolar molecules do not have an affinity for water or other polar molecules.
What do cohesion, surface tension, and adhesion have in common with reference to water?
All are properties related to hydrogen bonding.
The extraordinary qualities of water are emergent properties resulting from
hydrogen bonding
When the pH of a solution shifts from 7 to 3, how has the hydrogen ion concentration changed?
It has increased by 10,000 times.
Because the pH number is the negative log of the hydrogen ion concentration, a change from a pH of 7 to a pH of 3 increases the hydrogen ion concentration by 10,000 times. (7-3=4; 10^4=10,000).
What water-related evidence do scientists have that suggests life may exist on other planets?
In 2008, the robotic spacecraft Phoenix found ice present just under the material on Mars’s surface, and detected sufficient water vapor in the Martian atmosphere for frost to form.
Although life-forms haven’t been found on Mars, these new findings have reinvigorated the search for signs of life, past or present, on Mars and other planets.
The reason that coastal climates are more moderate than inland climates is due primarily to water’s high
specific heat.
Because of water’s high specific heat,
water’s temperature will change less when it absorbs or loses a given amount of heat. Thus, the oceans can absorb and store a huge amount of heat and release it later when the temperature or the air has dropped.
The amount of heat required to change the temperature of 1 g of any substance by one C is defined as
the specific heat of that substance.
The specific heat of a substance is defined as the
amount of heat that must be absorbed or lost to change the temperature of 1 g of that substance by one C.
Cells are surrounded by water, and cells themselves consist of about 70 to 95% water. As a result,
- the temperature of living things tend to change relatively slowly
- waste products produced by cell metabolism can be easily removed
- a variety of nutrient molecules is readily available as dissolved solutes
- and dissolved substances can be easily transported within a cell or between cells in multicellular organisms
Which of the following is a hydrophobic material?
wax
Adhesion is best described as
the clinging of one substance to another substance
Adhesion is the attraction
of one substance to another
You can fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this phenomenon?
surface tension
Water has a greater surface tension,
a measure of how difficult it is to break the surface of a liquid, than most other liquids
The partial charges on a water molecule occur because of
the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule
Because oxygen is more electronegative than hydrogen,
electrons of the polar bond spend more time closer to the oxygen atom, resulting in a slight negative charge on the oxygen atom and slight positive charges on the hydrogen atoms.
Water is a very versatile solvent because water molecules are
polar
Because molecules of polar solvents have a positive and a negative pole,
polar solvents are excellent solvents for ions and for other polar materials
The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as
the heat of vaporization of that substance
Heat of vaporization is the
quantity of heat a liquid must absorb for 1 h of it to be converted from the liquid to the gaseous state.
Which action would involve the greatest transfer of heat?
condensing 5 g of steam to liquid water.
This would release about 2,900 calories (580 calories/gram x 5 grams).
In a group of water molecules, hydrogen bonds form between
the oxygen atom in one water molecule and a hydrogen atom in another water molecule
The slightly negatively charged region of an oxygen atom of one water molecule is attracted to the
slightly positively charged region of a hydrogen atom of another water molecule
Adding acid tends to ______ of a solution
increase the hydrogen ion concentration and lower the pH
Because pH is a negative log,
its value is inversely proportional to the hydrogen ion concentration
A substance that minimizes changes in the concentration of H+ and OH- in a solution is a
buffer
Buffers are substances that
minimize changes in the concentration of hydrogen ions and hydroxide ions in a solution; therefore, buffers maintain a relatively constant pH.
Which of the following hydrocarbons has a double bond in its carbon skeleton?
C2H4
Which of the following examples describes a unique functional property of the carboxyl group?
the covalent bond between oxygen and hydrogen is so polar that hydrogen ions tend to dissociate from oxygen reversibly.
Which of the following molecules is a weak base?
R-NH2
The amino group (-NH2) of R-NH2 can function as a base. It can accept a proton (H+).
Pharmaceutical companies are selling close to $200 billion worth of single-enantiomer drugs. Why might it be important to use only one form of an enantiomer?
One enantiomer may provide an effective treatment whereas the other may be ineffective or even toxic.
Depending on the body’s ability to recognize and use different enantiomers, one version may have dangerous effects, as in the case of methamphetamine.
Carboxyl is to _______ as ________ is to base.
Acid …… amino
A carboxyl group has
acidic properties because it can donate a proton (hydrogen ion) to a solution. The amino group acts as a base because it can pick up or accept a proton (hydrogen ion) from a solution.
A pharmaceutical company was forced to recall a pain reliever medication that had been linked to the fatalities of several hundred people. Analysis of the recalled drug revealed the presence of two isomers due to an asymmetrical carbon atom in the drug molecule. What can be hypothesized from this observation?
The isomers are enantiomers, with one having toxic effects on humans.
Enantiomers are isomers that are
mirror images of each other and that differ in shape due to the presence of an asymmetric carbon. The remarkable sensitivity of organisms means that subtle differences in molecular structure can translate to different and unintended effects on organism function.
Organic chemistry is currently defined as
the study of carbon compounds
Which functional group would you predict is part of abscisic acid (ABA)?
Carboxyl
Compounds containing the carboxyl functional group (-COOH) are known as
carboxylic acids or organic acids. They can donate a hydrogen ion (proton) to a solution due to a highly polar oxygen atom of the functional group.
Using modern equipment, a former graduate student of Stanley Miller recently reanalyzed the sample results of volcano simulation experiments that Miller conducted along with his classis experiment described in the test. This reanalysis
identified additional organic compounds that had not been found by Miller.
Although the structures of the functional groups that are the most important in life vary, they share one thing in common: They
all are hydrophilic and increase the organic compound’s water solubility.
Functional groups are all
hydrophilic
Glucose and hexanoic acid each contain six carbon atoms, but they have completely different properties. Glucose is a nutrient found in food; hexanoic acid is poisonous. Their differences must be due to different
functional groups
Functional groups most commonly determine
chemical properties such as the polarity and reactivity of molecules
At the beginning of the 19th century, it was thought that the substances that made up living things were special and could not be synthesized by ordinary chemical methods. This now-discarded theory was called the theory of
vitalism
Vitalism is a belief in a
life force outside the jurisdiction of physical and chemical laws
The first organic molecule to be synthesized from inorganic substances that could be prepared directly from inorganic substances was
acetic acid
Acetic acid was the first organic molecule synthesized from
nothing but inorganic substances
Carbon atoms are the most versatile building blocks of the molecules used by living organisms because
each carbon atom acts as an intersection point from which a molecule can branch off in up to four directions
Carbon has the potential to form molecules that can be
straight, branched, or ringed. Along with the ability to form double and triple bonds, this ability permits the formation of an almost infinite number of different molecules
Which of the following functional groups is present in all amino acids?
-NH2
This is the amino group. This group is present in all amino acids.
The ionized or dissociated carboxyl group may be written as
-COO-
The carboxyl functional group (-COOH) is an
oxygen atom double-bonded to a carbon atom that is also bonded to a hydroxyl group. When a proton or hydrogen ion dissociates from the group, the negatively charged -COO- is the result
What is the three-dimensional shape created by hybrid orbitals that are formed when a carbon atom is covalently bonded with four other atoms?
a tetrahedron with carbon in the center.
The pairs of bonding electrons are oriented as distantly as possible from one another in a tetrahedron with the carbon atom at the center and the other four atoms at the vertices of the tetrahedron.
Which of the following are properties of hydrocarbons?
hydrophobic, nonpolar, good source of stored energy.
Because they are nonpolar, hydrocarbons are
hydrophobic. They also provide energy in the forms of things such as fossil fuels and fats.
A thiol is a molecule containing a
sulfhydryl functional group
which of the following functional groups is associated with a release of energy when removed from the carbon skeleton with water that cells can harvest to perform many functions?
phosphate.
Cleaving a phosphate group from ATP releases energy that is used to perform many cellular functions
Which chemical group is most likely to be responsible for an organic molecule behaving as a base?
amino
What are the six more important chemical elements of life?
carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur.
These are all capable of forming strong covalent bonds, important in building large, complex molecules
Which of the following molecules has a carboxyl functional group?
R-COOH
The molecule R-COOH contains the carboxyl functional group (-COOH). The presence of this group would make the molecule a weak acid
A molecule has one carbon-carbon double bond and four monovalent atoms or groups. How many different geometric isomers exist for this molecule?
two.
Only two geometric isomers exist. The number of structural isomers, however, is larger
Stanley Miller’s experiments were significant because he demonstrated that
a variety of simple organic compounds could be spontaneously synthesized from components in Earth’s primitive atmosphere.
By discharging an electrode in a mixture similar to Earth’s primitive atmosphere, Miller was able to synthesize a variety of simple organic molecules.
The carbon atom is tetravalent; this means that
a carbon atom can complete its valence shell by forming four covalent bonds
With four valence electrons, carbon usually shares its four electrons in covalent bonds to
complete its outer shell
A straight-chain carbon compound constructed from ______ must obtain at least one carbon-carbon double bond.
six hydrogen, three carbon.
Which of the following functional groups increases the solubility of organic compounds in water?
- NH2
- COH
- COOH
- SH
All of the functional groups are hydrophilic and thus increase the solubility of organic molecules in water
Which of the following groups is capable of hydrogen bonding with an oxygen atom on another functional group?
- Amino
- Sulfhydryl
- Hydroxyl
- and Carboxylic acid.
All of the listed functional groups are polar, thus capable of hydrogen bonding with the oxygen of another molecule
Which of these is found in all amino acids?
both -COOH and -NH2
For a compound to be an amino acid,
it must contain at least one carboxyl functional group and one amino functional group. In addition, it may contain one or more of the other functional groups
Ethanol, propanol, and methanol are three simple alcohols. They can be grouped together because they
all share the same functional group: a hydroxy
Alcohols are distinguished by the presence of the
hydroxyl (-OH) functional group
Which action could produce a carbonyl group?
the replacement of the -OH of a carboxyl group with hydrogen
Which is an organic molecule?
CH4
Compounds containing carbon are said to be
organic
What is ATP’s importance in the cell?
ATP stores the potential to react with water, thereby removing a phosphate group and releasing energy for cellular processes.
ATP releases energy during a hydrolysis reaction that removes a phosphate group
Which element is always associated with organic chemistry?
carbon
The water molecule is a
polar molecule: the opposite ends have opposite charges
polarity allows water molecules to form
hydrogen bonds with eachother
KNOW HOW TO DRAW A WATER MOLECULE AND WHERE THERE ARE COVALENT BONDS AND HYDROGEN BONDS
in a water molecule, oxygen is
electronegative
polar means that
electrons are shared unequally
Four of water’s properties that facilitate an environment for life are
(Water’s 4 emergent properties)
- cohesive behavior
- ability to moderate temperature
- expansion upon freezing
- versatility as a solvent
They all occur because water molecules are electrically attracted to one another
Cohesion of water molecules
Water molecules stay close to one another because of hydrogen bonding.
It happens in all forms (solid, liquid, gas).
H-bonds are fragile (1/20) but collectively strong.
Collectively hydrogen bonds hold water molecules together by a phenomenon called cohesion.
Cohesion
water likes to stick to water
Hydrogen bonds are why it is
cohesive
Cohesion helps the transport of
water against gravity in plants.
As water evaporates, more is pulled upward.
Adhesion is
an attraction between different substances, for example, between water and plant cell walls.
Adhesion
water sticking to other stuff
Surface tension is
a measure of how hard it is to break the surface of a liquid
surface tension is related to
cohesion.
the surface of water is an organized arrangement of water molecules that are H-bonded to the molecules below and the water below.
An invisible film.
- water striders
- glass of water
Moderation of temperature by water
water absorbs heat from warmer air and releases stored heat to cooler air.
water can absorb or release a large amount of heat with only a slight change in its own temperature
Heat is
a measure of the TOTAL amount of kinetic energy due to molecular motion.
Temperature measures
the intensity of heat due to the AVERAGE kinetic energy of molecules.
As the average speed of molecules increases we see an increase in the temperature.
Ex. a swimmer in the ocean has higher temperature than the water, but the ocean has more heat because of its volume.
Kinetic Energy
is the energy of motion
0 degrees celsius is
where water freezes
25 degrees celsius is
room temperature
37 degrees celsius is
body temperature
100 degrees celsius is
where water boils
Water’s high specific heat can be traced to
hydrogen bonding
heat is absorbed when
hydrogen bonds break
heat is released when
hydrogen bonds form
the high specific heat of water
minimizes temperature fluctuations within limits that permit life.
ex. oceans and organisms
evaporation
is the transformation of a substance from liquid to gas
Heat of evaporation
is the heat a liquid must absorb for 1g to be converted to gas
Evaporative cooling
a process that as a liquid evaporates, its remaning surface cools
the “hottest” molecules leave.
Evaporative cooling of water helps
stabilize temperatures.
Sweating humans, sweating plants.
Humidity inhibits evaporative cooling
Ice floats in liquid water because
hydrogen bonds in ice are more “ordered” making ice less dense
if ice sank,
all bodies of water would eventually freeze solid, making life impossible on earth
Expansion upon freezing
ice floats
Versatility as a solvent
Water: the solvent of life
solution=solvent + solute
a solution is
a liquid that is a homogenous mixture of substances.
A big mixture.
ex. salt water, sugar water, kool-aid
A solvent is
the dissolving agent of a solution
the wet stuff.
ex. water, alcohol
The solute is
the substance that is dissolved
the chalks/chunks/dissolved stuff.
ex. salt, sugar
An aqueous solution is
one in which water is the solvent
water is a versatile solvent due to
its polarity, which allows it to form hydrogen bonds easily.
when an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a
hydration shell
water can dissolve anything that is
ionic
water is the solvent of
life
Example of water expanding when frozen
ice floating in water
Examples of moderating temperature
sweating, ice cubes in a glass, going in the ocean
Example of cohesion
towel drying you off, bug sticking on top of water
A hydrophilic substance
is one that has an affinity for water.
water loving.
a hydrophobic substance
is one that does not have an affinity for water.
water hating.
oil molecules are
hydrophobic because they have relatively nonpolar bonds.
molecular mass is
the sum of all masses of all atoms in a molecule.
Take the mass of each atom and add them.
Numbers of molecules are usually measured in
moles, where 1 mole (mol)= 6.02 x 10^23 molecules.
avogadro’s number and the unit dalton were defined such that
6.02 x 10^23 = 1 g
the molecular mass of something can be
any number of grams and = 1 mole
Molarity (M) is
the number of moles of solute per liter of solution
The hydrogen atom leaves its electron behind and is transferred as a proton, or a
hydrogen ion (H+)
the molecule with the extra proton is now a
hydronium ion (H3O^+), though its often represented as H+
The molecule that lost the proton is now a
hydroxide ion (OH-)
Water is at a state of dynamic equilibrium in which
water molecules dissociate at the same rate at which they are being formed
Concentrations of H+ and OH- are
equal in pure water
An acid is
any substance that INCREASES the H+ concentration of a solution.
Donates H+
have more hydrogens
A base is
any substance that REDUCES the H+ concentration of a solution
have less hydrogens.
Donates OH- that interact with H+ to form water (NaOH)
A base is NOT defined as something that
adds OH-
pH=
concentration of hydrogen ions
the exponent
pH scale is a
long scale.
10 times differences between each consecutive number (like between 1 and 2, between 5 and 6, etc)
the pH scale is all about whats going on with
hydrogens
in any aqueous solution at 25 degrees celsius the product of H+ and OH- is constant and can be written as
[H+][OH-]=10^-14
For a neutral aqueous solution,
[H+] is 10^-7, so pH= -(7)=7
Acidic solutions have pH values
less than 7
Basic solutions have pH values
greater than 7
Acids increase hydrogens H+ but
acids are the lower numbers on the pH scale.
its an inverse relationship.
the internal pH of most living cells must remain close to
pH 7
Buffers are
substances that minimize changes in concentrations of H+ and OH- in a solution.
Most buffers consist of an
acid base pair that reversibly combines with H+
buffers try to
maintain a set point
confliction of blood vessels causes
wrinkling of skin on fingers because of the sympathetic nervous system.
organic chemistry is
the study of compounds that contain carbon.
study of carbons
organic compounds range from simple molecules to
colossal ones.
methane, protein, DNA, carbohydrates
Most organic compounds contain
hydrogen atoms in addition to carbon atoms
Although C,H,O,N ratios are uniform from one organisms to another, carbon’s versatility allows for an
inexhaustible variety of organic molecules
vitalism
the idea that organic compounds arise only in organisms was disproved when chemists synthesized these compounds
Mechanism
is the view that all natural phenomena are governed by physical and chemical laws
Stanley miller proved
a mechanism view
Stanley Miller’s classic experiment demonstrated the
abiotic synthesis of organic compounds.
Electron configuration is the key to an atom’s
characteristics
electron configuration determines
the kinds and number of bonds an atom will form with other atoms
Carbon can make
4 covalent bonds
hydrogen has
a valence of 1
oxygen has
a valence of 2
nitrogen has
a valence of 3
carbon has
a valence of 4
carbon atoms can partner with atoms other than
hydrogen
carbon can make
ALOT of different shapes
hydrocarbons are
organic molecules consisting of only carbon and hydrogen
hydrocarbons are
hydrophobic.
most of their bonds are nonpolar covalent carbon to hydrogen linkages
water likes things with
charges
water doesnt like
hydrophobic bonds
isomers are
compounds with the same molecular formula but different structures and properties
structural isomers
have same molecular formulas, but different shapes.
same number of like carbons and hydrogens or something.
they have different covalent arrangements of their atoms.
cis-trans isomers
have double bonds. have the same covalent bonds but differ in spatial arrangements.
cis isomer=
two X’s on same side
trans isomer=
the two X’s are on opposite sides
enantiomers
are isomers that are mirror images of each other
enantiomers are important in the
pharmaceutical industry.
two enantiomers of a drug may have different effects.
functional groups are
the components of organic molecules that are most commonly involved in chemical reactions
the number and arrangement of functional groups give
each molecule its unique properties.
functional groups give molecules their
very important qualities
the seven functional groups that are most important in the chemistry of life
hydroxyl group carbonyl group carboxyl group amino group sulfhydryl group phosphate group methyl group.
all of the seven functional groups are
hydrophilic thus increasing the solubility of organic compounds in water
hydroxyl
-OH
alcohols
polar
carbonyl
-C=O
aldehyde, ketone
isomers
Carboxyl
C=O
I
OH
carboxylic acid
acid
amino
NH2 N-H
I
H
amine
basesulfhydryl
-SH
thiol
Crosslink proteins
phosphate
O
II
O-P-O-
I
O-
organic phosphates
energy
methyl
H I C-H I H
methylated compounds
DNA (turns off DNA, controls DNA. important)
matter is made up of
elements
an element is
a substance that cannot be broken down to other substances by chemical reactions.
C, N, Na
a compound is
a substance consisting of two or more elements in a fixed ratio
NaCl, H2O.
a compound has characteristics different from those of its
elements
Carbon, Hydrogen, Oxygen, and nitrogen make up about
96% of living matter
most of the remaining 4% consists of
calcium, phosphorus, potassium, and sulfur
an atom is
the smallest unit of matter that still retains the properties of an element
an element consists of
unique atoms
atoms are composed of
subatomic particles
isotopes
are two atoms of an element that differ in number of neutrons
the chemical behavior of an atom is determined by
the distribution of electrons in electron shells
atomic #
number of protons
mass #
number of protons + neutrons
atomic mass
weight
p + n + e
the mass number is written as a
superscript to the left of an elements symbol
the atomic number is written as a
subscript to the left of an elements symbol
valence electrons
are electrons in the outermost shell or valence shell
the valence
of an element is how many electrons it still wants/ needs to fill up the shell
covalent bonds
strong and share.
is the sharing of a pair of valence electrons by two atoms.
in a covalent bond,
the shared electrons count as part of each atom’s valence shell
a molecule consists of
two or more atoms held together by covalent bonds
a single covalent bond or single bond is
the sharing of one pair of valence electrons
a double covalent bond or double bond is
the sharing of two pairs of valence electrons
electronegativity is
an atom’s attraction for the electrons in a covalent bond
the more electronegative an atom,
the more strongly it pulls shared electrons toward itself
non-polar covalent bonds
share electrons equally
polar covalent bonds
do not share electrons equally.
one atom is more electronegative.
unequal sharing of electrons causes a
partial positive or negative charge for each atom or molecule
ionic bonds
weaker and transfer electrons.
