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