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The basic structural and physiological unit of all living organisms is the


Based on the large numbers of offspring produced by many organisms, Darwin proposed that mortality was high and only a few individuals survived to reproduce. He referred to the differential reproductive success of individuals with particular variations as

natural selection.

A key point in Darwin's explanation of evolution is that

any trait that confers even a small increase in the probability that its possessor will survive and reproduce will be strongly favored and will spread through the population.

The initial accumulation of oxygen in the atmosphere was the result of photosynthesis from an organism most like modern


Scientists group species on an evolutionary tree that is based on

(the fossil record. physical structures. genomic sequencing.)All of the above

After observing that fish live in clean water but not in polluted water, researchers state that "polluted water kills fish." This statement is an example of

a hypothesis.

The main purpose of any single experiment is to

test a prediction that is based on a hypothesis.

Which of the following is not a domain on the tree of life?


Oceans were a good environment for early organisms because they

shielded organisms from ultraviolet light.

The part of the atom that determines how the atom behaves chemically is the


An atom that is neutrally charged contains

the same number of protons and electrons.

The atomic number of an element is the same as the number of _______ in each atom.


Phosphorus has an atomic number of 15 and an atomic mass of 31. How many neutrons does phosphorus have?


Because atoms can have the same number of protons but a different number of neutrons, elements have


An atom with _______ has an atomic mass of 14.

6 protons and 8 neutrons

Which of the following statements about the difference between ionic bonds and covalent bonds is true?

Electron sharing is more equal in the covalent bond.

What determines if a molecule is polar, nonpolar, or ionic?

The differences in the electronegativities of the atoms

A covalent bond is the sharing of _______ between atoms, whereas an ionic bond is the _______.

electrons; transfer of electrons from one atom to another

Cholesterol is composed primarily of carbon and hydrogen atoms. Therefore, one would expect cholesterol to be

insoluble in water.

Which of the following correctly states an unusual property of water?

The hydrogen bonds between water molecules continually form and break.

Sweating is a useful cooling device for humans because water

takes up a great deal of heat in changing from its liquid state to its gaseous state.

Surface tension and capillary action occur in water because it

has hydrogen bonds.

When sodium hydroxide (NaOH) is added to water, it ionizes, releasing OH- and Na+ ions. The resulting solution is


H2SO4 can ionize to yield two H+ ions and one SO42- ion. H2SO4 is therefore

an acid.

Which contains more molecules, a mole of hydrogen or a mole of carbon?

Both contain the same number of molecules.

How would you make 100 ml of an aqueous solution with a 0.25 M concentration of a compound that has a molecular weight of 200 daltons?

Take 5 grams of the compound and add water until the volume equals 100 ml.

A substance with a pH of 6.0 contains

10-6 moles of hydrogen ions.

Carbonic acid and sodium bicarbonate act as buffers in the blood. When a small amount of acid is added to this buffer, the H+ ions are used up as they combine with the bicarbonate ions. When this happens, the pH of the blood

does not change.

Which of the following does not represent a correct monomer/polymer pairing?


Molecules containing a large number of hydroxyl groups are

highly soluble in water.

In condensation reactions, the atoms that make up a water molecule are derived from

both of the reactants.

During the formation of a peptide linkage, a(n) _______ is formed.

molecule of water

Which of the following is responsible for making every amino acid unique?

"R" group

The side chain of leucine is a hydrocarbon. In a folded protein, where would you expect to find leucine?

(In the interior of a cytoplasmic enzyme. On the exterior of a protein embedded in a membrane.) Both a and b

What is the theoretical number of different proteins that you could make from 50 amino acids?


A β pleated sheet organization in a polypeptide chain is an example of _______ structure.


Quaternary structure is found in proteins

composed of subunits.

A(n) _______ protein is a protein that has become nonfunctional due to the loss of its three-dimensional structure.


A type of protein that functions by helping other proteins fold correctly is called a

chaperone protein.

Lactose, or milk sugar, which is composed of one glucose unit and one galactose unit, can be classified as a


Starch and glycogen, which are both polysaccharides, differ structurally in that glycogen _______, whereas starch _______.

is highly branched; is moderately branched

Lipids are

(insoluble in water. important for energy storage. hydrophobic. important constituents of biological membranes.) All of the above

A fat contains fatty acids and


Unsaturated fatty acids do not pack together due to

kinks in the hydrocarbon-chain ribozymes.

In a biological membrane, the phospholipids are arranged with the fatty acid chains facing the interior of the membrane. As a result, the interior of the membrane is


A nucleotide contains a pentose sugar, a phosphate group, and

a nitrogen-containing base.

The bases of nucleic acids are purines or pyrimidines. Purines and pyrimidines are distinguished by the fact that

purines are double-ring structures, whereas pyrimidines are single-ring structures.

Which of the following is not a difference between DNA and RNA?

DNA is a polymer, whereas RNA is a monomer.

What is attached to the 5´-carbon of deoxyribose in DNA?


What is the nucleotide sequence of the complementary strand of the DNA molecule: A A T G C G A?


What type of bond connects two complementary nucleotides together?


The central dogma of molecular biology states that

the information flow in a cell is from DNA to RNA to protein.

Spontaneous generation was finally disproved by

Francesco Redi and Louis Pasteur.

The Miller-Urey experiment showed that in any environment with conditions similar to those of Earth,

inorganic molecules would react to form organic molecules.

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