Chemistry practice test 1 – Flashcards
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A bond in which electrons are shared unequally
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polar covalent bond
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A bond in which electrons are completely lost or gained by the atoms involved
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Ionic Bond
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A bond in which electrons are equally shared
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Nonpolar covalent bond
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A type of bond important in typing different parts of the same molecule together into a three-dimensional structure
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Hydrogen bond
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Electrically charged particle due to loss of an electron
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Cation
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Neutral subatomic particle
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Neutron
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smallest particle of an element that retains its properties
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Atom
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smallest particle of a compound that still retains its properties
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Molecule
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what is water
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A compound
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what is carbon
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A element
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anything that occupies space and has mass
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Matter
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Although a man who weighs 175 pounds on earth would be lighter on the moon and heavier on jupiter, his _____________ would not be different
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Mass
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Is a function of, and varies with, gravity
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Weight
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A synthesis reaction always involves bond formation.
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True
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Chemical properties are determined primarily by neutrons.
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False
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A charged particle is correctly called an ion
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True
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Isotopes differ from each other only in the number of electrons contained.
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False
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About 60 to 80% of the volume of most living cells consists of organic compounds.
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False
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Lipids are a poor source of stored energy.
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False
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Glucose is an example of a monosaccharide
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True
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A molecule consisting of one carbon atom and two oxygen atoms is correctly written as CO2
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True
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The lower the pH, the higher the hydrogen ion concentration
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true
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Covalent bonds are generally weaker than ionic bonds.
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False
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Hydrogen bonds are strong bonds.
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False
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All organic compounds are covalently bonded.
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True
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In general, the category of lipids that we refer to as oils have:
A) long fatty acid chains.
B) a high degree of saturated bonds.
C) a high degree of unsaturated bonds.
D) a high water content.
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A higher degree of unsaturated bonds
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The genetic information is coded in DNA by
A) the regular alteration of sugar and phosphate molecules.
B) the sequence of the nucleotides.
C) the structure of the histones.
D) the three-dimensional structure of the double helix
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the sequence of the nucleotides
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Which of the following is not true of proteins?
A) They appear to be the molecular carriers of the coded hereditary information.
B) Their function depends on the three-dimensional shape.
C) Some types are called enzymes.
D) They may be denatured or coagulated by heat or acidity.
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They appear to be the molecular carries of the coded hereditary information
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The single most abundant protein in the body is:
A) glucose.
B) hemoglobin.
C) collagen.
D) DNA.
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collagen
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Carbohydrates are stored in the liver and muscles in the form of:
A) glucose.
B) triglycerides.
C) cholesterol.
D) glycogen
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glycogen
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The speed or rate of a chemical reaction is influenced by all of the following except:
A) the presence or absence of carbon.
B) the temperature.
C) the concentration of the reactants.
D) the presence of catalysts or enzymes
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the presence or absence of carbon
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Salts are always
A) hydrogen bonded
. B) ionic compounds.
C) double covalent compounds.
D) single covalent compounds
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ionic compounds
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A solution that has a pH of 2 could best be described as being:A) basic. B) acidic. C) neutral. D) slightly acidic.
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Acidic
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Which of the following would be regarded as an organic molecule?
A) H2O B) NaOH C) CH4 D) NaCl
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CH4
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A chain of 25 amino acids would be called a
A) nucleotide. B) protein. C) starch. D) peptide.
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Peptide
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A long chain of simple sugars would be a:
A) protein. B) nucleic acid. C) polysaccharide. D) monosaccharide.
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Polysaccharide
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Carbohydrates and proteins are built up from their basic building blocks by the
A) addition of a water molecule between each two units.
B) removal of a nitrogen atom between each two units.
C) addition of a carbon atom between each two units.
D) removal of a water molecule between each two units
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removal of a water molecule between each two units
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Which statement about enzymes is false?
A) Enzymes are composed mostly of protein.
B) Enzymes raise the activation energy needed to start a reaction.
C) Enzymes may be damaged by high temperature.
D) Enzymes are organic catalysts.
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Enzymes raise the activation energy needed to start a reaction
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Select the statement that is most correct regarding chemical bonds
A) Ionic bonds involve the sharing of electrons between two atoms.
B) Multiple bonds are not possible with covalent bonding.
C) Covalent bonding involves the transfer of one or more electrons from one atom to another.
D) Hydrogen bonds are very weak and often involve water.
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Hydrogen bonds are very weak and often involve water
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Select the most correct statement regarding nucleic acids.
A) RNA is a long, single-stranded molecule made up of the nucleotides A, T, G, and C.
B) DNA is a long, double-stranded molecule made up of A, T, G, and C nucleotides.
C) Three forms exist: DNA, RNA, and TDNA.
D) TDNA is considered a molecular slave of DNA.
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DNA is a long, double-stranded molecule made up of A,T,G, and C Nucleotide
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Select the correct statement about isotopes
A) All the isotopes of an element have the same number of neutrons.
B) Isotopes are rare and occur only in the heavier elements.
C) All the isotopes of an element are radioactive.
D) Isotopes of the same element have the same atomic number but differ in their atomic weights.
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Isotopes of the same element have the same atomic number but differ in their atomic weights.
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The four elements that make up about 96% of body matter are:
A) carbon, oxygen, phosphorus, calcium. B) nitrogen, hydrogen, calcium, sodium.
C) sodium, potassium, hydrogen, oxygen. D) carbon, oxygen, hydrogen, nitrogen.
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carbon, oxygen, hydrogen, nitrogen.
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Atom X has seventeen protons. How many electrons are in its valence shell?
A) 3 B) 10 C) 5 D) 7
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7
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If atom X has an atomic number of 74 it would have _______
A) 37 protons and 37 neutrons
B) 74 protons and roughly the same number of neutrons
C) 37 electrons
D) 74 protons and no neutrons
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74 protons and roughly the same number of neutrons
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The formula C6H12O6 means:
A) there are 6 calcium, 12 hydrogen and 6 oxygen atoms.
B) the substance is a colloid.
C) the molecular weight is 24.
D) there are 12 hydrogen, 6 carbon and 6 oxygen atoms.
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there are 12 hydrogen, 6 carbon and 6 oxygen atoms.
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The chemical symbol O = O means
A) the atoms are double bonded.
B) zero equals zero
C) both atoms are bonded and have zero electrons in the outer orbit.
D) this is an ionic bond with two shared electrons
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the atoms are double bonded.
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Dipole is:
A) a type of reaction. B) an organic molecule.
C) a type of bond. D) a polar molecule.
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a polar molecule
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CH4 means
A) there are four carbon and four hydrogen atoms.
B) this is an inorganic molecule.
C) there is one carbon and four hydrogen atoms.
D) this was involved in a redox reaction.
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there is one carbon and four hydrogen atoms
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Amino acids joining together to make a peptide is a good example of a ________ reaction
A) reversible
B) exchange
C) synthesis
D) decomposition
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synthesis
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The following is not an electrolyte.
A) NaOH B) H2O C) HCl D) Ca2CO3
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H2O
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Grapefruit juice (pH 3) has ________ times the concentration of coffee (pH 5).
A) 20 B) 100 C) 10 D) 1000
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100
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Sucrose is a ________.
A) polysaccharide B) monosaccharide C) triglyceride D) disaccharide
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disaccharide
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Neutral fats have a ________ ratio of fatty acids to glycerol
A) 2:1 B) 3:1 C) 1:1 D) 4:1
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3:1
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The atomic number is equal to the number of ________.
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Protons
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Molecules such as methane that share electrons have ________ bonds.
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covalent
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Polysaccharides with long chains of similar units are called ________.
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polymers
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In a DNA molecule guanine would connect to ________.
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Cytosine
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The ________ molecule directly provides energy for cellular work.
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ATP
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Starch is the stored carbohydrate in plants while ________ is the stored carbohydrate in animal
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glycogen
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Explain the difference between potential and kinetic energy
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Potential energy is the energy an object has relative to position. Kinetic energy is energy associated with a moving
object
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What advantages does ATP have in being the energy currency molecule?
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It is easy to store; it releases just the right amount of energy for the cell's needs so it is protected from excessive energy
release. A universal energy currency is efficient because a single system can be used by all the cells in the body.
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Describe the factors that affect chemical reaction rates.
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Temperature increases kinetic energy and therefore the force of molecular collisions. Particle size: smaller particles
move faster at the same temperature and therefore collide more frequently; also, smaller particles have more surface
area given the same concentration of reactants. Concentration: the higher the concentration, the greater the chance of
particles colliding. Catalysts increase the rate of the reaction at a given temperature. Enzymes are biological catalysts
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Protons and electrons exist in every atom nucleus except hydrogen. Is this statement true or false and why?
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False - Hydrogen has one proton and one electron. It is the neutron that hydrogen does not have
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Name four things you know about enzymes
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1. They are proteins. 2. They have specific binding sites for specific substrates. 3. They lower the activation barrier
for a specific reaction. 4. The names end in ase. 5. They can be denatured. 6. They can be used again and again.
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How can DNA be used to "fingerprint" a suspect in a crime?
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The DNA of a person is unique to that individual. By obtaining the DNA from nucleated cells from the crime scene
(e.g., tissue, sperm), heating it gently to separate the strands, combining it with the suspect's DNA, and allowing it to
reanneal, the relatedness can be determined by the amount of base pairing.
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a(n) _____________________ is a substance that consists entirely
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element
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the center of an atom is called the ______________
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nucleus
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Electrons in an atom occupy an orderly series of
electron shells or ________.
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energy levels
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A(n) ________ is a combination of two or more
atoms and has different physical and chemical
properties than its individual atoms
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compound
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Ions with a positive charge are called ________
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cations
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Ions with a negative charge are called ________.
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anions
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________ control the rate of chemical reactions that
occur in the human body.
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enzymes
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_______ molecules are compounds that contain
carbon as the primary structural atom.
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organic
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________ compounds do not contain carbon as the
primary structural atom.
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inorganic
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A(n) ________ is a homogeneous mixture
containing a solvent and a solute.
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solution
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Molecules that readily dissolve in water are called
________.
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hydrophilic
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Molecules that do not dissolve in water are called
________.
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hydrophobic
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The ________ of a solution is the negative
logarithm of the hydrogen ion concentration expressed in
moles per liter in the solution.
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pH
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________ are compounds that in solution maintain
pH within given limits.
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buffers
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________ are lipid molecules that form biological
membranes.
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phospholipids
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The molecule DNA contains a five-carbon sugar
called ________.
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deoxyribose
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the molecule RNA contains a five-carbon sugar
called ________.
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ribose
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The hydrolysis of ATP yields the molecule
________.
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ADP
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Identify the three components of a nucleotide.
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pentose, phosphate group, nitrogenous base
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Explain the role of water molecules in
polysaccharide formation.
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Water molecules are released in the dehydration
synthesis of polysaccharides.
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What role do buffer systems play in the human
body?
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Buffer systems maintain pH within normal limits by
removing or replacing hydrogen ions as needed
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Why is it life-threatening to have a high fever?
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A high body temperature can be life-threatening
because the heat can cause certain proteins, such as
vital enzymes, to become denatured. When this occurs,
the proteins become nonfunctional and if they catalyze
reactions that are necessary for life, life will cease.
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How does the DNA molecule control the
appearance and function of a cell?
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The DNA molecule controls the manufacture of
enzymes and structural proteins. By controlling the
manufacture of structural proteins, the DNA is able to
influence the physical appearance of a cell. By
controlling the production of enzymes, the DNA is able to
control all aspects of cellular metabolism and thus
control the activity and biological functions of the cell.
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The element sulfur has an atomic number of 16 and
an atomic weight of 32. How many neutrons are in the
nucleus of a sulfur atom?
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The number of neutrons in an atom is equal to the
atomic weight minus the atomic number. Thus, sulfur
has 32 - 16 = 16 neutrons. The atomic number indicates
the number of protons, so a neutral sulfur atom contains
16 protons plus 16 electrons to balance the protons
electrically. The electrons would be distributed as
follows: 2 in the first level, 8 in the second level, and the
remaining 6 in the third level.
