Which parts of atoms can interact (react) to form chemical bonds?
valence electrons
Atoms of oxygen have a total of 8 electrons. Are these atoms stable, and why or why not?
No, because the atoms have only 6 valence electrons, but need 8 for stability.
Carbon atoms have four valence electrons. Are they likely to react with other atoms, and why or why not?
Yes, because they can become more stable by doing so.
Which of the following is not produced through chemical bonding?
atoms
Which bonds often bind different parts of a molecule into a specific three-dimensional shape?
Hydrogen
Which of the following best defines covalent bonds?
the bond formed when shared electrons occupy a single orbital common to both atoms within a molecule
The numbers listed represent the number of electrons in the first, second, and third energy levels, respectively. On this basis, which of the following is an unstable or reactive atom?
2, 8, 1
What level of protein synthesis is represented by the coiling of the protein chain backbone into an alpha helix?
secondary structure
Except for elements 1 and 2, all other elements are stable with how many electrons in their outermost (valence) energy level?
8
Although his cholesterol levels were not high, Mr. Martinez read that cholesterol was bad for his health, so he eliminated all foods and food products containing this molecule. He later found that his cholesterol level dropped only 20%. Why did it not drop more?
Cholesterol is produced naturally by the liver, in addition to being ingested in foods.
Nonpolar molecules are the result of unequal electron pair sharing.
FalsePolar molecules are the result of unequal electron pair sharing. Nonpolar molecules are electrically balanced due to the equal sharing of electrons between the atoms of the molecules.
Atom X has 17 protons. How many electrons are in its valence shell?
7
You notice that you cannot read your book through a test tube of fluid held against the print, making it so blurred as to be unreadable. There is no precipitant in the bottom of the beaker, though it has been sitting for several days in a rack. What type of liquid is this?
colloid
The genetic information is coded in DNA by the ________.
sequence of the nucleotides
Which of the following is not true of proteins?
They appear to be the molecular carriers of coded hereditary information.
Salts are always ________.
ionic compounds
Which of the following is formed once the ions in the salt crystal have completely dissociated from one another?
a solution
Formation of hydrogen bonds requires hydrogen atoms and what else?
polar covalent bonds
Which of the following correctly ranks the types of chemical bonds, in order, from strongest to weakest?
covalent, ionic, hydrogen
Which of the following distinguishes hydrogen bonds from covalent bonds?
Only hydrogen bonds can form between molecules.
Which of the following is not a result of hydrogen bonds?
Two hydrogen atoms join together to form a molecule of hydrogen gas.
Suspensions may also be called emulsions.
False Colloids, not suspensions may also be called emulsions.
Which of the following is an example of a decomposition reaction?
MgO2 → Mg + O2
A decomposition reaction occurs when a larger molecule is broken down into smaller molecules or its constituent atoms.
cation
electrically charged particle due to loss of an electron
neutron
neutral subatomic particle
atom
smallest particle of an element that retains its properties
molecule
smallest particle of an element that retains its properties
molecule
smallest particle of a compound that still retains its properties
Which type(s) of subatomic particles can be located within the nucleus of an atom?
protons and neutrons
Which subatomic particles contribute to an atom's mass number but not its atomic number?
neutrons
An atom of oxygen has an atomic number of 8 and a mass number of 18. How many of each type of subatomic particle does it contain?
8 protons, 8 electrons, and 10 neutrons
The chemical symbol O=O means ________.
the atoms are double bonded
Choose the answer that best describes fibrous proteins.
are very stable and insoluble in water
Which of the following is NOT one of the three major types of chemical reactions?
hyperbolic
Most chemical reactions exhibit one of three recognizable patterns. They are either synthesis, decomposition, or exchange reactions.
Which of the following statements is false?
When the hydrogen ion concentration decreases, the hydroxyl ion concentration also decreases.
Which of the following does NOT describe enzymes?
Enzymes work by raising the energy of activation.
Which of the following does describe enzymes?
Some enzymes are protein plus a cofactor.
Each enzyme is chemically specific.Some enzymes are purely protein.
The four elements that make up about 96% of body matter are ________.
carbon, oxygen, hydrogen, nitrogen
The superscript preceding each hydrogen atomic symbol (H) represents which of the following?1H
the atomic mass of the corresponding atom
compound
water
element
carbon
compound 1
dry ice (frozen carbon dioxide)
mixture
blood
The basic structural material of the body consists of ________.
Proteins
A chemical reaction in which bonds are broken is usually associated with ________.
the release of energy
How many hydrogen atoms will nitrogen bond with to form a stable molecule?
3
Nitrogen has 5 electrons in its valence (outermost) electron shell. Therefore, it will form covalent bonds with three hydrogen atoms. Each single covalent bond includes the sharing of three pairs of electrons. The three electrons contributed by the hydrogen atoms will fill the valence shell of nitrogen.
Which of the following is NOT a difference between a compound and a mixture?
Mixtures are homogeneous while compounds are heterogeneous.
Mixtures differ from compounds in several important ways.
The chief difference between mixtures and compounds is that no chemical bonding occurs between the components of a mixture. The properties of atoms and molecules are not changed when they become part of a mixture. (2) Depending on the mixture, its components can be separated by physical means, straining, filtering, evaporation, and so on. Compounds, by contrast, can be separated into their constituent atoms only by chemical means (breaking bonds). (3) Some mixtures are homogenous, while others are heterogeneous. All compounds are homogeneous.
Select the correct statement about isotopes.
Isotopes of the same element have the same atomic number but differ in their atomic masses.
Which of the following is TRUE regarding the pH of a solution?
The more hydrogen ions in a solution, the more acidic the solution is.
energy
can be measured only by its effects on matter
matter
anything that occupies space and has mass
although a man who weighs 175 pounds on Earth would be lighter on the moon and heavier on Jupiter, his ___ would not be different
mass
weight
is a function of, and varies with, gravity
The single most abundant protein in the body is ________.
collagen
Why is it possible to safely drink a solution that contains a 50:50 mixture of equal concentrations of a strong acid and a strong base, either of which, if ingested separately, would be very caustic and damaging?
Salt and water are formed when a strong acid and base are mixed.
Which of the following does not describe uses for the ATP molecule?
pigment structure
Which of the following does describe uses for the ATP molecule?
chemical work mechanical work transport across membranes
If an oxygen atom were to form a chemical bond in which it gained two electrons, it would ______.
become more stable
Carbohydrates are stored in the liver and muscles in the form of ________.
glycogen
What does the formula C6H12O6 mean?
There are 12 hydrogen, 6 carbon, and 6 oxygen atoms.
colloids
heterogeneous, will not settle
suspensions
heterogeneous, will settle
solutions
homogeneous, will not settle or scatter light
Which of the following is an example of a suspension?
blood
In a covalent bond,
Atoms share one or more pairs of electrons.
Covalent bonds:
involve the sharing of one to three pairs of electrons.
Which of the following is true of polar covalent bonds?
The electrons are shared unequally.
A molecule of water (H2O) is formed by what type of bond?
polar covalent bonds
Which of the following is not considered a factor in influencing a reaction?
time
Which of the following is considered a factor in influencing a reaction?
concentration temperature particle size
Which property of water is demonstrated when we sweat?
high heat of vaporization
mechanical energy
legs moving the pedals of a bicycle
chemical energy
when the bonds of ATP are broken, energy is released to do cellular work
radiant energy
energy that travels in waves. part of the electromagnetic spectrum
electrical energy
represented by the flow of charged particles along a conductor, or the flow of ions across a membrane
What explains the negative charge on the oxygen atom within the water molecule?
Oxygen atoms have a stronger pull on the electrons shared within a covalent bond formed between oxygen and hydrogen.
Sucrose is a ________.
disaccharide
Kidneys play a major role in helping to maintain proper levels of Na+ and K+ ions in the blood. If the kidneys fail to function properly, one of the direct consequences would be_________.
impaired nerve impulse transmission
The major function of RNA is to carry out the genetic instructions for protein synthesis.
True
ATP is an unstable, high-energy molecule that provides body cells with a form of energy that is immediately usable.
True
Which of the following best describes an isotope?
structurally variant atoms, which have the same number of protons and electrons, but differ in the number of neutrons they contain
Which of the following would be regarded as an organic molecule?
CH4
Carbon is in it
What is a dipole?
a polar molecule
What is the primary energy-transferring molecule in cells?
ATP
Which of the following is NOT a compound?
oxygen gas
The lines drawn between hydrogen (H) atoms and the oxygen (O) atom in the structural diagram presented in the right of the figure each represent a ______.
polar covalent bond
A covalent bond in which electrons are shared unequally is termed a polar covalent bond.
Choose the correctly matched pair.
DNA and RNA are nucleic acids; they are built from nucleotides.
Water ________.
can form hydrogen bonds
Which of the following is TRUE of atomic weight?
Atomic weight of an element is approximately equal to the mass number of its most abundant isotope.
What is the classification of a solution with a pH of 8.3?
alkaline solution
In general, the lipids that we refer to as oils have ________.
a high degree of unsaturated bonds
Which of the following elements is necessary for proper conduction of nervous impulses?
Na
polar covalent bond
a bond in which electrons are shared unequally
ionic bond
a bond in which electrons are completely lost or gained by the atoms involved
nonpolar covalent bond
a bond in which electrons are shared equally
hydrogen bond
a type of bond important in tying differen parts of the same molecule together into a three-dimensional structure
Which of the following is the major positive ion outside cells?
sodium
What type of chemical bond joins sodium (element 11) and chlorine (element 17)?
ionic
Sodium gives up its valence shell electron (becoming a cation) to drop back to a stable energy level, and chlorine gains one electron (becoming an anion) to fill its valence shell and become stable.
What is the most abundant and important inorganic compound in living material?
water
Choose the answer that best describes HCO3-.
a bicarbonate ion
What is the difference between kinetic and potential energy?
Kinetic energy is energy in action, while potential energy is stored energy.
An element has an atomic number of 17 and a mass of 35. How many protons, neutrons, and electrons does the element have?
17 protons, 18 neutrons, and 17 electrons
The mass number is the sum of protons and neutrons in the atom. The atomic number is the number of protons in the atom. The number of protons equals the number of electrons in a chemically inactive atom
Each specific amino acid has a unique ______.
R group
What is a chain of more than 50 amino acids called?
protein
What is the most significant factor in the formation of a covalent bond?
the sharing of electron pairs between two atoms
A 23-year-old male was riding his road bike in 100-degree heat, when he suddenly became nauseated and weak. He called 911 from his cell phone. When the ambulance came, the paramedics started intravenous therapy for severe dehydration. Which physical property and which physiological role of water caused the dehydration, and why?
High heat of vaporization; water was lost when evaporating from the skin to cool the body.
A 65-year-old patient came to the emergency room with complaints of severe heartburn unrelieved by taking a "large handful" of antacids. Would you expect the pH to be relatively high, low, or normal for the patient's stomach contents, and why?
The pH would be high. Antacids are basic, and too many antacids would result in a relatively alkaline state.
Amino acids joining together to make a peptide is a good example of a(n) ________ reaction.
synthesis
Carbohydrates and proteins are built up from their basic building blocks by the ________.
removal of a water molecule between each two units
Which of the following is NOT one of the three basic steps involved in enzyme activity?
The substrate absorbs chemical energy from the enzyme after binding to its active site.
Which protein types are vitally important to cell function in all types of stressful circumstances?
molecular chaperones
The atomic weight is only an average of relative weights of an atom and its isotopes, and it may vary from the weight of a specific isotope.
True
Emulsions and colloids are the same thing.
True
Chemical properties are determined primarily by neutrons.
False
A charged particle is generally called an ion.
TRUE
Isotopes differ from each other only in the number of electrons contained.
False
About 60% to 80% of the volume of most living cells consists of organic compounds.
False
Lipids are a poor source of stored energy.
False
Current information theorizes that omega-3 fatty acids decrease the risk of heart disease.
True
Glucose is an example of a monosaccharide.
True
A molecule consisting of one carbon atom and two oxygen atoms is correctly written as CO2.
True
The lower the pH, the higher the hydrogen ion concentration.
True
Covalent bonds are generally less stable than ionic bonds.
False
Hydrogen bonds are comparatively strong bonds.
False
The fact that no chemical bonding occurs between the components of a mixture is the chief difference between mixtures and compounds
True
Alpha particles, although relatively weak energy particles, are second only to smoking as a cause of lung cancer.
True
No chemical bonding occurs between the components of a mixture.
True
All organic compounds contain carbon.
True
A dipeptide can be broken into two amino acids by dehydration synthesis.
False
The pH of body fluids must remain fairly constant for the body to maintain homeostasis.
True
Mixtures are combinations of elements or compounds that are physically blended together but are not bound by chemical bonds.
True
Buffers resist abrupt and large changes in the pH of the body by releasing or binding ions.
True
Which of the following elements is necessary for proper conduction of nervous impulses?
A) Fe
B) I
C) P
D) Na
D) Na
Choose the statement that is false or incorrect.
D) A key feature of the body's metabolism is the almost exclusive use of exergonic reactions by the body.
In general, the lipids that we refer to as oils have ________.
A) a high degree of unsaturated bonds
The genetic information is coded in DNA by the ________.
A) sequence of the nucleotides
Which of the following is not true of proteins?
B) They appear to be the molecular carriers of the coded hereditary information.
The single most abundant protein in the body is ________.
B) collagen
Carbohydrates are stored in the liver and muscles in the form of ________.
B) glycogen
Which of the following describes coenzymes?
C) organic molecules derived from vitamins
Which of the following is not a role of molecular chaperonins?
A) act as a biological catalyst
A chemical reaction in which bonds are broken is usually associated with ________.
B) the release of energy
Salts are always ________.
D) ionic compounds
The numbers listed represent the number of electrons in the first, second, and third energy levels, respectively. On this basis, which of the following is an unstable or reactive atom?
B) 2, 8, 1
A solution that has a pH of 2 could best be described as being ________.
A) acidic
Which of the following is the major positive ion outside cells?
D) sodium
Which of the following would be regarded as an organic molecule?
B) CH4
What is a chain of 25 amino acids called?
C) polypeptide
Which of the following constitutes a long chain of simple sugars?
B) polysaccharide
What level of protein synthesis is represented by the coiling of the protein chain backbone into an alpha helix?
C) secondary structure
Carbohydrates and proteins are built up from their basic building blocks by the ________.
B) removal of a water molecule between each two units
Which statement about enzymes is false?A) Enzym
es raise the activation energy needed to start a reaction.
B) Enzymes are composed mostly of protein.
C) Enzymes are organic catalysts.
D) Enzymes may be damaged by high temperature.
A) Enzymes raise the activation energy needed to start a reaction.
Which of the following statements is false?
D) Larger particles move faster than smaller ones and thus collide more frequently and more forcefully.
Which of the following is true regarding the concentration of solutions?
C) Molarity is one mole of solute per 1000 ml of solution.
Select the statement about mixtures that is correct.
A) A solution contains solvent in large amounts and solute in smaller quantities.
Choose the answer that best
describes HCO3-.
C) a bicarbonate ion
Select which reactions will usually be irreversible regarding chemical equilibrium in living systems.
A) glucose to CO2 and H2O
What happens in redox reactions?
A) both decomposition and electron exchange occur
Choose the answer that best describes fibrous proteins.
D) are very stable and insoluble in water
Which of the following does not describe the ATP molecule?
C) pigments
Select the most correct statement regarding nucleic acids.
A) DNA is a long, double-stranded molecule made up of A, T, G, and C bases.
Which of the following is an example of a suspension?
A) blood
Select the correct statement about isotopes.
B) Isotopes of the same element have the same atomic number but differ in their atomic masses.
The four elements that make up about 96% of body matter are ________.
A) carbon, oxygen, hydrogen, nitrogen
An example of a coenzyme is ________.
A) riboflavin (vitamin B2)
________ is fat soluble, produced in the skin on exposure to UV radiation, and necessary for normal bone growth and function.
D) Vitamin D
In liquid XYZ, you notice that light is scattered as it passes through. There is no precipitant in the bottom of the beaker, though it has been sitting for several days. What type of liquid is this?
C) colloid
Atom X has 17 protons. How many electrons are in its valence shell?
C) 7
Which protein types are vitally important to cell function in all types of stressful circumstances?
C) molecular chaperones
If atom X has an atomic number of 74 it would have which of the following?
D) 37 protons and 37 electrons
What does the formula C6H12O6 mean?
D) There are 12 hydrogen, 6 carbon, and 6 oxygen atoms.
Two good examples of a colloid would be Jell-O® and ________.
B) cytosol
An atom with a valence of 3 may have a total of ________ electrons.
D) 13
Which of the following is a neutralization reaction?
B) HCl + NaOH → NaCl + H2O
The chemical symbol OO means ________.
C) the atoms are double bonded
What is a dipole?
D) a polar molecule
What does CH4 mean?
C) There is one carbon and four hydrogen atoms.
Amino acids joining together to make a peptide is a good example of a(n) ________ reaction.
A) synthesis
Which of the following is not considered a factor in influencing a reaction?
B) time
Which of the following is not an electrolyte?
A) H2O
Which property of water is demonstrated when we sweat?
D) high heat of vaporization
Sucrose is a ________.
B) disaccharide
What is the ratio of fatty acids to glycerol in neutral fats?
C) 3:1
In a DNA molecule, the phosphate serves ________.
B) to hold the molecular backbone together
Heat shock proteins (hsp) are a type of protein called ________.
C) chaperonins
Which bonds often bind different parts of a molecule into a specific three-dimensional shape?
C) Hydrogen
The atomic number is equal to the number of ________.
protons (and electrons)
Molecules such as methane that are made of atoms that share electrons have ________ bonds
covalent
An atom with three electrons would have a valence of ________.
one
AB → A + B is an example of a(n) ________ reaction.
decomposition
________ have a bitter taste, feel slippery, and are proton acceptors.
Bases
A holoenzyme is composed of an apoenzyme and a(n) ________.
cofactor
In a DNA molecule, guanine would connect to ________.
cytosine
The ________ molecule directly provides energy for cellular work.
ATP
Hydrogen bonds are more like a type of weak ________ than true bonds.
attraction
Weak acids and bases make good ________.
buffers
Starch is the stored carbohydrate in plants, while ________ is the stored carbohydrate in animals.
glycogen
How many phosphates would AMP have attached to it?
