What is the difference between kinetic and potential energy?
Kinetic energy is energy in action, while potential energy is stored energy.
The three atoms shown differ in the number of ______.
neutrons
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
What do these four elements have in common?
hydrogen, carbon, oxygen and sodium
They all have an incomplete valence electron shell.
After the transfer of the electron, sodium will form an ion with ______.
Between a sodium atom and a chlorine atom
a charge of +1
Which of the following accurately describes what is occurring in the illustrated reaction?
between a hydrogen and chlorine atom
A single covalent bond is formed between carbon and each of the four hydrogen atoms.
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.
The chemical reaction shown at step C is an ______.
endergonic dehydration synthesis
The chloride ion (Cl-) indicated by the arrow is interacting most closely with which of the following?
a hydrogen atom within a water molecule
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
What is the classification of a solution with a pH of 8.3?
alkaline solution
All amino acids (such as the four represented in the figure) contain ______.
an amine group and a carboxyl group
Which of the following statements is true regarding the enzyme-catalyzed reaction (B) compared to the uncatalyzed reaction (A)?
Less energy input is required to start the reaction in the presence of enzyme.
Which organic molecules form the major structural materials of the body?
proteins
Which of the following is NOT considered a form of matter?
X rays
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 is NOT a subatomic particle?
molecule
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
Which particle is indicated by the arrow?
proton
Which of the following is NOT one of the three major types of chemical reactions?
hyperbolic
Which of the following is NOT a compound?
oxygen gas
If an oxygen atom were to form a chemical bond in which it gained two electrons, it would ______.
become more stable
How many hydrogen atoms will nitrogen bond with to form a stable molecule?
3
Based on the information in this figure, we can conclude that chlorine has an atomic number of ______.
17
Which of the following is an example of a decomposition reaction?
MgO2 → Mg + O2
Atomic number is equal to the number of neutrons in an atom's nucleus.
False
Which of the following is NOT a difference between a compound and a mixture?
Mixtures are homogeneous while compounds are heterogeneous.
Buffers help to stabilize blood pH.
True
Both molecule A and molecule B are classified as ______.
lipids
Suspensions may also be called emulsions.
False
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
What is the primary energy-transferring molecule in cells?
ATP
Foods are broken down into their building blocks by adding water. This would be an example of which characteristic of water?
Water acts as a reactant.
Water acts to dissolve molecules in the body. How does water dissolve the salt (NaCl) in your mouth from a salty pretzel?
Water acts as a solvent because the partial negative charge on the oxygen in water attracts sodium, while the partial positive charge on hydrogen attracts chloride. This results in the separation of sodium from chloride, thus breaking the ionic bond.
In plasma, a typical body fluid, protein floating around would be considered to be which of the following?
a solute, specifically both a colloid and an electrolyte
Electrolytes are charged particles called ions that are dissolved in body fluids. Which of the following ions would be considered a major anion in the body?
chloride
Which pH is more acidic, a pH of 3, a pH of 7, or a pH of 9?
pH of 3
Cortisol is a type of lipid hormone. Which type of lipid would cortisol be classified as?
steroid
Which four elements comprise approximately 96% of our body weight?
carbon, oxygen, hydrogen, and nitrogen.
The atomic mass of the helium atom shown is ______.
4 amu
The three atoms shown differ in the number of ______.
neutrons
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.
This figure depicts the formation of a(n) ______.
ionic bond
What holds the sodium and chloride ions together in a chemical bond?
an electrical attraction between opposite charges
How many valence shell electrons does the element carbon have?
4
Which of the following accurately describes what is occurring in the illustrated reaction?
A single covalent bond is formed between carbon and each of the four hydrogen atoms.
What type of bond is formed between the oxygen atom of one water molecule and the hydrogen atom of another water molecule?
hydrogen bond
What are the two fundamental roles of DNA?
to provide the instructions for protein synthesis, and replicate itself before cell division
Water ________.
can form hydrogen bonds
Molecule A is a ______.
phospholipid
Which of the following molecular features is found in molecule A, but NOT in molecule B?
a polar group
Which of the following is a primary function of molecule B?
energy storage
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 three atoms shown represent three unique __________.
Hydrogen, Helium, and Lithium
elements
Which of these elements is most likely to be unstable and therefore radioactive?
tritium
The superscript preceding each hydrogen atomic symbol (H) represents which of the following?
the mass number of the corresponding atom
The three atoms shown represent different __________.
Hydrogen, Deuterium, Tritium
isotopes
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
What is an ion?
an atom that has either gained or lost electron(s)
When an ionic bond forms, which part(s) of the atoms are directly involved?
the outermost electrons
How do ions form ionic bonds?
Ions of opposite electrical charges are attracted to each other to balance the charges.
Calcium’s atomic number is 20. It forms ions with 18 electrons. What is the electrical charge of a calcium ion?
+2
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
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.
Which of the following is FALSE?
The weight of matter remains constant wherever it is located.
In a solution, the solute is the substance present in the greatest amount.
False
Heterogeneous, will not settle.
Colloids
Heterogeneous, will not settle.
Suspensions
Heterogeneous, will not settle.
Solutions
Will not scatter light.
Solutions
What does CH4 mean?
There is one carbon and four hydrogen atoms.
Mixtures are combinations of elements or compounds that are physically blended together but are not bound by chemical bonds.
True
Amino acids joining together to make a peptide is a good example of a(n) ________ reaction.
synthesis
ATP → ADP + Pi is an example of a(n) ________ reaction.
decomposition
Forming glycogen as energy storage in the liver is an example of ________.
anabolism
The pH scale __________.
is based on the concentration of hydrogen ions in a solution
A weak base buffers an acid by completely dissociating and accepting all of the acid's H+.
False
Which response provides the best explanation as to why ionic compounds easily dissociate in water?
Its unusual polar arrangement allows more substances to dissolve in water than in any other chemical.
Which of the following would be regarded as an organic molecule?
CH4
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 a FALSE statement about carbohydrates?
The chemical composition of carbohydrates includes two oxygens and one hydrogen for every carbon present.
Which of the following is true about lipids?
Triglycerides are composed of three fatty acids and one glycerol and are stable because they do not dissolve in water.
The presence of what group differentiates most amino acids from each other?
an R group
What is represented by the chemicals at A?
substrates
What is represented by the chemical at B?
protein
Which of these terms would best classify the enzyme represented in the figure?
synthesis
Which of the following is true of protein structure?
Secondary protein structures are caused by hydrogen bonding between adjacent amine and carboxyl groups.
The single most abundant protein in the body is ________.
collagen
The major function of DNA is to store the genetic instructions that are used during protein synthesis
True
The genetic information is coded in DNA by the ________.
sequence of the nucleotides
In a DNA molecule, the phosphate serves ________.
to hold the molecular backbone together
Which of the following does not describe uses for the ATP molecule?
pigment structure
What is the primary energy-transferring molecule in cells?
ATP
How many hydrogen atoms will a single carbon atom bond with to form a stable molecule?
four
One carbon atom can combine with two oxygen atoms to form carbon dioxide. Use the diagram to predict the type of bond that would be necessary to join the oxygens to the carbon to form a stable molecule.
two double bonds
After the transfer of the electron, sodium will form an ion with __________.
a charge of +1
Rank the chemical bonds from relatively weakest to strongest.
I. Ionic
II. Covalent
III. Hydrogen
III < I < II
Atom X has 17 protons. How many electrons are in its valence shell (outermost energy level)?
7
Except for elements 1 and 2, all other elements are stable with how many electrons in their outermost (valence) energy level?
8
Suppose the following compounds were all dissolved in separate beakers of water in the same manner as the salt in the figure. Which of the resulting solutions would NOT conduct electricity?
sucrose
Which of the following is formed once the ions in the salt crystal have completely dissociated from one another?
a solution
Blood loss due to a moderate hemorrhage has several adverse effects on patient wellbeing. Why would administering IV fluids alone not be sufficient to return a patient to health?
Oxygen-carrying red blood cells lost along with the fluid component must also be replaced.
Why can dehydration be such a life-threating event?
It significantly alters the ratio of body water (solvent) to dissolved substances (solutes), such as sodium ions.
A dipeptide can be broken into two amino acids by dehydration synthesis.
False