A&P I/II Practice Q 2 Ch 2
What is the mass number of this atom? Diagram of an atom with six positive and six neutral particles in the nucleus and two shells with negative subatomic particles orbiting around the nucleus. The inner shell contains two particles and the outer contains four. What is the mass number of this atom? 12 2 6 18
12 Correct The mass number is equal to the sum of the protons and the neutrons. The protons are the positive subatomic particles, and the neutrons are the neutral subatomic particles; both are found in the nucleus.
Chlorine has an atomic number of 17. How many electrons will be in a chloride ion with a charge of -1? Chlorine has an atomic number of 17. How many electrons will be in a chloride ion with a charge of -1? -1 16 17 18
18 Correct The number of electrons will be 1 more than the number of protons: 17 protons and 18 electrons will give an overall -1 charge.
Sodium has an atomic number 11 and 12 neutrons. Its mass number is __________. 1 11 12 23
23 Correct The mass number is equal to the sum of the protons and the neutrons. Recall that the atomic number is equal to the number of protons in an atom.
A chemical system that resists changes in pH and prevents large swings in the pH is called __________. a base a buffer an acid an anion
A buffer Correct Typically, a buffer consists of a weak acid and its corresponding anion, and it can donate or accept free hydrogens.
Which of the following molar solutions has a neutral pH? A solution with a hydrogen ion concentration of 0.000001 molar A solution with a hydrogen ion concentration of 0.00001 molar A solution with a hydrogen ion concentration of 0.0000001 molar A solution with a hydrogen ion concentration of 0.00000001 molar
A solution with a hydrogen ion concentration of 0.0000001 molar Correct This solution has a pH of 7, which is neutral.
The primary source of chemical energy in the body is __________. ADP AMP ATP DNA
ATP Correct Adenosine triphosphate provides the energy for nearly every process that takes place inside our cells.
Which of the following molecules is a lipid with a four-ring hydrocarbon structure? Fatty acid Cholesterol Triglyceride Purine
Cholesterol Correct Cholesterol is a member of the class of steroids, which all share a four-ring hydrocarbon structure.
Which of the following statements about enzymes is INCORRECT? Enzymes are permanently altered in the reaction. Enzymes speed up reactions by lowering the activation energy. Enzymes do not alter the reactants or products. Enzymes are highly specific for individual substrates and reactions.
Enzymes are permanently altered in the reaction. Correct Enzymes are not permanently altered in the reaction.
Which of the following molecules contains polar covalent bonds? H2O CH4 NaCl H2
H2O Correct The bonds between the hydrogens and the oxygen are polar covalent bonds because of the high electronegativity of oxygen.
Neon has 10 electrons. Which of the following statements is true about neon? It has 8 valence electrons and is unstable. It has 2 valence electrons and is unstable. It has 8 valence electrons and is stable. It has 10 valence electrons and is stable.
It has 8 valence electrons and is stable. Correct If the valence shell of an atom is full, the atom is stable and unreactive. In this case, 2 electrons go in the first shell, and the remaining 8 electrons are in the valence shell.
This is an example of __________. Diagram of H2 (hydrogen gas). There are two hydrogen atoms. Each has 1 proton in the nucleus and there are 2 electrons in the middle between the two atoms and the electron orbital of each atom holds those same two electrons. This is an example of __________. a nonpolar covalent bond a hydrogen bond a polar covalent bond an ionic bond
a nonpolar covalent bond Correct The two hydrogen atoms share a pair of electrons equally because both have the same electronegativity.
The reaction A + B → AB is __________. a decomposition reaction an exchange reaction a synthesis reaction a catabolic reaction
a synthesis reaction Correct Reactions that build molecules from simpler subunits are called synthesis or anabolic reactions.
Which of the following is the appropriate label for the area with the question mark? Graph with y-axis measuring energy and x-axis measuring the progress of reaction in time. Trace begins at the level of energy of the reactants, then runs upwards to a higher energy of the transition state and then runs downwards to the energy of the products. The energy of the products is lower than the energy of the reactants. The area under the curve that runs from the energy level of the reactants, to the energy level of the transition state is highlighted in pink and designated with a question mark. Which of the following is the appropriate label for the area with the question mark? enzyme activation energy substrate energy released
activation energy Correct All chemical reactions require the input of some amount of energy to overcome so that the reactants reach their transition states and then form the products. This energy is called the activation energy (Ea).
This reaction is an example of __________. Diagram represents a reaction in which glucose and fructose (two monosaccharides) are combined to yield sucrose (a disaccharide). The structural formulas of glucose and fructose are shown and an OH on the glucose and H on the fructose are highlighted. A molecule of water is shown leaving as the reaction proceeds. This reaction is an example of __________. catabolic reaction dehydration synthesis exchange reaction hydrolysis
dehydration synthesis Correct Dehydration synthesis is an anabolic reaction in which two monomers are linked by a covalent bond and a water molecule is formed. Remember, water removed means dehydration.
The cations and anions that result when a salt dissolves are called __________. electrons and protons electrolytes catalysts buffers
electrolytes Correct All salts dissociate into electrolytes, as do some acids and bases. Electrolytes are named for the fact that they will conduct an electric current in water.
The reverse reaction to dehydration synthesis is __________. hydration synthesis anabolic reaction hydrolysis oxidation-reduction
hydrolysis Correct Hydrolysis is a catabolic reaction in which a molecule of water is added to break down a polymer. It is the reverse reaction to dehydration synthesis.
This fatty acid __________. Diagram of a fatty acid with a hydrocarbon chain that contains 17 carbons. There is a double bond between carbons 8 and 9. Where the double bond is located there is a bend or kink in the molecule. This fatty acid __________. contains multiple double bonds in its hydrocarbon chain is saturated would be the predominant type of fatty acid in animal fats is liquid at room temperature
is liquid at room temperature Correct Monounsaturated fatty acids like this one are generally liquid at room temperature because their bent hydrocarbon chains cannot pack tightly together.
Atoms that have the same number of protons but a different number of neutrons are called __________. isomers elements isotopes trace elements
isotopes Correct Isotopes of the same element have the same atomic number, but different mass number, because they have a different number of neutrons.
Water can cushion and protect the structures of the body because __________. it carries heat with it when it changes from a liquid to a gas it has a relatively high density it has a high heat capacity it can dissolve many solutes
it has a relatively high density Correct Since most of the body's organs are less dense than water, they are able to remain slightly suspended in their watery surroundings.
C2H8 is a(n) Nonpolar ionic molecule polar covalent molecule ionic compound nonpolar covalent molecule
nonpolar covalent molecule Correct If a molecule contains only carbon and hydrogen, it is nonpolar covalent.
The type of energy stored in the chemical bonds between atoms in a large molecule is __________. potential energy electrical energy mechanical energy kinetic energy
potential energy Correct Energy that is stored is called potential energy. In this example, potential energy is stored in the bonds between atoms of a complex molecule and has the potential to be released if the bonds are broken.
Positively charged subatomic particles are called __________. electrons neutrons protons nuclei
protons Correct A proton is a positive subatomic particle. The number of protons determines the element.
The level of protein structure that describes how two or more polypeptides interact to assemble into a protein is the __________. primary structure secondary structure tertiary structure quaternary structure
quaternary structure Correct Only proteins that have two or more polypeptides have a quaternary structure.
Alpha helices and beta-pleated sheets are examples of __________. primary protein structure secondary protein structure tertiary protein structure quaternary protein structure
secondary protein structure Correct The secondary structure of a protein consists of regular, repeated patterns of polypeptide folding, such as alpha helices and beta-pleated sheets. The polypeptide folds due to the formation of hydrogen bonds.
The chemical properties of an atom—in other words, how likely it is to form bonds and what types of bonds it will form—depend on its: __________. total number of neutrons mass number valence electrons number of protons
valence electrons Correct The number of electrons in the outermost shell of an atom, called valence electrons, determine how an atom interacts with other atoms and whether it will form bonds with a specific atom.
