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Problem L3.2
Some claim that the pH of your blood can be affected by eating acidic foods such as citrus. Do you believe this to be true? Explain your answer. (Hint: What happens when extra hydrogen ions are added to the blood?)
Problem L3.4
Explain how buffer systems in the body work if the pH of body fluids increases. Is this an example of a negative or a positive feedback loop? Explain.
Problem L2.1
In certain types of radioactive decay, the isotope releases a particle called an alpha particle, which contains two protons and two neutrons. When this happens, is the product still the same element? Why or why not?
Problem L2.2
Considering that water is a main component of the juices in the stomach and intestines, explain why digestion of lipids is more complicated than digestion of carbohydrates and proteins.
Problem L2.3
Explain why monosaccharides are polar and fatty acids are nonpolar even though they both contain the same atoms.
Problem L3.1
The polysaccharide cellulose is not digestible by humans, as we lack the enzyme cellulase, which is required to break it down. Certain dietary supplements contain the enzyme cellulase and claim that being able to break down cellulose will help a person lose weight. But what do you think would happen if we could digest the cellulose we ate?
Problem L3.3
Many drugs and poisons exert their effects by blocking one or more enzymes. How could blocking an enzyme lead to the death of a cell?
Problem 1a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The mass number of an atom is the sum of its neutrons and protons.
Problem 1b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Protons and neutrons have a positive charge and electrons have a negative charge.
Problem 1c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Valence electrons are the electrons in the outermost shell of an atom.
Problem 1d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Every element has a characteristic number of protons, which is called the element's mass number.
Problem 2
Isotopes are atoms with the same ______ number but different ______ numbers.
Problem 3
Which of the following statements correctly describes a solution?
a. In a solution the solute is chemically dissolved by the solvent.
b. Solutions involve large particles suspended in another component.
c. The particles in a solution will settle out if left to sit.
d. The amount of solute in a solution is expressed as the solution's concentration.
Problem 4
Explain the difference between an ionic and a covalent bond.
Problem 5
Identify each of the following molecules or compounds as ionic, polar covalent, or nonpolar covalent.
a. H2O _________
b. LiI _________
c. C10H22 _________
d. N2 _________
e. MgBr2 _________
f. H2S _________
Problem 6
What are hydrogen bonds, and how do they form?
Problem 7
Describe what takes place during a chemical reaction.
Problem 8
Match the following terms with the correct definition:
Endergonic reaction
Potential energy
Electrical energy
Anabolic reaction
Oxidation-reduction reaction
Chemical energy
Catabolic reaction
Kinetic energy
a. Energy in motion
b. Energy stored in chemical bonds
c. Reaction that consumes energy
d. A decomposition reaction
e. The energy of moving charged particles
f. Stored energy
g. Synthesis reaction
h. Reaction where electrons are transferred between reactants
Problem 9
Which of the following would not result in an increase in reaction rate?
a. Increase in temperature
b. Particles in the solid phase
c. Presence of a catalyst
d. Smaller particle size
Problem 10
An enzyme is a:
a. biological catalyst that increases the concentration of the products.
b. biological catalyst that increases the concentration of the reactants.
c. chemical that is used in a reaction, after which it can no longer be used by the cell.
d. biological catalyst that works by bringing its substrates closer to their transition states.
Problem 11
Which of the following is not a property of water?
a. Water has a high heat capacity.
b. Water doesn't take heat with it when it evaporates.
c. Water is a polar solvent in which many solutes will dissolve.
d. Water serves as a cushion and lubricant in the body.
Problem 12
With respect to their solubility in water, substances with nonpolar covalent bonds are__________, while substances with polar covalent and ionic bonds are__________.
Problem 13a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Acids dissociate in water to give hydrogen ions and an anion.
Problem 13b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
As a solution's pH rises, it becomes more acidic.
Problem 13c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
A buffer is a system of chemicals that resists a change in pH
Problem 13d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
A solution with a pH of 10 has more hydrogen ions than a solution with a pH of 2.
Problem 14
A salt is:
a. a metal cation bonded to a nonmetal anion.
b. a hydrogen ion donor.
c. an electrolyte that conducts electricity in water.
d. Both a and c are correct.
e. Both b and c are correct.
Problem 15
Compare and contrast the structures of phospholipids and triglycerides.
Problem 16a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Carbohydrates are the main source of fuel for the human body.
Problem 16b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The main storage form of glucose in the human body is starch.