Download Keystone Quiz—Biochemistry Unit

Keystone Quiz—Biochemistry Unit
Please choose the correct answer. Good Luck
1. Which statement best describes an effect of the low density of frozen water in a lake?
A. When water freezes, it contracts, decreasing the water level in a lake.
B. Water in a lake freezes from the bottom up, killing most aquatic organisms.
C. When water in a lake freezes, it floats, providing insulation for organisms below.
D. Water removes thermal energy from the land around a lake, causing the lake to freeze.
2. A leaf gently floats on a pond. Which of the following statements best explains why the leaf stays on top of
the water?
A. The leaf has nonpolar covalent bonds between its atoms
B. The density of the leaf is greater than the density of the water.
C. The water molecules are held together by hydrogen bonding.
D. The hydrogen and oxygen atoms in the water are held together by ionic bonds.
3. Carbon is able to form an immense diversity of organic molecules because of carbon’s
A.
B.
C.
D.
E.
F.
Tendency to form covalent bonds.
Ability to bond with up to four other atoms.
Capacity to form single and double bonds.
Ability to bond together to form extensive, branched, or unbranched “carbon skeletons.”
All of the choices are correct.
None of the choices are correct.
4. Which statement correctly describes how carbon’s ability to form four bonds makes it uniquely suited to
form macromolecules?
A. It forms short, simple carbon chains.
B. It forms large, complex, diverse molecules.
C. It forms covalent bonds with other carbon atoms.
D. It forms covalent bonds that can exist in a single plane.
Use the diagram below to answer the question.
5. The diagram shows a reaction that forms a polymer from two monomers. What is this type of reaction
called?
A. glycolysis
B. hydrolysis
C. photosynthesis
D. dehydration synthesis
6. Athletes are often concerned with the question of how much protein they need in their diets because of the
requirement of protein for growing muscles. Just as muscles need the basic building block of protein, protein
itself has basic building blocks also. Which of the following are the basic building blocks of protein?
A. amino acids ***
B. monosaccharides
C. nitrates
D. nucleotides
7. Which of the following units are repeatedly joined together to form a strand of DNA?
A. amino acids
B. fatty acids
C. nucleotides
D. polysaccharides
8. One category of organic compounds contains molecules composed of long hydrocarbon chains. The
hydrocarbon chains may be saturated or unsaturated.
Which of the following categories of organic compounds contains these molecules?
A. carbohydrates
B. lipids
C. nucleic acids
D. proteins
9. Which statement describes carbohydrates, lipids, proteins, and DNA?
(A) They are used to store genetic information.
(B) They are complex molecules made from smaller molecules.
(C) They are used to assemble larger inorganic materials.
(D) They are simple molecules used as energy sources.
10. Carbohydrates and proteins are two types of macromolecules. Which functional characteristic of proteins
distinguishes them from carbohydrates?
A. large amount of stored information
B. ability to catalyze biochemical reactions
C. efficient storage of usable chemical energy
D. tendency to make cell membranes hydrophobic
11. A researcher examines a molecule and finds that it speeds up and slows down certain chemical reactions.
Which type of organic molecule was examined?
A. carbohydrate
B. lipid
C. nucleic acid
D. protein
12. The clear protein of an egg white becomes opaque and firm when cooked because the heat
A. mutates the DNA.
B. turns the protein into carbohydrates.
C. stops protein formation.
D. changes the protein structure.
13. Substance A is converted to substance B in a metabolic reaction. Which statement best describes the role
of an enzyme during this reaction?
A. It adjusts the pH of the reaction medium.
B. It provides energy to carry out the reaction.
C. It dissolves substance A in the reaction medium.
D. It speeds up the reaction without being consumed.
14. Use the diagram below to answer the question that follows.
The diagram models how a poison bonds to the active site of an enzyme. Which function is the enzyme most
likely unable to perform because of the attachment of the poison molecule?
A. the release of stored chemical energy
B. the donation of electrons to the substrate
C. the supply of activation energy for a reaction
D. the catalysis of the reaction with the substrate
15. Individuals who lack lactase are unable to break down the sugar lactose. Which term best describes
lactase?
A enzyme
B fatty acid
C lipid
D starch
16. A scientist observes that, when the pH of the environment surrounding an enzyme is changed, the rate the
enzyme catalyzes a reaction greatly decreases. Which statement best describes how a change in pH can affect
an enzyme?
A. A pH change can cause the enzyme to change its shape.
B. A pH change can remove energy necessary to activate an enzyme.
C. A pH change can add new molecules to the structure of the enzyme.
D. A pH change can cause an enzyme to react with a different substrate.
17. In the human digestive system, the enzyme trypsin acts on proteins. The optimal temperature for the
enzyme is approximately 40°C.
Which of the following graphs shows how the activity of the enzyme most likely relates to the temperature of
the reaction environment?
A.
B.
C.
D.
graph A
graph B
graph C
graph D