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LHWHS AP Biology
Unit One - The Chemistry of Life
Practice Test Questions
NAME_____________________
Test Outline
~40 multiple choice (similar to packet of practice AP questions)
~18 short answer and problems (similar to quiz, lab, and hw questions)
Understand all labs, hw, quizzes, notes, and text book
( Chapters 2, 3, 4, 8.1-8.4, and the intro to sections 5.1, 5.2, 5.3, 5.4, 5.5 )
1. How many mL of 0.003 M NaOH are needed to neutralize
75 mL of 0.068 M HCl ?
1700 mL
2. What are the concentrations of CH3COOH and CH3COO - in a
0.65 M acetate buffer solution, which has a pH of 4.24.
The pKa for acetate is 4.76.
0.15 M CH3COO0.50 M CH3COOH
3. What is the pH of 0.075 M solution of weak acid HA if the Ka is 3.8 × 10-6
pH = 3.27
4. Many of the most important molecules in the cell are polymers made by
linking together long strings of monomers.
a) What does making a polymer do to the entropy of the system ?
-ΔS......decrease in entropy (randomness)
.......many things becoming one thing
b) Since making polymers is an endothermic process, how does the cell
get around this endergonic (+ ΔG) process and continue to make
macromolecules ?
Reactions in the cell are coupled with the breakdown of ATP which can
provide the energy needed to make larger molecules from smaller molecules.
5. An automobile accident victim has lost a great deal of blood. Should
paramedics administer (1) water , (2) fluid that approximates intracellular
fluid, or (3) fluid that approximates extracellular fluid. Explain your answer.
(3)
Blood is extracellular (outside the cell) fluid
6. Provide a simple description of the function of carbohydrates, lipids,
proteins, and nucleic acids.
Carbohydrates - made of C, H, O generally in a 1 :2: 1 ratio, polar molecules
- can be broken down and used for energy
- can form the structural components of cells and nucleic acids
- can function as receptors / signal molecules in cell membrane
Lipids - "greasy or oily" hydrocarbon chains, generally non-polar
- can be broken down and used for energy
- can function as receptors / signal molecules in cell membrane
- also includes pigments, vitamins, and hormones
Proteins - chains of amino acids, largest fraction of a cell (besides water),
- made of C, H, O, and N atoms
- large molecules, molecular weight is in thousands to millions amu
- includes enzymes (thousands of enzymes in every cell)
- structual components of cells and tissues
- can function as receptors / signal molecules in cell membrane
- can be broken down and used for energy
- can function as transport molecules controlling what comes in and out
of a cell
- examples include collagen, antibodies, digestive enzymes, hemoglobin
Nucleic Acids - make of DNA and RNA
- made of C, H, O, N, and P atoms
genetic material passed onto offspring
7. Do the "Concept check 8.2" on page 148. (Answers in Appendix A)
8. What are the pH, pOH, [H+], and [OH_] of 0.0068 M HCl ?
pH = 2.16 [H+] = 0.0068
pOH = 11.84 [OH-] = 1.45 × 10-12
9. How many mL of 0.04 M NaOH are needed to neutralize
40 mL of 0.15 M HCl ?
150 mL
----------------------
10. Predict the shift in equilibrium (left or right) for
the acetate buffer system when........
CH3COOH <======> H+ + CH3COO
-
a) a solution of HCl is added to the beaker left__________
b) sodium acetate (NaCH3CO2) salt is added to the beaker__left________
c) sodium hydroxide (NaOH) is added to the beaker_____right__
--------------------11. Which of the following would have the highest pH ?
Explain your reasoning.
0.1 M acetic acid.......Ka = 1.8 × 10 -5
0.1 M citric acid........Ka = 3.2 × 10 -7
0.1 M boric acid........Ka = 5.4 × 10 -10
Boric acid has the lowest value for Ka. It has the least amount of ionization.
It has the lowest concentration of [H+]. It has the highest pH
-------------------12. What is the ratio of conjugate base to acid for a primary phosphate
buffer system which has a pH of 2.58.
The Ka of hydrogen phosphate is 7.94 × 10-3.
pH = pKa + log [A-]
[HA]
3/1
13. What is the pH of 0.08 M solution of weak acid HA if
Ka for HA is 5.0 × 10-6 ?
pH = 3.2
14. Determine the percentage of water in an apple using the data below
Name of substance __Apple_________
Mass of dish ___1.35 g_______
Mass of dish and sample (before heating) ____9.65 g____
Mass of dish and sample (after heating) ____2.96 g_____
80 .6 %
Circle the structure which is larger in each pair
15. Nucleus of cell .........OR.........Glucose molecule
16. Eukaryote cell..........OR...........carbon atom
17. Protein molecule..........OR.........hydrogen ion
18. hydrogen ion...........OR ..........fatty acid molecule
------------------------------------ 19. Define hydrophobic and hydrophilic .
Hydrophobic materials will not blend or dissolve in water very readily.
Generally, this is characteristic of non- polar molecules.
Hydrophilic materials will blend, mix, and dissolve in water.
Generally, this is characteristic of polar molecules.
20. Provide an example of a protein
hemoglobin, albumin
21. List and very briefly explain the five types of biochemical reactions.
Group Transfer - moving one group of atoms/molecules from one molecule to
another ex: moving phosphate groups
Reduction / Oxidation reactions - moving charges (electrons) between molecules
ex: ioinzation of hydrogen ions in acidic solutions
ex: reacting glucose with Benedict's solution
Rearragement - moving groups of atoms/molecules around on the same
molecule
ex: moving a phosphate group to a different location on
the same molecule
Cleavage - breaking a molecule apart
ex: glucose breaking in half to form pyruvate
Condensation - joining two molecules together resulting in the formation of
water
ex: amino acids bonding together
22. List two properties or characteristic of......
see #6
carbohydrates - polar, used for energy
proteins - large molecules, often containing polar and non-polar regions,
control chemical reactions in the cell, can control passage of materials
in and out of the cell
nucleic acids - can be large molecules, major component of genes
lipids - generally non-polar, major component of cell membranes
23. Maleic acid is the cis isomer (CH2)2(COOH)2
Fumaric acid is the trans isomer (CH2)2(COOH)2
Draw the geometric isomers. Is there a chiral carbon ?
These drawings should be in your notes.
The COOH groups are on the same side of the double bond for the cis isomer.
The COOH groups are on different sides of the double bond for the trans isomer.
There is not a chiral carbon.
There is not a carbon with 4 different things bonded to it.
All carbons only have 3 things (hydrogen, oxygen, another carbon) bonded to it.
24. In your Oxidation of Sugars lab, glucose and fructose both reacted
positively with Benedict's Reagent. Starch and sucrose did not.
a. Describe what it means for a sugar to be oxidized.
A carbon atom in the sugar molecule lost electrons
For example, the charge (oxidation state) of the carbon atom
increased from +1 to +3 as it looses two electrons.
b. Why didn't starch and sucrose react with Benedict's.
Starch and sucrose did not have a carbon atom 'available' to loose electrons.
c. What did you have to do to starch and sucrose to get a positive
test with Benedict's ?
Adding HCl (hydrochloric acid) to starch and sucrose caused these molecules
to break apart. Once broken apart, carbon atoms were exposed and
'available' to be oxidized by the Benedict's solution.