Part A: Multiple Choice (15 Marks)
 

1. What determines the atomic number of an atom?
1. Number of electrons in the outermost energy level.
2. Total number of energy shells.
3. Arrangement of neutrons in the atomic nucleus.
4. Number of protons in the atomic nucleus.
2. What is the possible capacity of the outer electron shell of an atom of hydrogen (atomic number = 1)?

a. 1 electron
b. 2 electrons
c. 6 electrons
d. 8 electrons
 

3. The molecule C₂₄H₄₆O₂₃ is a(n):

a. protein
b. lipid
c. monosaccharide
d. polysaccharide
 

4. How does sodium acetate-acetic acid function as a buffer?

a. Acetate ion accepts OH^- ions
b. Acetate ion accepts H⁺ ions, depending on pH
c. Acetate ion accepts H⁺, and H⁺ accepts OH^-
d. Always increases pH
 

5. Of the two molecules shown below:

 

          NH₂ H                                                      H     H     H
           |       |                                                         |       |       |
CH₃--C -- C = O                                        H -- C -- C -- C -- C = O
           |       |                                                         |       |       |       |
          H     OH                                                    H     H     H     OH
 
a. both contain the amine group
b. both belong to the same family of biomolecules
c. both serve as monomer subunits of a polymer
d. all of the above
 

6. The presence of (-OH) in an organic compound tends to make that compound:

a. Hydrophobic
b. Basic
c. Hydrophillic
d. Acidic
 

7. Which of the following reactions requires the removal of water to form a covalent bond?

a. amylopectin -----> glucose subunits
b. alanine + glycine -----> dipeptide
c. cellulose -----> glucose
d. lactose -----> glucose + galactose
 

8. Which of the following is false about amylose?

a. It is made of several hundred glucose units.
b. It is a component of starch.
c. It has unbranched chains.
d. It has a C1,C2 linkage between monomers.
 

9. If you compare a molecule of chitin to a molecule of cellulose, what structural difference becomes evident?

a. Cellulose is formed from branching chains.
b. Chitin's monomers are slightly different in structure.
c. The glucose subunits are bonded differently in chitin.
d. Cellulose is a disaccharide.
 

10. Where is glycogen stored in vertebrate animals?

a. Liver and muscles
b. Brain and kidneys
c. Heart and blood
d. Pancreas and Intestines
 

11. Which of the following correctly matches an organic polymer with its respective monomers?

a. Protein and amino acids
b. Carbohydrates and polysaccharides
c. Hydrocarbon and monosaccharides
d. Lipid and steroids
 

12. Which of the following interactions does not involve a hydrogen bond?

a. The primary structure in proteins
b. Nitrogenous bases "pair up"
c. An  alpha-helix
d. Water molecules "stick" together
 

13. The bonds between amino acids are termed:

a. condensation bonds
b. peptide bonds
c. hydrogen bonds
d. 007
 

14. The main difference between ribose and deoxyribose is that:

a. deoxyribose is a hexose and ribose is a pentose sugar
b. deoxyribose has one less hydroxyl group than ribose
c. deoxyribose has had all of its oxygen removed
d. deoxyribose is a bigger sugar
 

15. When an inhibition molecule binds to an enzyme at a site other than the active site, the situation is referred to as:

a. Competitive inhibition
b. Irreversible inhibition
c. Allosteric inhibition
d. End product inhibition

1. Distinguish between isotope and isomer.(2 marks)
 

2. Define oxidation and give an example.(2 marks)
 

3. Describe how to prepare 2 L of a 0.1 M Sodium Acetate (CH₃COONa) solution. (4 marks)
 
4. Describe any two functional groups using the following:
 

Functional  Group	Structural  Formula	Molecule in which it is found?	Polar or Non-Polar?

 
5. Name two important uses of each of the following: (6 marks)
 
Lipids
 
Proteins

Nucleic Acids
 

6. State the importance of the following: (6 marks)
a. Activation Energy -
 
b. Ionic Bridges -
 
c. Conjugate Base in Buffers -
 

7. a. Using simplified structural formulas (indicate important functional groups) show the      reaction whereby a two monomers join to form a dimer(2 units).(Include everything necessary for the reaction to proceed.) (5 marks)
 

b. What type of reaction is this? (1 mark)
 

8. Identify the following structures(Be as specific as possible).

(4 marks)

b. Why are fats better at storing energy than carbohydrates.
 

10. Briefly describe one way that enzymes are regulated in the cell. (2 marks)
 

11. Briefly describe one way that enzymes are regulated in the cell. (2 marks)
 

12. The following diagram represents a small portion of DNA. Given the number and position of hydrogen bonds, label any four of the molecules indicated in the diagram. What is the name of the monomer subunits? (5 marks)

1.
2.
3.
4.
5. Cytosine
6. .
 

Monomer Unit:
_____________
 
 
 

13. Maltase is an enzyme found in the small intestine.

The following graph represents the data collected during an experiment performed under three pH conditions. Each reaction mixture contained 1 mg of maltase, 25 mL of a buffered solution (either pH 6, pH 8 or pH 9), and 50 mg of substrate. The temperature was maintained at 37^oC. (6 marks)

b. What "type" of reaction is catalyzed by maltase? (1 mark)
 

c. What conclusion can you make about maltase activity? (1 mark)
 

d. Describe what maltase is actually doing to the substrate at the molecular(bonds) level. (3 marks)
 
 

14. The primary structure of proteins is not a random arrangement of amino acids. Explain this statement. (3 marks)