Biochemistry Test

A) Ionic bond B) Nonpolar Covalent bond C) Polar Covalent bond Found in NaCl

A

Base your answer to the following question on the information and graph below and on your knowledge of biology. The pH of the internal environment of lysosomes (organelles that contain digestive enzymes) is approximately 4.5 while the pH of the surrounding cytoplasm is approximately 7. The average pH of the human stomach during digestion is approximately 2.5, while the average pH of the small intestine during digestion is about 8. The graph below shows how pH affects the enzymes activity of four different enzymes, A, B, C, and D. Which enzyme functions best in a pH environment most similar to that of human stomach enzymes? A) A B) B C) C D) D

A

Enzymes are produced as a direct result of which process? A) protein synthesis B) photosynthesis C) respiration D) enzymatic hydrolysis

A

In addition to a phosphate group, a DNA nucleotide could contain A) thymine and deoxyribose B) uracil and deoxyribose C) thymine and ribose D) uracil and ribose

A

Letter Z most likely represent molecules of A) water B) plant hormones C) glycogen D) nucleic acids

A

The primary structure of a protein is represented by the A) sequence of amino acids in the molecule B) pleating or coiling in the molecule C) spatial folding of the molecule D) aggregation of several tertiary proteins

A

This diagram best illustrates the relationship between A) enzymes and synthesis B) amino acids and glucose C) antigens and immunity D) ribosomes and sugars

A

Which molecule can be classified as organic? A) A B) B C) C D) D

A

Which pH has the highest concentration of H+ ion per liter of solution? A) pH 1 B) pH 4 C) pH 7 D) pH 9 E) pH 14

A

A-adenine C-cytosine G-guanine T-thymine Which base pairings normally occur during DNA replication? A) Guanine pairs with cytosine, Thymine pairs with thymine. B) Adenine pairs with thymine. Cytosine pairs with guanine. C) Thymine pairs with guanine. Cytosine pairs with adenine. D) Cytosine pairs with cytosine. Thymine pairs with thymine.

B

An example of a carbohydrate A) 1 B) 2 C) 3 D) 4 E) 5

B

How many different kinds of amino acids are there? A) 10 B) 20 C) 1 D) 100

B

Molecular structures are represented in the diagrams below. Structure 2 represents a chemical component of A) molecule 1, only B) molecules 1 and 5, only C) molecules 1, 3, and 4, only D) molecules 1, 3, 4, and 5

B

The atomic number of an atom is equal to the total number of its A) electrons, only B) protons, only C) electrons and neutrons D) electrons and protons E) protons and neutrons

B

The building blocks for this molecule are A) amino acids B) simple sugars C) fats D) molecular bases

B

The function of a specific enzyme is most directly influenced by its A) molecular size B) physical shape C) carrying capacity D) stored energy

B

The graph below shows the effect of temperatures on the relative rate of action of enzymes X on a protein. Which change would NOT affect the relative rate of actions of enzyme X? A) the addition of cold water when the reaction is at 50 degrees C B) an increase in temperature from 70 degrees C to 80 degrees C C) the removal of the protein when the reaction is at 30 degrees C D) a decrease in temperature from 40 degrees C to 10 degrees C

B

The letter represents different types of A) sugar molecules B) molecular bases C) enzymes D) proteins

B

What is the name of the bond linking sugar molecules together? A) Peptide bond B) Glycosidic bond C) Phosphodiester bond D) Ionic bond

B

Which group of atoms varies from one type of amino acid to another? A) 1 B) 2 C) 3 D) 4

B

Which groups consists entirely of organic molecules? A) protein, oxygen, fat B) protein, starch, fat C) water, carbon dioxide, oxygen D) water, starch, protein

B

Which statement about pH is correct? A) There are no hydrogen ions in a strong basic solution B) pure water has a neutral pH of 7 because the hydrogen ions concentration equals the hydroxyl (OH) ion concentrations C) The concentration of a solution with a pH of 5 is 5 times more acidic that a solution of pH 1 D) The concentration of hydrogen ions in a solution with a pH of 2 is 2000 times more acidic that a solution with a pH of 4

B

Which statement best describes enzymes? A) Every enzyme controls many different reactions. B) The rate of activity of an enzyme might change as pH changes. C) Temperature changes do not affect enzymes. D) Enzymes are produced from the building blocks of carbohydrates.

B

A) Ionic bond B) Nonpolar Covalent bond C) Polar Covalent bond Found in H2O

C

Base your answer to the following questions on the diagram below, which represents a chemical reaction that occurs in the human body, and on your knowledge of biology. Which statement describes a characteristic of molecule Z? A) Molecule Z will function at any temperature above 20 degree C. B) Molecular Z is composed of a string of molecular bases represented by A, T, G, and C) Molecular Z will function best at a specific pH D) Molecular Z is not specific, so this reaction can be controlled by any other chemical in the body.

C

Even though human proteins are synthesized from only 20 different amino acids, there are thousands of different proteins found in human cells. This great variety of proteins is possible because the A) size of a specific amino acid can vary within a protein B) chemical composition of a specific amino acid can vary C) sequence and number of amino acids can be different in each protein D) same amino acid can have many different properties

C

What are the building blocks of lipids? A) Glucose B) Amino acids C) Fatty acids and glycerol D) Nucleic acids

C

What do letters A and B represent? A) A- lipase; B- protease B) A- protease; B- maltase C) A- maltase; B- lipase D) A- maltase; B- protease

C

Which chemical formula represents a carbohydrate? A) CH4 B) C3H7O2N C) C12H22O22 D) C)2

C

Which substance is an inorganic molecule? A) starch B) DNA C) water D) fat

C

Which substances would most likely be present in the solution in the flask after 48 hours? A) amino acids, only B) amino acids and polypeptide, only C) polypeptides, amino acids, and enzyme molecules D) polysaccharides, amino acids, and enzyme molecules

C

A solution of an enzyme normally found in the human body was added to a flask containing a solution of proteins in distilled water, and then the flask was stoppered. This mixture was then maintained at a temperature of 27 degrees C and a pH of 7 for 48 hours. When the mixture was analyzed, the presence of amino acids was noted. The enzymatic solution most likely contained A) carbohydrates B) maltases C) lipases D) proteases

D

Isotopes of an element A) have the same number of neutrons B) have different numbers of protons C) have essentially different chemical properties D) have different numbers of neutrons E) have different charges

D

Letter Y most likely represents A) a neurotransmitter B) a hormone C) a lipid D) an enzyme

D

The sweet taste of freshly picked corn is due to the high sugar content in the kernels. Enzyme action converts about 50% of the sugar to starch within one day after picking. To preserve its sweetness, the freshly picked corn is immersed in boiling water for a few minutes, and then cooled. Which statement most likely explains why the boiled corn kernels remain sweet? A) Boiling destroys sugar molecules so they cannot be converted to starch. B) Boiling kills a fungus on the corn that is needed to convert sugar to starch. C) Boiling activates the enzymes that converts amino acids to sugar. D) Boiling deactivates the enzymes responsible for converting sugar to starch.

D

Where does a chemical bond form when a dipeptide is synthesized? A) an oxygen atom of a glucose molecule and a carbon atom of a lipid molecule B) a carbon atom and a hydrogen atom C) a variable side group and a nitrogen atom D) a nitrogen atom in an amino group and a carbon atom in a carboxyl group

D

Which chemical reaction is represented by the diagram below? A) dehydration synthesis of a dipeptide B) hydrolysis of a polypeptide C) dehydration synthesis of a lipid D) hydrolysis of a disaccharide

D