Unit 1 Practice Test 𖦹⋆｡°✩

Question 1

The carbohydrates glucose, galactose, and fructose have the same chemical formula
but different structural formulas, as represented in the figure. Which of the following statements about glucose, galactose, and fructose is most likely true?

Answer 1

A. The carbohydrates have the same properties because they have the same number of carbon, hydrogen, and oxygen atoms.

B. The carbohydrates have the same properties because they each have a single carbon-oxygen double bond.

C. The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.

D. The carbohydrates have different properties because they have different numbers of carbon-carbon bonds.

Question 2

✩ CORRECT ANSWER FOR 1.1, 1✩

Answer 2

C

Question 3

Water and ammonia interact to form hydrogen bonds, as represented in the figure. Which statement best helps explain the formation of the hydrogen bond represented in the figure?

Answer 3

A. The oxygen has a partial positive charge, and the nitrogen has a partial negative charge.

B. The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

C. The hydrogen attached to the oxygen has a partial negative charge, and the nitrogen also has a partial negative charge.

D. The nitrogen has a partial positive charge, and the hydrogen attached to the oxygen also has a partial positive charge.

Question 4

✩ CORRECT ANSWER FOR 1.1, 2✩

Answer 4

B

Question 5

Figure 1 is a diagram of water molecules at the air-water interface at the surface of a pond. Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water’s surface?

Answer 5

A. Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles to form under the feet of the insect.

B. Ionic bonds between molecules at the surface of the water provide an electric charge, which attracts the feet of the insect, keeping it on the surface.

C. Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the weight of the insect.

D. Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

Question 6

✩ CORRECT ANSWER FOR 1.1, 3✩

Answer 6

D

Question 7

Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules?

Answer 7

A. Rabbits eat plants and use energy absorbed from the plants to make carbon atoms from electrons, protons, and neutrons in the air.

B. Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules.

C. Rabbits eat plants and use water absorbed from the plants to hydrolyze CO2, which the rabbits breathe in from the air and use as a carbon source.

D. Rabbits eat plants and make carbon-containing molecules by using carbon atoms that the plants absorbed from the soil and stored in the cells of their leaves.

Question 8

✩ CORRECT ANSWER FOR 1.2, 1✩

Answer 8

B

Question 9

The figure shows a model of the exchange of matter between the organisms that live together in an aquarium. The model includes matter exchange between plants, fish, and bacteria. The bacteria are represented as rod-shaped organisms living in the gravel at the bottom of the aquarium. Which of the following statements best describes how molecules released by the fish become nutrients for the plants?

Answer 9

A. The carbon dioxide molecules released by the fish are converted by the bacteria to oxygen atoms, which are used by the plants to make water molecules.

B. The oxygen molecules released by the fish are converted by the bacteria to ammonia molecules, which are used by the plants to make lipids and fatty acids.

C. The nitrites released by the fish are converted by the bacteria to carbon dioxide molecules, which are used by the plants to make carbohydrates.

D. The ammonia molecules released by the fish are converted by the bacteria to nitrates, which are used by the plants to make proteins and nucleic acids.

Question 10

✩ CORRECT ANSWER FOR 1.2, 2✩

Answer 10

D

Question 11

✩ CORRECT ANSWER FOR 1.2, 3✩
… review chart

Answer 11

C

Question 12

✩ CORRECT ANSWER FOR 1.3, 1✩

… short answer

Question 13

Which of the following best describes the formation of the bond shown in Figure 1 ?

Answer 13

A. An ionic bond is formed between a carbon atom of one amino acid and the nitrogen atom of the other amino acid.

B. An ionic bond is formed when the negative charge of an
group is balanced by the positive charge of a hydrogen ion.

C. A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2O

D. A covalent bond is formed that replaces the

Question 14

✩ CORRECT ANSWER FOR 1.3, 2✩

Answer 14

C

Question 15

Figure 1 represents a common process that occurs in organisms. Which of the following is an accurate description of the process shown in Figure 1 ?

Answer 15

A. The linking of amino acids with an ionic bond as an initial step in the protein synthesis process

B. The formation of a more complex carbohydrate with the covalent bonding of two simple sugars

C. The hydrolysis of amino acids with the breaking of covalent bonds with the release of water

D. The formation of a covalent peptide bond in a dehydration synthesis reaction

Question 16

✩ CORRECT ANSWER FOR 1.3, 3✩

Answer 16

D

Question 17

Polypeptides are continuously being formed and degraded. One of these processes is shown. Which statement is the most accurate description of the reaction shown in Figure 1?

Answer 17

A. It represents monomers linked by dehydration synthesis.

B. It represents a polypeptide chain that folds to form the tertiary structure.

C. It represents a polypeptide chain that is denatured into the primary structure.

D. It represents a polypeptide chain that is broken down through a hydrolysis reaction.

Question 18

✩ CORRECT ANSWER FOR 1.3, 4✩

Answer 18

D

Question 19

The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure. Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?

Answer 19

A. Linoleic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

B. Linoleic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing closely together.

C. Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

D. Palmitic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing closely together.

Question 20

✩ CORRECT ANSWER FOR 1.4, 1✩

Answer 20

C

Question 21

Which of the following best describes the structures of carbohydrates?

Answer 21

A. They only occur as disaccharides.

B. They occur as monomers, chains of monomers, and branched structures.

C. They only occur as long and branched structures.

D. They occur as chains of monomers that hydrogen bond with complementary chains of monomers.

Question 22

✩ CORRECT ANSWER FOR 1.4, 2✩

Answer 22

B

Question 23

Which of the following best describes how amino acids affect the tertiary structure of a protein?

Answer 23

A. The number of amino acids determines the tertiary structure of the protein.

B. The interactions of the different R-groups with other R-groups and with their environment determine the tertiary structure of the protein.

C. The R-group of the last amino acid that is added to a growing polypeptide chain determines the next amino acid that is added to the chain.

D. The sequence of the amino acids in the polypeptide chain determines the protein’s primary structure but has no effect on its tertiary structure.

Question 24

✩ CORRECT ANSWER FOR 1.4, 3✩

Answer 24

B

Question 25

The CFTR protein is made up of 1480 amino acids linked together in a chain. Some humans produce a version of the CFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein?

Answer 25

A. It will have no observable effect on the structure of the CFTR protein.

B. It will affect the primary structure of the CFTR protein, but the other levels of protein structure will not be affected.

C. It will affect the secondary and tertiary structures of the CFTR protein, but the primary structure will not be affected.

D. It will affect the primary, secondary, and tertiary structures of the CFTR protein.

Question 26

✩ CORRECT ANSWER FOR 1.5, 1✩

Answer 26

D

Question 27

Researchers compared similar proteins from related organisms in different habitats. They found that the proteins from organisms living in harsh environments had a greater number of cysteine amino acids than did proteins from organisms not living in harsh environments. The structure of cysteine is shown. Bonds can form between the sulfur atom of different cysteine amino acids (S-S bonds). Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?

Answer 27

A. The change has no effect on the stability of the protein because only one type of amino acid is involved.

B. The change leads to increased protein stability because of an increased number of
bonds in the tertiary structure of the proteins.

C. The change leads to decreased protein stability because of an increased number of
bonds in the tertiary structure of the proteins.

D. The change leads to increased protein stability only when the added cysteine amino acids are next to other cysteine amino acids in the primary structure.

Question 28

✩ CORRECT ANSWER FOR 1.5, 2✩

Answer 28

B

Question 29

✩ CORRECT ANSWER FOR 1.5, 3✩
… short answer question

Question 30

✩ CORRECT ANSWER FOR 1.5, 4✩
… diagrams

Answer 30

A

Question 31

DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNA and RNA?

Answer 31

A. DNA contains four types of nitrogenous bases, whereas RNA contains only two types of nitrogenous bases.

B. The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

C. A DNA molecule is composed of two parallel strands with the same 5’ to 3’
directionality, whereas an RNA molecule is composed of only one 5’ to 3’ strand.

D. Phosphate groups provide rigidity to DNA, but RNA is flexible and contains no phosphate groups.

Question 32

✩ CORRECT ANSWER FOR 1.6, 1✩

Answer 32

B

Question 33

Figure 1 represents a nucleic acid fragment that is made up of four nucleotides linked together in a chain. Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

Answer 33

A. The 5’ to 3’ orientation of the nucleotide chain

B. The identity of each nitrogenous base

C. The charges on the phosphate groups

D. The type of bond linking the nucleotides together

Question 34

✩ CORRECT ANSWER FOR 1.6, 2✩

Answer 34

B

Question 35

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2?

Answer 35

A. Nucleic acid 1 contains only purines, whereas nucleic acid 2 contains only pyrimidines.

B. Nucleic acid 1 contains the sugar ribose, whereas nucleic acid 2 contains the sugar deoxyribose.

C. Nucleic acid 1contains positively charged phosphate groups, whereas nucleic acid 2 does not.

D. Nucleic acid 1 contains adenine-thymine base pairs, whereas nucleic acid 2 does not.

Question 36

✩ CORRECT ANSWER FOR 1.6, 3✩

Answer 36

D