practice

Question 1

Which of the following types of cells lack(s) a nucleus?

Answer 1

Archea

Question 2

Investigating the molecular structure of DNA in order to understand the chemical basis of inheritance is an example of which approach utilized in the study of biology?

Answer 2

Reductionism

Question 3

Which of the following represents the correct hierarchy of biological organization from large scale to smaller scale?

Answer 3

biosphere → ecosystems → communities → populations → organisms

Question 4

Which of the following statements describes a controlled experiment?

Answer 4

an experiment with at least two groups, one of which does not receive the experimental treatment

Question 5

Inductive Reasoning

Question 6

Which four of the 92 naturally occurring elements make up approximately 96% of the mass of the human body?

Answer 6

carbon, oxygen, nitrogen, hydrogen

Question 7

Which of the following is the key characteristic that is ultimately responsible for the unique chemical properties of each element?

Answer 7

Each element has a unique number of protons.

Question 8

An ionic bond is formed by

Answer 8

transfer of an electron from one atom to another.

Question 9

A covalent bond is formed by

Answer 9

sharing of a pair of electrons between two atoms.

Question 10

Which bond or interaction would be most difficult to disrupt when compounds are put into water?

Answer 10

van der Waals interaction

Question 11

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

Answer 11

polar covalent bonds.

Question 12

The attraction between the slight negative charge of one water molecule to the slight positive charge of another water molecule results in which of the following interactions?

Answer 12

a hydrogen bond

Question 13

Conversion of liquid water to water vapor requires breaking which of the following types of bonds?

Answer 13

hydrogen bonds

Question 14

Hydrophobic substances such as vegetable oil are

Answer 14

nonpolar substances that repel water molecules

Question 15

Glucose has a molecular mass of 180 g/mol. How many glucose molecules are present in 100 grams of glucose?

Answer 15

(100/180) × 6.02 × 10^23

Question 16

If the pH of a solution is increased from pH 5 to pH 7, it means that the

Answer 16

concentration of OH- is 100 times greater than what it was at pH 5.

Question 17

Which of the following statements about buffer solutions is true?

Answer 17

They maintain a relatively constant pH when either acids or bases are added to them.

Question 18

Which of the following will be most soluble in water?

Answer 18

organic hydrocarbons with hydroxyl groups attached

Question 19

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?

Answer 19

C18H32O16

Question 20

Humans can digest starch but not cellulose because

Answer 20

humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose.

Question 21

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

Answer 21

as a disaccharide

Question 22

A molecule with the formula C18H36O2 is most likely a

Answer 22

fatty acid.

Question 23

Which of the following large biological molecules will self-assemble into a bilayer when mixed with water?

Answer 23

phospholipids

Question 24

Which two functional groups are always found in amino acids?

Answer 24

carboxyl and amino

Question 25

What structural feature makes the 20 common amino acids different from one another?

Answer 25

different side chains (R groups) attached to an α carbon

Question 26

The side chain (R group) of the amino acid serine is —CH2—OH. The side chain of the amino acid leucine is —CH2—CH—(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?

Answer 26

Serine would be on the exterior, and leucine would be in the interior of the globular protein.

Question 27

Lactase is an enzyme composed of a single polypeptide that hydrolyzes the disaccharide lactose to produce monosaccharides. The optimal pH for lactase activity is 6. Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity, likely due to the disruption of

Answer 27

the secondary and tertiary structures of the enzyme.

Question 28

In a normal cellular protein, where would you expect to find a hydrophilic amino acid such as asparagine?

Answer 28

on the exterior surface of the protein, interacting with water

Question 29

If cells are grown in a medium containing radioactive 32P, which of these molecules will be radioactively labeled?

Answer 29

nucleic acids

Question 30

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA

Answer 30

contains one less oxygen atom than the sugar in RNA.