Exam 1 Q&A

Question 1

The atomic number of nitrogen is 7. Which of the following explains the greater mass number of nitrogen-15 compared to nitrogen-14? Nitrogen-15 contains ________.

A) 7 neutrons and nitrogen-14 contains 8 neutrons
B) 8 neutrons and nitrogen-14 contains 7 neutrons
C) 8 protons and nitrogen-14 contains 7 protons
D) 15 protons and nitrogen-14 contains 14 protons

Answer 1

B) 8 neutrons and nitrogen-14 contains 7 neutrons

Question 2

Which of the following types of representation would work best to indicate the type and number of atoms in a molecule?

A) molecular formula
B) structural formula
C) ball-and-stick model
D) space-filling model

Answer 2

A) molecular formula

Question 3

About 25 of the 92 natural elements are known to be essential to life. Four of these 25 elements make up approximately 96% of living matter. Which of the following elements account for most of the remaining 4% of an organism’s mass?

A) carbon, oxygen, hydrogen, nitrogen
B) calcium, potassium, phosphorus, sulfur
C) oxygen, hydrogen, calcium, nitrogen
D) carbon, hydrogen, nitrogen, oxygen

Answer 3

B) calcium, potassium, phosphorus, sulfur

Question 4

The reactivity of an atom arises from ________.

A) the average distance of the outermost electron shell from the nucleus
B) the existence of empty orbitals or spaces in the valence shell
C) the sum of the potential energies of all the electron shells
D) the potential energy of the valence shell

Answer 4

B) the existence of empty orbitals or spaces in the valence shell

Question 5

In the term trace element, the adjective trace means that ________.

A) the element is required in very small amounts
B) the element can be used as a label to trace atoms through an organism’s metabolism
C) the element is very rare on Earth
D) the element enhances health but is not essential for the organism’s long-term survival

Answer 5

A) the element is required in very small amounts

Question 6

Which statement is true of all atoms that are anions?

A) The atom has more electrons than protons.
B) The atom has more protons than electrons.
C) The atom has fewer protons than does a neutral atom of the same element.
D) The atom has more neutrons than protons.

Answer 6

A) The atom has more electrons than protons.

Question 7

How would you describe a buffer solution?

A) weak acid and its conjugate base
B) strong acid and its conjugate base
C) weak base and its conjugate acid
D) strong base and its conjugate acid

Answer 7

A) weak acid and its conjugate base

Question 8

Which of the following can be attributed to water’s high specific heat?

A) Oil and water do not mix well.
B) A lake heats up more slowly than the air around it.
C) Ice floats on water.
D) Sugar dissolves in hot tea faster than in iced tea.

Answer 8

B) A lake heats up more slowly than the air around it.

Question 9

Which of the following statements correctly describes the property of hydrophobic substances such as vegetable oil?

A) nonpolar substances that repel water molecules
B) nonpolar substances that have an attraction for water molecules
C) polar substances that repel water molecules
D) polar substances that have an affinity for water

Answer 9

A) nonpolar substances that repel water molecules

Question 10

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

A) 4.0M
B) 10⁻¹⁰M
C) 10⁻⁴M
D) 10⁴M

Answer 10

C) 10⁻⁴M

Question 11

Which of the following is a hydrophobic material?

A) paper
B) table salt
C) wax
D) sugar

Answer 11

C) wax

Question 12

An amino acid is to a protein as a glucose molecule is to ________.

A) glycogen
B) a lipid
C) nucleic acid
D) a tripeptide

Answer 12

A) glycogen

Question 13

Which of the following statements is correct regarding starch and cellulose?

A) They are polymers of glucose.
B) They are cis and trans isomers of each other.
C) They are used for energy storage in plants and animals.
D) They are structural components of the plant cell wall.

Answer 13

A) They are polymers of glucose.

Question 14

Which part of an amino acid gives it its unique identity?

A) the long carbon-hydrogen tails of the molecule
B) the carboxyl and amino groups
C) the components of its side chain
D) the glycerol molecule that forms the backbone of the amino acid

Answer 14

C) the components of its side chain

Question 15

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the α form. Which of the following could amylase break down?

A) glycogen, starch, and amylopectin
B) glycogen and cellulose
C) cellulose and chitin
D) starch, chitin, and cellulose

Answer 15

A) glycogen, starch, and amylopectin

Question 16

The structural level of a protein least affected by a disruption in hydrogen bonding is the ________.

A) primary level
B) secondary level
C) tertiary level
D) quaternary level

Answer 16

A) primary level

Question 17

Which statement about unsaturated fats is true?

A) They are more common in animals than in plants.
B) They have double bonds in their fatty acid chains.
C) They generally solidify at room temperature.
D) They contain more hydrogen than do saturated fats having the same number of carbon atoms.

Answer 17

B) They have double bonds in their fatty acid chains.

Question 18

Which of the following categories includes all others in the list?

A) disaccharide
B) polysaccharide
C) starch
D) carbohydrate

Answer 18

D) carbohydrate

Question 19

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

A) 5’-AGCT-3’ with 5’-TCGA-3’
B) 5’-GCGC-3’ with 5’-TATA-3’
C) 5’-ATGC-3’ with 5’-GCAT-3’
D) All of these pairs are correct.

Answer 19

C) 5’-ATGC-3’ with 5’-GCAT-3’

Question 20

When H. V. Wilson exposed two species of differently pigmented sponges to a chemical that disrupted intercellular junctions, the cells of the sponges dissociated. Wilson then removed the chemical that caused dissociation and mixed the cells of the two species. He found that the sponges reassembled and that the cells from one species did not interact or form associations with the cells of the other species.

Which of the following statements provides the most plausible explanation for the results of this experiment?

A) The two species of sponge had different enzymes that functioned in the reassembly process.
B) The molecules responsible for cell-cell adhesion (cell junctions) were irreversibly destroyed during the experiment.
C) The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.
D) One cell functioned as an organizer for each organism, thereby attracting only cells of the same species.

Answer 20

C) The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.

Question 21

Which of the following pairs of organism groups consist solely of prokaryotic cells?

A) Bacteria and Eukarya
B) Bacteria and Archaea
C) Archaea and fungi
D) Bacteria and protists

Answer 21

B) Bacteria and Archaea

Question 22

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is abundant in liver cells and primarily responsible for detoxification processes?

A) rough endoplasmic reticulum
B) smooth endoplasmic reticulum
C) Golgi apparatus
D) nuclear envelope

Answer 22

B) smooth endoplasmic reticulum

Question 23

Which cell would be best for studying lysosomes?

A) muscle cell
B) nerve cell
C) bacterial cell
D) phagocytic white blood cell

Answer 23

D) phagocytic white blood cell

Question 24

Cyanide binds to at least one molecule involved in producing ATP. In a cell exposed to cyanide, most of the cyanide will be in ________.

A) mitochondria
B) ribosomes
C) peroxisomes
D) lysosomes

Answer 24

A) mitochondria

Question 25

Q: Which structure is common to plant and animal cells? A) chloroplast B) central vacuole C) mitochondrion D) centriole

Answer 25

C) mitochondrion

Question 26

Which structure is part of the endomembrane system? A) mitochondrion B) Golgi apparatus C) chloroplast D) centrosome

Answer 26

B) Golgi apparatus

Question 27

Q: Which of the following is present in a prokaryotic cell? A) mitochondrion B) ribosome C) nuclear envelope D) chloroplast

Answer 27

B) ribosome

Question 28

Which of the following types of molecules will diffuse through a cell membrane most readily? A) large hydrophobic molecules B) small hydrophobic molecules C) large polar molecules D) small ionic molecules

Answer 28

B) small hydrophobic molecules

Question 29

A defect in which of the following molecules would dramatically reduce the rate of diffusion of water across cell membranes? A) sodium-potassium pump B) aquaporins C) gated ion channels D) ATP

Answer 29

B) aquaporins

Question 30

Which of the following statements best explains the reason that lipids and proteins are free to move laterally in membranes? A) The interior of the membrane is filled with liquid water. B) Lipids and proteins repulse each other in the membrane. C) Hydrophilic portions of the lipids are in the interior of the membrane. D) There are only weak hydrophobic interactions in the interior of the membrane.

Answer 30

D) There are only weak hydrophobic interactions in the interior of the membrane.

Question 31

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly ________. A) spread in a continuous layer over the inner and outer surfaces of the membrane B) confined to the hydrophobic interior of the membrane C) embedded in a lipid bilayer D) randomly oriented in the membrane, with no fixed inside-outside polarity

Answer 31

C) embedded in a lipid bilayer

Question 32

Which of the following processes includes all the others? A) osmosis B) diffusion of a solute across a membrane C) passive transport D) transport of an ion down its electrochemical gradient

Answer 32

C) passive transport

Question 33

Which of the following factors would tend to increase membrane fluidity? A) a greater proportion of unsaturated phospholipids B) a greater proportion of saturated phospholipids C) a lower temperature D) a relatively high protein content in the membrane

Answer 33

A) a greater proportion of unsaturated phospholipids

Question 34

In what way do the membranes of a eukaryotic cell vary? A) Phospholipids are found only in certain membranes. B) Certain proteins are unique to each membrane. C) Only certain membranes of the cell are selectively permeable. D) Only certain membranes are constructed from amphipathic molecules.

Answer 34

B) Certain proteins are unique to each membrane.

Question 35

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions? A) The enzyme contains both α-helix and β-pleated sheet regions. B) The enzyme is subject to both competitive inhibition and allosteric regulation. C) The enzyme is composed of at least two identical subunits. D) The enzyme has two distinct active sites.

Answer 35

D) The enzyme has two distinct active sites.

Question 36

The figure displays the relationship between initial rate of product formation and reactant concentration in an enzyme-catalyzed reaction with a fixed amount of enzyme. Which of the following statements best explains the shape of the rate curve at high reactant concentration? A) Feedback inhibition by product occurs at high reactant concentrations. B) Most enzyme molecules are occupied by substrate at high reactant concentrations. C) The reaction nears equilibrium at lower reactant concentrations. D) The rate of the reverse reaction increases at high reactant concentrations.

Answer 36

B) Most enzyme molecules are occupied by substrate at high reactant concentrations.

Question 37

Which of the following statements is consistent with the second law of thermodynamics? A) A gain of free energy in a system is never associated with conversion of energy from one form to another. B) A constant input of energy is required to maintain the high level of organization associated with living cells. C) Without an input of energy, the entropy of an organism would tend to decrease over time. D) Every energy transformation performed by an organism decreases the entropy of the universe.

Answer 37

B) A constant input of energy is required to maintain the high level of organization associated with living cells.

Question 38

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? A) Additional substrate will be formed. B) The reaction will change from endergonic to exergonic. C) The free energy of the system will change. D) Nothing; the reaction will stay at equilibrium.

Answer 38

D) Nothing; the reaction will stay at equilibrium.

Question 39

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. A) exergonic; spontaneous B) exergonic; endergonic C) free energy; entropy D) work; energy

Answer 39

B) exergonic; endergonic

Question 40

Most cells cannot harness heat to perform work because A) heat does not involve a transfer of energy. B) cells do not have much thermal energy; they are relatively cool. C) temperature is usually uniform throughout a cell. D) heat can never be used to do work.

Answer 40

C) temperature is usually uniform throughout a cell.

Question 41

Some bacteria are metabolically active in hot springs because ________. A) they are able to maintain a lower internal temperature B) high temperatures make catalysis unnecessary C) their enzymes have high optimal temperatures D) their enzymes are completely insensitive to temperature

Answer 41

C) their enzymes have high optimal temperatures

Question 42

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to ________. A) add more of the enzyme B) heat the solution to 90°C C) add more substrate D) add a noncompetitive inhibitor

Answer 42

A) add more of the enzyme

Question 43

Which of the summary statements below best describes the results of the following reaction? C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy A) C₆H₁₂O₆ is oxidized and O₂ is reduced. B) O₂ is oxidized and H₂O is reduced. C) CO₂ is reduced and O₂ is oxidized. D) O₂ is reduced and CO₂ is oxidized.

Answer 43

A) C₆H₁₂O₆ is oxidized and O₂ is reduced.

Question 44

A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply? A) The athlete will have to sit down and rest. B) Catabolic processes will be activated to generate additional ATP. C) ATP will be transported into the cells from the circulatory system. D) Anabolic processes will be activated to produce new mitochondria.

Answer 44

B) Catabolic processes will be activated to generate additional ATP.

Question 45

A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body? A) released as CO₂ and H₂O B) converted to heat and then released C) converted to ATP, which weighs much less than fat D) eliminated from the body as feces

Answer 45

A) released as CO₂ and H₂O

Question 46

In mitochondria, exergonic redox reactions ________. A) are the source of energy driving prokaryotic ATP synthesis B) provide the energy that establishes the proton gradient C) reduce carbon atoms to carbon dioxide D) are coupled via phosphorylated intermediates to endergonic processes

Answer 46

B) provide the energy that establishes the proton gradient

Question 47

Most CO₂ from catabolism is released during ________. A) glycolysis B) the citric acid cycle C) lactate fermentation D) electron transport

Answer 47

B) the citric acid cycle

Question 48

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A) the citric acid cycle B) the electron transport chain C) glycolysis D) reduction of pyruvate to lactate

Answer 48

C) glycolysis

Question 49

1. Describe the differences and similarities between active and passive transport. 2. Compare simple diffusion, osmosis, and facilitated diffusion.

Answer 49

1. Active Transport vs. Passive Transport: Differences: Active transport requires energy (usually in the form of ATP) to move molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. It often involves specific transport proteins. Passive transport does not require energy; it moves molecules down their concentration gradient, from higher to lower concentration, following the natural flow of substances. Similarities: Both processes involve the movement of substances across cell membranes. They can use transport proteins (though not always in passive transport) to facilitate the movement. Both are essential for maintaining cellular homeostasis by regulating the internal environment of the cell. 2. Simple Diffusion, Osmosis, and Facilitated Diffusion: Simple Diffusion: This is the movement of small, nonpolar molecules or gases (like oxygen or carbon dioxide) directly through the phospholipid bilayer of the cell membrane without the assistance of proteins, moving from an area of high concentration to low concentration until equilibrium is reached. Osmosis: A specific type of diffusion involving the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration, aiming to balance the solute concentrations on both sides of the membrane. Facilitated Diffusion: This involves the transport of substances (often larger or polar molecules like glucose) down their concentration gradient through the cell membrane with the help of transport proteins (channels or carriers) but without the expenditure of cellular energy. It allows for the passage of molecules that cannot diffuse directly through the lipid bilayer