BIO111 Exam 1 Actual Exam V1 | BIO111 General Biology (BIO111
Exam 1) | University of California, Los Angeles
1. Which of the following is the best definition of a scientific hypothesis?
A. A tentative explanation that can be tested and is falsifiable
B. A proven fact based on several years of experimentation
C. An educated guess that does not require further investigation
D. A mathematical formula used to predict natural phenomena
Answer: A
Rationale: A hypothesis is a proposed explanation for a set of observations that leads to
predictions that can be tested. To be valid in science, it must be possible to prove the
hypothesis wrong through experimentation. This stage is crucial in the scientific method
because it allows researchers to narrow down potential causes for observed phenomena.
2. In the hierarchy of biological organization, which level contains all the individuals of a
single species living within a specific area?
A. Biosphere
B. Community
C. Population
D. Ecosystem
Answer: C
Rationale: A population consists of all individuals of a particular species that live in the
same geographic area at the same time. This level of organization is distinct from a
community, which includes multiple species, and an ecosystem, which includes abiotic
factors. Understanding populations is fundamental to studying ecology and evolutionary
changes over time.
3. What is the smallest unit of matter that retains the properties of an element?
A. Molecule
B. Proton
C. Atom
D. Cell
Answer: C
,Rationale: An atom is the basic building block of chemistry and the smallest unit of an
element. While subatomic particles like protons exist, they do not individually possess the
chemical characteristics of the element. This concept forms the foundation for
understanding how matter is structured at the most fundamental level.
4. Which type of chemical bond involves the sharing of a pair of valence electrons by two
atoms?
A. Ionic bond
B. Hydrogen bond
C. Van der Waals interaction
D. Covalent bond
Answer: D
Rationale: Covalent bonds occur when two atoms share electrons to complete their outer
shells, providing stability to the resulting molecule. These bonds can be polar or nonpolar
depending on the electronegativity of the participating atoms. They are generally stronger
than ionic or hydrogen bonds in biological aqueous environments.
5. Water’s high specific heat is primarily a result of what?
A. The high molecular weight of water molecules
B. The presence of trace amounts of salt
C. The formation and breaking of hydrogen bonds
D. The low density of ice compared to liquid water
Answer: C
Rationale: Specific heat refers to the amount of heat absorbed or lost to change the
temperature of a substance. In water, heat must first break hydrogen bonds before the
molecules can move faster, which moderates temperature fluctuations. This property is
vital for maintaining stable temperatures in aquatic environments and within living
organisms.
6. A solution with a pH of 3 is how many times more acidic than a solution with a pH of 5?
A. 100 times
B. 20 times
C. 2 times
D. 1000 times
Answer: A
, Rationale: The pH scale is logarithmic, meaning each unit represents a tenfold change in
the concentration of hydrogen ions. A jump from pH 5 to pH 3 represents two units, which
translates to 10 squared or 100 times the concentration. This sensitivity highlights how
even minor pH changes can drastically affect biological chemistry.
7. Why is carbon considered the ‘backbone’ of life?
A. It is the most abundant element in the Earth’s crust
B. It is not reactive and maintains structure perfectly
C. It is the only element that can form hydrogen bonds
D. It can form up to four covalent bonds with other atoms
Answer: D
Rationale: Carbon’s tetravalence allows it to form large, complex, and diverse molecules
including chains, rings, and branched structures. These structures serve as the foundation
for the four main classes of biological macromolecules. Without this versatility, the
structural complexity required for life would not be possible.
8. Which functional group is characterized by a formula of -OH and is highly polar?
A. Carboxyl group
B. Phosphate group
C. Amino group
D. Hydroxyl group
Answer: D
Rationale: The hydroxyl group consists of an oxygen atom bonded to a hydrogen atom,
commonly found in alcohols and sugars. It increases the solubility of organic molecules in
water by forming hydrogen bonds. This functional group is essential for the chemistry of
carbohydrates and many other biomolecules.
9. Which process links monomers together to form polymers by removing a water molecule?
A. Hydrolysis
B. Dehydration reaction
C. Hydrogenation
D. Oxidation
Answer: B
Rationale: In a dehydration reaction, one monomer provides a hydroxyl group (-OH) and
another provides a hydrogen (-H), releasing water as a byproduct. This process allows the
Exam 1) | University of California, Los Angeles
1. Which of the following is the best definition of a scientific hypothesis?
A. A tentative explanation that can be tested and is falsifiable
B. A proven fact based on several years of experimentation
C. An educated guess that does not require further investigation
D. A mathematical formula used to predict natural phenomena
Answer: A
Rationale: A hypothesis is a proposed explanation for a set of observations that leads to
predictions that can be tested. To be valid in science, it must be possible to prove the
hypothesis wrong through experimentation. This stage is crucial in the scientific method
because it allows researchers to narrow down potential causes for observed phenomena.
2. In the hierarchy of biological organization, which level contains all the individuals of a
single species living within a specific area?
A. Biosphere
B. Community
C. Population
D. Ecosystem
Answer: C
Rationale: A population consists of all individuals of a particular species that live in the
same geographic area at the same time. This level of organization is distinct from a
community, which includes multiple species, and an ecosystem, which includes abiotic
factors. Understanding populations is fundamental to studying ecology and evolutionary
changes over time.
3. What is the smallest unit of matter that retains the properties of an element?
A. Molecule
B. Proton
C. Atom
D. Cell
Answer: C
,Rationale: An atom is the basic building block of chemistry and the smallest unit of an
element. While subatomic particles like protons exist, they do not individually possess the
chemical characteristics of the element. This concept forms the foundation for
understanding how matter is structured at the most fundamental level.
4. Which type of chemical bond involves the sharing of a pair of valence electrons by two
atoms?
A. Ionic bond
B. Hydrogen bond
C. Van der Waals interaction
D. Covalent bond
Answer: D
Rationale: Covalent bonds occur when two atoms share electrons to complete their outer
shells, providing stability to the resulting molecule. These bonds can be polar or nonpolar
depending on the electronegativity of the participating atoms. They are generally stronger
than ionic or hydrogen bonds in biological aqueous environments.
5. Water’s high specific heat is primarily a result of what?
A. The high molecular weight of water molecules
B. The presence of trace amounts of salt
C. The formation and breaking of hydrogen bonds
D. The low density of ice compared to liquid water
Answer: C
Rationale: Specific heat refers to the amount of heat absorbed or lost to change the
temperature of a substance. In water, heat must first break hydrogen bonds before the
molecules can move faster, which moderates temperature fluctuations. This property is
vital for maintaining stable temperatures in aquatic environments and within living
organisms.
6. A solution with a pH of 3 is how many times more acidic than a solution with a pH of 5?
A. 100 times
B. 20 times
C. 2 times
D. 1000 times
Answer: A
, Rationale: The pH scale is logarithmic, meaning each unit represents a tenfold change in
the concentration of hydrogen ions. A jump from pH 5 to pH 3 represents two units, which
translates to 10 squared or 100 times the concentration. This sensitivity highlights how
even minor pH changes can drastically affect biological chemistry.
7. Why is carbon considered the ‘backbone’ of life?
A. It is the most abundant element in the Earth’s crust
B. It is not reactive and maintains structure perfectly
C. It is the only element that can form hydrogen bonds
D. It can form up to four covalent bonds with other atoms
Answer: D
Rationale: Carbon’s tetravalence allows it to form large, complex, and diverse molecules
including chains, rings, and branched structures. These structures serve as the foundation
for the four main classes of biological macromolecules. Without this versatility, the
structural complexity required for life would not be possible.
8. Which functional group is characterized by a formula of -OH and is highly polar?
A. Carboxyl group
B. Phosphate group
C. Amino group
D. Hydroxyl group
Answer: D
Rationale: The hydroxyl group consists of an oxygen atom bonded to a hydrogen atom,
commonly found in alcohols and sugars. It increases the solubility of organic molecules in
water by forming hydrogen bonds. This functional group is essential for the chemistry of
carbohydrates and many other biomolecules.
9. Which process links monomers together to form polymers by removing a water molecule?
A. Hydrolysis
B. Dehydration reaction
C. Hydrogenation
D. Oxidation
Answer: B
Rationale: In a dehydration reaction, one monomer provides a hydroxyl group (-OH) and
another provides a hydrogen (-H), releasing water as a byproduct. This process allows the
