BIO 189 Exam 1 (Midterm): Fundamentals of Biology -
Arizona College Updated and Latest Questions and Correct
Answers with Rationale
1. Which level of biological organization is the smallest unit that can carry out all functions of life?
A. Organelle
B. Molecule
C. Tissue
D. Cell
Ans: D
Explanation: The cell is universally recognized as the basic structural and functional unit of all living
organisms. While organelles perform specific tasks, they cannot survive independently outside of the
cellular environment. All living things are composed of one or more cells according to the cell theory. This
level of organization marks the transition from non-living chemical components to a living system.
Consequently, the cell is the simplest entity that exhibits all the hallmarks of life.
2. In the scientific method, what is a tentative explanation for an observation that is testable?
A. Theory
B. Conclusion
C. Law
D. Hypothesis
Ans: D
Explanation: A hypothesis is a proposed explanation for a specific phenomenon observed in the natural
world. It must be framed in a way that allows it to be proven false through experimentation or
,observation. Unlike a general observation, a hypothesis leads to specific predictions that can be
measured. It serves as a starting point for further investigation within the scientific process. Over time,
multiple supported hypotheses may contribute to the development of a broader scientific theory.
3. What type of chemical bond involves the complete transfer of electrons from one atom to another?
A. Non-polar covalent bond
B. Hydrogen bond
C. Ionic bond
D. Polar covalent bond
Ans: C
Explanation: Ionic bonds form when one atom gives up one or more electrons to another atom. This
transfer creates ions with opposite charges that are then attracted to each other. For example, sodium
and chlorine react to form sodium chloride through this electrostatic attraction. These bonds typically
occur between metals and non-metals with significant differences in electronegativity. Understanding
ionic bonding is crucial for learning how salts and minerals behave in biological fluids.
4. What property of water allows it to resist drastic changes in temperature?
A. High specific heat
B. Low density as a solid
C. Universal solvent ability
D. Cohesion
Ans: A
, Explanation: Water has a high specific heat, meaning it must absorb a large amount of energy to raise its
temperature. This property is primarily due to the extensive hydrogen bonding between water
molecules. In biological systems, this helps organisms maintain a stable internal temperature despite
external environmental shifts. Large bodies of water also help regulate the climate of surrounding land
masses. This thermal stability is essential for the survival of life in various aquatic and terrestrial
habitats.
5. A solution with a pH of 3 is considered to be:
A. Strongly basic
B. Strongly acidic
C. Neutral
D. Weakly acidic
Ans: B
Explanation: The pH scale measures the concentration of hydrogen ions in a solution on a scale from 0 to
14. A pH of 7 is neutral, while values below 7 represent acidic conditions. Because the scale is logarithmic,
a pH of 3 is ten times more acidic than a pH of 4. Such acidic environments can denature proteins and
affect cellular functions if not buffered. Biological systems often use buffers to maintain a pH near
neutrality for optimal enzyme activity.
6. Which macromolecule is primarily used for long-term energy storage and insulation?
A. Proteins
B. Carbohydrates
C. Nucleic acids
D. Lipids
Arizona College Updated and Latest Questions and Correct
Answers with Rationale
1. Which level of biological organization is the smallest unit that can carry out all functions of life?
A. Organelle
B. Molecule
C. Tissue
D. Cell
Ans: D
Explanation: The cell is universally recognized as the basic structural and functional unit of all living
organisms. While organelles perform specific tasks, they cannot survive independently outside of the
cellular environment. All living things are composed of one or more cells according to the cell theory. This
level of organization marks the transition from non-living chemical components to a living system.
Consequently, the cell is the simplest entity that exhibits all the hallmarks of life.
2. In the scientific method, what is a tentative explanation for an observation that is testable?
A. Theory
B. Conclusion
C. Law
D. Hypothesis
Ans: D
Explanation: A hypothesis is a proposed explanation for a specific phenomenon observed in the natural
world. It must be framed in a way that allows it to be proven false through experimentation or
,observation. Unlike a general observation, a hypothesis leads to specific predictions that can be
measured. It serves as a starting point for further investigation within the scientific process. Over time,
multiple supported hypotheses may contribute to the development of a broader scientific theory.
3. What type of chemical bond involves the complete transfer of electrons from one atom to another?
A. Non-polar covalent bond
B. Hydrogen bond
C. Ionic bond
D. Polar covalent bond
Ans: C
Explanation: Ionic bonds form when one atom gives up one or more electrons to another atom. This
transfer creates ions with opposite charges that are then attracted to each other. For example, sodium
and chlorine react to form sodium chloride through this electrostatic attraction. These bonds typically
occur between metals and non-metals with significant differences in electronegativity. Understanding
ionic bonding is crucial for learning how salts and minerals behave in biological fluids.
4. What property of water allows it to resist drastic changes in temperature?
A. High specific heat
B. Low density as a solid
C. Universal solvent ability
D. Cohesion
Ans: A
, Explanation: Water has a high specific heat, meaning it must absorb a large amount of energy to raise its
temperature. This property is primarily due to the extensive hydrogen bonding between water
molecules. In biological systems, this helps organisms maintain a stable internal temperature despite
external environmental shifts. Large bodies of water also help regulate the climate of surrounding land
masses. This thermal stability is essential for the survival of life in various aquatic and terrestrial
habitats.
5. A solution with a pH of 3 is considered to be:
A. Strongly basic
B. Strongly acidic
C. Neutral
D. Weakly acidic
Ans: B
Explanation: The pH scale measures the concentration of hydrogen ions in a solution on a scale from 0 to
14. A pH of 7 is neutral, while values below 7 represent acidic conditions. Because the scale is logarithmic,
a pH of 3 is ten times more acidic than a pH of 4. Such acidic environments can denature proteins and
affect cellular functions if not buffered. Biological systems often use buffers to maintain a pH near
neutrality for optimal enzyme activity.
6. Which macromolecule is primarily used for long-term energy storage and insulation?
A. Proteins
B. Carbohydrates
C. Nucleic acids
D. Lipids
