1 | Page
NAS 2 TCC EXAM 2025/2026 | 140+ VERIFIED EXAM QUESTIONS &
CORRECT ANSWERS | GRADED A+ | COVERS BIOLOGY, CHEMISTRY,
GENETICS & HUMAN PHYSIOLOGY.
1.
A student in NAS 2 at TCC is reviewing cell theory and asks why cells are
considered the basic unit of life when tissues and organs perform more complex
functions. The instructor explains that all higher levels of biological organization
depend on cellular activity. Without cells, no tissue or organ could exist because
they provide structural integrity, metabolic functions, and genetic continuity. For
example, muscle contraction depends on myocytes, nerve transmission depends on
neurons, and immunity depends on lymphocytes. Based on this concept, what is
the fundamental principle of the cell theory that explains why cells are the
foundation of life?
Correct Answer: All living organisms are made up of cells, and the cell is the
basic structural and functional unit of life.
2.
,2 | Page
During a lab in NAS 2, students examine plant and animal cells under a
microscope. One student observes that plant cells have rigid structures that animal
cells lack, while animal cells appear more flexible. The instructor explains that this
difference is due to unique cellular components. Plant cells have structures that
provide support, storage, and protection, while animal cells rely more on
extracellular elements and cytoskeleton for shape. These structures also influence
osmosis, growth, and mechanical resistance. What structure distinguishes plant
cells from animal cells and gives them their rigid, box-like shape?
Correct Answer: The cell wall, composed primarily of cellulose, which
provides rigidity and protection to plant cells.
3.
A professor in NAS 2 assigns a case study on energy production in cells. A student
writes that human muscle cells produce energy by both aerobic and anaerobic
processes depending on oxygen availability. The instructor corrects them,
emphasizing that aerobic respiration yields significantly more ATP per glucose
molecule, while anaerobic pathways are less efficient and produce lactic acid as a
byproduct. This is why athletes experience muscle fatigue during intense exercise.
Based on cellular metabolism principles, where does aerobic respiration primarily
occur in eukaryotic cells?
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Correct Answer: Aerobic respiration occurs in the mitochondria, where
glucose is broken down to produce ATP through the Krebs cycle and oxidative
phosphorylation.
4.
In an NAS 2 discussion on biomolecules, a student confuses carbohydrates with
proteins, assuming they serve identical functions. The instructor clarifies that
carbohydrates are primarily energy sources and structural components, while
proteins are essential for enzymatic activity, structural support, transport, and
signaling. Proteins are made of amino acids, while carbohydrates are made of
monosaccharides such as glucose. The class further explores how proteins fold into
complex structures to perform highly specific biological roles. What is the primary
difference in composition between carbohydrates and proteins?
Correct Answer: Carbohydrates are composed of carbon, hydrogen, and
oxygen (typically in a 1:2:1 ratio), whereas proteins are composed of amino
acids containing carbon, hydrogen, oxygen, and nitrogen.
5.
, 4 | Page
A student studying for an NAS 2 exam encounters a question about DNA and
RNA. They recall that both molecules are nucleic acids composed of nucleotides,
but they differ in structure, sugar components, nitrogenous bases, and biological
roles. The instructor emphasizes that DNA stores genetic information in the
nucleus and directs protein synthesis indirectly, while RNA plays direct roles in
transcription and translation. The student then remembers that only RNA contains a
nitrogenous base absent in DNA. Which base is found in RNA but not in DNA?
Correct Answer: Uracil, which replaces thymine in RNA.
6.
A student in NAS 2 is studying osmosis and diffusion. They mistakenly think that
osmosis applies to all solutes, but the instructor clarifies that osmosis specifically
refers to water movement across a selectively permeable membrane. The instructor
provides an example of a red blood cell placed in a hypertonic solution, where
water leaves the cell, causing it to shrink. Conversely, in a hypotonic solution,
water enters the cell, causing it to swell and possibly burst. Based on this concept,
what is the driving force behind osmosis?
Correct Answer: Osmosis is driven by the movement of water molecules from
an area of low solute concentration to an area of high solute concentration
across a selectively permeable membrane.
NAS 2 TCC EXAM 2025/2026 | 140+ VERIFIED EXAM QUESTIONS &
CORRECT ANSWERS | GRADED A+ | COVERS BIOLOGY, CHEMISTRY,
GENETICS & HUMAN PHYSIOLOGY.
1.
A student in NAS 2 at TCC is reviewing cell theory and asks why cells are
considered the basic unit of life when tissues and organs perform more complex
functions. The instructor explains that all higher levels of biological organization
depend on cellular activity. Without cells, no tissue or organ could exist because
they provide structural integrity, metabolic functions, and genetic continuity. For
example, muscle contraction depends on myocytes, nerve transmission depends on
neurons, and immunity depends on lymphocytes. Based on this concept, what is
the fundamental principle of the cell theory that explains why cells are the
foundation of life?
Correct Answer: All living organisms are made up of cells, and the cell is the
basic structural and functional unit of life.
2.
,2 | Page
During a lab in NAS 2, students examine plant and animal cells under a
microscope. One student observes that plant cells have rigid structures that animal
cells lack, while animal cells appear more flexible. The instructor explains that this
difference is due to unique cellular components. Plant cells have structures that
provide support, storage, and protection, while animal cells rely more on
extracellular elements and cytoskeleton for shape. These structures also influence
osmosis, growth, and mechanical resistance. What structure distinguishes plant
cells from animal cells and gives them their rigid, box-like shape?
Correct Answer: The cell wall, composed primarily of cellulose, which
provides rigidity and protection to plant cells.
3.
A professor in NAS 2 assigns a case study on energy production in cells. A student
writes that human muscle cells produce energy by both aerobic and anaerobic
processes depending on oxygen availability. The instructor corrects them,
emphasizing that aerobic respiration yields significantly more ATP per glucose
molecule, while anaerobic pathways are less efficient and produce lactic acid as a
byproduct. This is why athletes experience muscle fatigue during intense exercise.
Based on cellular metabolism principles, where does aerobic respiration primarily
occur in eukaryotic cells?
,3 | Page
Correct Answer: Aerobic respiration occurs in the mitochondria, where
glucose is broken down to produce ATP through the Krebs cycle and oxidative
phosphorylation.
4.
In an NAS 2 discussion on biomolecules, a student confuses carbohydrates with
proteins, assuming they serve identical functions. The instructor clarifies that
carbohydrates are primarily energy sources and structural components, while
proteins are essential for enzymatic activity, structural support, transport, and
signaling. Proteins are made of amino acids, while carbohydrates are made of
monosaccharides such as glucose. The class further explores how proteins fold into
complex structures to perform highly specific biological roles. What is the primary
difference in composition between carbohydrates and proteins?
Correct Answer: Carbohydrates are composed of carbon, hydrogen, and
oxygen (typically in a 1:2:1 ratio), whereas proteins are composed of amino
acids containing carbon, hydrogen, oxygen, and nitrogen.
5.
, 4 | Page
A student studying for an NAS 2 exam encounters a question about DNA and
RNA. They recall that both molecules are nucleic acids composed of nucleotides,
but they differ in structure, sugar components, nitrogenous bases, and biological
roles. The instructor emphasizes that DNA stores genetic information in the
nucleus and directs protein synthesis indirectly, while RNA plays direct roles in
transcription and translation. The student then remembers that only RNA contains a
nitrogenous base absent in DNA. Which base is found in RNA but not in DNA?
Correct Answer: Uracil, which replaces thymine in RNA.
6.
A student in NAS 2 is studying osmosis and diffusion. They mistakenly think that
osmosis applies to all solutes, but the instructor clarifies that osmosis specifically
refers to water movement across a selectively permeable membrane. The instructor
provides an example of a red blood cell placed in a hypertonic solution, where
water leaves the cell, causing it to shrink. Conversely, in a hypotonic solution,
water enters the cell, causing it to swell and possibly burst. Based on this concept,
what is the driving force behind osmosis?
Correct Answer: Osmosis is driven by the movement of water molecules from
an area of low solute concentration to an area of high solute concentration
across a selectively permeable membrane.
