NLN NEX Science actual Exam 2026/2027 | 250+ Practice
Questions, Correct Answers & Detailed Rationales
BIOLOGY: CELLS, GENETICS & MICROBIOLOGY
1. Which structure is considered the basic functional unit of life?
A. Tissue
B. Cell
C. Organ
D. Organ system
Correct Answer: B. Cell
Rationale: The cell is the smallest structural and functional unit capable of
carrying out the processes necessary for life.
2. Which organelle is primarily responsible for producing ATP in eukaryotic cells?
A. Nucleus
B. Golgi apparatus
C. Mitochondrion
D. Lysosome
Correct Answer: C. Mitochondrion
Rationale: Mitochondria generate most cellular ATP through aerobic cellular
respiration.
3. What is the primary function of ribosomes?
A. Lipid storage
B. Protein synthesis
,C. DNA replication
D. Waste removal
Correct Answer: B. Protein synthesis
Rationale: Ribosomes translate messenger RNA into polypeptide chains during
protein synthesis.
4. Which organelle contains most of a eukaryotic cell's genetic material?
A. Nucleus
B. Lysosome
C. Ribosome
D. Centriole
Correct Answer: A. Nucleus
Rationale: The nucleus houses the cell's chromosomes, which contain DNA.
5. Which molecule carries hereditary information in humans?
A. ATP
B. DNA
C. Glucose
D. Lipid
Correct Answer: B. DNA
Rationale: DNA stores the genetic instructions that determine inherited
characteristics and guide cellular functions.
6. Which process produces two genetically similar daughter cells?
A. Meiosis
B. Fertilization
,C. Mitosis
D. Crossing over
Correct Answer: C. Mitosis
Rationale: Mitosis produces two daughter cells with essentially the same
chromosome number and genetic information as the parent cell.
7. What is the primary purpose of meiosis?
A. Tissue repair
B. Production of gametes
C. Protein synthesis
D. Cellular respiration
Correct Answer: B. Production of gametes
Rationale: Meiosis produces haploid sperm or eggs and reduces chromosome
number by half.
8. Which structure regulates what enters and leaves a cell?
A. Cell membrane
B. Nucleolus
C. Chromosome
D. Cytoskeleton
Correct Answer: A. Cell membrane
Rationale: The plasma membrane is selectively permeable and controls
movement of substances into and out of the cell.
9. Movement of particles from an area of higher concentration to an area of
lower concentration is called:
, A. Active transport
B. Diffusion
C. Endocytosis
D. Filtration
Correct Answer: B. Diffusion
Rationale: Diffusion is passive movement down a concentration gradient.
10. What is osmosis?
A. Movement of proteins through a membrane
B. Movement of water across a selectively permeable membrane
C. Movement of glucose using ATP
D. Breakdown of DNA
Correct Answer: B. Movement of water across a selectively permeable
membrane
Rationale: Osmosis is the passive movement of water across a selectively
permeable membrane toward the side with greater solute concentration.
11. Which transport mechanism requires cellular energy?
A. Simple diffusion
B. Osmosis
C. Active transport
D. Facilitated diffusion
Correct Answer: C. Active transport
Rationale: Active transport uses cellular energy, usually ATP, to move substances
against a concentration gradient.
12. Which molecule is the primary energy currency of cells?
Questions, Correct Answers & Detailed Rationales
BIOLOGY: CELLS, GENETICS & MICROBIOLOGY
1. Which structure is considered the basic functional unit of life?
A. Tissue
B. Cell
C. Organ
D. Organ system
Correct Answer: B. Cell
Rationale: The cell is the smallest structural and functional unit capable of
carrying out the processes necessary for life.
2. Which organelle is primarily responsible for producing ATP in eukaryotic cells?
A. Nucleus
B. Golgi apparatus
C. Mitochondrion
D. Lysosome
Correct Answer: C. Mitochondrion
Rationale: Mitochondria generate most cellular ATP through aerobic cellular
respiration.
3. What is the primary function of ribosomes?
A. Lipid storage
B. Protein synthesis
,C. DNA replication
D. Waste removal
Correct Answer: B. Protein synthesis
Rationale: Ribosomes translate messenger RNA into polypeptide chains during
protein synthesis.
4. Which organelle contains most of a eukaryotic cell's genetic material?
A. Nucleus
B. Lysosome
C. Ribosome
D. Centriole
Correct Answer: A. Nucleus
Rationale: The nucleus houses the cell's chromosomes, which contain DNA.
5. Which molecule carries hereditary information in humans?
A. ATP
B. DNA
C. Glucose
D. Lipid
Correct Answer: B. DNA
Rationale: DNA stores the genetic instructions that determine inherited
characteristics and guide cellular functions.
6. Which process produces two genetically similar daughter cells?
A. Meiosis
B. Fertilization
,C. Mitosis
D. Crossing over
Correct Answer: C. Mitosis
Rationale: Mitosis produces two daughter cells with essentially the same
chromosome number and genetic information as the parent cell.
7. What is the primary purpose of meiosis?
A. Tissue repair
B. Production of gametes
C. Protein synthesis
D. Cellular respiration
Correct Answer: B. Production of gametes
Rationale: Meiosis produces haploid sperm or eggs and reduces chromosome
number by half.
8. Which structure regulates what enters and leaves a cell?
A. Cell membrane
B. Nucleolus
C. Chromosome
D. Cytoskeleton
Correct Answer: A. Cell membrane
Rationale: The plasma membrane is selectively permeable and controls
movement of substances into and out of the cell.
9. Movement of particles from an area of higher concentration to an area of
lower concentration is called:
, A. Active transport
B. Diffusion
C. Endocytosis
D. Filtration
Correct Answer: B. Diffusion
Rationale: Diffusion is passive movement down a concentration gradient.
10. What is osmosis?
A. Movement of proteins through a membrane
B. Movement of water across a selectively permeable membrane
C. Movement of glucose using ATP
D. Breakdown of DNA
Correct Answer: B. Movement of water across a selectively permeable
membrane
Rationale: Osmosis is the passive movement of water across a selectively
permeable membrane toward the side with greater solute concentration.
11. Which transport mechanism requires cellular energy?
A. Simple diffusion
B. Osmosis
C. Active transport
D. Facilitated diffusion
Correct Answer: C. Active transport
Rationale: Active transport uses cellular energy, usually ATP, to move substances
against a concentration gradient.
12. Which molecule is the primary energy currency of cells?
