PAX Science NLN Exam – Questions with Answers –
2025/2026 Edition
Section 1: Biology (Q1–Q50)
1. Which organelle is the primary site of ATP production?
A. Mitochondrion
B. Nucleus
C. Ribosome
D. Golgi apparatus
Answer: A
Rationale: Mitochondria generate most of the cell's ATP through aerobic respiration.
2. Which structure controls what enters and exits the cell?
A. Cell wall
B. Cell membrane
C. Cytoplasm
D. Nucleolus
Answer: B
Rationale: The cell membrane is selectively permeable and regulates transport.
3. Which molecule carries genetic information from DNA to the ribosome?
A. tRNA
B. rRNA
C. mRNA
D. DNA polymerase
Answer: C
Rationale: Messenger RNA (mRNA) transcribes DNA and carries the code to ribosomes.
4. During which phase of mitosis do chromosomes align at the cell equator?
A. Prophase
B. Anaphase
C. Telophase
D. Metaphase
Answer: D
Rationale: Metaphase is when chromosomes line up at the metaphase plate.
5. What is the basic unit of life?
A. Cell
B. Tissue
,C. Organ
D. Atom
Answer: A
Rationale: The cell is the smallest structural and functional unit of living things.
6. Which organelle contains digestive enzymes?
A. Ribosome
B. Lysosome
C. Mitochondrion
D. Golgi apparatus
Answer: B
Rationale: Lysosomes contain hydrolytic enzymes that break down waste and cellular debris.
7. Which process produces gametes?
A. Mitosis
B. Binary fission
C. Meiosis
D. Budding
Answer: C
Rationale: Meiosis produces haploid gametes (sperm and egg).
8. Which base pairs with adenine in DNA?
A. Guanine
B. Cytosine
C. Uracil
D. Thymine
Answer: D
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds.
9. Which blood cells fight infection?
A. White blood cells
B. Red blood cells
C. Platelets
D. Plasma
Answer: A
Rationale: White blood cells (leukocytes) defend the body against pathogens.
10. Which organ produces insulin?
A. Liver
B. Pancreas
,C. Kidney
D. Stomach
Answer: B
Rationale: Beta cells in the pancreatic islets secrete insulin.
11. Which system transports oxygen and nutrients?
A. Digestive
B. Nervous
C. Circulatory
D. Endocrine
Answer: C
Rationale: The circulatory system transports blood, oxygen, nutrients, and wastes.
12. Which part of a neuron receives signals?
A. Axon
B. Myelin
C. Synapse
D. Dendrite
Answer: D
Rationale: Dendrites receive electrochemical signals from other neurons.
13. Which molecule is the universal energy currency of the cell?
A. ATP
B. DNA
C. RNA
D. NADH
Answer: A
Rationale: ATP powers most cellular processes.
14. Which organelle synthesizes proteins?
A. Lysosome
B. Ribosome
C. Mitochondrion
D. Vacuole
Answer: B
Rationale: Ribosomes translate mRNA into polypeptide chains.
15. What is the movement of water across a semipermeable membrane called?
A. Diffusion
B. Active transport
, C. Osmosis
D. Filtration
Answer: C
Rationale: Osmosis is the passive movement of water down its concentration gradient.
16. Which kingdom includes mushrooms?
A. Plantae
B. Animalia
C. Protista
D. Fungi
Answer: D
Rationale: Mushrooms are fungi; they are heterotrophic decomposers.
17. Which type of bond shares electrons?
A. Covalent
B. Ionic
C. Hydrogen
D. Metallic
Answer: A
Rationale: Covalent bonds form when atoms share electron pairs.
18. Which organ pumps blood throughout the body?
A. Lungs
B. Heart
C. Liver
D. Kidney
Answer: B
Rationale: The heart is a muscular pump that circulates blood.
19. Which process do plants use to make food?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Fermentation
Answer: C
Rationale: Photosynthesis converts light energy into glucose using CO₂ and water.
20. Which part of the brain controls balance and coordination?
A. Cerebrum
B. Medulla
2025/2026 Edition
Section 1: Biology (Q1–Q50)
1. Which organelle is the primary site of ATP production?
A. Mitochondrion
B. Nucleus
C. Ribosome
D. Golgi apparatus
Answer: A
Rationale: Mitochondria generate most of the cell's ATP through aerobic respiration.
2. Which structure controls what enters and exits the cell?
A. Cell wall
B. Cell membrane
C. Cytoplasm
D. Nucleolus
Answer: B
Rationale: The cell membrane is selectively permeable and regulates transport.
3. Which molecule carries genetic information from DNA to the ribosome?
A. tRNA
B. rRNA
C. mRNA
D. DNA polymerase
Answer: C
Rationale: Messenger RNA (mRNA) transcribes DNA and carries the code to ribosomes.
4. During which phase of mitosis do chromosomes align at the cell equator?
A. Prophase
B. Anaphase
C. Telophase
D. Metaphase
Answer: D
Rationale: Metaphase is when chromosomes line up at the metaphase plate.
5. What is the basic unit of life?
A. Cell
B. Tissue
,C. Organ
D. Atom
Answer: A
Rationale: The cell is the smallest structural and functional unit of living things.
6. Which organelle contains digestive enzymes?
A. Ribosome
B. Lysosome
C. Mitochondrion
D. Golgi apparatus
Answer: B
Rationale: Lysosomes contain hydrolytic enzymes that break down waste and cellular debris.
7. Which process produces gametes?
A. Mitosis
B. Binary fission
C. Meiosis
D. Budding
Answer: C
Rationale: Meiosis produces haploid gametes (sperm and egg).
8. Which base pairs with adenine in DNA?
A. Guanine
B. Cytosine
C. Uracil
D. Thymine
Answer: D
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds.
9. Which blood cells fight infection?
A. White blood cells
B. Red blood cells
C. Platelets
D. Plasma
Answer: A
Rationale: White blood cells (leukocytes) defend the body against pathogens.
10. Which organ produces insulin?
A. Liver
B. Pancreas
,C. Kidney
D. Stomach
Answer: B
Rationale: Beta cells in the pancreatic islets secrete insulin.
11. Which system transports oxygen and nutrients?
A. Digestive
B. Nervous
C. Circulatory
D. Endocrine
Answer: C
Rationale: The circulatory system transports blood, oxygen, nutrients, and wastes.
12. Which part of a neuron receives signals?
A. Axon
B. Myelin
C. Synapse
D. Dendrite
Answer: D
Rationale: Dendrites receive electrochemical signals from other neurons.
13. Which molecule is the universal energy currency of the cell?
A. ATP
B. DNA
C. RNA
D. NADH
Answer: A
Rationale: ATP powers most cellular processes.
14. Which organelle synthesizes proteins?
A. Lysosome
B. Ribosome
C. Mitochondrion
D. Vacuole
Answer: B
Rationale: Ribosomes translate mRNA into polypeptide chains.
15. What is the movement of water across a semipermeable membrane called?
A. Diffusion
B. Active transport
, C. Osmosis
D. Filtration
Answer: C
Rationale: Osmosis is the passive movement of water down its concentration gradient.
16. Which kingdom includes mushrooms?
A. Plantae
B. Animalia
C. Protista
D. Fungi
Answer: D
Rationale: Mushrooms are fungi; they are heterotrophic decomposers.
17. Which type of bond shares electrons?
A. Covalent
B. Ionic
C. Hydrogen
D. Metallic
Answer: A
Rationale: Covalent bonds form when atoms share electron pairs.
18. Which organ pumps blood throughout the body?
A. Lungs
B. Heart
C. Liver
D. Kidney
Answer: B
Rationale: The heart is a muscular pump that circulates blood.
19. Which process do plants use to make food?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Fermentation
Answer: C
Rationale: Photosynthesis converts light energy into glucose using CO₂ and water.
20. Which part of the brain controls balance and coordination?
A. Cerebrum
B. Medulla
