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Human Physiology & Organ Systems (Biology) Solved Questions & Notes (2026) - Apex Rankers

Natural & Physical Sciences > Biology > Human Physiology & Organ Systems

45 Total Solved Questions
~68 mins Estimated Reading Time
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Human Physiology & Organ Systems

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Q. 1 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
Which blood vessels carry oxygenated blood from the lungs back to the left atrium of the human heart?
A
Pulmonary Veins
✓ Correct
B
Pulmonary Arteries
C
Superior Vena Cava
D
Coronary Arteries
💡 Step-by-Step Explanation & Concept Rationale
Pulmonary veins are the only veins in adults carrying oxygen-rich blood, delivering it from pulmonary capillaries to the left atrium.
Q. 2 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
What is the functional, microscopic filtration and reabsorption unit of the human kidney?
A
Nephron
✓ Correct
B
Neuron
C
Alveolus
D
Hepatic lobule
💡 Step-by-Step Explanation & Concept Rationale
Each human kidney contains approximately 1 million nephrons composed of glomeruli, Bowman's capsules, and renal tubules.
Q. 3 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
Which hormone secreted by the Beta cells of the Islets of Langerhans lowers blood glucose levels by promoting cellular glucose uptake?
A
Insulin
✓ Correct
B
Glucagon
C
Cortisol
D
Thyroxine (T4)
💡 Step-by-Step Explanation & Concept Rationale
Insulin facilitates cellular uptake and glycogen synthesis, lowering plasma glucose concentrations.
Q. 4 Biology & Medical Sciences
Difficulty: MEDIUM (1 Mark)
Which neurotransmitter is released at the neuromuscular junction to trigger skeletal muscle contraction?
A
Acetylcholine (ACh)
✓ Correct
B
Dopamine
C
Serotonin
D
GABA
💡 Step-by-Step Explanation & Concept Rationale
Motor neurons release acetylcholine into the synaptic cleft, binding to nicotinic receptors and causing muscle depolarization.
Q. 5 Biology & Medical Sciences
Difficulty: MEDIUM (1 Mark)
Which region of the human brain acts as the primary autonomic control center for heartbeat, respiration, and vasomotor tone?
A
Medulla Oblongata
✓ Correct
B
Cerebellum
C
Cerebrum
D
Thalamus
💡 Step-by-Step Explanation & Concept Rationale
The medulla oblongata in the brainstem houses the cardiac, respiratory, and vasomotor centers regulating vital life functions.
Q. 6 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
Which enzyme is primarily responsible for unzipping the double-stranded DNA during replication?
A
DNA Ligase
B
DNA Polymerase
C
DNA Helicase
✓ Correct
D
Topoisomerase
💡 Step-by-Step Explanation & Concept Rationale
DNA Helicase breaks hydrogen bonds between nitrogenous base pairs, unwinding the double helix at the replication fork.
Q. 7 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #8: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Tryptophan
B
Alanine
C
Valine
D
Methionine
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 8 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #13: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Methionine
✓ Correct
B
Alanine
C
Valine
D
Tryptophan
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 9 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #18: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Alanine
B
Methionine
✓ Correct
C
Valine
D
Tryptophan
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 10 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #23: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Valine
B
Alanine
C
Methionine
✓ Correct
D
Tryptophan
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 11 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #28: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Tryptophan
B
Alanine
C
Valine
D
Methionine
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 12 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #33: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Methionine
✓ Correct
B
Alanine
C
Valine
D
Tryptophan
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 13 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In cell biology & macromolecular biochemistry #38: Which amino acid is the starting codon (AUG) in eukaryotic protein synthesis?
A
Alanine
B
Methionine
✓ Correct
C
Valine
D
Tryptophan
💡 Step-by-Step Explanation & Concept Rationale
AUG codes for methionine in eukaryotes (and formylmethionine in prokaryotes), serving as the universal start codon.
Q. 14 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
The process by which RNA is synthesized using a DNA template strand is called:
A
Replication
B
Translation
C
Transcription
✓ Correct
D
Reverse transcription
💡 Step-by-Step Explanation & Concept Rationale
RNA polymerase catalyzes the transcription of genetic code from DNA into messenger RNA (mRNA).
Q. 15 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #8: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Northern Blotting
B
Gel Electrophoresis
C
Southern Blotting
D
Polymerase Chain Reaction (PCR)
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 16 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #13: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Polymerase Chain Reaction (PCR)
✓ Correct
B
Gel Electrophoresis
C
Southern Blotting
D
Northern Blotting
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 17 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #18: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Gel Electrophoresis
B
Polymerase Chain Reaction (PCR)
✓ Correct
C
Southern Blotting
D
Northern Blotting
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 18 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #23: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Southern Blotting
B
Gel Electrophoresis
C
Polymerase Chain Reaction (PCR)
✓ Correct
D
Northern Blotting
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 19 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #28: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Northern Blotting
B
Gel Electrophoresis
C
Southern Blotting
D
Polymerase Chain Reaction (PCR)
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 20 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #33: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Polymerase Chain Reaction (PCR)
✓ Correct
B
Gel Electrophoresis
C
Southern Blotting
D
Northern Blotting
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 21 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In molecular genetics #38: What molecular technique is used to amplify minute quantities of specific DNA segments in vitro?
A
Gel Electrophoresis
B
Polymerase Chain Reaction (PCR)
✓ Correct
C
Southern Blotting
D
Northern Blotting
💡 Step-by-Step Explanation & Concept Rationale
PCR utilizes thermal cycling with Taq polymerase to exponentially amplify targeted DNA sequences.
Q. 22 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
The universal blood donor group in the ABO and Rh system is:
A
O Positive (O+)
B
AB Positive (AB+)
C
O Negative (O-)
✓ Correct
D
A Negative (A-)
💡 Step-by-Step Explanation & Concept Rationale
O- red blood cells lack A, B, and Rh (D) surface antigens, preventing hemolytic transfusion reactions in diverse recipients.
Q. 23 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In human organ physiology #8: What is the primary digestive enzyme in saliva that begins carbohydrate digestion by breaking starch into maltose?
A
Lipase
B
Pepsin
C
Trypsin
D
Salivary Amylase (Ptyalin)
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
Salivary amylase hydrolyzes alpha-1,4 glycosidic bonds in starch to initiate carbohydrate digestion in the oral cavity.
Q. 24 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In human organ physiology #13: What is the primary digestive enzyme in saliva that begins carbohydrate digestion by breaking starch into maltose?
A
Salivary Amylase (Ptyalin)
✓ Correct
B
Pepsin
C
Trypsin
D
Lipase
💡 Step-by-Step Explanation & Concept Rationale
Salivary amylase hydrolyzes alpha-1,4 glycosidic bonds in starch to initiate carbohydrate digestion in the oral cavity.
Q. 25 Biology & Medical Sciences
Difficulty: EASY (1 Mark)
In human organ physiology #18: What is the primary digestive enzyme in saliva that begins carbohydrate digestion by breaking starch into maltose?
A
Pepsin
B
Salivary Amylase (Ptyalin)
✓ Correct
C
Trypsin
D
Lipase
💡 Step-by-Step Explanation & Concept Rationale
Salivary amylase hydrolyzes alpha-1,4 glycosidic bonds in starch to initiate carbohydrate digestion in the oral cavity.
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