NEET Full Mock Test 2026 – Free Practice with Explanations
NEET Full Mock Test with Answers and Explanations | MCQAdda — Practice Questions
1. A patient suffers from recurrent bacterial infections despite having a normal T-cell count. Laboratory investigations reveal a severe deficiency of circulating antibodies. Which cell type is most likely affected?
- (A) Cytotoxic T lymphocytes
- (B) Plasma cells
- (C) Natural killer cells
- (D) Macrophages
Answer: (B) Plasma cells
Plasma cells are differentiated B-lymphocytes that produce antibodies. A deficiency results in impaired humoral immunity while T-cell count may remain normal.
2. During DNA replication, a mutation prevents the formation of RNA primers. Which process will be affected first?
- (A) Joining of Okazaki fragments
- (B) Initiation of DNA synthesis
- (C) Removal of RNA primers
- (D) DNA proofreading
Answer: (B) Initiation of DNA synthesis
DNA polymerase cannot initiate DNA synthesis without RNA primers synthesized by primase.
3. A C₄ plant is transferred to an environment with high CO₂ concentration and low temperature. Which process is expected to decrease significantly?
- (A) Calvin cycle
- (B) Photorespiration
- (C) Glycolysis
- (D) Photophosphorylation
Answer: (B) Photorespiration
High CO₂ suppresses the oxygenase activity of RuBisCO, reducing photorespiration.
4. Which event directly triggers the opening of voltage-gated calcium channels at the synaptic terminal?
- (A) Binding of neurotransmitter
- (B) Arrival of an action potential
- (C) ATP hydrolysis
- (D) Sodium-potassium pump activity
Answer: (B) Arrival of an action potential
Arrival of an action potential depolarizes the terminal, opening voltage-gated Ca²⁺ channels and initiating neurotransmitter release.
5. A mutation damages the glomerular filtration membrane but leaves renal tubules intact. Which abnormality is most likely observed?
- (A) Glucose in urine
- (B) Proteinuria
- (C) Increased urine pH
- (D) Reduced urea excretion
Answer: (B) Proteinuria
Damage to the filtration membrane allows plasma proteins to enter the filtrate, causing proteinuria.
6. During the cardiac cycle, closure of the semilunar valves marks the beginning of:
- (A) Ventricular systole
- (B) Isovolumetric relaxation
- (C) Ventricular ejection
- (D) Atrial systole
Answer: (B) Isovolumetric relaxation
Closure of the aortic and pulmonary valves initiates ventricular relaxation before AV valves open.
7. In meiosis, crossing over occurs during:
- (A) Leptotene
- (B) Zygotene
- (C) Pachytene
- (D) Diplotene
Answer: (C) Pachytene
Crossing over takes place during pachytene of Prophase I after homologous chromosomes have paired.
8. Which hormone primarily increases blood calcium concentration by stimulating osteoclast activity?
- (A) Calcitonin
- (B) Parathyroid hormone
- (C) Thyroxine
- (D) Calcitriol
Answer: (B) Parathyroid hormone
PTH increases blood calcium by promoting bone resorption, increasing renal calcium reabsorption and activating vitamin D.
9. Which structure contains the highest concentration of RuBisCO in C₄ plants?
- (A) Mesophyll chloroplast
- (B) Bundle sheath chloroplast
- (C) Epidermal cells
- (D) Guard cells
Answer: (B) Bundle sheath chloroplast
RuBisCO is localized mainly in bundle sheath chloroplasts in C₄ plants.
10. A person is unable to digest milk due to deficiency of lactase. Which type of biomolecule remains undigested?
- (A) Protein
- (B) Lipid
- (C) Disaccharide
- (D) Polysaccharide
Answer: (C) Disaccharide
Lactose is a disaccharide hydrolyzed by lactase into glucose and galactose.
11. Which species exhibits the highest bond order?
- (A) O₂
- (B) O₂⁺
- (C) O₂⁻
- (D) O₂²⁻
Answer: (B) O₂⁺
Removal of one antibonding electron increases the bond order from 2 to 2.5.
12. Which compound undergoes nucleophilic substitution most readily?
- (A) Chlorobenzene
- (B) Vinyl chloride
- (C) tert-Butyl chloride
- (D) Fluorobenzene
Answer: (C) tert-Butyl chloride
Tertiary alkyl halides readily undergo SN1 reactions due to stable carbocation formation.
13. For an exothermic reaction at equilibrium, increasing the temperature will:
- (A) Increase K
- (B) Shift equilibrium toward products
- (C) Shift equilibrium toward reactants
- (D) Have no effect
Answer: (C) Shift equilibrium toward reactants
According to Le Chatelier's principle, heat acts as a product in exothermic reactions.
14. Which oxide is amphoteric?
- (A) Na₂O
- (B) Al₂O₃
- (C) SO₃
- (D) CaO
Answer: (B) Al₂O₃
Aluminium oxide reacts with both acids and bases.
15. The strongest reducing agent among the following is:
- (A) Li
- (B) Na
- (C) K
- (D) Cs
Answer: (A) Li
Lithium has the most negative standard reduction potential among alkali metals and is the strongest reducing agent in aqueous solution.