CUET PG 2026 Life Science Question Paper with Solutions

Which protein is often referred to as the "guardian of the genome" due to its role in cell cycle arrest?

• (A) p21
• (B) p53
• (C) Cyclin D
• (D) Rb protein

What is the standard sequence of steps in a PCR (Polymerase Chain Reaction) cycle?

• (A) Annealing → Denaturation → Extension
• (B) Denaturation → Annealing → Extension
• (C) Extension → Denaturation → Annealing
• (D) Annealing → Extension → Denaturation

Which nitrogen source is most commonly used by plants for inorganic nitrogen fixation?

• (A) Nitrite (NO_2^-)
• (B) Nitrate (NO_3^-)
• (C) Ammonia (NH_3)
• (D) Molecular nitrogen (N_2)

During cellular fractionation, which organelle typically forms part of the pellet when centrifuged at 1000g for 10 minutes?

• (A) Ribosomes
• (B) Nucleus
• (C) Endoplasmic Reticulum
• (D) Lysosomes

In gel electrophoresis of DNA, toward which electrode do the DNA fragments migrate?

• (A) Positive electrode (Anode)
• (B) Negative electrode (Cathode)
• (C) Both electrodes equally
• (D) They do not migrate

What is the primary composition of lipid rafts found in plasma membranes?

• (A) Phospholipids and carbohydrates
• (B) Cholesterol and sphingolipids
• (C) Proteins and nucleic acids
• (D) Glycoproteins and triglycerides

Which immunoglobulin class is primarily involved in mucosal immunity?

• (A) IgG
• (B) IgA
• (C) IgM
• (D) IgE

According to Chargaff's rules, which base relationship is constant across all species?

• (A) (A = C)
• (B) (A = G)
• (C) (A = T)
• (D) (G = T)

What happens to the Vmax of an enzyme-catalyzed reaction when the substrate concentration is equal to the Km?

• (A) (V = V_{max})
• (B) (V = \frac{V_{max}}{2})
• (C) (V = 2V_{max})
• (D) (V = 0)

Which hormone is primarily responsible for the "fight or flight" response in human physiology?

• (A) Cortisol
• (B) Adrenaline (Epinephrine)
• (C) Insulin
• (D) Thyroxine

In the lac operon, which molecule acts as the inducer to initiate transcription?

• (A) Lactose
• (B) Allolactose
• (C) Glucose
• (D) Galactose

Which technique is specifically used to detect the presence of a specific DNA sequence in a sample?

• (A) Western blotting
• (B) Southern blotting
• (C) Northern blotting
• (D) ELISA

What is the role of Topoisomerase during the process of DNA replication?

• (A) Synthesizes RNA primers
• (B) Unwinds the DNA helix
• (C) Relieves supercoiling ahead of the replication fork
• (D) Joins Okazaki fragments

Which amino acid is the universal initiator for protein synthesis in eukaryotes?

• (A) Methionine
• (B) Valine
• (C) Leucine
• (D) Alanine

What are the two primary components of a Typhoid Vi vaccine?

• (A) Vi capsular polysaccharide and carrier protein
• (B) Lipopolysaccharide and toxin
• (C) Attenuated bacteria and adjuvant
• (D) DNA plasmid and viral vector