NEET previous year questions (PYQ)

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Plant stomata close rapidly under severe soil moisture deficit and drought stress.

Reason (R): Abscisic acid (ABA) synthesized during drought induces potassium and anion efflux from guard cells, causing loss of turgor pressure.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Work done by an electrostatic field in moving a test charge along a closed path is zero.

Reason (R): The electrostatic Coulomb force is a conservative force whose line integral around any closed loop vanishes identically.

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

Which molecular enzymes are fundamentally required to cut the plasmid vector and seal the insulin cDNA insert?

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

What chemical bonds cross-link Chain A and Chain B to stabilize the functional tertiary structure of human insulin?

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

What chemical bonds cross-link Chain A and Chain B to stabilize the functional tertiary structure of human insulin?

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Gastric enzyme pepsin requires an acidic environment to digest dietary proteins.

Reason (R): Hydrochloric acid secreted by parietal cells creates optimum pH (1.5 to 2.0) and cleaves inactive pepsinogen into active pepsin.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): The electrical conductivity of an intrinsic semiconductor increases with rise in temperature.

Reason (R): With increase in temperature, covalent bonds rupture, generating additional free conduction electrons and mobile holes.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Systemic arteries have thick, elastic muscular walls compared to veins.

Reason (R): Arterial blood flows under high, pulsatile hydrostatic pressure generated by ventricular systole.

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

In natural proinsulin produced by human pancreatic $\beta$-cells, which extra peptide sequence is present and cleaved during maturation?

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

Why is human insulin synthesized via recombinant DNA technology superior to animal-derived insulin?

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Noble gases possess positive or zero electron gain enthalpy.

Reason (R): Noble gases have completely filled stable electronic valence shell configurations ($ns^2 np^6$).

Refer to the Case Study 'Case Study: Recombinant Human Insulin Synthesis in Modern Biotechnology' to answer:

Which molecular enzymes are fundamentally required to cut the plasmid vector and seal the insulin cDNA insert?

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): DNA replication in all prokaryotic and eukaryotic organisms is semi-conservative.

Reason (R): Each daughter double helix retains one intact parental template strand and one newly synthesized complementary strand.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Energy flow through ecological food webs is strictly unidirectional.

Reason (R): Solar energy captured by autotrophic producers is dissipated as metabolic heat and cannot revert back to solar radiation, diminishing at successive trophic levels.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Energy flow through ecological food webs is strictly unidirectional.

Reason (R): Solar energy captured by autotrophic producers is dissipated as metabolic heat and cannot revert back to solar radiation, diminishing at successive trophic levels.