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🔬 Biology  ·  Principles of Inheritance and Variation  ·  NEET

The SOS response in E. coli is triggered by:

Answer: DNA damage (RecA coprotease activity).

  • A Prolonged nutrient starvation activating the stringent response
  • B DNA damage (RecA coprotease activity)
  • C Exposure to high temperature alone, triggering heat-shock proteins
  • D Osmotic stress activating compatible solute accumulation pathways

Correct answer: B. DNA damage (RecA coprotease activity)

Explanation: SOS response: DNA damage causes RecA to become activated as a coprotease. It cleaves LexA repressor, inducing DNA repair genes including RecA, UvrA, and error-prone polymerases.

Monohybrid Cross: Tt x TtParent 1 (Tt)Parent 2 (Tt)gametes: T, t (from each parent)TtTtTTTtTtttRatio 1 TT : 2 Tt : 1 tt (3 tall : 1 short if T = tall is dominant)

Punnett square for a monohybrid cross between two heterozygous (Tt) parents, showing the 3:1 phenotypic ratio predicted by Mendel's Law of Segregation.

Concept context

Mendel's laws, inheritance patterns, DNA structure, and molecular biology. Core of NEET biology.

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