The term 'ACE2' is talked about in the context of

Answer: D. ACE2 is discussed in the context of SPREAD OF VIRAL DISEASES. ACE2 (ANGIOTENSIN-CONVERTING ENZYME 2) is a HUMAN MEMBRANE-BOUND ENZYME that physiologically regulates blood pressure by cleaving angiotensin II into angiotensin (1-7). It is expressed on the surface of cells in the LUNGS, HEART, KIDNEYS, INTESTINES, AND BLOOD VESSELS. ACE2 burst into global public health discourse because IT IS THE PRIMARY RECEPTOR USED BY SARS-CoV-2 (the virus that causes COVID-19) to enter human cells. The mechanism: - The SARS-CoV-2 SPIKE (S) PROTEIN binds with high affinity to ACE2 on the human cell surface. - Cellular protease TMPRSS2 cleaves the spike, allowing membrane fusion. - The viral RNA enters the host cell and hijacks ribosomes. - This receptor-binding affinity explains the virus's high transmissibility. ACE2 is also the receptor for the earlier SARS-CoV (2003) and HCoV-NL63 (a common-cold coronavirus). ACE2 expression patterns explain WHY COVID-19 primarily affects the respiratory tract and why patients with cardiovascular comorbidities (where ACE2 is involved) had worse outcomes. Therapeutic strategies have included recombinant soluble ACE2 as a 'decoy' to bind virus. Distractors: (A) Genes in GM plants: unrelated to ACE2 — Bt cry genes, glyphosate resistance genes, etc. (B) India's satellite navigation system = IRNSS/NavIC, not ACE2. (C) Wildlife radio collars = telemetry technology, not ACE2. Source: NCERT Class 12 Biology 'Human Health and Disease' / WHO COVID-19 technical briefings.