Subtopic: Fundamentals of Biomolecules, enzyme kinetics
Question Statement:
A thermometer measuring body temperature follows a first-order response with
a time constant of 40 seconds. The instrument will reach 95% of its steady-state
output at __________ seconds.
(Round off to the nearest integer)
Options:
(A) 60
(B) 80
(C) 120
(D) 160
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2025 Q.42)**
**1. Governing Concept**:
- **Topic**: Plant Biotechnology & Somatic Embryogenesis
- In plant tissue culture, **somatic embryogenesis** is the process where somatic cells differentiate into bipolar embryos through developmental stages resembling zygotic embryos:
- **Dicot Somatic Embryogenesis Stages**:
1. **Globular stage**: Spherical cluster of proliferating cells without vascular differentiation.
2. **Heart-shaped stage**: Bilateral symmetry is established by the emergence of two cotyledonary primordia.
3. **Torpedo stage**: Elongation along the longitudinal axis; hypocotyl and root-shoot poles differentiate.
4. **Cotyledonary stage**: Full maturation of cotyledons followed by desiccation and germination.
**2. Option Analysis**:
- **Option (A) is INCORRECT**: Inverts the developmental sequence by placing heart before globular.
- **Option (B) is CORRECT**: Accurately traces the strict morphological sequence: `Globular → Heart → Torpedo → Cotyledonary`.
- **Option (C) is INCORRECT**: Torpedo stage occurs after heart stage, not before.
- **Option (D) is INCORRECT**: Cotyledonary stage is the mature terminal stage, not intermediate.
**3. Final Answer**:
- **Correct Choice**: **B**
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