Which one of the following is NOT an algorithm for building phylogenetic trees?
(A) Maximum parsimony (B) Neighbor joining
(C) Maximum likelihood (D) Bootstrap
Options:
(A) Maximum parsimony
(B) Neighbor joining
(C) Maximum likelihood
(D) Bootstrap
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2016 Q.08)**
**1. Governing Concept & Question Classification**:
- **Section**: General Aptitude (GA)
- **Question Type**: **MCQ** (2 Marks)
- **Topic**: Reasoning (Alphabetical Series & Pattern Recognition)
**2. Detailed Step-by-Step Derivation**:
- The given series has blocks of increasing length:
$\text{Term 1: B (1 letter)}$
$\text{Term 2: FH (2 letters)}$
$\text{Term 3: LNP (3 letters)}$
$\text{Term 4: ? ? ? ? (4 letters)}$
- Convert letters to their alphabetical positions ($A=1, B=2, \dots, Z=26$):
- Term 1: $\text{B} \to [2]$
- Term 2: $\text{FH} \to [6, 8]$
- Term 3: $\text{LNP} \to [12, 14, 16]$
- Analyze the internal structure of each block:
- Letters within each block increase by $+2$ (consecutive even positions).
- Analyze the transition between blocks:
- End of Term 1 ($2$) to Start of Term 2 ($6$): $+4$.
- End of Term 2 ($8$) to Start of Term 3 ($12$): $+4$.
- Therefore, the start of Term 4 must be:
$\text{Last position of Term 3} + 4 = 16 + 4 = 20 \implies \text{T}$
- Generating the 4 letters of Term 4 starting from 20 with step $+2$:
- Letter 1: $20 \implies \text{T}$
- Letter 2: $22 \implies \text{V}$
- Letter 3: $24 \implies \text{X}$
- Letter 4: $26 \implies \text{Z}$
- Term 4 is **TVXZ**.
- **Option-by-Option Evaluation**:
- **Option (A) [INCORRECT]**: SUWY starts at 19 (odd positions).
- **Option (B) [INCORRECT]**: TUVW increases by $+1$ instead of $+2$.
- **Option (C) [CORRECT]**: TVXZ precisely follows the $+4$ inter-block shift and $+2$ intra-block progression.
- **Option (D) [INCORRECT]**: TWXZ has an irregular $+3$ gap between T and W.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **C**
- **Scoring Criteria**: +2.0 Marks (Negative marking: -0.67 marks).
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