A biological process is involved in the ________ treatment of industrial effluent.
(A) primary (B) secondary (C) tertiary (D) quaternary
Options:
(A) primary
(B) secondary
(C) tertiary
(D) quaternary
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2016 Q.18)**
**1. Governing Concept & Question Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Topic**: Bioinformatics & Phylogenetics (Phylogenetic Algorithms vs. Statistical Resampling)
**2. Detailed Step-by-Step Analysis**:
- Phylogenetic tree construction algorithms compute tree topologies from molecular sequence data:
- **Maximum Parsimony**: A character-based algorithm that searches for the tree requiring the minimum total number of evolutionary changes.
- **Neighbor Joining**: A distance-based clustering algorithm that iteratively joins pairs of operational taxonomic units (OTUs) to minimize total branch length.
- **Maximum Likelihood**: A probabilistic algorithm that evaluates tree topologies under explicit substitution models to find the tree that maximizes the likelihood of the observed sequences.
- **UPGMA**: A distance matrix clustering method that constructs ultrametric trees.
- **Bootstrap (Bootstrapping)** is **NOT** a tree-building algorithm. It is a non-parametric statistical resampling technique that generates pseudoreplicate datasets by sampling alignment columns with replacement to evaluate the statistical confidence/support of individual clades within a tree.
- **Option-by-Option Evaluation**:
- **Option (A) [INCORRECT]**: Maximum parsimony is a bona fide tree-building algorithm.
- **Option (B) [INCORRECT]**: Neighbor joining is a bona fide tree-building algorithm.
- **Option (C) [INCORRECT]**: Maximum likelihood is a bona fide tree-building algorithm.
- **Option (D) [CORRECT]**: Bootstrap is a statistical resampling procedure for estimating tree branch reliability, not an algorithm for constructing trees.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **D**
- **Scoring Criteria**: +1.0 Mark (Negative marking: -0.33 marks).
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