Subtopic: Fundamentals of Biomolecules, enzyme kinetics
Question Statement:
Which of the following are TRUE for Treponema pallidum?
P. It is the causative agent of syphilis
Q. It is a spirochete
R. It is a non-motile bacterium
S. It is generally susceptible to penicillin
Choose the correct combination.
Options:
(A) In competitive inhibition, substrate and inhibitor compete for the same active site of an enzyme
(B) Addition of a large amount of substrate to an enzyme cannot overcome uncompetitive inhibition
(C) A transition state analogue in enzyme catalyzed reaction increases the rate of product formation
(D) In non-competitive inhibition, K
m of an enzyme for its substrate remains constant as the
concentration of the inhibitor increases
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2016 Q.14)**
**1. Governing Concept & Question Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Topic**: Microbiology & Medical Bacteriology (Characteristics of *Treponema pallidum*)
**2. Detailed Step-by-Step Analysis**:
- Let us evaluate each statement concerning *Treponema pallidum* (the causative agent of venereal syphilis):
- **P. It is a spirochete**: **TRUE**. *T. pallidum* is a thin, tightly coiled, helical/spiral bacterium belonging to the phylum Spirochaetes.
- **Q. It is a rod**: **FALSE**. It is a spirochete (corkscrew-shaped), not a rod (bacillus).
- **R. It is the causative agent of syphilis**: **TRUE**. *T. pallidum* subsp. *pallidum* causes human syphilis, characterized by primary chancres, secondary rashes, and tertiary neurosyphilis.
- **S. It is the causative agent of gonorrhea**: **FALSE**. Gonorrhea is caused by *Neisseria gonorrhoeae* (a Gram-negative diplococcus).
- Therefore, statements **P and R only** are TRUE.
- **Option-by-Option Evaluation**:
- **Option (A) [INCORRECT]**: Statement Q is false.
- **Option (B) [CORRECT]**: P (it is a spirochete) and R (causative agent of syphilis) are completely true.
- **Option (C) [INCORRECT]**: Statements Q and S are both false.
- **Option (D) [INCORRECT]**: Statement S is false.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **B**
- **Scoring Criteria**: +1.0 Mark (Negative marking: -0.33 marks).
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