INI-CET 2017 - Microbiology PYQs Practice Questions

Q: Which causative organism is responsible for this disease?

Coxsackie virus. ***Coxsackie virus*** - The images show typical lesions of **Hand-Foot-and-Mouth Disease (HFMD)**, characterized by **oral ulcers** (herpangina) and a vesiculopapular rash on the **palms, soles**, and sometimes buttocks. - HFMD is most commonly caused by **Coxsackie virus A16** and other enteroviruses. *Human herpes virus 7* - This virus is primarily associated with **roseola infantum (exanthem subitum)**, characterized by rapid onset of high fever followed by a rash after the fever breaks. - The rash is typically maculopapular and found on the trunk, not primarily on the palms, soles, and mouth as seen in the image. *Pox virus* - Poxviruses cause diseases like **smallpox** and **molluscum contagiosum**, which present with different types of lesions. - **Smallpox** lesions are deep-seated, painful pustules that evolve synchronously, and **molluscum contagiosum** manifests as pearly, umbilicated papules, neither matching the depicted oral and acral rash. *Molluscum contagiosum virus* - Molluscum contagiosum virus (MCV) is a type of **poxvirus** that causes the skin infection **molluscum contagiosum**. - Its characteristic lesions are **dome-shaped, pearly papules with central umbilication**, which are not consistent with the vesicular lesions and oral ulcers shown in the image. [Practice more Microbiology PYQs on OnCourse]

Q: Identify the organism seen in the slide shown below.

Nocardia asteroides. ***Nocardia asteroides*** - The image exhibits **branching, beaded, filamentous rods** that stain **acid-fast**, key characteristics of *Nocardia*. - These morphological features, especially the irregular acid-fast staining and branching, differentiate it from other bacteria. *Streptococcus pyogenes* - *Streptococcus pyogenes* are Gram-positive cocci typically arranged in **chains**, showing none of the filamentous or branching forms seen in the image. - They are **not acid-fast** and would not appear as pink/red rods on an acid-fast stain. *M. tuberculosis* - While *M. tuberculosis* is **acid-fast** and appears as red rods, it typically presents as **straight or slightly curved rods**, not the extensively branching, beaded filaments observed. - It does not form the complex filamentous structures characteristic of *Nocardia*. *Corynebacterium diphtheriae* - *Corynebacterium diphtheriae* are Gram-positive, **club-shaped rods** that often assume V or L forms (palisades), and are not acid-fast. - This bacterium does not exhibit the extensive branching or beaded appearance characteristic of the organism in the image. [Practice more Microbiology PYQs on OnCourse]

Q: Which of the following bacteria has the flagellar characteristic shown in the image?

Leptospira icterohaemorrhagicae. ***Leptospira icterohaemorrhagicae*** - The image displays **endoflagella** (axial filaments) located beneath the **outer membrane**, which is characteristic of **spirochetes**. - *Leptospira icterohaemorrhagicae* is a spirochete and possesses these internal flagella, allowing for its distinctive corkscrew motility. *Helicobacter pylori* - *Helicobacter pylori* is a gram-negative bacterium that typically has **lophotrichous flagella** (multiple flagella at one pole), which are external, not internal. - Its motility is crucial for penetrating the gastric mucus, but it does not utilize endoflagella. *Mycobacterium tuberculosis* - *Mycobacterium tuberculosis* is a non-motile bacterium and **lacks flagella** altogether. - Its cell wall structure, rich in mycolic acid, contributes to its pathogenicity and resistance but not to motility via flagella. *Vibrio cholerae* - *Vibrio cholerae* is a gram-negative bacterium that possesses a **single polar flagellum** (monotrichous), which is external. - This external flagellum is essential for its motility in aquatic environments and in the human intestine. [Practice more Microbiology PYQs on OnCourse]

Q: Amongst the four choices, select the virus whose life cycle is shown. (AIIMS Nov 2017)

Hepatitis B. ***Hepatitis B*** - The image clearly depicts the formation of **cccDNA (covalently closed circular DNA)** in the host cell nucleus, a unique and defining characteristic of the Hepatitis B virus life cycle. - The process of **reverse transcription** (synthesis of DNA from an RNA template) occurring within the core particle in the cytoplasm, followed by its movement to the nucleus to form cccDNA, is specific to Hepatitis B. *Herpes simplex* - Herpes simplex viruses are **DNA viruses** that replicate entirely within the nucleus, and their replication does not involve an RNA intermediate or the formation of cccDNA. - They also undergo **budding from the inner nuclear membrane** into the perinuclear space, which differs from the ER budding shown. *HIV* - HIV is a **retrovirus** that utilizes reverse transcriptase to convert its RNA genome into DNA, which then integrates into the host genome. However, it does not form cccDNA. - While it does involve reverse transcription, the overall replication strategy, particularly the integration step and the budding from the cell membrane, differs significantly from the depicted process. *Influenza* - Influenza is an **RNA virus** that replicates in the nucleus (unlike most RNA viruses) but does not involve a DNA intermediate or cccDNA formation. - Its replication cycle involves transcription of viral RNA into mRNA and replication of viral RNA genomes, which is distinct from the complex DNA to RNA to DNA cycle shown. [Practice more Microbiology PYQs on OnCourse]

Q: Identify the fungal organism in this slide stained with Gomori-methenamine silver stain. (AIIMS Nov 2017)

Acute angle branching, aspergillus. **Acute angle branching, aspergillus** - The image shows **septate hyphae** with **acute angle (45-degree) branching**, which is characteristic of *Aspergillus* species. - While *Aspergillus* can be identified by conidial heads in culture, in tissue sections stained with Gomori-methenamine silver (GMS) stain, these morphological features are key. *Acute angle branching, rhizopus* - **Rhizopus** species typically exhibit **non-septate or sparsely septate hyphae** with **irregular branching**, often at wide angles. - This morphology differs from the regularly septate, acutely branching hyphae seen in the image. *Right angle branching, aspergillus* - **Aspergillus** hyphae characteristically show **acute angle (45-degree) branching**, not right-angle branching. - The hyphae are also **septate**, a feature that is clearly visible in the image. *Right angle branching, mucor* - **Mucor** species, like other Mucorales (e.g., *Rhizopus*, *Lichtheimia*), are known for their **non-septate or sparsely septate hyphae** with **wide-angle (often right-angle) branching**. - The hyphae in the image are clearly septate and branch acutely, ruling out *Mucor*. [Practice more Microbiology PYQs on OnCourse]

Question 1

Which causative organism is responsible for this disease?

Accepted Answer

Coxsackie virus

Answer

Human herpes virus 7

Answer

Pox virus

Answer

Molluscum contagiosum virus

Question 2

Identify the organism seen in the slide shown below.

Accepted Answer

Nocardia asteroides

Answer

Streptococcus pyogenes

Answer

M. tuberculosis

Answer

Corynebacterium diphtheriae

Question 3

Which of the following bacteria has the flagellar characteristic shown in the image?

Accepted Answer

Leptospira icterohaemorrhagicae

Answer

Helicobacter pylori

Answer

Mycobacterium tuberculosis

Answer

Vibrio cholerae

Question 4

Amongst the four choices, select the virus whose life cycle is shown. (AIIMS Nov 2017)

Accepted Answer

Hepatitis B

Answer

Herpes simplex

Answer

HIV

Answer

Influenza

Question 5

Identify the fungal organism in this slide stained with Gomori-methenamine silver stain. (AIIMS Nov 2017)

Accepted Answer

Acute angle branching, aspergillus

Answer

Acute angle branching, rhizopus

Answer

Right angle branching, aspergillus

Answer

Right angle branching, mucor

Question 6

Which of the following parasite's life cycle is shown below?

Accepted Answer

Fasciola hepatica

Answer

Clonorchis sinensis

Answer

Paragonimus westermani

Answer

Schistosoma japonicum

Question 7

Which of the following fits into the life cycle of the picture given below? (AIIMS May 2017)

Accepted Answer

Entamoeba histolytica

Answer

Giardia lamblia

Answer

Balantidium coli

Answer

Entamoeba coli

Question 8

The image shown below shows egg of? (AIIMS May 2017)

Accepted Answer

A. lumbricoides

Answer

A. duodenale

Answer

E. vermicularis

Answer

Strongyloides stercoralis

Question 9

Identify the organism shown below. (AIIMS May 2017)

Accepted Answer

Nocardia

Answer

Mycobacterium tuberculosis

Answer

Mycobacterium leprae

Answer

Actinomyces

INI-CET 2017 — Microbiology