Histology Practice Questions

Q: Identify the type of cartilage shown in the figure:

Hyaline cartilage. ***Hyaline cartilage*** - This image displays a relatively **homogenous, glassy matrix** with numerous chondrocytes housed in lacunae, which is characteristic of hyaline cartilage. - The absence of prominent fibers (like elastic fibers or thick collagen bundles) further supports the identification as hyaline cartilage, which is rich in fine **Type II collagen fibers**. *Elastic cartilage* - Elastic cartilage contains abundant **elastic fibers** in its matrix, which would appear as distinct, dark-staining fibers under appropriate staining (e.g., orcein or resorcin-fuchsin). - Its presence allows for more flexibility and elasticity, found in locations such as the **external ear** and **epiglottis**. *Fibrocartilage* - Fibrocartilage is characterized by a dense arrangement of **Type I collagen fibers** organized in thick bundles, often appearing as wavy or swirling patterns within the matrix. - It also contains fewer, more widely spaced chondrocytes than hyaline cartilage, and is typically found in structures needing high tensile strength, like **intervertebral discs** and **menisci**. *White fibrocartilage* - While "white fibrocartilage" is an older historical term sometimes used to describe fibrocartilage (due to its whitish appearance from dense collagen), it is **not a separate histological classification**. - Modern histology recognizes only three types of cartilage: hyaline, elastic, and fibrocartilage. The image shows the typical features of hyaline cartilage, not the dense collagen bundles characteristic of fibrocartilage.

Q: Identify the marked layer in the given histological section.

Inner plexiform layer. ***Inner plexiform layer*** - The arrow points to a **synaptic layer** characterized by a dense network of **axons, dendrites**, and synapses between bipolar cells, amacrine cells, and ganglion cells. - This layer is distinguished by its **reticular appearance** and its position between the inner nuclear layer (nuclei of bipolar, amacrine, and horizontal cells) and the ganglion cell layer. *Outer plexiform layer* - This layer is located more externally in the retina, between the **outer nuclear layer** and the **inner nuclear layer**. - It is where photoreceptors (rods and cones) synapse with bipolar and horizontal cells. *Inner limiting layer* - The **innermost layer** of the retina, adjacent to the vitreous humor. - It is a thin, acellular membrane formed by the basal laminae of the Müller cells. *Outer limiting layer* - This layer is situated internally to the **photoreceptor layer** (rods and cones). - It is not a true membrane but rather a series of intercellular junctions (adherens junctions) between photoreceptor cells and Müller cells.

Q: All are correct about the **X** mark in antibody structure except: (Recent NEET Pattern 2016-17)

Each of these chains has three domains in constant region. ***Each of these chains has three domains in constant region*** - This statement is incorrect. The "X" mark in the image points to a **light chain** of an antibody. Light chains are composed of **one variable domain** and **one constant domain**, not three constant domains. *Composed up of kappa and lambda chains* - This statement is correct. Light chains (**marked X**) can be either **kappa (κ)** or **lambda (λ)**, determining the isotype of the light chain. - While an individual antibody molecule will only have one type of light chain (either two kappa or two lambda), the overall antibody pool in a human body contains both types. *Has molecular weight of 25,000* - This statement is correct. The **light chain** (marked X) has an approximate **molecular weight of 25 kDa**. - This molecular weight is characteristic for both kappa and lambda light chains. *Kappa:lambda occur in ratio of 2:1* - This statement is correct. In humans, **kappa light chains** are generally found in about **twice the abundance as lambda light chains** in serum antibodies. - This ratio is important for assessing clonality in lymphoproliferative disorders.

Q: Identify the type of agar.

Chocolate agar. ***Chocolate agar*** - This agar is distinctly **brown** due to the lysis of red blood cells by heating, which releases hemoglobin and gives it a chocolate-like appearance, despite containing no actual chocolate. - It is an enriched medium used for the isolation of fastidious bacteria such as *Haemophilus influenzae* and pathogenic *Neisseria* species. *Blood agar* - Blood agar is typically **red** because it contains intact red blood cells. - It is a general-purpose enriched medium used to detect **hemolytic activity** of bacteria. *MacConkey agar* - MacConkey agar is usually **pink or reddish-purple** in color. - It is a selective and differential medium used for the isolation of gram-negative enteric bacteria, differentiating them based on **lactose fermentation**. *Nutrient agar* - Nutrient agar is a general-purpose medium that is typically **pale yellowish** or straw-colored. - It supports the growth of a wide range of non-fastidious organisms and is not specifically designed for fastidious bacteria.

Q: In which of the following phase of bacterial growth curve does sporulation start?

C. ***Correct Option C*** - Phase C is the **stationary phase**, where the rate of cell growth equals the rate of cell death due to **nutrient depletion** or waste accumulation. - **Sporulation** typically begins in the **late stationary phase** as bacteria sense unfavorable conditions and initiate endospore formation as a survival mechanism. - This is the most characteristic phase for sporulation to start, triggered by nutrient limitation and environmental stress. *Incorrect Option A* - Phase A represents the **lag phase**, where bacteria are adapting to a new environment and preparing for growth. - During this phase, cells synthesize enzymes and other molecules needed for reproduction, but conditions are favorable and sporulation is not initiated. *Incorrect Option B* - Phase B is the **exponential or log phase**, characterized by rapid and synchronous cell division with optimal growth conditions. - Nutrients are abundant and there is no physiological trigger for bacteria to initiate sporulation during this phase. *Incorrect Option D* - Phase D is the **death phase**, where the population rapidly declines due to lack of resources and toxic waste accumulation. - While some sporulation may continue into this phase, sporulation is **initiated** earlier in the late stationary phase (C), not in the death phase.

Q: Identify the structure marked as $X$ :

Fimbriae. ***Fimbriae*** - The image shows numerous short, hair-like appendages covering the surface of the bacteria, which are characteristic features of **fimbriae**. - Fimbriae are primarily involved in **adhesion to surfaces**, including host cells, and are crucial for bacterial colonization and pathogenicity. - They are typically **numerous (hundreds per cell)** and **short (0.5-10 μm)**, which matches the structures visible in the image. - Fimbriae enable bacteria to attach to epithelial surfaces, making them important virulence factors in pathogenic bacteria. *Pili* - **Pili** (specifically sex pili or conjugative pili) are longer, tubular structures (usually 1-4 per cell) used for **bacterial conjugation** and DNA transfer. - While the terms "pili" and "fimbriae" were historically used interchangeably, modern microbiology distinguishes them: **pili are for conjugation**, while **fimbriae are for adhesion**. - The structures shown are too numerous and short to be pili, which are typically sparse and longer. *Villi* - **Villi** are finger-like projections found in the small intestine of eukaryotes, designed to increase surface area for absorption. - They are a feature of **eukaryotic cells** and tissues, not prokaryotic bacteria, making this completely incorrect for bacterial structures. *Flagella* - **Flagella** are longer, whip-like appendages (10-20 μm or more) primarily used for bacterial **motility**. - The structures shown are short and numerous, not long and sparse like flagella, which would typically be fewer in number (1-10) and distinctively longer than what's visible in the image.

Q: All are true about the terminal area marked 'X' in this bacteria except:

Strongly eosinophilic. ***Strongly eosinophilic*** - The terminal areas marked 'X' represent **metachromatic granules** (also called volutin granules) which stain reddish-purple with methylene blue, a basic dye, indicating they are **basophilic**, not eosinophilic. - Eosinophilic structures stain well with acidic dyes like eosin, resulting in a pink or red color. *Volutin granules* - The terminal areas marked 'X' are characteristic **volutin granules**, also known as **metachromatic granules**, which are inclusions seen in certain bacteria. - These granules are prominent in *Corynebacterium diphtheriae*, which typically exhibits a **club-shaped** or **cuneiform** morphology. *Function as storage reservoir for phosphate* - Volutin granules primarily serve as a **storage reservoir for inorganic polyphosphate**, which is crucial for the bacterium's energy metabolism and various cellular processes. - This stored phosphate can be utilized when environmental phosphate levels are low. *Also found in Yersinia pestis* - **Bipolar staining**, which resembles prominent granules at the ends of the bacteria (similar to the appearance of volutin granules), is a characteristic feature of *Yersinia pestis*. - This gives *Yersinia pestis* a distinctive "safety pin" appearance on Wright-Giemsa or Wayson stain.

Q: The following line diagram is of a gram positive organism. Name the cell wall component marked as $X$.

Teichoic acid. ***Teichoic acid*** - The image shows a **gram-positive cell wall**, characterized by a thick layer of **peptidoglycan** (the reddish-brown horizontal layers) situated above the **cytoplasmic membrane**. - Structure X represents **teichoic acids**, which are polymers embedded within and extending through the peptidoglycan layer of gram-positive bacteria, sometimes covalently linked to the cytoplasmic membrane (then called lipoteichoic acids). *Porin* - **Porins** are found in the **outer membrane** of **gram-negative bacteria** and in the membranes of some organelles like mitochondria, not in the thick peptidoglycan layer of gram-positive bacteria. - They form channels for the passage of small hydrophilic molecules. *Aromatic amino acid* - **Aromatic amino acids** (e.g., phenylalanine, tyrosine, tryptophan) are building blocks of proteins and are present in various cellular structures but are not a distinctive macromolecular component of the bacterial cell wall itself that would be depicted in this manner. - This option refers to a monomer unit rather than a structural polymer of the cell wall. *Peptidoglycan* - **Peptidoglycan** is the main structural component of both gram-positive and gram-negative bacterial cell walls, forming a thick, rigid layer in gram-positive bacteria. - In the provided diagram, the reddish-brown hatched layers represent the **peptidoglycan**, while X specifically points to the thread-like structures extending from it, which are **teichoic acids**.

Q: The cells marked as $X$ are called:

Supporting cells. ***Supporting cells*** - The cells marked as 'X' in the image are the **supporting cells**, also known as **sustentacular cells**, which are essential components of the **olfactory epithelium**. - These cells provide **structural support**, **nourishment**, and **electrical insulation** to the olfactory receptor neurons. - They are **columnar cells** with apical microvilli and contain **lipid droplets** and **pigment granules**. *Olfactory receptor neurons* - These are the **bipolar sensory neurons** that detect odors, located between the supporting cells. - They have a **dendritic knob** with cilia extending into the mucus layer and an **axon** that projects through the cribriform plate. - Not the cells marked as 'X' in this image. *Basal cells* - These are **small, round stem cells** located at the base of the olfactory epithelium. - They serve as **progenitor cells** for regeneration of olfactory receptor neurons. - Located at a different position than the cells marked 'X'. *Bowman's glands* - These are **serous glands** located in the lamina propria beneath the olfactory epithelium. - They secrete **mucus** that dissolves odorants and facilitates olfaction. - These are glandular structures, not the epithelial cells marked in the image.

Q: The area marked as $X$ is called:

Spiral canal of modiolus. ***Spiral canal of modiolus*** - The image shows a cross-section of the **organ of Corti** within the cochlea. Modiolus is the central bony pillar of the cochlea, and the **spiral canal of modiolus** contains the **spiral ganglion**, which consists of the cell bodies of the auditory nerve. The arrow points to a collection of neurons, clearly indicating this structure. - The spiral ganglion neurons receive input from the hair cells and transmit auditory information to the brain. *Endolymphatic sac* - The **endolymphatic sac** is located within the dura mater of the posterior cranial fossa and is involved in the absorption and regulation of **endolymph** fluid. - It is not depicted in this image, which focuses on the sensory structures of the **cochlea**. *Tunnel of Corti* - The **tunnel of Corti** is a triangular-shaped space within the organ of Corti, formed by the inner and outer pillar cells. It is filled with **cortilymph**. - While present in the organ of Corti, the area marked 'X' is clearly positioned to indicate the collection of **neuronal cell bodies** (ganglion) rather than this specific extracellular space. *Scala tympani* - The **scala tympani** is one of the three fluid-filled chambers of the cochlea, located below the basilar membrane. It contains **perilymph** and transmits sound vibrations. - The marked area 'X' indicates a cellular structure (spiral ganglion) within the modiolus, not a fluid-filled chamber of the cochlea.

Question 1

Identify the type of cartilage shown in the figure:

Accepted Answer

Hyaline cartilage

Answer

Elastic cartilage

Answer

Fibrocartilage

Answer

White fibrocartilage

Question 2

Identify the marked layer in the given histological section.

Accepted Answer

Inner plexiform layer

Answer

Outer plexiform layer

Answer

Inner limiting layer

Answer

Outer limiting layer

Question 3

All are correct about the **X** mark in antibody structure except: (Recent NEET Pattern 2016-17)

Accepted Answer

Each of these chains has three domains in constant region

Answer

Composed up of kappa and lambda chains

Answer

Has molecular weight of 25,000

Answer

Kappa:lambda occur in ratio of 2:1

Question 4

Identify the type of agar.

Accepted Answer

Chocolate agar

Answer

Blood agar

Answer

MacConkey agar

Answer

Nutrient agar

Question 5

In which of the following phase of bacterial growth curve does sporulation start?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 6

Identify the structure marked as $X$ :

Accepted Answer

Fimbriae

Answer

Villi

Answer

Pili

Answer

Flagella

Question 7

All are true about the terminal area marked 'X' in this bacteria except:

Accepted Answer

Strongly eosinophilic

Answer

Volutin granules

Answer

Function as storage reservoir for phosphate

Answer

Also found in Yersinia pestis

Question 8

The following line diagram is of a gram positive organism. Name the cell wall component marked as $X$.

Accepted Answer

Teichoic acid

Answer

Porin

Answer

Aromatic amino acid

Answer

Peptidoglycan

Question 9

The cells marked as $X$ are called:

Accepted Answer

Supporting cells

Answer

Olfactory receptor neurons

Answer

Bowman's glands

Answer

Basal cells

Question 10

The area marked as $X$ is called:

Accepted Answer

Spiral canal of modiolus

Answer

Endolymphatic sac

Answer

Tunnel of Corti

Answer

Scala tympani

Histology — MCQs

Histology — MCQs

On this page

Practice by Chapter

Want unlimited practice?