Q.1 Which of the following describes the shape of cocci bacteria?
Rod-shaped
Spherical
Spiral
Comma-shaped
Explanation - Cocci bacteria are spherical in shape, as opposed to bacilli (rod-shaped) or spirilla (spiral).
Correct answer is: Spherical
Q.2 Bacilli bacteria are best described as:
Spherical
Rod-shaped
Spiral
Filamentous
Explanation - Bacilli are rod-shaped bacteria, a common bacterial morphology.
Correct answer is: Rod-shaped
Q.3 Spirilla bacteria are characterized by:
Spherical shape
Rod-like chains
Rigid spiral shape
Comma-like shape
Explanation - Spirilla are rigid spiral-shaped bacteria that differ from flexible spirochetes.
Correct answer is: Rigid spiral shape
Q.4 Which bacterial arrangement is described as a chain of cocci?
Staphylococci
Streptococci
Diplococci
Tetrads
Explanation - Streptococci refers to chains of cocci, whereas staphylococci form clusters.
Correct answer is: Streptococci
Q.5 What does 'staphylococci' describe?
Pairs of cocci
Chains of cocci
Clusters of cocci
Spiral cocci
Explanation - Staphylococci appear as grape-like clusters of spherical cells.
Correct answer is: Clusters of cocci
Q.6 Vibrio species typically have what shape?
Rod
Comma-shaped
Spiral
Spherical
Explanation - Vibrio species like Vibrio cholerae are curved rod-shaped, resembling a comma.
Correct answer is: Comma-shaped
Q.7 Which group of bacteria are known for their flexible spiral shape?
Spirilla
Spirochetes
Vibrio
Cocci
Explanation - Spirochetes are flexible spiral-shaped bacteria, unlike rigid spirilla.
Correct answer is: Spirochetes
Q.8 Diplococci are:
Cocci in chains
Cocci in pairs
Cocci in clusters
Cocci in tetrads
Explanation - Diplococci appear in pairs, as seen in Neisseria species.
Correct answer is: Cocci in pairs
Q.9 Which bacterial genus is typically spiral in shape?
Escherichia
Bacillus
Spirillum
Streptococcus
Explanation - Spirillum are classic spiral-shaped bacteria.
Correct answer is: Spirillum
Q.10 Gram staining differentiates bacteria based on:
DNA content
Ribosomal RNA
Cell wall composition
Metabolic pathways
Explanation - Gram-positive and Gram-negative bacteria differ mainly in cell wall peptidoglycan structure.
Correct answer is: Cell wall composition
Q.11 Gram-positive bacteria stain:
Pink
Purple
Green
Colorless
Explanation - Gram-positive bacteria retain crystal violet stain due to thick peptidoglycan layers.
Correct answer is: Purple
Q.12 Gram-negative bacteria stain:
Purple
Blue
Pink
Yellow
Explanation - Gram-negative bacteria appear pink after Gram staining due to safranin counterstain.
Correct answer is: Pink
Q.13 Which bacterial cell wall component is unique to Gram-negative bacteria?
Teichoic acids
Peptidoglycan
Lipopolysaccharide
Mycolic acid
Explanation - Lipopolysaccharides (LPS) are found in the outer membrane of Gram-negative bacteria.
Correct answer is: Lipopolysaccharide
Q.14 Which of the following genera contains acid-fast bacteria?
Streptococcus
Escherichia
Mycobacterium
Bacillus
Explanation - Mycobacterium species have waxy mycolic acids that retain carbol fuchsin dye in acid-fast staining.
Correct answer is: Mycobacterium
Q.15 Which staining technique is used to identify acid-fast bacteria?
Gram stain
Ziehl-Neelsen stain
Endospore stain
Capsule stain
Explanation - Ziehl-Neelsen stain identifies acid-fast bacteria such as Mycobacterium tuberculosis.
Correct answer is: Ziehl-Neelsen stain
Q.16 Which structure helps in bacterial motility?
Fimbriae
Flagella
Capsule
Pili
Explanation - Flagella are whip-like appendages responsible for bacterial motility.
Correct answer is: Flagella
Q.17 Fimbriae are primarily used for:
Motility
DNA transfer
Attachment
Spore formation
Explanation - Fimbriae are hair-like structures that help bacteria adhere to surfaces.
Correct answer is: Attachment
Q.18 Which structure protects bacteria from phagocytosis?
Cell wall
Fimbriae
Capsule
Pili
Explanation - Capsules are protective layers that prevent immune system phagocytosis.
Correct answer is: Capsule
Q.19 Which bacterial arrangement refers to groups of four cocci?
Diplococci
Tetrads
Streptococci
Staphylococci
Explanation - Tetrads are arrangements of four cocci grouped together in a square formation.
Correct answer is: Tetrads
Q.20 The term 'pleomorphic' refers to bacteria that:
Are always rod-shaped
Have a spiral form
Vary in shape and size
Form clusters
Explanation - Pleomorphic bacteria exhibit variability in shape and size, such as Mycoplasma.
Correct answer is: Vary in shape and size
Q.21 Which genus includes rod-shaped, endospore-forming bacteria?
Bacillus
Escherichia
Streptococcus
Neisseria
Explanation - Bacillus are rod-shaped bacteria capable of forming endospores.
Correct answer is: Bacillus
Q.22 Which bacterial genus is spherical and Gram-positive?
Streptococcus
Bacillus
Spirillum
Vibrio
Explanation - Streptococcus is Gram-positive and spherical in shape.
Correct answer is: Streptococcus
Q.23 Which bacterial genus is rod-shaped and Gram-negative?
Escherichia
Streptococcus
Staphylococcus
Mycobacterium
Explanation - Escherichia coli is a rod-shaped, Gram-negative bacterium.
Correct answer is: Escherichia
Q.24 Which of the following is NOT a bacterial shape?
Cocci
Bacilli
Spirilla
Conidia
Explanation - Conidia are asexual spores of fungi, not a bacterial shape.
Correct answer is: Conidia
Q.25 Which bacterial shape resembles a corkscrew?
Cocci
Bacilli
Spirochetes
Vibrio
Explanation - Spirochetes are corkscrew-shaped bacteria such as Treponema pallidum.
Correct answer is: Spirochetes