Examl 1:l BIOl 205/l BIO205l (NEWl 2025/l
2026l Update)l Microbiologyl Guide|l
Questionsl &l Answers|l Gradel A|l 100%l
Correctl (Verifiedl Solutions)-l GCU
QUESTION
Definel Scanningl Electronl Microscopy:
Answer:
Scanningl electronl microscopyl (SEM)l isl al typel ofl microscopyl thatl usesl al beaml ofl
electronsl tol producel high-resolutionl imagesl ofl thel surfacel ofl al sample,l enablingl
visualizationl ofl thel topography,l morphology,l andl compositionl ofl thel samplel atl thel
micrometerl tol nanometerl scale.
QUESTION
Definel Discoveryl ofl Microscopy:
Answer:
Thel discoveryl ofl microscopyl refersl tol thel inventionl andl developmentl ofl instrumentsl
andl techniquesl thatl allowedl thel visualizationl andl studyl ofl objectsl thatl arel tool smalll tol
bel seenl withl thel nakedl eye,l includingl microorganisms,l andl revolutionizedl thel fieldsl ofl
biologyl andl medicine.
QUESTION
Knowl thel typesl ofl bacterial basedl onl morphologyl (cocci,l bacilli,l etc.)
Answer:
1.l Bacterial canl bel classifiedl basedl onl theirl morphologyl orl shape,l whichl canl bel
sphericall (cocci),l rod-shapedl (bacilli),l spirall (spirilla),l orl curvedl (vibriol orl comma-
shaped).l
2.l Coccil canl bel furtherl classifiedl asl single,l inl pairsl (diplococci),l inl clustersl
(staphylococci),l orl inl chainsl (streptococci),l
,3.l Bacillil canl bel single,l inl pairsl (diplobacilli),l orl inl chainsl (streptobacilli).
QUESTION
Bel ablel tol labell thel structuresl thatl comprisel bacteriall cells:
Answer:
1.l Celll membranel (plasmal membrane):l Al thin,l flexiblel layerl ofl lipidsl andl proteinsl thatl
surroundsl thel cytoplasml andl separatesl thel interiorl ofl thel celll froml thel externall
environment.
2.l Celll wall:l Al rigidl layerl thatl liesl outsidel thel celll membranel andl providesl structurall
supportl andl protectionl tol thel cell.
3.l Capsule:l Al slimy,l protectivel layerl thatl liesl outsidel thel celll walll andl helpsl thel celll
tol evadel thel hostl immunel system.
4.l Flagellum:l Al long,l whip-likel structurel thatl extendsl froml thel celll surfacel andl enablesl
thel celll tol move.
5.l Pili:l Short,l hair-likel structuresl thatl protrudel froml thel celll surfacel andl helpl bacterial
tol attachl tol surfacesl orl tol otherl bacteria.
6.l Cytoplasm:l Al gel-likel substancel thatl fillsl thel celll andl containsl variousl enzymesl andl
cellularl components,l includingl thel nucleoidl (bacteriall DNA),l ribosomes,l andl inclusionl
bodies.
QUESTION
Understandl thel functionl ofl importantl cellularl structures:
Answer:
1.l Celll membranel (plasmal membrane):l Regulatesl thel transportl ofl substancesl inl andl outl
ofl thel celll andl helpsl maintainl thel cell'sl internall environment.
2.l Celll wall:l Providesl structurall supportl andl protectionl tol thel cell.
3.l Capsule:l Protectsl thel celll froml hostl immunel responsesl andl helpsl bacterial tol adherel
tol surfaces.
4.l Flagellum:l Enablesl thel celll tol movel towardsl nutrientsl orl awayl froml harmfull
substances.
5.l Pili:l Facilitatel adhesionl tol surfaces,l transferl ofl geneticl materiall betweenl bacterial
(conjugation),l andl formationl ofl biofilms.
6.l Cytoplasm:l Containsl thel bacteriall DNAl andl variousl enzymesl necessaryl forl
metabolisml andl otherl cellularl processes.
7.l Nucleoid:l Containsl thel bacteriall DNA.
, 8.l Ribosomes:l Synthesizel proteins.
9.l Inclusionl bodies:l Storel energyl reservesl orl otherl materials.
QUESTION
Knowl thel differencel betweenl Graml Positivel &l Negativel Bacteria:
Answer:
Gram-positivel bacterial havel al thickl layerl ofl peptidoglycanl inl theirl celll walls,l whichl
retainsl thel crystall violetl stainl inl al Graml stain,l causingl theml tol appearl purplel underl
thel microscope,l whilel Gram-negativel bacterial havel al thinl layerl ofl peptidoglycanl andl anl
outerl membranel containingl lipopolysaccharidesl andl porins,l whichl preventl thel crystall
violetl stainl froml penetratingl thel celll wall.
QUESTION
Knowl thel partsl ofl thel celll envelopel andl howl itl aidsl inl bacteriall defensel againstl
antibiotics:
Answer:
Thel bacteriall celll envelopel consistsl ofl thel outerl membranel (inl Gram-negativel bacteria),l
thel peptidoglycanl layer,l andl thel cytoplasmicl membrane,l whichl providel al physicall
barrierl againstl thel entryl ofl toxicl substancesl andl antibioticsl intol thel bacteriall cell,l
makingl itl difficultl forl antibioticsl tol penetratel thel celll andl targetl essentiall cellularl
processes.
QUESTION
Knowl howl celll walll compositionl isl appliedl inl staining:
Answer:
Celll walll compositionl isl importantl inl stainingl becausel itl determinesl thel abilityl ofl al
bacteriall celll tol retainl orl losel al stain.l Forl example,l Gram-positivel bacterial withl thickl
peptidoglycanl layersl retainl thel crystall violetl stainl inl al Graml stain,l whilel Gram-negativel
bacterial withl thinl peptidoglycanl layersl andl anl outerl membranel losel thel crystall violetl
stainl butl retainl thel counterstain,l safranin.
2026l Update)l Microbiologyl Guide|l
Questionsl &l Answers|l Gradel A|l 100%l
Correctl (Verifiedl Solutions)-l GCU
QUESTION
Definel Scanningl Electronl Microscopy:
Answer:
Scanningl electronl microscopyl (SEM)l isl al typel ofl microscopyl thatl usesl al beaml ofl
electronsl tol producel high-resolutionl imagesl ofl thel surfacel ofl al sample,l enablingl
visualizationl ofl thel topography,l morphology,l andl compositionl ofl thel samplel atl thel
micrometerl tol nanometerl scale.
QUESTION
Definel Discoveryl ofl Microscopy:
Answer:
Thel discoveryl ofl microscopyl refersl tol thel inventionl andl developmentl ofl instrumentsl
andl techniquesl thatl allowedl thel visualizationl andl studyl ofl objectsl thatl arel tool smalll tol
bel seenl withl thel nakedl eye,l includingl microorganisms,l andl revolutionizedl thel fieldsl ofl
biologyl andl medicine.
QUESTION
Knowl thel typesl ofl bacterial basedl onl morphologyl (cocci,l bacilli,l etc.)
Answer:
1.l Bacterial canl bel classifiedl basedl onl theirl morphologyl orl shape,l whichl canl bel
sphericall (cocci),l rod-shapedl (bacilli),l spirall (spirilla),l orl curvedl (vibriol orl comma-
shaped).l
2.l Coccil canl bel furtherl classifiedl asl single,l inl pairsl (diplococci),l inl clustersl
(staphylococci),l orl inl chainsl (streptococci),l
,3.l Bacillil canl bel single,l inl pairsl (diplobacilli),l orl inl chainsl (streptobacilli).
QUESTION
Bel ablel tol labell thel structuresl thatl comprisel bacteriall cells:
Answer:
1.l Celll membranel (plasmal membrane):l Al thin,l flexiblel layerl ofl lipidsl andl proteinsl thatl
surroundsl thel cytoplasml andl separatesl thel interiorl ofl thel celll froml thel externall
environment.
2.l Celll wall:l Al rigidl layerl thatl liesl outsidel thel celll membranel andl providesl structurall
supportl andl protectionl tol thel cell.
3.l Capsule:l Al slimy,l protectivel layerl thatl liesl outsidel thel celll walll andl helpsl thel celll
tol evadel thel hostl immunel system.
4.l Flagellum:l Al long,l whip-likel structurel thatl extendsl froml thel celll surfacel andl enablesl
thel celll tol move.
5.l Pili:l Short,l hair-likel structuresl thatl protrudel froml thel celll surfacel andl helpl bacterial
tol attachl tol surfacesl orl tol otherl bacteria.
6.l Cytoplasm:l Al gel-likel substancel thatl fillsl thel celll andl containsl variousl enzymesl andl
cellularl components,l includingl thel nucleoidl (bacteriall DNA),l ribosomes,l andl inclusionl
bodies.
QUESTION
Understandl thel functionl ofl importantl cellularl structures:
Answer:
1.l Celll membranel (plasmal membrane):l Regulatesl thel transportl ofl substancesl inl andl outl
ofl thel celll andl helpsl maintainl thel cell'sl internall environment.
2.l Celll wall:l Providesl structurall supportl andl protectionl tol thel cell.
3.l Capsule:l Protectsl thel celll froml hostl immunel responsesl andl helpsl bacterial tol adherel
tol surfaces.
4.l Flagellum:l Enablesl thel celll tol movel towardsl nutrientsl orl awayl froml harmfull
substances.
5.l Pili:l Facilitatel adhesionl tol surfaces,l transferl ofl geneticl materiall betweenl bacterial
(conjugation),l andl formationl ofl biofilms.
6.l Cytoplasm:l Containsl thel bacteriall DNAl andl variousl enzymesl necessaryl forl
metabolisml andl otherl cellularl processes.
7.l Nucleoid:l Containsl thel bacteriall DNA.
, 8.l Ribosomes:l Synthesizel proteins.
9.l Inclusionl bodies:l Storel energyl reservesl orl otherl materials.
QUESTION
Knowl thel differencel betweenl Graml Positivel &l Negativel Bacteria:
Answer:
Gram-positivel bacterial havel al thickl layerl ofl peptidoglycanl inl theirl celll walls,l whichl
retainsl thel crystall violetl stainl inl al Graml stain,l causingl theml tol appearl purplel underl
thel microscope,l whilel Gram-negativel bacterial havel al thinl layerl ofl peptidoglycanl andl anl
outerl membranel containingl lipopolysaccharidesl andl porins,l whichl preventl thel crystall
violetl stainl froml penetratingl thel celll wall.
QUESTION
Knowl thel partsl ofl thel celll envelopel andl howl itl aidsl inl bacteriall defensel againstl
antibiotics:
Answer:
Thel bacteriall celll envelopel consistsl ofl thel outerl membranel (inl Gram-negativel bacteria),l
thel peptidoglycanl layer,l andl thel cytoplasmicl membrane,l whichl providel al physicall
barrierl againstl thel entryl ofl toxicl substancesl andl antibioticsl intol thel bacteriall cell,l
makingl itl difficultl forl antibioticsl tol penetratel thel celll andl targetl essentiall cellularl
processes.
QUESTION
Knowl howl celll walll compositionl isl appliedl inl staining:
Answer:
Celll walll compositionl isl importantl inl stainingl becausel itl determinesl thel abilityl ofl al
bacteriall celll tol retainl orl losel al stain.l Forl example,l Gram-positivel bacterial withl thickl
peptidoglycanl layersl retainl thel crystall violetl stainl inl al Graml stain,l whilel Gram-negativel
bacterial withl thinl peptidoglycanl layersl andl anl outerl membranel losel thel crystall violetl
stainl butl retainl thel counterstain,l safranin.
