Cell Biology and Cell Structure MCQs 2026

In the plasma membrane bilayer, the hydrophilic phosphate heads of phospholipids face

1. AOnly the cytoplasmic side✓
2. BBoth the outer and inner aqueous surfaces✓
3. COnly the extracellular side✓
4. DThe hydrophobic core of the membrane✓

Contractile vacuoles, which expel excess water, are most typically found in

1. APlant root cells✓
2. BFreshwater protists such as Paramecium✓
3. CHuman liver cells✓
4. DFungal hyphae✓

Centrioles are typically absent in the cells of

1. AAnimals✓
2. BMost flowering plants✓
3. CInsects✓
4. DGreen algae such as Chlamydomonas✓

Cilia and flagella share a common internal structure of microtubules arranged as

1. AA solid bundle of nine microtubules✓
2. BSix pairs of microtubules in a circle✓
3. CA "9+2" arrangement of microtubule doublets✓
4. DThree central microtubules only✓

Compared with cilia, flagella are typically

1. AAbsent in eukaryotic cells✓
2. BShorter and more numerous per cell✓
3. CLonger and fewer in number per cell✓
4. DNon-motile structures✓

The endosymbiotic theory proposes that mitochondria and chloroplasts originated from

1. AFree-living prokaryotes engulfed by an ancestral host cell✓
2. BFolded regions of the plasma membrane✓
3. CFragments of the nuclear envelope✓
4. DVesicles budded from the Golgi apparatus✓

As a cell increases in size, its surface-area-to-volume ratio

1. AIncreases proportionally✓
2. BDecreases, limiting efficient exchange with the environment✓
3. CRemains constant regardless of size✓
4. DBecomes irrelevant to cell function✓

The Golgi apparatus is structurally organized into flattened, stacked membrane sacs known as

1. ACristae✓
2. BThylakoids✓
3. CNucleosomes✓
4. DCisternae✓

Cholesterol embedded within the animal cell plasma membrane primarily functions to

1. ACatalyze ATP synthesis✓
2. BTransport oxygen across the membrane✓
3. CRegulate membrane fluidity across temperature changes✓
4. DForm covalent bonds with DNA✓

The nuclear envelope is described as a double membrane because it consists of

1. ATwo identical layers of cellulose✓
2. BAn outer membrane continuous with the rough ER and an inner membrane✓
3. CTwo layers of peptidoglycan✓
4. DA single membrane folded twice✓

Lysosomes are sometimes called "suicide bags" of the cell because they can

1. AStore excess water and ions✓
2. BSynthesize new membrane lipids✓
3. CProduce toxins to kill pathogens✓
4. DRupture and digest the cell's own contents✓

Ribosomes found within mitochondria and chloroplasts resemble those of

1. AEukaryotic cytoplasm (80S)✓
2. BThe nuclear envelope✓
3. CBacteria (70S)✓
4. DThe Golgi apparatus✓

Chloroplasts capture light energy and convert it into chemical energy within stacks of membranes called

1. AGrana (thylakoid stacks)✓
2. BCristae✓
3. CCisternae✓
4. DNucleosomes✓

Intermediate filaments differ from microtubules and microfilaments mainly in that they

1. AProvide mechanical strength rather than motility functions✓
2. BAre hollow and composed of tubulin✓
3. CAre involved in ATP synthesis✓
4. DForm the mitotic spindle during cell division✓

The cell face of the Golgi apparatus that receives transport vesicles from the endoplasmic reticulum is called the

1. ATrans face✓
2. BMedial face✓
3. CCis face✓
4. DDistal face✓

The organelle that acts as the control centre of the eukaryotic cell by housing most genetic material is the

1. AMitochondrion✓
2. BGolgi apparatus✓
3. CNucleus✓
4. DLysosome✓

Which of these is found in animal cells but absent in typical plant cells

1. ACell wall✓
2. BCentrioles✓
3. CChloroplast✓
4. DLarge central vacuole✓

Stem cells are characterized mainly by their ability to

1. ASelf-renew and differentiate into specialized cell types✓
2. BProduce ATP only✓
3. CLack a nucleus✓
4. DUndergo meiosis only✓

Which type of electron microscope produces a 3D surface image of a specimen

1. ATransmission electron microscope✓
2. BLight microscope✓
3. CPhase contrast microscope✓
4. DScanning electron microscope✓

Which organelle is unique to plant cells and site of photosynthesis

1. AChloroplast✓
2. BMitochondrion✓
3. CLysosome✓
4. DCentriole✓

Integral membrane proteins that span the entire lipid bilayer are also called

1. APeripheral proteins✓
2. BTransmembrane proteins✓
3. CGlycoproteins only✓
4. DCytoskeletal proteins✓

Which molecule forms the basic structural framework of the plasma membrane's bilayer

1. ACholesterol✓
2. BProtein✓
3. CPhospholipid✓
4. DCarbohydrate✓

The double membrane structure enclosing the mitochondrion's matrix has folds called

1. AThylakoids✓
2. BGrana✓
3. CCisternae✓
4. DCristae✓

Schleiden and Schwann jointly proposed that

1. AAll living organisms are composed of cells✓
2. BCells arise only from pre-existing cells✓
3. CDNA is the genetic material✓
4. DMitochondria produce ATP✓

Which scientist first observed live cells and called them animalcules using a simple microscope

1. ARobert Hooke✓
2. BAnton van Leeuwenhoek✓
3. CMatthias Schleiden✓
4. DTheodor Schwann✓

Which theory states that cells are the basic structural and functional unit of life

1. ATheory of evolution✓
2. BGerm theory✓
3. CCell theory✓
4. DTheory of recapitulation✓

Vacuoles in plant cells primarily function to

1. AMaintain turgor pressure and store nutrients✓
2. BSynthesize proteins✓
3. CProduce ATP✓
4. DReplicate DNA✓

Peroxisomes are primarily involved in

1. AProtein synthesis✓
2. BLipid synthesis✓
3. CATP production✓
4. DBreakdown of fatty acids and detoxification of hydrogen peroxide✓

Microfilaments are primarily composed of the protein

1. ATubulin✓
2. BActin✓
3. CKeratin✓
4. DMyosin only✓

Which cytoskeletal component is the thickest and made of tubulin

1. AMicrofilaments✓
2. BIntermediate filaments✓
3. CMicrotubules✓
4. DActin filaments✓

Centrioles play a key role in the formation of the

1. ACell wall✓
2. BNuclear membrane✓
3. CGolgi apparatus✓
4. DSpindle fibers during cell division✓

Plasmodesmata are channels connecting adjacent

1. APlant cells✓
2. BAnimal cells✓
3. CBacterial cells✓
4. DFungal cells✓

Which junction prevents leakage of fluids between epithelial cells

1. AGap junction✓
2. BTight junction✓
3. CDesmosome✓
4. DPlasmodesmata✓

Which cell junction allows direct communication between cytoplasms of adjacent cells

1. ATight junction✓
2. BDesmosome✓
3. CAdherens junction✓
4. DGap junction✓

Crossing over between homologous chromosomes occurs during

1. AMitosis✓
2. BMeiosis II✓
3. CMeiosis I (prophase I)✓
4. DInterphase✓

Meiosis reduces the chromosome number from diploid to

1. AHaploid✓
2. BTriploid✓
3. CTetraploid✓
4. DRemains diploid✓

Meiosis results in the formation of how many daughter cells from one parent cell

1. ATwo✓
2. BFour✓
3. CSix✓
4. DEight✓

Cytokinesis in plant cells occurs through the formation of a

1. ACleavage furrow✓
2. BContractile ring✓
3. CCell plate✓
4. DNuclear membrane✓

Cytokinesis in animal cells occurs by

1. AFormation of a cleavage furrow✓
2. BFormation of a cell plate✓
3. CNuclear division only✓
4. DChromosome condensation✓

Sister chromatids separate and move to opposite poles during

1. AProphase✓
2. BMetaphase✓
3. CTelophase✓
4. DAnaphase✓

During which phase of mitosis do chromosomes align at the cell's equatorial plate

1. AProphase✓
2. BMetaphase✓
3. CAnaphase✓
4. DTelophase✓

DNA replication occurs during which phase of the cell cycle

1. AG1 phase✓
2. BG2 phase✓
3. CProphase✓
4. DS phase✓

Chromatin condenses into visible chromosomes during which phase of the cell cycle

1. AProphase of mitosis✓
2. BInterphase✓
3. CG1 phase✓
4. DTelophase✓

The site of ribosomal RNA synthesis within the nucleus is the

1. ANucleoplasm✓
2. BChromatin✓
3. CNucleolus✓
4. DNuclear membrane✓

The nuclear envelope is perforated by structures called

1. ARibosomes✓
2. BNuclear pores✓
3. CCristae✓
4. DCentrioles✓

The process by which cells expel materials via vesicles fusing with the plasma membrane is

1. AEndocytosis✓
2. BPinocytosis✓
3. CExocytosis✓
4. DPhagocytosis✓

The uptake of large particles by a cell through membrane invagination is termed

1. AExocytosis✓
2. BDiffusion✓
3. COsmosis✓
4. DEndocytosis✓

A cell placed in a hypertonic solution will most likely undergo

1. ALysis✓
2. BPlasmolysis or crenation✓
3. CNo change✓
4. DMitosis✓

Movement of molecules against their concentration gradient using ATP is called

1. AActive transport✓
2. BOsmosis✓
3. CSimple diffusion✓
4. DFiltration✓

Movement of water across a semipermeable membrane from higher to lower water potential is called

1. AActive transport✓
2. BFacilitated diffusion✓
3. CSimple diffusion✓
4. DOsmosis✓

Bacterial cell walls are primarily composed of

1. ACellulose✓
2. BChitin✓
3. CPeptidoglycan✓
4. DPectin✓

The cell wall of fungi is mainly composed of

1. AChitin✓
2. BCellulose✓
3. CPeptidoglycan✓
4. DLignin✓

Ribosomes in eukaryotic cells are of which sedimentation type

1. A30S✓
2. B50S✓
3. C70S✓
4. D80S✓

Lysosomes are primarily responsible for

1. AIntracellular digestion✓
2. BProtein folding✓
3. CEnergy production✓
4. DDNA replication✓

Which organelle modifies, sorts, and packages proteins for secretion

1. ANucleus✓
2. BMitochondrion✓
3. CGolgi apparatus✓
4. DRibosome✓

The main function of the smooth endoplasmic reticulum is

1. AProtein synthesis✓
2. BATP production✓
3. CPhotosynthesis✓
4. DLipid synthesis and detoxification✓

Which organelle is responsible for synthesizing proteins on its surface

1. ARough endoplasmic reticulum✓
2. BSmooth endoplasmic reticulum✓
3. CGolgi apparatus✓
4. DPeroxisome✓

Which organelle is known as the powerhouse of the cell

1. AGolgi apparatus✓
2. BMitochondrion✓
3. CLysosome✓
4. DRibosome✓

The fluid mosaic model of the plasma membrane was proposed by

1. ARobert Hooke✓
2. BCamillo Golgi✓
3. CSinger and Nicolson✓
4. DWatson and Crick✓

Which type of cell lacks a true membrane-bound nucleus

1. AProkaryotic cell✓
2. BEukaryotic cell✓
3. CPlant cell✓
4. DAnimal cell✓

Which cell theory postulate states that all cells arise from pre-existing cells

1. ASchleiden's postulate✓
2. BSchwann's postulate✓
3. CHooke's postulate✓
4. DVirchow's postulate✓

Who is credited with first observing and naming cells while examining cork under a microscope

1. ARobert Brown✓
2. BRobert Hooke✓
3. CAnton van Leeuwenhoek✓
4. DMatthias Schleiden✓

The site of light-independent reactions of photosynthesis is the

1. AThylakoid membrane✓
2. BStroma of chloroplast✓
3. CCytoplasm✓
4. DCell wall✓

Which structure provides rigidity and shape to plant cells

1. APlasma membrane✓
2. BNuclear envelope✓
3. CCell wall✓
4. DCytoskeleton✓

The primary component of the plant cell wall is

1. AChitin✓
2. BCellulose✓
3. CPeptidoglycan✓
4. DKeratin✓