Cell Biology and Cell Structure MCQs 2026

Intermediate filaments differ from microtubules and microfilaments mainly in that they

1. A Provide mechanical strength rather than motility functions ✓
2. B Are hollow and composed of tubulin ✓
3. C Are involved in ATP synthesis ✓
4. D Form the mitotic spindle during cell division ✓

Centrioles are typically absent in the cells of

1. A Animals ✓
2. B Most flowering plants ✓
3. C Insects ✓
4. D Green algae such as Chlamydomonas ✓

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

1. A Grana (thylakoid stacks) ✓
2. B Cristae ✓
3. C Cisternae ✓
4. D Nucleosomes ✓

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

1. A A solid bundle of nine microtubules ✓
2. B Six pairs of microtubules in a circle ✓
3. C A "9+2" arrangement of microtubule doublets ✓
4. D Three central microtubules only ✓

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

1. A Store excess water and ions ✓
2. B Synthesize new membrane lipids ✓
3. C Produce toxins to kill pathogens ✓
4. D Rupture and digest the cell's own contents ✓

Compared with cilia, flagella are typically

1. A Absent in eukaryotic cells ✓
2. B Shorter and more numerous per cell ✓
3. C Longer and fewer in number per cell ✓
4. D Non-motile structures ✓

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

1. A Increases proportionally ✓
2. B Decreases, limiting efficient exchange with the environment ✓
3. C Remains constant regardless of size ✓
4. D Becomes irrelevant to cell function ✓

The endosymbiotic theory proposes that mitochondria and chloroplasts originated from

1. A Free-living prokaryotes engulfed by an ancestral host cell ✓
2. B Folded regions of the plasma membrane ✓
3. C Fragments of the nuclear envelope ✓
4. D Vesicles budded from the Golgi apparatus ✓

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

1. A Two identical layers of cellulose ✓
2. B An outer membrane continuous with the rough ER and an inner membrane ✓
3. C Two layers of peptidoglycan ✓
4. D A single membrane folded twice ✓

Cholesterol embedded within the animal cell plasma membrane primarily functions to

1. A Catalyze ATP synthesis ✓
2. B Transport oxygen across the membrane ✓
3. C Regulate membrane fluidity across temperature changes ✓
4. D Form covalent bonds with DNA ✓

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

1. A Cristae ✓
2. B Thylakoids ✓
3. C Nucleosomes ✓
4. D Cisternae ✓

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

1. A Trans face ✓
2. B Medial face ✓
3. C Cis face ✓
4. D Distal face ✓

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

1. A Only the cytoplasmic side ✓
2. B Both the outer and inner aqueous surfaces ✓
3. C Only the extracellular side ✓
4. D The hydrophobic core of the membrane ✓

Ribosomes found within mitochondria and chloroplasts resemble those of

1. A Eukaryotic cytoplasm (80S) ✓
2. B The nuclear envelope ✓
3. C Bacteria (70S) ✓
4. D The Golgi apparatus ✓

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

1. A Mitochondrion ✓
2. B Golgi apparatus ✓
3. C Nucleus ✓
4. D Lysosome ✓

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

1. A Plant root cells ✓
2. B Freshwater protists such as Paramecium ✓
3. C Human liver cells ✓
4. D Fungal hyphae ✓

Which organelle is unique to plant cells and site of photosynthesis

1. A Chloroplast ✓
2. B Mitochondrion ✓
3. C Lysosome ✓
4. D Centriole ✓

Stem cells are characterized mainly by their ability to

1. A Self-renew and differentiate into specialized cell types ✓
2. B Produce ATP only ✓
3. C Lack a nucleus ✓
4. D Undergo meiosis only ✓

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

1. A Robert Hooke ✓
2. B Anton van Leeuwenhoek ✓
3. C Matthias Schleiden ✓
4. D Theodor Schwann ✓

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

1. A Peripheral proteins ✓
2. B Transmembrane proteins ✓
3. C Glycoproteins only ✓
4. D Cytoskeletal proteins ✓

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

1. A Cholesterol ✓
2. B Protein ✓
3. C Phospholipid ✓
4. D Carbohydrate ✓

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

1. A Thylakoids ✓
2. B Grana ✓
3. C Cisternae ✓
4. D Cristae ✓

Schleiden and Schwann jointly proposed that

1. A All living organisms are composed of cells ✓
2. B Cells arise only from pre-existing cells ✓
3. C DNA is the genetic material ✓
4. D Mitochondria produce ATP ✓

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

1. A Theory of evolution ✓
2. B Germ theory ✓
3. C Cell theory ✓
4. D Theory of recapitulation ✓

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

1. A Cell wall ✓
2. B Centrioles ✓
3. C Chloroplast ✓
4. D Large central vacuole ✓

Vacuoles in plant cells primarily function to

1. A Maintain turgor pressure and store nutrients ✓
2. B Synthesize proteins ✓
3. C Produce ATP ✓
4. D Replicate DNA ✓

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

1. A Transmission electron microscope ✓
2. B Light microscope ✓
3. C Phase contrast microscope ✓
4. D Scanning electron microscope ✓

The cell wall of fungi is mainly composed of

1. A Chitin ✓
2. B Cellulose ✓
3. C Peptidoglycan ✓
4. D Lignin ✓

Bacterial cell walls are primarily composed of

1. A Cellulose ✓
2. B Chitin ✓
3. C Peptidoglycan ✓
4. D Pectin ✓

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

1. A Active transport ✓
2. B Facilitated diffusion ✓
3. C Simple diffusion ✓
4. D Osmosis ✓

Movement of molecules against their concentration gradient using ATP is called

1. A Active transport ✓
2. B Osmosis ✓
3. C Simple diffusion ✓
4. D Filtration ✓

A cell placed in a hypertonic solution will most likely undergo

1. A Lysis ✓
2. B Plasmolysis or crenation ✓
3. C No change ✓
4. D Mitosis ✓

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

1. A Exocytosis ✓
2. B Diffusion ✓
3. C Osmosis ✓
4. D Endocytosis ✓

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

1. A Endocytosis ✓
2. B Pinocytosis ✓
3. C Exocytosis ✓
4. D Phagocytosis ✓

The nuclear envelope is perforated by structures called

1. A Ribosomes ✓
2. B Nuclear pores ✓
3. C Cristae ✓
4. D Centrioles ✓

The site of ribosomal RNA synthesis within the nucleus is the

1. A Nucleoplasm ✓
2. B Chromatin ✓
3. C Nucleolus ✓
4. D Nuclear membrane ✓

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

1. A Prophase of mitosis ✓
2. B Interphase ✓
3. C G1 phase ✓
4. D Telophase ✓

DNA replication occurs during which phase of the cell cycle

1. A G1 phase ✓
2. B G2 phase ✓
3. C Prophase ✓
4. D S phase ✓

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

1. A Prophase ✓
2. B Metaphase ✓
3. C Anaphase ✓
4. D Telophase ✓

Sister chromatids separate and move to opposite poles during

1. A Prophase ✓
2. B Metaphase ✓
3. C Telophase ✓
4. D Anaphase ✓

Cytokinesis in animal cells occurs by

1. A Formation of a cleavage furrow ✓
2. B Formation of a cell plate ✓
3. C Nuclear division only ✓
4. D Chromosome condensation ✓

Cytokinesis in plant cells occurs through the formation of a

1. A Cleavage furrow ✓
2. B Contractile ring ✓
3. C Cell plate ✓
4. D Nuclear membrane ✓

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

1. A Two ✓
2. B Four ✓
3. C Six ✓
4. D Eight ✓

Meiosis reduces the chromosome number from diploid to

1. A Haploid ✓
2. B Triploid ✓
3. C Tetraploid ✓
4. D Remains diploid ✓

Crossing over between homologous chromosomes occurs during

1. A Mitosis ✓
2. B Meiosis II ✓
3. C Meiosis I (prophase I) ✓
4. D Interphase ✓

Which cell junction allows direct communication between cytoplasms of adjacent cells

1. A Tight junction ✓
2. B Desmosome ✓
3. C Adherens junction ✓
4. D Gap junction ✓

Which junction prevents leakage of fluids between epithelial cells

1. A Gap junction ✓
2. B Tight junction ✓
3. C Desmosome ✓
4. D Plasmodesmata ✓

Plasmodesmata are channels connecting adjacent

1. A Plant cells ✓
2. B Animal cells ✓
3. C Bacterial cells ✓
4. D Fungal cells ✓

Centrioles play a key role in the formation of the

1. A Cell wall ✓
2. B Nuclear membrane ✓
3. C Golgi apparatus ✓
4. D Spindle fibers during cell division ✓

Which cytoskeletal component is the thickest and made of tubulin

1. A Microfilaments ✓
2. B Intermediate filaments ✓
3. C Microtubules ✓
4. D Actin filaments ✓

Microfilaments are primarily composed of the protein

1. A Tubulin ✓
2. B Actin ✓
3. C Keratin ✓
4. D Myosin only ✓

Peroxisomes are primarily involved in

1. A Protein synthesis ✓
2. B Lipid synthesis ✓
3. C ATP production ✓
4. D Breakdown of fatty acids and detoxification of hydrogen peroxide ✓

Which structure provides rigidity and shape to plant cells

1. A Plasma membrane ✓
2. B Nuclear envelope ✓
3. C Cell wall ✓
4. D Cytoskeleton ✓

The primary component of the plant cell wall is

1. A Chitin ✓
2. B Cellulose ✓
3. C Peptidoglycan ✓
4. D Keratin ✓

The site of light-independent reactions of photosynthesis is the

1. A Thylakoid membrane ✓
2. B Stroma of chloroplast ✓
3. C Cytoplasm ✓
4. D Cell wall ✓

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

1. A Robert Brown ✓
2. B Robert Hooke ✓
3. C Anton van Leeuwenhoek ✓
4. D Matthias Schleiden ✓

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

1. A Schleiden's postulate ✓
2. B Schwann's postulate ✓
3. C Hooke's postulate ✓
4. D Virchow's postulate ✓

Which type of cell lacks a true membrane-bound nucleus

1. A Prokaryotic cell ✓
2. B Eukaryotic cell ✓
3. C Plant cell ✓
4. D Animal cell ✓

The fluid mosaic model of the plasma membrane was proposed by

1. A Robert Hooke ✓
2. B Camillo Golgi ✓
3. C Singer and Nicolson ✓
4. D Watson and Crick ✓

Which organelle is known as the powerhouse of the cell

1. A Golgi apparatus ✓
2. B Mitochondrion ✓
3. C Lysosome ✓
4. D Ribosome ✓

Which organelle is responsible for synthesizing proteins on its surface

1. A Rough endoplasmic reticulum ✓
2. B Smooth endoplasmic reticulum ✓
3. C Golgi apparatus ✓
4. D Peroxisome ✓

The main function of the smooth endoplasmic reticulum is

1. A Protein synthesis ✓
2. B ATP production ✓
3. C Photosynthesis ✓
4. D Lipid synthesis and detoxification ✓

Which organelle modifies, sorts, and packages proteins for secretion

1. A Nucleus ✓
2. B Mitochondrion ✓
3. C Golgi apparatus ✓
4. D Ribosome ✓

Ribosomes in eukaryotic cells are of which sedimentation type

1. A 30S ✓
2. B 50S ✓
3. C 70S ✓
4. D 80S ✓

Lysosomes are primarily responsible for

1. A Intracellular digestion ✓
2. B Protein folding ✓
3. C Energy production ✓
4. D DNA replication ✓