MCQs

Bacterial cell walls are made of peptidoglycan (glycan chains cross-linked by short peptides), whereas plant walls rely on cellulose.

Exocytosis involves routing transport vesicles from the Golgi to the plasma membrane, where they fuse to release their contents outside.

A desmotubule is a continuous tube of specialized endoplasmic reticulum that runs through the center of a plasmodesmatal channel.

Both plant and animal cells rely on the conserved F1​F0​-ATP synthase complex to generate ATP through oxidative phosphorylation.

Lacking a rigid cell wall allows the animal plasma membrane to stretch, fold, and change shape smoothly, guided by the dynamic cytoskeleton.

Hemicelluloses are branched polysaccharides that form hydrogen bonds with cellulose microfibrils, anchoring the structural meshwork.

Cilia and flagella grow out from a basal body, a structural template built from a modified centriole with a 9+0 microtubule triplet layout.

Turgor pressure acts as a hydraulic jack, stretching the primary wall when specific enzymes loosen the cross-linked cellulose fibers.

As a plant cell matures, the central vacuole expands dramatically, compressing the active cytoplasm into a thin layer against the wall.

The Casparian strip is a suberized chemical barrier in the endodermis that forces water to enter the living protoplast via symplastic transport.

The plasma membrane contains transport proteins and acts as the true selective barrier regulating what enters or leaves the cytoplasm.

The random, multi-directional alignment of microfibrils allows the primary wall to stretch and expand uniformly in response to turgor.

Proteinoplasts are specialized, non-pigmented leukoplasts optimized to store high-density protein reserves inside seeds and kernels.

The smooth ER houses the key enzyme pathways required for lipid metabolism, cholesterol processing, and steroid hormone biosynthesis.

When water loss exceeds intake, turgor pressure drops to zero, causing the soft tissues of the plant to lose structural rigidity and wilt.

While cellulose is built by plasma membrane enzymes, non-cellulose wall polysaccharides are synthesized in the Golgi and shipped out via vesicles.

Six connexin proteins assemble to form a hemichannel called a connexon; when aligned with a neighbor, it creates a functional gap junction.

The phragmoplast is an array of microtubules and filaments that forms during late mitosis, guiding Golgi vesicles to the cell plate site.

Cholesterol inserts its rigid steroid ring core between phospholipid tails, stabilizing the membrane and regulating fluid properties.