MCQs

Amyloplasts are a specific type of leukoplast that converts glucose into starch grains, storing them in roots, tubers, and seeds.

Proposed by Singer and Nicolson, the fluid mosaic model describes the membrane as a fluid phospholipid bilayer embedded with proteins.

The smooth ER in hepatocytes contains cytochrome P450 enzyme families that chemically modify and detoxify hydrophobic drugs and toxins.

The nucleolus functions as a ribosome manufacturing center, transcribing rRNA and combining it with proteins to form ribosomal subunits.

Tight junctions form a continuous fluid-tight seal between adjacent cell membranes, preventing materials from leaking between cells.

Invaginating the inner mitochondrial membrane into cristae creates a large surface area for housing electron transport chain complexes.

A hypertonic environment draws water out of the animal cell, collapsing its volume and causing the cell membrane to wrinkle and shrivel.

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.