Pakistan MCQs

Peptidoglycan forms a strong mesh around bacterial cells.
Its thickness differs between Gram-positive and Gram-negative bacteria.

Cytoplasm includes the cytosol and suspended structures.
Many metabolic reactions occur there.

The cytoskeleton includes microtubules, microfilaments, and intermediate filaments.
It supports transport, division, and movement.

Microtubules form tracks for motor proteins.
They also form the mitotic spindle, cilia, and flagella.

Microfilaments are mainly composed of actin.
They participate in cell crawling, cytokinesis, and muscle contraction.

Diffusion results from random molecular motion.
It continues until concentration differences are reduced.

Ribosomes translate mRNA into polypeptide chains.
They occur freely in cytoplasm or attached to rough ER.

Rough ER has ribosomes attached to its surface.
It folds and modifies proteins entering the endomembrane system.

Smooth ER lacks ribosomes.
It synthesizes lipids and helps detoxify chemicals.

The Golgi receives materials from the ER.
It modifies and directs them to their destinations.

The nucleus stores chromosomes in eukaryotic cells.
It also regulates gene expression and cell activities.

The nucleolus is a dense region inside the nucleus.
It produces rRNA and assembles ribosomal subunits.