Pakistan MCQs

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.

Water moves toward the side with higher effective solute concentration.
Osmosis affects cell volume and turgor.

Channels and carriers help polar or charged substances cross membranes.
No direct energy input is required.

Active transport uses pumps or coupled carriers.
It maintains ion gradients and cell homeostasis.

The plasma membrane surrounds material and pinches inward.
Phagocytosis and pinocytosis are forms of endocytosis.

Lysosomes break down macromolecules and damaged cell parts.
Their enzymes work best in an acidic environment.

Mitochondria convert energy from nutrients into ATP.
They contain their own DNA and ribosomes.

Chloroplasts contain chlorophyll and photosynthetic membranes.
They convert light energy into chemical energy.

The central vacuole stores water, ions, pigments, and wastes.
Its pressure helps support plant tissues.

All organisms are made of one or more cells.
Cells perform the fundamental processes required for life.

Modern cell theory states that cells come from existing cells.
Cell division provides continuity of life.