PPSC MCQs

Organ systems coordinate complex tasks.
Examples include the digestive and circulatory systems.

Xylem conducts water and dissolved minerals from roots.
It also helps support the plant.

Phloem transports sucrose and other organic nutrients.
Movement can occur toward growing or storage tissues.

Mitochondria produce much of the cell's ATP through respiration.
ATP supplies usable energy for cellular work.

Ribosomes join amino acids according to genetic instructions.
They may be free in the cytoplasm or attached to rough ER.

The cell membrane is selectively permeable.
It regulates exchange between the cell and its environment.

The plant cell wall is mainly made of cellulose.
It supports the cell and helps prevent bursting.

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

Diffusion is driven by random particle motion.
Net movement continues down a concentration gradient.

Cooling slows metabolism of many microorganisms.
It also slows enzyme activity and spoilage reactions.

High salt concentration lowers available water through osmosis.
Many spoilage microbes cannot grow well under these conditions.

Concentrated sugar binds water and creates high osmotic pressure.
This inhibits many microorganisms.