MTTC Missed Topics Practice Test

Water and nutrient movement in plants happens through the vascular transport system made up of xylem and phloem. Xylem conducts water and mineral nutrients from the roots upward to the rest of the plant, using vessels and tracheids, and is often dead at maturity to allow free flow of water. Phloem transports sugars and other organic nutrients from where they are produced or stored (sources) to where they are needed or stored (sinks), via sieve-tube elements assisted by companion cells.

The other tissue groups mentioned don’t form the main transport network. Cortex and endodermis are involved in storage and regulating movement into the vascular system but aren’t the primary conduits. Epidermis and guard cells are outer tissues related to protection and gas exchange, not transport. Pith and mesophyll are internal stem and leaf tissues associated with storage and photosynthesis, not the plant’s transport system.