Chapter 23 Review Sheet Chapter 23 1. In plants, the element that plays a critical role in the making of proteins and the development of roots, stems, and leaves is _________________________. 2. In phloem tissue, the activity of sieve tube elements is believed to be controlled by ___________________. 3. The tissue that enables roots to grow thicker and branch is the ____________________. 4. The roots of grasses are ____________________ roots. 5. The tissue that enables plants to grow from their tips as long as they live is the ______________________. 6. Water loss from tree bark is prevented by ___________________________. 7. In roots, the outermost layer of cells that absorbs water and nutrients is the ____________________________. 8. If a plant receives too much fertilizer, it may suffer from ______________________. 9. White potatoes, which store food in thick, underground stems, are _____________________. 10. The waterproof, waxy coating of many leaves is the ___________________________. 11. In the complex mixture of soil, decaying plant and animal matter make up the _______________________. 12. The number of tree rings can be used to determine the _________________________. 13. The opening and closing of stomata is controlled by changes in _____________________. 14. The upper layer of mesophyll in a leaf is the __________________________. 15. A mangrove tree, whose roots are in mud, obtains oxygen through large spaces in ___________________________. 16. List the major elements required in plants. 17. In angiosperms, xylem tissue consists of tracheids and _________________________. 18. Phloem tissue consists of companion cells and ______________________________. 19. The top layer of a soil profile is ____________________.b 20. The only plant tissue that produces new cells is __________________ tissue. 21. When plants lose too much water and begin to wilt, their stomata ____________________.