Why does vascular cambium produce annual rings in xylem but not in phloem? What will be an ideal response?
Secondary xylem is produced within the vascular cambium, and new layers of xylem are deposited
around the old layers. As a result, the older layers of xylem are not damaged. Secondary phloem is
deposited outside the vascular cambium. As the tree gets larger in diameter, the secondary phloem is
crushed, stretched and continually replaced. As a result older layers are not visible.
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A bond that joins atoms that have opposite charges is a(n)
a. covalent bond. b. hydrogen bond. c. ionic bond. d. coordinate covalent bond. e. polar covalent bond.
The vocal cords are located in the
A) epiglottis. B) pharynx. C) trachea. D) larynx. E) bronchi.
Acute Glomerulonephritis is a sequalae of repeated infection with Streptococcus pyogenes. The pathogenesis involved in this complication is antigen-antibody complex precipitation on the surface of the glomerulous cell membrane
a. true b. false
Major changes in ocean conditions during the early Cambrian period were probably linked most closely to the evolution of __________.
a. cyanobacteria b. algae c. suspension-feeding animals d. large and motile predatory animals e. vertebrates