[Campbell Biology P.816] A botanist observes a mature woody stem that has significantly incr... | Practice Question

A botanist observes a mature woody stem that has significantly increased in girth over several years. Based on the provided information, which statement best explains this observation?

  • A: The stem's primary meristems continued to divide and differentiate, leading to increased diameter.
  • B: The vascular cambium produced an equal amount of secondary xylem and phloem, causing uniform expansion.
  • C: The lateral meristems, specifically the vascular cambium and cork cambium, became active, adding secondary xylem (wood), secondary phloem, and cork cells, leading to increased thickness.
  • D: The plant's cells expanded significantly due to increased water absorption, causing the stem to swell.

Explanation

The text clearly states that 'Secondary growth is made possible by two lateral meristems extending along the length of a shoot or root where primary growth has ceased.' It further explains that 'A stem or root thickens as secondary xylem, secondary phloem, and cork cells are added.' This directly explains the observed increase in girth.