Q.In which season the vessels of angiosperms are larger in size, why?

Step 1. Recall the seasonal pattern of cambial activity. The chapter explains that in the spring season, the vascular cambium is very active and produces a large number of xylary elements with wide lumens (vessels/tracheids that are fairly thin-walled) - this wood is called spring wood or early wood. In winter, by contrast, the cambium is less active and produces xylary elements with narrow lumens and thick walls - autumn wood or late wood.

Step 2. Explain why spring specifically favours wide vessels. Spring is typically the start of a favourable growing season, when the plant needs to move large volumes of water and dissolved minerals rapidly to support renewed growth (new leaves, shoot elongation, flowering). Wide-lumened vessels offer far less resistance to bulk water flow than narrow ones, so producing them in spring meets this seasonal demand for high-volume conduction. …

Recall the cambium's spring-wood/autumn-wood activity pattern and connect wide spring …

• Confusing spring wood (wide lumen) with autumn wood (narrow lumen).
• Giving only 'spring' as the answer without explaining the underlyi …