Question 4
In a young dicotyledonous stem, before any wood has formed, which tissue carries out the supporting function?
The right answer is the one marked above.
Collenchyma in the cortex. It forms a cylinder a few cells thick just inside the epidermis, and holds the young stem up until wood is formed.
Collenchyma can do this because it stays alive and can stretch as the stem grows. A tissue as rigid as sclerenchyma would stop the stem lengthening.