Explain why it is necessary for plants to have their leaves spread out. The diagram below represents the transverse section through a young dicotyledonous stem and a structure, F, obtained from the same section.

Here are the answers to the questions:

1. Explain why it is necessary for plants to have their leaves spread out.
Leaves are spread out to maximize the surface area exposed to sunlight. This allows for maximum absorption of light energy, which is essential for the process of photosynthesis to produce food for the plant.

2. The diagram below represents the transverse section through a young dicotyledonous stem and a structure, F, obtained from the same section.

• (a) (i) Identify the part labelled E.

  • E: Cambium

• (a) (ii) State the function of the part labelled E.

  • The cambium is responsible for secondary growth, producing new xylem and phloem cells, which increases the girth (width) of the stem.

• (b) (i) Label the part Z, on the section from which structure E was obtained.

  • Z: Xylem

• (b) (ii) State two ways in which structure F is structurally adapted to its functions.

  • 1. The xylem vessels within structure F have lignified walls, which provide mechanical support to the plant and prevent the vessels from collapsing under tension during water transport.
  • 2. The phloem sieve tubes within structure F have sieve plates with pores, allowing for the efficient, continuous flow of manufactured food substances (sugars) throughout the plant.

2 zimekamilika. Zimebaki 3 leo — tuma inayofuata.