Video Transcript
Water can also be lost from a woody
plant through small pores in the stem. What are these pores called? (A) Glands, (B) hydathodes, (C)
lenticels, or (D) stomata.
The stem of a plant plays an
important role in gas exchange, as well as in the absorption and diffusion of
water. The surfaces of the stems of some
woody plants like those mentioned in the question contain raised openings called
lenticels. Lenticels are a site of gas
exchange between the stem and the atmosphere surrounding the stem. More precisely, they are the site
of lenticular transpiration. This describes how water vapor,
which is shown in our diagram as blue dots, can move from the stem through the
lenticels and into the external environment. Though only a minimal volume of
water is lost from the plant through lenticular transpiration, it does describe one
of the ways that water can be lost from a woody plant stem.
Water can also be lost from a plant
through stomatal transpiration. But as stomata are only found on
leaves and the question is asking us about pores found on the stem through which
water can be lost, stomata cannot be our correct answer. Water can also be lost from plants
through a process called guttation through structures called hydathodes. But as hydathodes, like stomata,
are found on plant leaves and not on the stem, this cannot be our correct
answer.
Glands are structures typically
found in animal bodies, which produce hormones. Although plants do produce
hormones, they don’t have glands. Also, glands are not generally
associated with water loss, so this is not our correct answer. So we’ve worked out that the pores
in a woody plant stem through which water can be lost are called lenticels.
