12.3 Stems

What functions do plant stems fulfill the plant?

Stems are a place where water or carbohydrates can be stored, stems also raise and support the leaves and reproductive organs raising the leaves maximize their exposure to sunlight, so they are able to photosynthesize better. It can also help protect the plant from injury and herbivores.

What is cork cambium and what does it do?

Cork cambium is a meristematic layer in a woody plant that produces cork. It helps prevent water loss from the stem.

Do all plants have cork cambium?

No not all plants have cork cambium. It’s not found in non-woody plants such as grass and herbs

Do mature cells of xylem tissue have nuclei? Explain.

**Xylem cells that reach maturity become hollow and dead. In this case, it no longer contains cell organelles, such as nucleus**.

Do mature cells of phloem tissue in angiosperms have nuclei?

No, mature cells of phloem tissue in angiosperms do not have nuclei. They lose their nuclei as they mature, which allows for more space for the transportation of nutrients and sugars.

label the phloem cell

gymnosperms

xylem tissue cell types: tracheids phloem tissue cell types: sieve cells

angiosperms

xylem tissue cell type: **tracheids vessel elements** Phloem tissue cell types: **sieve tube elements companion cells**

Which plant group has a more diverse cellular makeup of xylem and phloem tissue?

Angiosperms have a more diverse cellular makeup of xylem and phloem tissue compared to other plant groups, such as gymnosperms and ferns. This diversity allows angiosperms to be more adaptable to different environments and to have a wider range of functions.

What are the xylem tissue cell types for each plant group?

In gymnosperms, the xylem tissue consists mainly of tracheids. In ferns and other seedless vascular plants, the xylem tissue consists of tracheids and sometimes also of sclerenchyma fibers.

Why can’t sieve tube elements stand alone as the main cell type for phloem tissue?

Sieve tube elements cannot stand alone as the main cell type for phloem tissue because they lack important organelles, such as nuclei and ribosomes, which are necessary for protein synthesis and other cellular functions. They also require the support of companion cells, which provide the necessary metabolic support for sieve tube elements to function properly. Without companion cells, sieve tube elements would not be able to transport nutrients and sugars effectively throughout the plant.

How is the location of vascular bundles in monocot stems different from the location of vascular bundles in eudicot stems.

The location of vascular bundles in monocot stems is scattered throughout the stem, whereas in eudicot stems, the vascular bundles are arranged in a ring around the pith. This difference in arrangement is due to the way in which the stem develops during embryogenesis.

How are vascular cambium and cork cambium similar? How are they different?

Vascular cambium and cork cambium are both lateral meristems that increase the girth of the stem or root. However, vascular cambium produces secondary xylem and phloem, while cork cambium produces cork cells.

Vascular cambium grows rapidly and produces large xylem cells with hin walls in the

spring

fewer xylem cells are produced in the_________and they thick celled walls

summer

Aspirin (used to relieve pain and reduce inflammation)

bark of the willow tree

Paclitaxel (used to treat cancer)

bark of the pacific yew tree

sieve cell

are plant cells that transport nutrients and sugars throughout the plant. They are elongated cells with sieve plates that allow for fluid movement between cells.

Herbaceous

are soft-stemmed plants that are not woody or hard. They die back to the ground at the end of the growing season and are often grown for their flowers.

Perforation plates

are structures in plant cells that allow water and nutrients to move freely between adjacent cells. They are found in xylem cells and are important for the efficient transport of water and nutrients throughout the plant.

sieve plate

allows the movement of nutrients and sugars between adjacent cells. It is found in phloem tissue and is important for the efficient transport of nutrients throughout the plant.

Sieve tube elements

are cells in plant phloem tissue that transport nutrients and sugars throughout the plant. They are long, thin cells without a nucleus and other organelles, which allows for efficient transport. They are usually accompanied by companion cells.

Vessel elements

in plant xylem tissue that transport water and minerals throughout the plant. They are long, tube-like cells that lack a nucleus and other organelles, which allows for efficient transport. They are usually stacked on top of each other to form a continuous column.