Video Transcript
Which of the following is true
about the pith of dicot stems? (A) It has a role in storage. (B) It is composed of parenchyma
cells. (C) It is located in the central
portion of the stem. Or (D) all of the answers are
correct.
This question asks us to identify
the true statement about the pith, which is a component of the stem in dicot
plants. Let’s review some components of a
typical dicot stem to try and answer this question correctly. It’s worth noting that monocot
plant stems have a slightly different structure. The outermost layer of cells in the
plant stem and also in their leaves, roots, and flowers is called the epidermis. The epidermis forms a protective
layer between the external environment and the plant’s inner tissues.
Moving inward from the epidermis
are several layers of spongy tissues that make up a region called the cortex,
consisting of two types of simple plant tissues: parenchyma and collenchyma. Simple tissues are made up of cells
that are structurally and functionally very similar to each other. The majority of the cortex is made
up of soft fleshy parenchyma tissue. The cells in parenchyma tissues
have plenty of air spaces between them to promote gas exchange and chloroplasts to
carry out photosynthesis. The collenchyma tissue in the
cortex is found directly below the epidermis of growing stems. Collenchyma cells have thickened
reinforced cell walls to provide structural support and some flexibility to growing
regions of the plant.
We can also see several vascular
bundles in this diagram, which make up the plant’s transport system. One vascular bundle has been
circled in orange. Each vascular bundle contains
phloem tissue and xylem tissue. Phloem is responsible for
transporting sugars and amino acids up and down the plant stem, primarily from the
leaves as this is where most of them will be produced to the different parts of the
plant that require them. Xylem is responsible for
transporting water and some dissolved mineral ions up the stem from the roots to all
the other parts of the plant.
The innermost region of the plant
stem consists of a spongy tissue called pith. The pith is composed of parenchyma
cells. The main function of the pith is to
store essential nutrients like water and sugars. We need to identify true statements
about the pith, which we just learned is composed of parenchyma cells, located in
the center of the plant stem, and aids in the storage of molecules. Therefore, the correct answer to
our question is option (D). All of the answers are correct.
