Xylem and phloem Flashcards
What is xylem?
Xylem is the tissue that transports water and ions from the roots to the rest of the plant.
Xylem plays a crucial role in supporting the plant’s structure and facilitating nutrient transport.
What are the main cell types found in xylem?
- Xylem vessels
- Tracheids
- Xylem parenchyma
Each type has a specific function, contributing to the overall transport and support system of the plant.
What is the function of xylem vessels?
Xylem vessels transport water and minerals from the roots to the other parts of the plant.
They form long tubes that extend from the roots to the stem and leaves.
What structural feature provides strength to xylem tissue?
Tracheids provide strength to the tissue.
Tracheids are elongated cells that also assist in water transport.
What is the role of xylem parenchyma?
Xylem parenchyma consists of thin-walled living cells that act as packing tissue between the xylem vessels.
They play a role in storage and support.
What are the two types of sections used to study xylem?
- Transverse section (TS)
- Longitudinal section (LS)
These sections help in examining the arrangement and structure of xylem cells.
What is phloem?
Phloem is the tissue that transports organic molecules to the tissues of the plant.
Unlike xylem, all cells in the phloem are alive.
What do phloem sieve tubes contain?
Phloem sieve tubes contain little cytoplasm and few or no organelles.
This adaptation allows for more efficient transport of nutrients.
What are companion cells?
Companion cells accompany sieve tube cells and provide support needed to keep them alive.
They contain numerous mitochondria, rough ER, and a large dense nucleus.
What is the function of mitochondria in companion cells?
Mitochondria in companion cells provide ATP, which is required for active transport.
This energy is essential for the transport of substances into and out of the sieve tubes.
How are companion cells connected to sieve tube elements?
Companion cells and sieve tube elements are connected via plasmodesmata.
This connection allows for communication and transport of materials between cells.
Fill in the blank: The walls of xylem vessels are made of _______.
[lignin]
Lignin provides structural support and makes the walls impermeable to water.
True or False: The cell walls of phloem are made of lignin.
False
Phloem cell walls are made of cellulose.
What are the end walls of phloem sieve tubes called?
Sieve plates
Sieve plates are perforated by small pores that allow cytoplasmic strands to pass through.
What cell type is associated with phloem to aid in transport?
Companion cells
Companion cells are closely associated with sieve tube elements and play a crucial role in the transport process.
What is the function of plasmodesmata in phloem?
Allow cytoplasmic strands to pass between phloem sieve tube elements
Plasmodesmata are small channels that connect the cytoplasm of adjacent cells.
What do vascular bundles contain?
Both xylem and phloem
Vascular bundles also include cambium and other cells.
What type of tissue is cambium?
Meristematic tissue
Cambium can keep dividing by mitosis.
What is the nature of transport cells in xylem?
Dead cells
Xylem vessels are composed of dead cells that facilitate the upward transport of water.
What is the nature of transport cells in phloem?
Alive cells
Phloem cells, such as sieve tube elements and companion cells, are alive and involved in the transport of nutrients.
What is the cell wall composition of xylem?
Thick, lignin-rigid, impermeable
The rigidity of xylem cell walls helps in supporting the plant structure.
What is the cell wall composition of phloem?
Thin, cellulose-flexible, permeable
The flexible nature of phloem cell walls allows for the transport of nutrients.
What does phloem transport?
Products of photosynthesis, e.g., amino acids
Phloem transports these products to and from sites of photosynthesis to growing regions and sites of storage.
In which direction does xylem transport water and minerals?
From roots upwards
Xylem primarily transports water and mineral ions absorbed from the soil.
