transportation Flashcards
(20 cards)
What is the primary function of xylem?
Transport water and dissolved minerals from roots to all parts of plants
Formed mainly by xylem vessel cells.
What are the adaptations of xylem vessel cells for water transport?
- Dead cells with no nucleus and no cytoplasm
- No end walls between cells
- Thick and lignified cell walls
These adaptations enhance water flow and provide support.
How do the dead cells in xylem vessel cells enhance water flow?
There is no nucleus and no cytoplas, they form a hollow tube to enhance water flow
This structure minimizes resistance against water movement.
Why are there no end walls between xylem vessel cells?
To reduce resistance against the flow of water and minerals
This allows for free movement within the xylem.
What is the primary function of phloem?
Transport organic food solution (mainly sucrose) from leaves to the rest of the plant
Formed by sieve tube elements and companion cells.
What types of cells are involved in the formation of phloem?
- Sieve tube elements
- Companion cells
Each type plays a crucial role in transporting food.
What adaptations do phloem have for food transport?
- Sieve tube elements are cylindrical cells with cytoplasm, but no nucleus and no vacuole
- End-walls with pores to form sieve plates
- Paired with companion cells
These features facilitate the movement of the food solution.
What is the role of companion cells in phloem?
Support and regulate the metabolism of sieve tube elements
They contain dense cytoplasm and a nucleus.
What is the function of the epidermis in stems?
Protecting tissues inside
It may also have stomata for gas exchange.
What is the role of cambium in stems?
Consists of actively dividing tissue that forms new xylem and phloem
This results in a thicker stem.
What is the composition of cortex and pith in stems?
Both are formed by thin-walled cells
They provide flexible mechanical support.
What is the function of the epidermis in roots?
Protecting tissues inside and facilitating gas exchange
It contains specialized root hair cells for absorption.
How does the cortex in roots support the plant?
Formed by thin-walled cells outside of vascular bundles, provides mechanical support to the root
Stores starch granules that serves as an energy reserve.
What is the transpiration pull process?
- Water is pulled up in xylem from roots to leaves
- Water is drawn from the xylem
- A water potential difference is developed
- Water moves into spongy mesophyll cells by osmosis
- Evaporation of water occurs
- Water vapor diffuses out via stomata
This process is essential for water transport in plants.
How does atmospheric temperature affect transpiration rate?
Transpiration rate increases with temperature up to a certain limit
Higher temperatures increase the rate of water evaporation.
How does relative humidity influence transpiration rate?
Transpiration rate decreases with higher relative humidity
A smaller concentration gradient slows down diffusion.
What is the effect of light intensity on transpiration rate?
Transpiration rate increases with light intensity
Increased light causes stomata to open wider.
How does air movement affect transpiration rate?
Transpiration rate increases with wind speed
Higher wind speeds maintain a steeper concentration gradient.
Why are the xylem cells very thick and lignified?
- To provide physical support to non-woody plants
- WIthstand transpiration pull so xylem doesn’t collapse during transport of water and minerals
