Topic 3.3 - Transport in Plants Flashcards
(53 cards)
Why do plants require a transport system?
To ensure that all cells of the plant receive a sufficient amount of nutrients through the combined action of xylem and phloem tissues
What does the xylem tissue enable in plants?
Xylem tissue allows water and dissolved minerals to travel up the plant in the passive process of transpiration
What does the phloem tissue enable in plants?
Phloem tissues enables sugars to reach all parts of the plant in the active processes of translocation
Why is simple diffusion insufficient as plants grow bigger?
Increased distance between roots and leaves necessitates efficient transport mechanisms to move water, minerals, and photosynthates effectively
Despite lower metabolic rates, why do plants still need efficient transport systems?
To ensure a steady supply of water and minerals for photosynthesis and other metabolic processes
Why is diffusion alone inadequate in larger plants?
Larger plants have a reduced SA: V ratio, meaning there is less surface area relative to their volume for diffusion to occur
What do xylem and phloem do in the vascular bundle?
They enable transport of substances and provide structural support
What is the arrangement of xylem vessels in the root, and why?
Xylem vessels are arranged at the centre of the vascular bundle, in an X shape to withstand mechanical forces like pulling
What is the pericycle in the root vascular bundle?
An inner layer of meristem cells
What surrounds the X-shaped xylem vessels in roots?
The endodermis, a layer of cells supplying the xylem with water
Where is the xylem located in the stem and what is its role?
Xylem is located inside to provide support and flexibility
Where is the phloem found in the stem?
On the outside of the vascular bundle
What is the role of cambium in the vascular bundle?
It is a layer of meristem cells involved in producing new xylem and phloem tissue
What do vascular bundles form in leaves?
The midrib and veins
What vein pattern is found in dicotyledonous leaves?
A network of veins starting at the midrib and spreading outwards for transport and support
What is the structure of xylem vessels?
Long cylinders made f dead tissue with open ends, containing pits, and thickened with lignin in spiral patterns
What is the function of xylem vessels?
Transport water and mineral ions from roots to leaves and provides structure support
How does lignin benefit the xylem?
Provides mechanical strength and flexibility
What cells make up the phloem?
Living cells including sieve tube elements and companion cells
What features do sieve tube elements have?
No nucleus, few organelles, joined by sieve plates for sap flow
How do companion cells support sieve plates for sap flow?
Provide ATP for active transport and are rich in organelles
What is the function of the phloem?
Transports organic substances (mainly sucrose) from sources to sinks and enables translocation
What is transpiration?
The process where leaves absorb water via roots, move it upward, and release it as water vapour through leaf stomata
What is the transpiration stream?
The movement of water up the stem, supplying water for photosynthesis, growth, and cooling via evaporation
