Miss Lee - Plant Transport Flashcards
Why do plants require a transport system?
- A transport system ensures that all the cells of a plant receive a sufficient amount of nutrients e.g. water, minerals, sugars to live.
- Plants have a relatively small surface area:volume ratio but have a high metabolic rate.
- This is achieved by the combined action of xylem tissue and phloem tissue.
What is a Cotyledons
Cotyledons are organs that act as food stores for the developing embryo.
What are Dicots
Dicots are plants that make seeds that contain 2 cotyledons
What are the 2 main groups of dicots
1) Herbaceousdicots(non-woody stem) e.g. daisies
2) Woody dicots e.g. oak
What is the vascular system in plants
A plant has a series of transport vessels running through the roots, stems, and leaves
What are Herbaceous dicots vascular systems are made up of
Herbaceous dicots vascular systems are made up of 2
types of transport vessels; Xylem and Phloem.
How are they arranged together in a vascular system
They are arranged together in vascular bundles in the stem, roots, and leaves
What are xylem vessels
- Long continuous columns of dead cells
- Transports water and mineral ions from root→shoot→leaves.
- One direction movement only(upwards)
- Also provide structural support (cell wall composed of lignin)
What are phloem vessels
- Living tissue
- Transports food(organic solutes e.g. sucrose) from leaves to the rest of the plant (translocation).
- Transport is bidirectional (solutes can move up and down a plant)
Why do plants need a transport system
- SA:V Ratio:
- As the size of an plant increases, its surface area to volume ratio decreases.
- This means it has relatively less surface area available for substances to diffuse through, so the rate of diffusion may not be fast enough to meet its cells requirements.
- Large plants therefore cannot rely on diffusion alone to supply their cells with substances such as food and oxygen and to remove waste products.
- This is why they require specialised transport systems.
What are the three plant processes
Photosynthesis, respiration and active transport
What is photosynthesis
plants producing glucose, through sunlight
What is respiration in a plant
plants supplying energy
Why does active transport happen in a plant
energy required to move and transport substances
What are the two transport systems
Translocation and transpiration
What is the transpiration system
- The movement of water molecules and dissolved minerals ions
- Xylem vessels
- Passive process
What is translocation
- The movement of sugars (Sucrose) & amino acids
- Phloem vessel – sieve & companion cells
- Active process
What is the vascular bundle
- Xylem and Phloem are arranged in vascular bundles in the roots, stems and leaves.
- There is a layer of cambium in between xylem and phloem, that is meristem cells which are involved in production of new xylem and phloem tissue
- Vasculartissueisdistributedthroughouttheplant
- Vascular tissue is made up of xylem and phloem tissue
- As well as the transport of substances the vascular bundle has structural support purposes
What does the vascular bundle in the roots look like and why is it different
- This provides a ‘drill’ like structure
- This enables the plant to push down into the root
- Xylem tissues is the strongest so is in the centre – X structure
- Phloem in four separate sections
What does the Vascular Bundle in the leaf look like and differentiate from the other vascular bundles
- Xylem is located on top of the phloem
* Thisonlyappliestodicotyledonousplants,other plants types have a different structure – you don’t need to know these
What does the Vascular Bundle in the Stem look like and why is it different
- Xylem is located on the inside – in non-wooded plants
- This provides additional support to the stem
- The cambium layer contains meristem cells
How many and what different types of cell build up the xylem tissues
4 types of cell • Xylem vessels • Tracheids (not found in herbaceous dicots) • Parenchyma • Fibres
Xylem tissue adaptations
1 ) Xylem vessels are very long , tube - like structures formed from cells ( vessel elements ) joined end to end .
2 ) There are no end walls on these cells , making an uninterrupted tube that allows water to pass up through the middle easily .
3 ) The cells are dead , so they contain no cytoplasm .
4 ) Their walls are thickened with a woody substance called lignin , which helps to support the xylem vessels and stops them collapsing inwards . Lignin can be deposited in xylem walls in different ways , e.g. in a spiral or as distinct rings ,
5 ) The amount of lignin increases as the cell gets older .
6 ) Water and ions move into and out of the vessels through small pits in the walls where there’s no lignin .
How many and what different types of cell build up the phloem tissues
Phloem tissue is composed of 4 different types of tissue: • Sievetubeelements • Companioncell • Parenchyma • Fibres
What are the sieve tube elements adaptations in the phloem
1 ) These are living cells that form the tube for transporting solutes through the plant .
2 ) They are joined end to end to form sieve tubes .
3 ) The ‘ sieve parts are the end walls , which have lots of holes in them to allow solutes to pass through .
4 ) Unusually for living cells , sieve tube elements have no nucleus , a very thin layer of cytoplasm and few organelles
5 ) The cytoplasm of adjacent cells is connected through the holes in the sieve plates .
What are the adaptations in the companion cells in the phloem
1 ) The lack of a nucleus and other organelles in sieve tube elements means that they can’t survive on their own . So there’s a companion cell for every sieve tube element .
2 ) Companion cells carry out the living functions for both themselves and their sieve cells . For example , they provide the energy for the active transport of solutes .
What is a herbaceous dicotyledonous plant
herbaceous dicotyledonous plant is a plant which has vascular bundles
