Back to AI Flashcard MakerBiology /LGS A-Level OCR Biology - Transport in Plants
What makes up the vascular bundle, from inwards out?
Xylem Cambium Phloem Sclerenchyma
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Key Terms
Term
Definition
What makes up the vascular bundle, from inwards out?
Xylem Cambium Phloem Sclerenchyma
What is the function of the cambium?
It is meristematic and differentiates to form xylem and phloem as the plant grows
What is the advantage of xylem vessels not being completely lignified?
It allows for the stem to flex and move slightly (e.g in the wind)
What is the function of lignin in Xylem?
It strengthen the walls to resist the forces generated by water moving up the stem
Give an example of what a plant uses glucose for
Aerobic respiration
Give an example of what a plant uses lipids for
Cell membranes
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| Term | Definition |
|---|---|
What makes up the vascular bundle, from inwards out? | Xylem Cambium Phloem Sclerenchyma |
What is the function of the cambium? | It is meristematic and differentiates to form xylem and phloem as the plant grows |
What is the advantage of xylem vessels not being completely lignified? | It allows for the stem to flex and move slightly (e.g in the wind) |
What is the function of lignin in Xylem? | It strengthen the walls to resist the forces generated by water moving up the stem |
Give an example of what a plant uses glucose for | Aerobic respiration |
Give an example of what a plant uses lipids for | Cell membranes |
Give an example of what a plant uses proteins for | Enzymes for reactions |
Give an example of what a plant uses nucleic acids for | DNA replication |
What are assimilates? | The products of photosynthesis/respiration |
Describe how sucrose is transported from the mesophyll cells to the phloem | companion cells actively pump H+ ions out of the cell and into surrounding mesophyll cells H+ diffuse back into the companion cell, down a diffusion gradient and co-transport sucrose into the companion cell sucrose diffuses down a concentration gradient into sieve tube elements |
Describe how sucrose is moved along the phloem | sucrose enters the phloem which lowers the water potential of the phloem water enters by osmosis water also enter from the xylem water entering the phloem forces the contents to flow this is known as mass flow |
Describe how sucrose moves from the phloem to plant cells | sucrose and other assimilates leave the phloem by diffusion the cells then use the sucrose keeping the sucrose concentration of the cell lower than the xylem and maintaining a concentration gradient |
What do plant cells use sucrose for? | converting it to starch for storage | - use it for respiration |
How do guard cells differ from the lower epidermal cells? | they contain chloroplasts | - they have extra cellulose thickening on the inner side of the cell |
Outline how guard cells open | cells surrounding guard cells actively pump K+ ions into the guard cells, making their water potential more negative water enters by osmosis as water potential of guard cells is more negative than surrounding cells guard cells swell but because inner wall is thicker than outer wall as cell swells a pore opens up |
What is crucial about the cell walls of guard cells? | -the inner wall is thicker than the outer wall |
Outline how guard cells close | K+ ions diffuse out of the guard cells and back into epidermal cells no longer more negative water potential in guard cells so water leaves by osmosis guard cells become flaccid |
Give 4 ways plants generally conserve water | waxy cuticle stomata on underside of leaf closable stomata roots that grow down to the water in the soil |
What is a xerophyte? | Plants with adaptions that enable them to survive in dry habitats or habitats where water is in short supply in the envrionment |
Give two examples of xerophytes | Confiers and marram grass |
In what kind of environment may water loss become a really problem for plants? | Hot, dry, breezy conditions |
How do sunken stomata help to adapt a plant to hot dry conditions? | reduce air movement creating a microclimate of still, humid air that reduces the water vapour potential gradient so reduces transpiration |
How does a reduction in the number of stomata adapt xerophytes? | -reduces water loss by transpiration |
What is a downside of reduced numbers of stomata? | -reduces gas exchange capillaries |
How does a reduction in the number of leaves adapt xerophytes? | -water loss is greatly reduced by minimising the amount of water loss by transpiration |