Plants
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- Created by: scxrlettgrace
- Created on: 13-03-21 12:25
Marram Grass adaptations
thick waxy cuticle
rolled leaves - trap air to increase humidity
rolled leaves - trap air to increase humidity
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Cacti adaptations
spines to reduce SA
widespread roots to take advantage of nearby water
widespread roots to take advantage of nearby water
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Hydrophyte adaptations
large air spaces to keep afloat allowing absorption of sunlight
stomata on upper epidermis for gaseous exchange
stomata on upper epidermis for gaseous exchange
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What do hydathodes do?
release water from hydrophytes allowing evaporation
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How is sucrose loaded into sieve tubes?
ATP actively transports H+ ions out of companion cells
increasing conc of H+ outside of cell, making concentration gradient
H+ diffuse back into companion cell by special cotransporter proteins with sucrose molecules, sucrose diffuses into sieve tubes
increasing conc of H+ outside of cell, making concentration gradient
H+ diffuse back into companion cell by special cotransporter proteins with sucrose molecules, sucrose diffuses into sieve tubes
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How is sucrose moved down the phloem?
sucrose loaded in - reducing WP
water moves in by osmosis - increasing HP
Sap moved down HP gradient to sink
sucrose removed - increasing WP
water leaves - reducing HP
water moves in by osmosis - increasing HP
Sap moved down HP gradient to sink
sucrose removed - increasing WP
water leaves - reducing HP
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What does sucrose diffuse through when leaving the phloem?
plasmodesmata
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What is the transpiration stream?
movement of water from the soil through the plant to the air surrounding the leaves
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How is water moved through the roots?
-root hair cells absorb mineral ions and water
-water moves across root cortex down water potential gradient to endodermis
-mineral ions actively transported into medulla reducing WP causing osmosis into medulla also
-water moves across root cortex down water potential gradient to endodermis
-mineral ions actively transported into medulla reducing WP causing osmosis into medulla also
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What is the endodermis?
layer of cells surrounding medulla and xylem also known as starch sheath
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What is the purpose of the Casparian *****?
forces water to move into symplast pathway as it blocks apoplast pathway, makes mineral ions have to pass into cytoplasm through plasma membrane, which has transporter proteins to pump mineral ions into medulla
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What is root pressure?
pressure in the root medulla builds up and forces water into and up the xylem
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What is the transpiration pull?
forces of cohesion attract molecules to one another forming continuous column, as water lost at leaves water pulled up creating tension
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Why are the xylem vessels strengthened by lignin?
lignin prevents collapse of the vessels under tension
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What happens when the water column is broken?
water column can still be maintained through another vessel via the bordered pits
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How does the narrowness of the vessels help the xylem function?
narrow vessels allow capillary action as the forces of attraction between water molecules and the side of the vessels pulls water upwards
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Why is transpiration important?
-maintain turgidity in plant
- supply water for cell growth
-transport of mineral ions
- supply water for cell growth
-transport of mineral ions
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How does the structure of companion cells help it to function?
many mitochondria for active transport of H+ ions
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How does the structure of sieve tubes help it to function?
no nucleus and little cytoplasm to leave space for mass flow
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How does the structure of the xylem prevent the flow of water not being impeded?
no nucleus
lignin to prevent collapsing
lignin to prevent collapsing
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How are palisade cells specialised?
many chloroplast for photosynthesis
large vacuole so chloroplasts nearer edge of cell reducing diffusion distance
large vacuole so chloroplasts nearer edge of cell reducing diffusion distance
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How are guard cells specialised?
one side thicker - enable bending
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How are root hair cells specialised?
hair-like projection increases SA
carrier proteins to actively transport mineral ions
mitochondria to produce ATP
carrier proteins to actively transport mineral ions
mitochondria to produce ATP
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What is the structure of epidermal tissue?
impregnated with waxy substances forming cuticle to reduce water loss
flattened cells
forms protective layer of cells covering leaves, stems and roots
flattened cells
forms protective layer of cells covering leaves, stems and roots
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What is the structure of meristematic tissue?
found in root and shoot tips
contains stem cells for mitosis and cell differentiation
no chloroplasts
thin walls containing little cellulose
contains stem cells for mitosis and cell differentiation
no chloroplasts
thin walls containing little cellulose
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What prevents plant cells from dividing?
large vacuole ad rigid cellulose cell wall
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How do meristems differentiate to form xylem vessels?
lignin deposited in cell walls to make them waterproof
ends of cells break down to form continuous columns
ends of cells break down to form continuous columns
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How do meristems differentiate to from phloem vessels?
sieve tubes lose most organelles and sieve plates develop between them
companion cells have lots of mitochondria for ATP
companion cells have lots of mitochondria for ATP
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What is the function of parenchyma tissue?
packing tissue to fill spaces between other tissues
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What is the function of collenchyma tissues?
strengthen vascular bundles with their thick cellulose walls
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What is the function of sclerenchyma tissue?
lignified walls to strengthen stems
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Other cards in this set
Card 2
Front
Cacti adaptations
Back
spines to reduce SA
widespread roots to take advantage of nearby water
widespread roots to take advantage of nearby water
Card 3
Front
Hydrophyte adaptations
Back
Card 4
Front
What do hydathodes do?
Back
Card 5
Front
How is sucrose loaded into sieve tubes?
Back
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