Plants (Leaf, Gas Exchange etc)

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What structures are contained in a leaf paliside cell?
Long thin cells that form a continuous layer to absorb sunlight. Chloroplasts arranged in the best way to collect the max amount of sunlight. Vacuole to push cytoplasm and chloroplasts to the edge of the cell.
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What is inside a chloroplast?
Double-plasma membrane - highly selective + envelopes chloroplast. Grana - stacks of 100x thylakoids containing chlorophyll. Stroma - a fluid filled matrix where 2nd stage photosynthesis takes place.
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What are the adaptations of a chloroplast ?
Grana have a large surface area for 1st stage of photosynthesis. Stroma contain all enzymes needed for 2nd stage of photosynthesis. Chloroplasts have both ribosomes and DNA to make proteins on the go.
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What is the role of the mesophyll in gas exchange?
It is the main surface are for gas exchange and has a large surface and large interconnected spaces for gas diffusiom.
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What are the roles of the stomata and guard cells?
The stomata open to allow gas exchange and close to prevent evaporation. Guard cells control the opening and closing of stomata.
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Three adaptions of xerophytes?
Sunken stomata - to trap moist air. Few stomata - less places for water to escape. Waxy cuticles - waterproof the leaves.
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How does water move into the roots?
The water potential is higher in the soil due to the uptake of ions and minerals into the roots. Therefore the water will move into the root hair cell by osmosis along a water potential gradient.
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Describe the apoplastic pathway?
When water enters the root hair cell via osmosis along a water potential gradient it pulls more water behind it due to cohesive properties. This causes a tension that draws water into the cell walls. Th walls are very absorbent and have lots of water
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Apoplastic Pathway ctd
filled spaces which offer little resistance. When the water travelling via this pathway reaches the endodermis it is blocked by the waxy casparian strip. This redirects the water back into the cytoplasm where it enters the endodermis.
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Describe the symplastic pathway?
Water enters the root hair cell via osmosis. The root hair cell now has a higher water potential then the first cortical cell so water moves into the cortical cell by osmosis. Now the 1st cortical cell has a higher wp then the 2nd, so a water
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Symplastic pathway ctd
potential gradient. This carries water through the cytoplasm of each cell via the plasmodesmata straight to the endodermis and then the xylem.
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Root Pressure?
The movement of water entering the roots via osmosis along a water potential gradient creates a tension the shoves water up the xylem as it is taken up by the root hairs.
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Cohesion-Tension?
Water is a polar molecule so molecules will 'stick' together due to hydrogen bonds making them cohesive. When transpiration occurs a tension is created which pulls water into the leaf. Because they are cohesive all water molecules are pulled up.
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Other cards in this set

Card 2

Front

What is inside a chloroplast?

Back

Double-plasma membrane - highly selective + envelopes chloroplast. Grana - stacks of 100x thylakoids containing chlorophyll. Stroma - a fluid filled matrix where 2nd stage photosynthesis takes place.

Card 3

Front

What are the adaptations of a chloroplast ?

Back

Preview of the front of card 3

Card 4

Front

What is the role of the mesophyll in gas exchange?

Back

Preview of the front of card 4

Card 5

Front

What are the roles of the stomata and guard cells?

Back

Preview of the front of card 5
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