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16 Cards in this Set
- Front
- Back
- 3rd side (hint)
What is the leaf composed of?
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- Parenchyma, internal mesophyll and vascular tissue
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Name the tissue that: - stores food - allows gas exchange - has a xylem and phloem |
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State the main visual properties of the leaf .
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- thin,
- flat - low dry matter content - large surface area: volume ratio |
4 points
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State the main functions of a leaf
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- photosynthesis
- Gas exchange - evapotranspiration |
Looking for 3 main processes which a leaf carries out
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State the structure of the upper epidermis
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- Single layer of cells
- No chloroplasts - has narrow air spaces - few stomata (if present) |
4 main points
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State the function of the upper epidermis
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- increases the light amount so it reaches to palisade cells.
- holds the contents intact - strengthens/ supports upper leaf |
Whats the point of having a thin layer of cells? How can the leaf withstand strong winds?
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Leaves have a thin, shiny, waxy layer of what? Do all leaves have this coating? If not, what do they have instead?
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- Waxy layer of cutin i.e. cuticle
- Some leaves have hairs. |
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What is the function of the cuticle or cutin?
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- reduces water loss
- prevents pathogen infection - reflects harmful UV rays - prevents overheating - allows little transpiration |
Stops the entry of what? Reduces the loss what? Reflects what? Prevents what? Allows what?
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State the structure of palisade mesophyll cells?
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- single layer
- Column shaped (shade lvs) or >1 layer in (non shade) - packed with chloroplasts (4-5x more in shade leaves) |
State any variations in shade or non shade leaves.
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What is the function of the palisade mesophyll cells?
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Photosynthesis
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the reason why leaves exist
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State the structure of the spongy mesophyll cells
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- loose cells
- variable number of layers - with air spaces - contain fewer chloroplasts - less photosynthesis |
Remember how it compares to palisade cells? Will it photosynthesis more or less?
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the reason why cells have a thin cellulose cell wall is because...
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- to allow gas exchange (fast diffusion in air spaces) b/w cells for respn and phsyn
- H2O diffusion via evaporation from cells --> air spaces for transpiration from stomata - helps maintain cells turgidty --> keeps leaf turgid and upright |
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State the structure of the lower epidermis.
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- single layer of cells- very thin cuticle - perforated with pores (stomata)- stomata are controlled by guard cells.
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What is the function of the stomata and guard cells?
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- allows gas exchange (O2 in and CO2 out) respiration vice versa for photosynthesis
- H2O vapour out by evapotranspiration (cooling) |
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Name the 2 types of vascular tissue in the leaf.
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- Midrib and veins
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State the function of the midrib and veins
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- support leaf & maintain shape with strengthening tissue aid
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State the function of veins in a leaf |
- veins transprt H2O + mineral ions to leaf from roots/ stem by the xylem - veins transport C compounds (sugars) from photosynthesis to other parts of the plant (stem + roots) |
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