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Published byAlicia Córdoba Carrasco Modified over 6 years ago
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Review Are plants autotrophic or heterotrophic?
What are the names of the male and female parts of the flower? What is the function of: Roots? Stems? Leaves? What makes plants green? What plant vessels are responsible for transporting water and sugar throughout the plant? How do plants get energy to help them grow?
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Specialized Plant Tissues
Essential questions: How does water travel from the ground to the tops of the tallest trees? What enables plants to grow taller than any other living thing? Could a plant survive if all of its leaves were cut off? Why or why not?
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Review: Roots, stems, leaves
Roots – absorb water and nutrients Stems – provide support and water transport Leaves – absorb sunlight, site of photosynthesis
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Photosynthesis Leaves absorb light and carry out most of the photosynthesis in the plant (photosynthesis = how plants make sugar from sunlight)
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Cross Section of a leaf – Photosynthesis
Photosythesis occurs in the mesophyll tissue. Stomata are the pore-like openings on the bottom side of the leaf that allow gases needed for photosynthesis to diffuse in and out of the leaf The opening and closing of stomata is controlled by guard cells
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Plant growth Most plants produce new cells by mitosis for the entire time that they are alive – they don’t stop growing like we do! They only produce these new cells at the tips of their roots and the tops of their stems (shoots).
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Transpiration Transpiration is the loss of water through leaves --What vascular tissue do you think replenishes this lost water? How is this water replaced?! The combination of root pressure, capillary action, and transpiration pull provides enough force for water to move up the xylem tissues of even the tallest of trees. XYLEM
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Water enters the plant by osmosis
Osmosis is the movement of molecules from an area where there are lots of tightly packed molecules to an area where there are less molecules Roots absorb water by osmosis When there is more water in the soil than in roots, roots will absorb water from the soil.
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Water Transport in Plants
Transpiration pull – as water evaporates from leaves, each water molecule pulls on the lower water molecules to move them up the plant Root pressure – the roots exert some pressure on the water to move it up the tree Capillary action – water rises higher in thin tubes (xylem and phloem are very thin, tube-like structures!)
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Gas Exchange Carbon Dioxide Oxygen
What gas do plants take in during photosynthesis? What gas do plants then give off that helps us survive? Carbon Dioxide Oxygen Plant leaves allow gases to enter and exit the plant by opening and closing their stomata. Guard cells control this opening and closing Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose excessive water
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Cross Section of a leaf – Gas exchanges
Gas exchange also occurs in air spaces in the mesophyll tissue. Gases enter and exit the leaf through the stomata. If plants kept stomata open all of the time, they would lose too much water from transpiration. The opening and closing of stomata is controlled by guard cells
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If you were a leaf… Would you keep your stomata open at night?
Would you open your stomata if you had too much water? Would you open your stomata if it was 110 degrees and extremely sunny?
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