PSS 10: Plant Growth
Terms
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What is dormancy?
What can dictate this? -
-the period of inactivity
-winter, drought, etc -
What determines the length of dormancay?
What is it in Vermont? -
-geographic location and plant species
-October through April - What are the two phases of dormancy?
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1) Rest period: will NOT grow
2) Dormant yet reactive: plant will grow if given a favorable environment (Feb-April) - -What is a nice stem to force into flower?
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-forsythia
-crab apples
-hyacinths - What occurs during the vegetative phase of plant growth?
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-food resources to produce leaves, stems, and roots
-juvenile phase where reproduction can't occur but plant appears mature - What occurs during the reproductive phase of plant growth?
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-sugars and starches are stored
-the plant flowers, produces seeds and fruit -
What is senescence?
How does it vary? -
-rapid or gradual cycle until death
-in hardy perennials, only above ground part senescences
-in wood trees and shrubs, only fruits and leaves scnescence - What regulates a plants vegetative and reproductive cycles?
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-age/maturity of the plant
-CHO/nitrogen balance - What does CHO/Nitrogen balance have to do with reproduction?
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-CHO's come from photosynthesis in leaves
-Nitrogen is taken up by roots
-Too much Nitrogen can prevent a plant from flowering (reproduction) - What makes up a cell wall?
- -polysaccharides (long chains of simple sugars like glucose)
- What is cellulose in terms of glucose composition?
- -unbranched polymer of several 1000 glucose molecules
- What is hemicellulose?
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-like cellulose, but branched
-combustible
-indigestible by mammals, but ruminants have special bacteria to do this in stomach) - Who made the first microscope and when?
- -Robert Hooke in 1665
- What makes cells hard?
- -lignin (polymers of phenolic acid)
- What is the purpose of lignin?
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-hardens cellulose walls
-resists microbial decomposition
-causes yellowing in paper - What are the three layers of cell walls and what makes up each?
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-primary cell wall (cellulose and pectin)
-middle lamella (pectin)
-secondary cell wall (cellulose and lignin) *may not always be present - What causes fruit rot?
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-bacteria/fungi breaking down pectin
-similar to mortar between bricks - What are the pores and strands that connect cells?
- -plasmodesmata
- What percentages make up cells?
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-85-90% water
-10-15% organic and inorganic substances whether dissolved (CHO's) or colloidal (proteins and fats) - What is mRNA?
- -relays genetic information from nucleus to ribosomes (often attached to ER, where proteins are made)
- What is in the nucleus of a cell?
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-chromosomes
-DNA - What are plastids and where are they found?
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-found in cytoplasm
-leucoplasts (colorless)
-chromoplasts (colored) - What is a chloroplast?
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-a chromoplast that contains chlorophyll
-photosynthesis occurs here
-have grana (stacked)
-has stroma (surrounds grana where CO2 is converted to CHO's) - What is mitochondria?
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-power center for cell which has proteins and phospholipids
-makes ATP which carries energy - What are vacuoles?
- membrane-lined cavities in the cytoplasm filled with cell sap and controls turgor
- What makes up cell sap?
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-water, salts, and organic materials
(90% water, 8% sugar, 2% minerals/AA/other)