Reproduction in Angispermophytes (9.3.1-6)
9.3.2
Distinguish between pollination, fertilization,+ seed dispersal
POLLINATION: the transfer of pollen grains from the anther to stigma
FERTILIZATION: fusion of male + female gametes
SEED DISPERSAL: mechanisms for distributing seeds away from the parent plant
9.3.4
Explain the conditions needed for the germination of a typical seed:
EVOLUTION (of the seed): key adaptations of plants to terrestial life
SEED DORMANCY: increases chance that germination will occur @ appropriate time
ENVIRONMENTAL CUES:
*O2 +H2O >> needed by all plants to germinate, initiate inhibition + activate cellular respiration
*Desert >> substantial rainfall that wahses away inhibitors from seed coat (testa)
*Chaparral >> fire + intense heat
*Temperature + subarctic zones >> extended exposure to cold
*Passage thru animal digestive tract >> exposure to digestive enzymes wears down seed coat (testa)
LENGTH OF DORMANCY: varies from days -> decades
9.3.5
Outline the metabolic processes during the germinaton of a starchy seed:
*Imbibition: absorption of H2O, due to low H2O potential in dry seed and causes seed to swell, rupruring the seed coat + triggering metabolic chnages in the embryo, causing it to resume growth.*
-Gibberllic acid (GA) is released by embryo, diffuses thru-out seed, reaching aleurone, the outer layer of seed
-a-amylase (digestive enzyme) is released when aleurone triggered by GA
-endosperm starch hydrolyzed in2 maltose by digestive enzyme
-cotyledon absorbs maltose from endosperm into embryo
-seedling grows from embryo fueled by the energy fom maltose; stored lipids + proteins also hydrolyzed allowing for embryo's growth + development
9.3.6
Explain how flowering is controlled in long-day and short-day plants, including the role of phytochrome:
>phytochrome is a pigment that exists in plants in 2 forms:
1.) Pr - absorbs white/red light
2.) Pfr - absorbs dark/far-red light
>in white/red light, Pfr is converted -> Pr
>Pfr acts as a promoter of flowering in long-day plants
>it also acts as an inhibitor of flowering in short-day plants
Wednesday, March 25, 2009
9.1-9.3
9.1.1:9.1.2:• Number of cotyledons -- The number of cotyledons found in the embryo is the actual basis for distinguishing the two classes of angiosperms, and is the source of the names Monocotyledonae and Dicotyledonae. The cotyledons are the "seed leaves" produced by the embryo. They serve to absorb nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis.
• Pollen structure -- The first angiosperms had pollen with a single furrow or pore through the outer layer. This feature is retained in the monocots, but most dicots are descended from a plant which developed three furrows or pores in its pollen.
•Number of flower parts -- If you count the number of petals, stamens, or other floral parts, you will find that monocot flowers tend to have a number of parts that is divisible by three, usually three or six. Dicot flowers on the other hand, tend to have parts in multiples of four or five. This character is not always reliable, however, and is not easy to use in some flowers with reduced or numerous parts.
• Leaf veins -- In monocots, there are usually a number of major leaf veins which run parallel the length of the leaf; in dicots, there are usually numerous auxillary veins which reticulate between the major ones. As with the number of floral parts, this character is not always reliable, as there are many monocots with reticulate venation, notably the aroids and Dioscoreales.
9.1.3: •Xylem: Bring water to replace losses due to transpiration, and inorganic minerals from the soil.
• Phloem: Transports products of photosynthesis out of the leaf.
• Stoma: A pore that allows CO2 for photosynthesis to diffuse in and O2 to diffuse out.
• Guard Cells: this pair of cells can open or close the stoma and so control the amount of transpiration.
• Upper Epidermis: a continuous layer of cells covered by a thick waxy cuticle. It prevents water loss from the upper surface even when heated by sunlight.
• Lower Epidermis: is in a cooler position and has a thinner waxy cuticle.
• Spongy mesophyll: consists of loosely packed rounded cells with few chloroplasts. This tissue provides the main gas exchange surface so must be near the stomata in the lower epidermis.
• Palisade mesophyll: consists of densely packed cylindrical cells with many chloroplasts. This is the main photosynthetic tissue and is positions near the upper surface where the light intensity is highest
Topic 9.1.4:
-Bulbs: modified leaves (onion, garlic)-
Tubers: modified stems (potato, gladiola)-
Storage root: carrot-
Tendril: modified leaf (ivy)
9.1.5:
Apical meristems are sometimes referred to as primary meristems, and lateral meristems as cambium. Meristems generate new cells for growth of the plant.9.1.6:-meristems are regions where cells continue to divide and grow, often throughout the life of the plant.- apical meristems are located at the tip of the root and stem, increasing the length of the plant, and also producing new leaves and flowers.-later meristems, or cambium, are found in vascular bundles and increase the diameter of the plant by producing xylem and phloem.- in the stems of younger plants, the vascular cambium is located discretely in bundles.-in the stems of older plants, the cambium is a complete ring.-lateral meristems also increases the root diameter.
9.1.7:
-auxin is a plant hormone that stimulates cell elongation.-one of the processes that auxin controls is phototropism: directional growth toward the source of light.-in shoot tips, proteins called phototropins absorb light, changing shape in respone to certain light wavelengths.-phototropins in a light-induced conformation bind to receptors which stimulate transcription/translation of genes producing glycoprotiens.-these glycoprotiens locate in membranes facilitating transport of auxin between cells.-shoot tips respond to light intensity by producing more auxin on the side with less light, main that side grow longer, thus bending he shoot tip toward the light.-plant cells have membrane bound auxin receptor proteins.-auxin efflux carriers are membrane proteins that pump auxin laterally.-auxin stimulates the pumping of hydrogen ions out of cells and into cell walls.-hydrogen ions lower the pH, which loosens connections between cellulose micofibrils.cell turgor pressure causes cell expansion, since the cellulose micofibrils without cross connections provide less resistance.-higher concentrations of auxin on shadier side of shoot tip causes greater cell elongation, moving shoot tip toward light.
9.2.1:-branching: extensive branching of roots greatly increases overall root surface area exposed to extracellular fluid.-root hairs: individual root epidermal cells grow extensive elongations grealy increasing the surface are of individual root epidermal cells to extracellular fluid.
9.2.2:There are three processes: diffusion of mineral ions, fungal hyphae, and mass flow of water in the soil carrying ions.
9.2.3:-because the concentration of mineral ions is usually lower in the soil than in the root, active transport is used to concentrate mineral ions to the root.-because active transport requires ATP, root epidermal cells ar rich in mitochondria and require a supply of oxygen for cellular respiration.- active transport: ATP oxidation provides the energy for protons to be pumped from the inside to the outside of root epidermal cell membranes = chemiosis, producing a H+ membrane potential.-cations, such as K+, are driven from the extracellular fluid into the intracellular fluid, through membrane channels, by their electrical charge repulsion from the H+'s concentrated in the extracellular fluid.-anions, such as NO3-, move from the extracellular fluid into intracellular fluid, through membrane channels, by co-transport with H+, which moves down its diffusion gradient.
9.2.4:-thickened cellulose: both xylem and phloem cells have thick secondary cell walls composed primarily of cellulose, providing rigidity.-cell turgor: plant cell vacuoles have low water potential; water enters the cell and vacuole by osmosis, causing the cell to swell against its wall with a pressure against the cell wall which provides rigidity.-lignified xylem: vascular tissue cells reinforced with a helical or ring-shaped thickenings of the cellulose cell wall impregnated with lignin, which makes the cell walls hard, providing resistance to pressure.
9.2.5:Transpiration is the loss of water vapor from the leaves and stems of plants.
9.2.6:Xylem vessels:a. thick-walled, elongated vascular tissue cells1) arranged end-to-end2) connected by perforated end-platesb. xylem cells die a maturity1) leaving a continuous microtube for transporting water and dissolved mineral ions.2) from the roots to the above-ground portions of the plant.-transpiration pull:a. evaporation:1) water vapor diffuses the moist air spaces of the spongy mesophyll where water potential is higher.2) to the drier air outside where water potential is lower.3) via stomatab. cohesion:1) as the spongy mesophyll air spaces lose water by evaporation its water potential decreases.2) water flows from the xylem, where water potential is higher.3) through the mesophyll to the air spaces, down its water potential gradient.4) the cohesion of water molecules, due to hydrogen bonding.5) enables transpiration to pull water up the narrow xylem vessels.6) without these columns of water breaking apartc. adhesion:1) the cell walls of the xylem are charged, attracting water molecules.2) the adhesive attraction of water to xylem vessel walls moves them up the stem against gravity.3) adhesion is important when sap starts to rise in plants that were leafless through the winter4) adhesion also helps prevent the column of water-filled xylem vessels from breakingd. transpiration:1) solar-powered evaporation from the leaves2) creates a continuous transpiration pull3) transmitted all the way from the leaves to the roots
9.2.7:
9.2.8:
9.2.9:-light:a. guard cells close the stomata in darkness, so transpiration is much greater in light.b. open stomata increases the rate of diffusion of CO2 needed for photosynthesis.c. but also increasing transpiration water loss through stomata.-temperature:a. rate of transpiration water loss through stomata is doubled for every 1o degrees C. increase in temperature.b. higher temperature also increase the rate of diffusion and reduces the relative humidity in the air outside the leaf.-wind:a. removes water vapor from leaf, reducing water potential around leaf.b. thus increasing the water potential gradient between the leaf and its surroundings.c.and therefore increasing the rate of transpirational water loss.-humidity:a. as humidity decreases, water potential around leaf is reduced.b. thus increasing the water potential gradient between the leaf and its surroundings.c. and therefore increasing the rate of trainspirational water loss.
9.2.10:-reduced leaves: minimized water loss by reducing leaf surface area.-thickened waxy cuticle: minimizes water loss by limiting water loss through epidermis.-reduced number of stomata: minimizes water loss through leaves.-succulence: stems specialized for water storage maximizes retention of water available during infrequent rains.
9.2.11:-translocation is the movement of substances from one part of a plant to another in the phloem.-symplastic route: sucrose manufactured in mesophyll cells travels intracellularly to phloem sieve-tube members (STMs)- apoplasctic route: sucrose manufactured in mesophyll cells travels extracellularly to companion cells and STMs.a. proton pumps: driven by ATP, pumps H+s into extracellular environment.b. sucrose enters companoin cells and STMs by co-transportc. as H+ moves down its concentration gradient into compation cells and STMs.-pressure flow in a sieve tube:a. loading of sucrose into the STMs at the source.b. reduces the water potential inside STMs, causing water to enter osmosis .c. absoprtion of water generates hydrostatic pressure.d. that forces the phloem sap to flow along the tube.e. gradient of pressure in the tube is reinforced by the unloading of sucrose.f. and the consequent loss of water, from the sieve tube at its sink.
9.3.1
9.3.2:-pollination: the transfer of pollen grians from the anther to the stigma-fertilization: fusion of male and female gametes-seed dispersal: mechanism for distributing seeds away from the parent plant.
9.3.3
9.3.4:-Seeds vary in their light requirements and, therefore, this factor need not be included.-evolution of the seeed: key adaptation of plants to terrestrial life.-seed dormancy increases chance that gemination will occur at appropriate time.-environmental cues:a. oxygen & water:1. needed by all seeds to germinate.2. to initiate inhibition and activate cellular respiration.b. desert:1. substantial rainfall.2. washing inhinitors from seed coat,c. chaparral:1. fire.2. intense heat.d. temperature & subartic zones:1. extended exposure to cold.e. passage through animal digestive tract.
9.3.5:Absorption of water precedes the formation of gibberellin in the embryo’s cotyledon. This stimulates the production of amylase, which catalyses the breakdown of starch to maltose. This subsequently diffuses to the embryo for energy release and growth.
9.3.6:-phytochrome is a pigment that exists in plants in two forms:-Pr, absorbs white/red light-Pfg absorbs dark/far-red lights-in white or red light Pr is converted to Pfr-in far-red lights or in darkness, Pfr gradually reverts to Pr-Pfr acts as a promoter of flowering in long-day plants-Pfr acts as an inhibitor of flowering in short-day plants
9.1.1:9.1.2:• Number of cotyledons -- The number of cotyledons found in the embryo is the actual basis for distinguishing the two classes of angiosperms, and is the source of the names Monocotyledonae and Dicotyledonae. The cotyledons are the "seed leaves" produced by the embryo. They serve to absorb nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis.
• Pollen structure -- The first angiosperms had pollen with a single furrow or pore through the outer layer. This feature is retained in the monocots, but most dicots are descended from a plant which developed three furrows or pores in its pollen.
•Number of flower parts -- If you count the number of petals, stamens, or other floral parts, you will find that monocot flowers tend to have a number of parts that is divisible by three, usually three or six. Dicot flowers on the other hand, tend to have parts in multiples of four or five. This character is not always reliable, however, and is not easy to use in some flowers with reduced or numerous parts.
• Leaf veins -- In monocots, there are usually a number of major leaf veins which run parallel the length of the leaf; in dicots, there are usually numerous auxillary veins which reticulate between the major ones. As with the number of floral parts, this character is not always reliable, as there are many monocots with reticulate venation, notably the aroids and Dioscoreales.
9.1.3: •Xylem: Bring water to replace losses due to transpiration, and inorganic minerals from the soil.
• Phloem: Transports products of photosynthesis out of the leaf.
• Stoma: A pore that allows CO2 for photosynthesis to diffuse in and O2 to diffuse out.
• Guard Cells: this pair of cells can open or close the stoma and so control the amount of transpiration.
• Upper Epidermis: a continuous layer of cells covered by a thick waxy cuticle. It prevents water loss from the upper surface even when heated by sunlight.
• Lower Epidermis: is in a cooler position and has a thinner waxy cuticle.
• Spongy mesophyll: consists of loosely packed rounded cells with few chloroplasts. This tissue provides the main gas exchange surface so must be near the stomata in the lower epidermis.
• Palisade mesophyll: consists of densely packed cylindrical cells with many chloroplasts. This is the main photosynthetic tissue and is positions near the upper surface where the light intensity is highest
Topic 9.1.4:
-Bulbs: modified leaves (onion, garlic)-
Tubers: modified stems (potato, gladiola)-
Storage root: carrot-
Tendril: modified leaf (ivy)
9.1.5:
Apical meristems are sometimes referred to as primary meristems, and lateral meristems as cambium. Meristems generate new cells for growth of the plant.9.1.6:-meristems are regions where cells continue to divide and grow, often throughout the life of the plant.- apical meristems are located at the tip of the root and stem, increasing the length of the plant, and also producing new leaves and flowers.-later meristems, or cambium, are found in vascular bundles and increase the diameter of the plant by producing xylem and phloem.- in the stems of younger plants, the vascular cambium is located discretely in bundles.-in the stems of older plants, the cambium is a complete ring.-lateral meristems also increases the root diameter.
9.1.7:
-auxin is a plant hormone that stimulates cell elongation.-one of the processes that auxin controls is phototropism: directional growth toward the source of light.-in shoot tips, proteins called phototropins absorb light, changing shape in respone to certain light wavelengths.-phototropins in a light-induced conformation bind to receptors which stimulate transcription/translation of genes producing glycoprotiens.-these glycoprotiens locate in membranes facilitating transport of auxin between cells.-shoot tips respond to light intensity by producing more auxin on the side with less light, main that side grow longer, thus bending he shoot tip toward the light.-plant cells have membrane bound auxin receptor proteins.-auxin efflux carriers are membrane proteins that pump auxin laterally.-auxin stimulates the pumping of hydrogen ions out of cells and into cell walls.-hydrogen ions lower the pH, which loosens connections between cellulose micofibrils.cell turgor pressure causes cell expansion, since the cellulose micofibrils without cross connections provide less resistance.-higher concentrations of auxin on shadier side of shoot tip causes greater cell elongation, moving shoot tip toward light.
9.2.1:-branching: extensive branching of roots greatly increases overall root surface area exposed to extracellular fluid.-root hairs: individual root epidermal cells grow extensive elongations grealy increasing the surface are of individual root epidermal cells to extracellular fluid.
9.2.2:There are three processes: diffusion of mineral ions, fungal hyphae, and mass flow of water in the soil carrying ions.
9.2.3:-because the concentration of mineral ions is usually lower in the soil than in the root, active transport is used to concentrate mineral ions to the root.-because active transport requires ATP, root epidermal cells ar rich in mitochondria and require a supply of oxygen for cellular respiration.- active transport: ATP oxidation provides the energy for protons to be pumped from the inside to the outside of root epidermal cell membranes = chemiosis, producing a H+ membrane potential.-cations, such as K+, are driven from the extracellular fluid into the intracellular fluid, through membrane channels, by their electrical charge repulsion from the H+'s concentrated in the extracellular fluid.-anions, such as NO3-, move from the extracellular fluid into intracellular fluid, through membrane channels, by co-transport with H+, which moves down its diffusion gradient.
9.2.4:-thickened cellulose: both xylem and phloem cells have thick secondary cell walls composed primarily of cellulose, providing rigidity.-cell turgor: plant cell vacuoles have low water potential; water enters the cell and vacuole by osmosis, causing the cell to swell against its wall with a pressure against the cell wall which provides rigidity.-lignified xylem: vascular tissue cells reinforced with a helical or ring-shaped thickenings of the cellulose cell wall impregnated with lignin, which makes the cell walls hard, providing resistance to pressure.
9.2.5:Transpiration is the loss of water vapor from the leaves and stems of plants.
9.2.6:Xylem vessels:a. thick-walled, elongated vascular tissue cells1) arranged end-to-end2) connected by perforated end-platesb. xylem cells die a maturity1) leaving a continuous microtube for transporting water and dissolved mineral ions.2) from the roots to the above-ground portions of the plant.-transpiration pull:a. evaporation:1) water vapor diffuses the moist air spaces of the spongy mesophyll where water potential is higher.2) to the drier air outside where water potential is lower.3) via stomatab. cohesion:1) as the spongy mesophyll air spaces lose water by evaporation its water potential decreases.2) water flows from the xylem, where water potential is higher.3) through the mesophyll to the air spaces, down its water potential gradient.4) the cohesion of water molecules, due to hydrogen bonding.5) enables transpiration to pull water up the narrow xylem vessels.6) without these columns of water breaking apartc. adhesion:1) the cell walls of the xylem are charged, attracting water molecules.2) the adhesive attraction of water to xylem vessel walls moves them up the stem against gravity.3) adhesion is important when sap starts to rise in plants that were leafless through the winter4) adhesion also helps prevent the column of water-filled xylem vessels from breakingd. transpiration:1) solar-powered evaporation from the leaves2) creates a continuous transpiration pull3) transmitted all the way from the leaves to the roots
9.2.7:
9.2.8:
9.2.9:-light:a. guard cells close the stomata in darkness, so transpiration is much greater in light.b. open stomata increases the rate of diffusion of CO2 needed for photosynthesis.c. but also increasing transpiration water loss through stomata.-temperature:a. rate of transpiration water loss through stomata is doubled for every 1o degrees C. increase in temperature.b. higher temperature also increase the rate of diffusion and reduces the relative humidity in the air outside the leaf.-wind:a. removes water vapor from leaf, reducing water potential around leaf.b. thus increasing the water potential gradient between the leaf and its surroundings.c.and therefore increasing the rate of transpirational water loss.-humidity:a. as humidity decreases, water potential around leaf is reduced.b. thus increasing the water potential gradient between the leaf and its surroundings.c. and therefore increasing the rate of trainspirational water loss.
9.2.10:-reduced leaves: minimized water loss by reducing leaf surface area.-thickened waxy cuticle: minimizes water loss by limiting water loss through epidermis.-reduced number of stomata: minimizes water loss through leaves.-succulence: stems specialized for water storage maximizes retention of water available during infrequent rains.
9.2.11:-translocation is the movement of substances from one part of a plant to another in the phloem.-symplastic route: sucrose manufactured in mesophyll cells travels intracellularly to phloem sieve-tube members (STMs)- apoplasctic route: sucrose manufactured in mesophyll cells travels extracellularly to companion cells and STMs.a. proton pumps: driven by ATP, pumps H+s into extracellular environment.b. sucrose enters companoin cells and STMs by co-transportc. as H+ moves down its concentration gradient into compation cells and STMs.-pressure flow in a sieve tube:a. loading of sucrose into the STMs at the source.b. reduces the water potential inside STMs, causing water to enter osmosis .c. absoprtion of water generates hydrostatic pressure.d. that forces the phloem sap to flow along the tube.e. gradient of pressure in the tube is reinforced by the unloading of sucrose.f. and the consequent loss of water, from the sieve tube at its sink.
9.3.1
9.3.2:-pollination: the transfer of pollen grians from the anther to the stigma-fertilization: fusion of male and female gametes-seed dispersal: mechanism for distributing seeds away from the parent plant.
9.3.3
9.3.4:-Seeds vary in their light requirements and, therefore, this factor need not be included.-evolution of the seeed: key adaptation of plants to terrestrial life.-seed dormancy increases chance that gemination will occur at appropriate time.-environmental cues:a. oxygen & water:1. needed by all seeds to germinate.2. to initiate inhibition and activate cellular respiration.b. desert:1. substantial rainfall.2. washing inhinitors from seed coat,c. chaparral:1. fire.2. intense heat.d. temperature & subartic zones:1. extended exposure to cold.e. passage through animal digestive tract.
9.3.5:Absorption of water precedes the formation of gibberellin in the embryo’s cotyledon. This stimulates the production of amylase, which catalyses the breakdown of starch to maltose. This subsequently diffuses to the embryo for energy release and growth.
9.3.6:-phytochrome is a pigment that exists in plants in two forms:-Pr, absorbs white/red light-Pfg absorbs dark/far-red lights-in white or red light Pr is converted to Pfr-in far-red lights or in darkness, Pfr gradually reverts to Pr-Pfr acts as a promoter of flowering in long-day plants-Pfr acts as an inhibitor of flowering in short-day plants
Friday, February 13, 2009
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