Plants
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Catégorie :Category: nCreator TI-Nspire
Auteur Author: RNDMPRSN
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 4.07 Ko KB
Mis en ligne Uploaded: 26/01/2025 - 20:23:50
Uploadeur Uploader: RNDMPRSN (Profil)
Téléchargements Downloads: 3
Visibilité Visibility: Archive publique
Shortlink : http://ti-pla.net/a4478541
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 4.07 Ko KB
Mis en ligne Uploaded: 26/01/2025 - 20:23:50
Uploadeur Uploader: RNDMPRSN (Profil)
Téléchargements Downloads: 3
Visibilité Visibility: Archive publique
Shortlink : http://ti-pla.net/a4478541
Description
Fichier Nspire généré sur TI-Planet.org.
Compatible OS 3.0 et ultérieurs.
<<
Timing & Coordination in Plants ´ Plant hormones play a crucial role in the timing of activities ´ Alone and together, plant hormones target specific parts of a plant and produce a specific effect. ´ Breaking dormancy ´ Seed germination Hormones, plant growth & fruiting ´ AUXINS & GIBBERELLINS ´ Important in promoting the growth and development of shoots. ´ ETHYLENE ´ Gaseous plant hormone. ´ Gibberellins are important in breaking bud dormancy ´ Work with auxins to promote ripening in fruit ´ Buds often burst following a cold period Leaf and Flower Development Fruit Development ´ ETHYLENE & AUXINS ´ ABSCISIC ACID (ABA) ´ A decline in auxins and increase in ethylene work together to bring about leaf drop. ´ Promotes dormancy ´ Prevents growth under unfavourable conditions. ´ Conserves resources at a time when there is not enough light for photosynthesis. Seed Germination " Gibberellins are necessary for seed germination. " Stimulate cell division and elongation allowing the root to penetrate the seed coat. " Many seeds do not germinate unless exposed to a period of wet, cold (5°C) conditions. This is called cold stratification . " ABA accumulates in seeds during fruit production. High levels promote dormancy of embryos. Another important plant hormone& ´ Cytokinins ´ Promote cell division (cytokinesis) ´ They play a role in ensuring the roots and shoots grow at equal rates ´ Stimulate growth of fruit Plant Response to Herbivory ´ Plants have evolved many interspecies relationships. ´ Product of natural selection ´ SYMBIOTIC RELATIONSHIPS: ´ E.g. Plants & fungi à MYCORRHIZAE ´ Increase the nutrient and water absorption in the roots of the plant. ´ Since a plant is a primary producer, most of the interactions with other species do not benefit the plant. ´ Food source for animals ´ Subject to infection by viruses, bacteria & fungi ´ Plants have developed both physical & chemical defenses against herbivory (animals eating plants) ´PHYSICAL DEFENSES TRICHOMES: " Glandular (top left) are poisonous " Non-glandular (top right) are non-poisonous but cause irritation. THORNS " Modified branches or stems CHEMICAL DEFENSES ´Stimulus ´An insect (or other animal) feeding on the plant ´Response ´Production of a chemical that ´Harms the animal ´Recruits predatory animals that help defend the plant (E.g. corn plants) E.g. the Jackbean produces an amino acid (canavanine) that resembles arginine (one of the 20 amino acid used in building proteins). When canavanine is substituted for arginine, the shape of the protein is different, therefore its function differs and the insect dies! A leaf damaged by a caterpillar releases compounds that attract parasitoid wasps. The wasps inject their eggs into the caterpillar and the larvae eat the caterpillar from the inside out!! Plant Defenses Against Pathogens ´ The hypersensitive response: ´Causes cell and tissue death near the infection site. ´Induces the production of chemicals to kill pathogen. ´Stimulates changes in cell wall to confine pathogen. ´Prevents the spread of the infection. Lesions are sometimes referred to as rings of death occur around the sites of the infection. ´Systemic Acquired Resistance: ´Causes systemic expression of defense genes. ´Long lasting response (several days) ´Likely triggered by salicylic acid, a chemical produced at the infection site. Tropisms and Growth Responses ´ Tropisms are directional growth responses to external stimuli. ´ They may be positive (towards stimulus) or negative (away from stimulus) ´ Tropisms are identified according to the type of stimulus involved: ´ Phototropism&&&.Light ´ Hydrotropism&&&Water ´ Chemotropism&&.Chemical ´ Thigmotropism&&.Touch Nastic Movement ´ Movements that occur in response to environmental stimuli ´ Unlike tropic movements, the direction of the response is NOT dependent on the direction of the stimulus. Closing of the Venus fly trap The effect of auxins on plant growth ´ Phototropism ´ Plants have photoreceptors in tip of shoots. ´ Detect light ´ In response to light, cells in the tip produce auxin that diffuses down the shoot of the plant. ´ Auxins accumulate in the part of the plant away from the light source ´ Higher concentration of auxins à more cell elongation à shoot bends toward the light. Made with nCreator - tiplanet.org
>>
Compatible OS 3.0 et ultérieurs.
<<
Timing & Coordination in Plants ´ Plant hormones play a crucial role in the timing of activities ´ Alone and together, plant hormones target specific parts of a plant and produce a specific effect. ´ Breaking dormancy ´ Seed germination Hormones, plant growth & fruiting ´ AUXINS & GIBBERELLINS ´ Important in promoting the growth and development of shoots. ´ ETHYLENE ´ Gaseous plant hormone. ´ Gibberellins are important in breaking bud dormancy ´ Work with auxins to promote ripening in fruit ´ Buds often burst following a cold period Leaf and Flower Development Fruit Development ´ ETHYLENE & AUXINS ´ ABSCISIC ACID (ABA) ´ A decline in auxins and increase in ethylene work together to bring about leaf drop. ´ Promotes dormancy ´ Prevents growth under unfavourable conditions. ´ Conserves resources at a time when there is not enough light for photosynthesis. Seed Germination " Gibberellins are necessary for seed germination. " Stimulate cell division and elongation allowing the root to penetrate the seed coat. " Many seeds do not germinate unless exposed to a period of wet, cold (5°C) conditions. This is called cold stratification . " ABA accumulates in seeds during fruit production. High levels promote dormancy of embryos. Another important plant hormone& ´ Cytokinins ´ Promote cell division (cytokinesis) ´ They play a role in ensuring the roots and shoots grow at equal rates ´ Stimulate growth of fruit Plant Response to Herbivory ´ Plants have evolved many interspecies relationships. ´ Product of natural selection ´ SYMBIOTIC RELATIONSHIPS: ´ E.g. Plants & fungi à MYCORRHIZAE ´ Increase the nutrient and water absorption in the roots of the plant. ´ Since a plant is a primary producer, most of the interactions with other species do not benefit the plant. ´ Food source for animals ´ Subject to infection by viruses, bacteria & fungi ´ Plants have developed both physical & chemical defenses against herbivory (animals eating plants) ´PHYSICAL DEFENSES TRICHOMES: " Glandular (top left) are poisonous " Non-glandular (top right) are non-poisonous but cause irritation. THORNS " Modified branches or stems CHEMICAL DEFENSES ´Stimulus ´An insect (or other animal) feeding on the plant ´Response ´Production of a chemical that ´Harms the animal ´Recruits predatory animals that help defend the plant (E.g. corn plants) E.g. the Jackbean produces an amino acid (canavanine) that resembles arginine (one of the 20 amino acid used in building proteins). When canavanine is substituted for arginine, the shape of the protein is different, therefore its function differs and the insect dies! A leaf damaged by a caterpillar releases compounds that attract parasitoid wasps. The wasps inject their eggs into the caterpillar and the larvae eat the caterpillar from the inside out!! Plant Defenses Against Pathogens ´ The hypersensitive response: ´Causes cell and tissue death near the infection site. ´Induces the production of chemicals to kill pathogen. ´Stimulates changes in cell wall to confine pathogen. ´Prevents the spread of the infection. Lesions are sometimes referred to as rings of death occur around the sites of the infection. ´Systemic Acquired Resistance: ´Causes systemic expression of defense genes. ´Long lasting response (several days) ´Likely triggered by salicylic acid, a chemical produced at the infection site. Tropisms and Growth Responses ´ Tropisms are directional growth responses to external stimuli. ´ They may be positive (towards stimulus) or negative (away from stimulus) ´ Tropisms are identified according to the type of stimulus involved: ´ Phototropism&&&.Light ´ Hydrotropism&&&Water ´ Chemotropism&&.Chemical ´ Thigmotropism&&.Touch Nastic Movement ´ Movements that occur in response to environmental stimuli ´ Unlike tropic movements, the direction of the response is NOT dependent on the direction of the stimulus. Closing of the Venus fly trap The effect of auxins on plant growth ´ Phototropism ´ Plants have photoreceptors in tip of shoots. ´ Detect light ´ In response to light, cells in the tip produce auxin that diffuses down the shoot of the plant. ´ Auxins accumulate in the part of the plant away from the light source ´ Higher concentration of auxins à more cell elongation à shoot bends toward the light. Made with nCreator - tiplanet.org
>>
