1 / 9

name two plant growth substances indole acetic acid (IAA) – an auxin

name two plant growth substances indole acetic acid (IAA) – an auxin gibberellic acid (GA) – a gibberellin identify the site of IAA production IAA is produced by the apical meristems state the effects of IAA at the cellular level

chi
Download Presentation

name two plant growth substances indole acetic acid (IAA) – an auxin

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. name two plant growth substances • indole acetic acid (IAA) – an auxin • gibberellic acid (GA) – a gibberellin • identify the site of IAA production • IAA is produced by the apical meristems • state the effects of IAA at the cellular level • IAA promotes cell division, elongation and differentiation at the apical mertistems

  2. state the effects of IAA at the organ level • root growth • stimulated by low concentrations of IAA • inhibited by high concentrations of IAA • shoot growth • not effected by low concentrations of IAA • stimulated by high concentrations of IAA • inhibited by very high concentrations of IAA • phototropism

  3. describe the role of IAA in apical dominance • apical bud produces high concentration of IAA • transported down shoot • inhibits growth of the lateral (side) buds • the strength of apical dominance varies

  4. describe the role of IAA in leaf abscission • leaf abscission is the process by which a plant drops its leaves (and fruit) • IAA levels decrease in the abscission layer at the base of the leaf stalk • cell walls in this layer weaken due to low IAA levels – leaf falls

  5. describe the role of IAA in fruit formation • following pollination and fertilisation – high levels of IAA produced by the embryo stimulate the ovary wall to develop into the fruit • in unpollinated flowers the unfertilised ovules do not become seeds • treating such flowers with high levels of IAA produces seedless fruit

  6. discuss two practical applications of auxins • herbicides • high levels of auxin • increase rate of metabolism • kills plant • more effective on broad-leaved plants – selective weedkiller • rooting powder • low level of auxin • stimulates root growth of cutting

  7. describe the effect of GA on dormancy • tree buds dormant over winter • increasing levels of GA in spring • dormancy broken –bud opens

  8. describe the effect of GA on dwarf plants • GA promotes stem elongation • dwarf plants have shortage of GA (genetic disorder) • applying GA increases length of internodes

  9. describe the role of GA in germination • water absorbed by seed • embryo produces low concentration of GA • GA diffuses to aleurone layer • cells of aleurone layer secrete α-amylase • α-amylase breaks starch down to sugar (maltose) • sugar diffuses to embryo allowing respiration and growth • model of hormone action • test

More Related