8 Evidences supporting the Acid Growth Theory (a) stem and coleoptile sections excrete protons in response to auxin, lowering the pH of the apoplast.(b) treatment of auxin-sensitive tissues with acidic buffers of pH 5.0 can cause cells to elongate at rates comparable to that induced by auxin.(c) neutral buffers infiltrated into the apoplast can inhibit auxin-induced growth.(d) the fungal toxin fusicoccin, whose main action is to promote extensive acidification of the apoplast, also causes rapid cell elongation.ตัวอย่างผลการทดลองที่ประกอบการเสนอทฤษฎีดังกล่าว
9 Growth curve “unicellular organism” กราฟการเติบโต (growth curve) เป็นกราฟความสัมพันธ์ระหว่างค่าวัดการเติบโตและเวลา โดยทั่วไปมักพบแบบ sigmoid แต่อาจพบรูปแบบเส้นกราฟลักษณะอื่น ๆ ก็ได้Figure 1 Growth of the unicellular green alga Chlamydomonas. Growth is assessed by a count of the number of cells per milliliter at increasing times after the cells are placed in fresh growth medium. Temperature, light, and nutrients provided are optimal for growth. An initial lag period during which cells may synthesize enzymes required for rapid growth is followed by a period in which cell number increases exponentially. This period of rapid growth is followed by a period of slowing growth in which the cell number increases linearly. Then comes the stationary phase, in which the cell number remains constant or even declines as nutrients are exhausted from the medium.
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