Acid growth protons (H ions) to be pumped out of the cell into the cell wall. As a result, the cell wall solution becomes more acidic. This activates expansin activity, causing the wall to become more extensible and to undergo wall stress relaxation, which enables the cell to take up water and to expand. Acid growth Acid growth refers to the ability of plant cells and plant cell walls to elongate or expand quickly at low (acidic) pH. This form of growth does not involve an increase in cell number. During acid growth, plant cells enlarge rapidly because the cell walls are
The Limits to Growth over "The Limits to Growth" concluded in 1978 that optimistic attitudes had won out, causing a general loss of momentum in the environmental movement. While summarizing a large number of opposing arguments, the article concluded that "scientific arguments for and against each position ... have, it would seem, played only a small part in the general acceptance of alternative perspectives." In 1989, a symposium was held in Hanover, Lower Saxony, entitled "Beyond the Limits to Growth: Global Industrial Society, Vision or Nightmare?" In 1993, "Beyond the Limits" was published as a 20-year update on the original material. "Limits to Growth: