Q.Explain why waterlogged soil is harmful to the roots of most land plants, with reference to gaseous exchange and fermentation.

[!TLDR]

Waterlogged soil has no air spaces, so roots lose their oxygen supply and must ferment, which yields little ATP and accumulates toxic ethanol/lactic acid, damaging or killing roots. …

Root cells have no stomata or lenticels of their own and instead obtain oxygen by diffusion from air spaces between soil particles, through the thin walls of the epidermis and root hairs. When soil is waterlogged, these air spaces are filled with water rather than air, sharply reducing the oxygen available to root cells. Deprived of oxygen, root cells are forced to switch from aerobic respiration to fermentation, which yields only glycolysis's modest net 2 ATP per glucose rather than the far larger yield of aerobic respiration, so the roots are energetically starved. At the same time, fermentation's end-product (ethanol or lactic acid) steadily accumulates within the root cells and, at high enough concentration, becomes …

Trace the causal chain: waterlogging removes soil air spaces, which removes the root's oxygen supply, which forces ferme …

Attributing root damage in waterlogged soil simply to 'too much water' without explaining the actual mechanism -- loss of the oxygen needed for aerobi …