Page 99 - Biology Form Two

Biology for Secondary Schools

FOR ONLINE READING ONLY

Figure 4.20: Leaf undergone gutation
At night root pressure drives the flow of water out of the plant leaves, rather than
transpiration pull. The differences between guttation and transpiration are shown
in Table 4.2.
Table 4.2: Differences between guttation and transpiration
Guttation Transpiration

(i) Occurs early in the morning and at (i) Occurs during the day
night
(ii) Takes place through hydathodes (ii) Takes place through the stomata

(iii) Takes place at low temperatures (iii) Takes place at high temperature
(iv) Water is lost in liquid form through (iv) Water is lost in form of vapour via
the hydathodes the stomata
(v) Root pressure plays a vital role in (v) Root pressure is not involved in
this process this process
(vi) Takes place on the margin of the (vi) Takes place mostly in the lower
leaf surface of the leaf
(vii) Hindered by dry conditions (vii) Favoured by dry conditions
(viii) Never results in wilting of the (viii) Excessive transpiration results in
plant wilting of the plant
(ix) Cannot be regulated since (ix) Can be regulated since stomata can
hydathodes do not open or close open and close

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