Page 19 - Modul Konsep Tekanan Zat Pada Makhluk Hidup

Daya Isap Daun

M e l a l u i d a u n a k a n t e r j a d i p e l e p a s a n u a p a i r y a n g d i s e b u t t r a n s p i r a s i . K a r e n a a i r d a l a m
t u b u h t u m b u h a n m e m b e n t u k b e n a n g a i r , m a k a l e p a s n y a m o l e k u l a i r p a d a d a u n a k a n
d i i k u t i n a i k n y a a i r p a d a a k a r d a n b a t a n g . S e l a n j u t n y a a i r d a r i t a n a h j u g a a k a n t e r s e r a p
m a s u k k e a k a r .

Faktor Eksternal

F a k t o r - f a k t o r e k s t e r n a l p e n t i n g m e l i p u t i :
1 . F a k t o r k l i m a t i k , m e l i p u t i s u h u u d a r a , k e l e m b a b a n , c a h a y a ( i n t e n s i t a s & l a m a
p e n c a h a y a a n ) , k e c e p a t a n a n g i n
2 . F a k t o r e d a f i k , t e r u t a m a k e l e m b a b a n ( k a d a r a i r t a n a h ) d a n s u h u t a n a h K e a d a a n d i

d a l a m j a r i n g a n d a n d i l u a r j a r i n g a n s e c a r a s i s t e m i k a k a n m e n e n t u k a n t e r b e n t u k n y a
b e d a ( g r a d i e n ) p o t e n s i a l a i r a n t a r a t a n a h - j a r i n g a n - u d a r a . B e d a p o t e n s i a l a i r i n i
m e n j a d i s a l a h s a t u p e n d o r o n g a l i r a n a i r ( w a t e r s t r e a m ) m u l a i d a r i p e n y e r a p a n –
p e n g a n g k u t a n – p e l e p a s a n ( t r a n s p i r a s i ) .
Sifat Pengangkutan di Floem

1 . T e r j a d i d a l a m d u a a r a h s e c a r a b e r s a m a a n ( b i d i r e c t i o n a l t r a n s p o r t )
2 . M e n g a n g k u t a s i m i l a t b e r u p a g u l a s u k r o s a , b u k a n b e r u p a g l u k o s a
3 . S e l a i n s u k r o s a , m e l a l u i f l o e m d i a n g k u t p u l a i o n - i o n , a i r , a s a m - a s a m o r g a n i k , a s a m
a m i n o d a n j u g a h o r m o n t u m b u h a n .
4 . B a n y a k t e o r i t e n t a n g t r a n s p o r d a l a m f l o e m , d i a n t a r a n y a a d a l a h t e o r i a l i r a n m a s s a
( m a s s f l o w , b u l k f l o w ) , y a n g t e r j a d i k a r e n a a d a n y a p e r b e d a a n ( g r a d i e n ) s u k r o s a
a n t a r a b a g i a n d a u n – b a t a n g d a n a k a r . T e o r i i n i s a n g a t d i k e n a l d e e n g a n t e o r i M u n k

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