الأسبوع 8 · الفصل 6 «انتقال الماء في النباتات»: 6-1 النتح، 6-2 مسار الماء، مقال من نعم النيل · 3 دروس
2
Roots, stem, leaves: the road of water
Science P6: Term 1, Chapter 6, pp. 54–61
GoalTrace the path of water from roots to leaves.
New words
root · the plant part that takes in waterxylem · the thin tubes that carry water up the stemwilt · to droop because there is not enough water
Explanation
A plant is like a tower with a water road inside. The roots take in water from the soil. Thin tubes in the stem, called xylem, carry the water up to the leaves. This road is continuous from the roots to the leaves. When water leaves the leaves by transpiration, more water is pulled up the tubes behind it. If the plant does not get enough water, it wilts, but after watering it usually stands up again. You can see the road with a white flower or a celery stalk in water that has a few drops of food colouring in it: the colour climbs the stalk. An adult cuts the stalk, and nobody eats it. Look for the coloured lines. The water does not stay in the roots.
roots take in water→water climbs the stem→leaves→water vapour leaves into the air
Worked examples
Mariam leaves a white flower in a glass of water with red food colouring overnight. In the morning the petals show red lines. The colour travelled up through the stem.
Time
What we see
before watering
leaves drooping
after watering
leaves upright again
A wilted tomato plant on a balcony looks tired in the afternoon. After watering, it stands up again in an hour or two. The water moved up to the leaves.
A cut flower in a vase also lets water climb up the stem. Changing the water helps it last longer.
Class activity
Colour climb. With a grown-up, put a white flower or a celery stalk in water with a few drops of food colouring. An adult trims the end of the stalk. Check after a few hours and look for coloured lines. Do not eat it. Draw the water road.
Practice
1
Which tubes carry water up the stem?
Xylem.
2
Which part takes in water from the soil?
The roots.
3
What happens to a wilted plant after watering?
It usually recovers and stands up.
4
Why did the white flower show coloured lines?
Coloured water travelled up the stem tubes into the petals.
