Biology Question
32 Rajah 23 menunjukkan sejenis tumbuhan hidrofit.
Diagram 23 shows a type of hydrophyte.
Rajah 23 Diagram 23
Antara penyesuaian berikut, yang manakah membolehkan tumbuhan itu terapung di atas permukaan air?
Which of the following adaptation enables the plant to be afloat on the surface of water?A Kutikel yang nipis pada permukaan daun.
Thin cuticle on the leaves surface.
B Permukaan daun yang diliputi dengan lignin.
Surface of leaves covered with lignin.
C Kehadiran aerenkima pada batang dan daunnya.
Presence of aerenchyma in the stem and leaves.
D Dinding batang ditebalkan dengan sel dan pektin.
The stem wall is thickened by cell and pectin.
Biology Solution
Let’s approach this question from a physics perspective:
In order for an object to float in water, it must have lower density than water. A ping pong ball floats in the water due to the relatively great volume of air contained within it.
And how do plants achieve this? They must have air “pockets” within their tissues in order to float.
Aerenchyma tissues contain air spaces, which make hydrophytes “lighter, i.e., less dense” than water, therefore allowing them to float!