Question

Plants get water through the roots because of
A. Capillarity
B. Viscosity
C. Gravity
D. Elasticity

Answer 1

Hint: In order to determine how plants get water through their roots we study the definitions and properties of each of the list of choices given to us and pick the most appropriate one.

Complete Step-by-Step solution:
A. Capillarity:
Capillarity of a liquid is defined as the tendency of the liquid to flow through narrow spaces without the effect of any external forces like gravity on it. It occurs because of the surface tension of the liquid.
Example: Water moving across a paper or towel.

B. Viscosity
Viscosity of a liquid is defined as the resistance of a liquid to deformation at a given rate. Different liquids have different viscosities. It occurs due to the internal friction of a liquid.
Example: Some liquids like glass, peanut butter have very high viscosity that they behave like solids. They resist motion because their molecules offer a lot of internal friction.

C. Gravity
Gravity is defined as the phenomenon by which a body of mass or energy is brought towards one another. It occurs between all the objects in this universe including stars and planets.
Example: Earth’s gravitational force.

D. Elasticity
Elasticity of a body is defined as the ability to restore to its original shape after being under the influence of a force which tries to distort its shape.
Example: Polymer materials like rubber are highly elastic in nature.

In plants, one of the tissues used for transport is “Xylem”. The basic function of xylem is to transport water for the roots to the stems and the leaves. The transfer of water using xylem in plants occurs using the capillary theory.
Hence plants get water through the roots because of capillary action.
Option A is the correct answer.

Note – In order to answer this type of question the key is to know the different concepts of physics that take place in different processes of a plant. One such phenomena is absorbing water from the soil. One more such phenomena is photosynthesis. It is a process by which most of the plants and a few other living organisms convert light energy into chemical energy. The photons present in the light waves are absorbed by them.