Question

Why does the seed swell up after soaking

Answer 1

The dry cell has no sap inside when water enters into the cell sap then the cell volume increases and the seed swells.

Answer 2

On January 9, 1948, a 220-foot (67 m) steel schooner named the Cali left Guayaquil, Ecuador, loaded with grain, bound for Santiago, Cuba. On January 27, the Cali began taking on water during a storm near Grand Cayman Island. As the seawater leaked in, the grain swelled up so much that it ruptured the hull and destroyed the ship!

To the casual observer, seeds appear lifeless and simple. However, under the right conditions, they will germinate (start growing). But this process depends heavily on the presence of water. God designed seeds with the amazing ability to soak up and hold the water necessary for the complex processes of life.

Most seeds, such as grains, beans, corn, and nuts, undergo a resting phase before they begin growing into new plants. During this phase, most seeds contain very little moisture. The seed coat, or outer skin, keeps water out. The chemical processes that keep the cells functioning in the seed are slowed almost to a halt. Seeds can remain in this resting state for months, years, or even centuries. The delay allows seeds to survive harsh, unsuitable environmental conditions. It also allows time for transportation by wind, water, animals, or people.

When conditions become favorable, the seed coat goes through a marvelous transformation that allows water to soak the seed. The process of seeds absorbing water is called imbibition.

During imbibition, a seed can swell to several times its original size. This swelling can cause tremendous pressure—often over 1,000 pounds per square inch (6900 kPa). Swelling seeds can break rocks and concrete or, in the case of the Cali, rupture a steel cargo ship. This swelling bursts the seed coat, allowing the new plant to grow and lodging the plant in place so it can’t wash away or be blown away by wind. The expanding plant can then take root in even the hardest soils.