Why is water needed for seed germination

simply bio 1, textbook

A1 –W– The pictures show you the germination of the bean. Put the sketches in the right order. B1 v The seed coat bursts and the radicle begins to grow. B2 v The plant grows, the cotyledons dry up. B3 v The radicle grows into the ground and, together with the secondary roots, gives the seedling support. B5 v The leaves unfold and begin to produce chlorophyll when exposed to light. B4 v The seed absorbs water and swells up more and more. 1 Germination is the name given to the processes involved in sprouting and growing a plant from a seed. You could also call it the “birth” of the plant. Whether germination works depends on a number of factors. Some seeds only germinate in the dark, others only in the light. Many seeds can “wait” until the conditions for germination are good. This rest period is called dormancy. How is a seed structured? A small plant, the seedling or embryo, is already in the seed coat. The seedling already has a root and a sprout. In the case of the bean, the two large, thick cotyledons take care of the seedling because it has no leaves and cannot yet feed itself (page 134). The small radicle and the sprout lie between the cotyledons. You can also see the tiny leaves. How does germination work? The seedling needs moisture, oxygen and warmth to germinate. The dry seed absorbs water from the surrounding earth. It begins to swell. This means that the seed gets bigger and bigger from the moisture. Eventually the seed coat bursts. The radicle begins to grow into the soil. It becomes the main root of the plant. Together with the secondary roots, which start to grow a little later, it gives the plant support. The sprout bores up through the earth. It is curved like a hook and pulls the leaves out of the ground. From now on the plant can feed. In order to continue to grow, the seedling needs light, water and minerals. He gets minerals from the soil or the water. The cotyledons are no longer needed. They dry up and fall off. Seedlings are healthy Some seedlings - more precisely, their sprouts - can be eaten. You may know them from cress or bean sprouts. They contain a lot of vitamins and minerals and can be easily grown at home. ➝ Workbook page 59 132 Germination - a plant sprouts for test purposes only - property of the publisher öbv

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