A plant needs roots for two chief reasons: 1. As a means of anchoring itself to the ground. 2. To absorb water and minerals from the soil. The roots of most plants grow in the soil. By elongating their tips, roots are always coming into contact with new portions of soil. Thousands of tiny hairs project from the surface of the young root which absorb the materials from the soil. Types of roots: 1. Some plants have large bulbous roots called taproots. 2. Grasses have fibrous root systems. Soil in which there are many fibrous roots is protected from erosion. 3. Some tropical orchids that grow on trees have spongy roots.
All of us have had the experience of being thirsty at times, but can you imagine how it would feel to be thirsty for days? If a human being has absolutely nothing to drink for five to six days, he will die . Feeling thirsty is simply our body's way of telling us to replenish its liquid supply. 1. The reason for this thirst is caused by a change in the salt content of our blood . 2. There is a certain normal amount of salt and water in our blood . 3. When this changes by having more salt in relation to water in our blood, thirst results. There is a part of our brain called the 'Thirst centre'(Hypothalamus) . It responds to the amount of salt in our blood. When there is a change, it sends messages to the back of the throat. From there, messages go to the brain, and it is this combination of feelings that makes us say we are thirsty. *Avoid eating too much of salt*