In: Biology
Ans. Plant living in water (hydrophytes) faces no shortage of water and water is not a barrier in growth and development for them. When plants evolved to live on land, shortage of water comes into play. In order to cope with this problem, plants evolved. They have thick cuticle ( waxy coating) the leaves to reduce the loss of water. Deep and strong root system to absorb water from deep soil. This will enhance water availability in plants. Closure of stomata when water falls short in plant body due to flaccid guard cells is a mechanism to avoid further loss of water from the plant. Modification of leaves into spines is observed in some plant and is an adaptive feature to prevent water loss. In arthropods, the presence of thick shell or cuticle covering the body is a mechanism to avoid water loss. Many insects close trachea and spiracles with coverings to reduce water loss when open respiration is not necessary. In vertebrates, water loss is prevented by forming concentrated urine. Uriotelic is the mode of excretion of concentrated urine and is found in humans. It involves excretion of urea along with urine. Birds and reptile are uriotelic where uric acid is excreted. These help in prevention of water loss. Water tight skin prevents water loss. Hairs present on skin also help in water loss. Inhabiting in moist habitat is also a method to save water.