question_answer

  Rohit's father told him that various pipes are responsible for transport of blood in our body. But he thinks that these are of single type. Describe the types of blood vessels present in our body. Explain the function of each to help Rohit. Or Hemant says his grandmother that water and minerals are transported from root to leaf in plant. To help his grandmother, explain the mechanism of water and minerals transport in plant.

Answer:

  Three types of blood vessels are connected to form a closed system in human body. (i) Arteries These are wide, thick elastic walled vassels, which carry blood from heart to all body parts. Arteries carry oxygenated blood except pulmonary artery, which carries deoxygenated blood from heart to lungs. (ii) Capillaries Arteries keep dividing further into smaller vessels and finally for the smallest vessels called capillaries. These have permeable wall and exchange gases, nutrients and waste products across the tissues.         (1) (iii) Veins The capillaries combine together to form thin walled vessels called veins. Veins carry deoxygenated blood from body organs to the heart. Pulmonary vein carries oxygenated blood from lungs to the heart.                                Or The mechanism of transport of water and minerals in plants is as follows (i) The  xylem  forms  an  interconnected network of vascular tissues, which create a continuous channel from root tracheids to all plant parts.                                                                                                                                           (1) (ii) The cells of root hair in contact with soil take up ions, which create an ion concentration gradient between root and soil.                                                                                                                                                               (1) (iii) The water flows into root from soil due to osmosis.                                                                                                  (1) (iv) Stomata loose water to the surroundings through transpiration. This creates a suction force, which pulls water upwards to heights.                                                                                                                                                        (1)                               (v) The steady movement of water into the root from the soil pushes water upwards.                                                   (1)