Cytokinins are plant hormones that primarily promote cell division (cytokinesis) in the presence of auxins. They are also crucial in delaying senescence (aging) of leaves by helping to maintain protein and nucleic acid content, a phenomenon known as the Richmond-Lang effect. They are synthesized mainly in root apices.
Explanation:
Transpiration from stomata creates negative water potential in leaves, generating a tension (transpiration pull) that draws water upward through the xylem from roots. This cohesion-tension mechanism is the primary driver of water transport in tall trees. Root pressure and capillary action are minor forces.
Explanation:
The spinal cord is a long tubular bundle of nervous tissue extending from the medulla oblongata to the level of the first/second lumbar vertebra (L1-L2), where it tapers into the conus medullaris. Below this, nerves form the cauda equina. It transmits impulses between the brain and body and coordinates reflexes.
Explanation:
Nitrogen is an essential component of amino acids (proteins) and nitrogenous bases of nucleic acids (DNA, RNA). Phosphorus is in nucleic acids and ATP, potassium is an ion, calcium is structural. The nitrogen cycle makes atmospheric N₂ available to organisms through fixation.
No comments yet. Be the first to start the discussion!