In the process some of the mass of the hydrogen atoms is converted into energy in the form of light. The same process occurs in thermonuclear (fusion) bombs. In the Sun the process occurs in a controled manner. In a bomb it happens all at once in a big chain-reaction explosion.
Phloem. Definition. noun. A tissue in a vascular plant that functions primarily in transporting organic food materials (e.g. sucrose) from the photosynthetic organ (leaf) to all the parts of the plant.
1.Xylem parenchyma are the only living cells of Xylem,rest all cells are dead. 2.Phloem fibres are the only dead cells of phloem,rest all are living. 3.Vessels in xylem and seive tubes in phloem are a characterstic feature of Angiosperms i.e. flowering plants. 4.Gymnosperms and pteridophytes have trachieds for ascent of sap(conduction of water) and sieve cells for translocation.