A DID system can be used for fax and voice mail as well as for live voice connections. Compared to regular PBX service, DID saves the cost of a switchboard operator, calls go through faster, and callers feel they are calling a person rather than a company.
Key Concepts: In dicotyledonous leaves there are two types of mesophyll cells, palisade mesophyll and spongy mesophyll. Palisade mesophyll cells form a layer beneath the upper epidermis whereas spongy mesophyll cells are internal to the lower epidermis.
The palisade mesophyll, bundle sheath and spongy mesophyll are known as the ground parenchyma. There is a system of air spaces which communicate with the air chambers behind the stomata (which are like our pores). Since the mesophyll cells contain chloroplasts the tissue is also referred to as chlorenchyma . To sum it up, the functions of the Mesophyll are......... * The palisade cells are responsible for photosynthesis because they contain chloroplasts.