Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms' activities.owever, not all organisms that use light as a source of energy carry out photosynthesis, since photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon. In plants, algae and cyanobacteria, photosynthesis releases oxygen.
Describe the mechanism of clonal selection. The binding of an antigen receptor to an epitope initiates events that activate the lymphocyte. Once activated, a B or T cell undergoes multiple cell divisions. For each activated cell, the result of this proliferation is a clone.ntibodies and B cell receptors. Antibodies have the same Y-shaped organization as B cell antigen receptors, but they are secreted rather than membrane bound. It is the antibodies, rather than the B cells themselves, that actually help defend against pathogens.
Pattern recognition receptors bind conserved molecular structures found in large groups of pathogens, termed pathogen-associated molecular patterns (49). There are various groups of pattern recognition receptors, which can be secreted, expressed om the cell surface, or resident in intracellular compartments (48).The Toll-like receptors (TLRs) are one of the most important pattern recognition receptor families and are the main topic of this review.rosophila TLRs Are Not True Pattern Recognition Receptors The insect immune defense involves the induction of different antimicrobial peptides in the fat body, the functional equivalent of the mammalian liver (for a review, see reference 26).