Which of the following statements is true regarding t cell receptors? (select all that apply.) they are formed by the rearrangement of v, j, c, and d gene segments. they contain variable and constant regions. they can be found in the bloodstream independent of t cells. they recognize antigen-mhc complexes. they are composed of two heavy (h) chains and two light (l) chains.

The true statements about he T cell receptors are 1, 2 and 4.

T cell receptors are the molecules found on the surface of the T lymphocytes. V(D)J recombination is the unique mechanism of genetic recombination that occurs only in the lymphocytes during the early stages of T and B cell maturation resulting in the T cell receptors. They recognize antigen fragments bound to MHC molecules. Majority of the T cell receptors consists of an alpha chain and a beta chain and a few with gamma and delta chains. Each chain is composed of a variable and a constant region. Within these chains are the complementary determining regions (CDRs) which determine the antigen to which the T cell receptor will bind.  

the circled areas are referred to   as sunspots.   the sunspots are cooler than the   surrounding area.

sunspots are temporary phenomena on the photosphere of the sun that appear visibly as dark spots compared to surrounding regions. they correspond to concentrations of magnetic field flux that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere.