Each question in this quiz is timed.
1- lipid A is a cell wall component of :
gram - positive bacteria
gram - negative bacteria
fungi
algae
2- all of the followings about mesosomes are true except :
present in prokaryotes
lateral type play arole in cell division
Invaginations from CM
high efficiency of active transport
3- which is the following statement is true concerning fimbriae :
most gram -ve bacteria have aset of fimbraie
present only in motile strains
once removed they do not regenerate during cell growth
they are longer & thicker than flagella
4- the following acts as areceptor site for attractants & repellents :
sex pili
cell membrane
flagella
cell wall
5- failure to synthesize CW leads to production of :
mycoplasma
spheroplast
none of the above
all of the above
positive selection of T cells :
(a)cell recognising self Ag are selected to survive
(b)cells recognizing foreign MHC are selected to die
(c)result in self tolerance
(d)occure in Bm
(e)cells recognising MHc mol are selected to survive
positive feed back stimulation of T cells is mediated by
(a)IfN gama
(b)Il2
(c)Cd40l
(d)none of the above
Naive T &B cell lymphocytes are
(a)effector cells
(b)mature cells befor encoutering Ag
(c)present in scondary lymphoid organs
(d)all above
(e) b&c
MHC class 2 on Apcs is recognized by t cell through
(a)CD8
(b)TcR
(c)CD 4
(d)CD3
which of following interact with MHC for stabilization
(a)CD4
(b)CD 3
(c)TCR
(d)TLRs
