1.	For each of the following suggestions, judge whether it is true or
false and then justify  a conclusion.

a)	Skeletal muscle:
i.	Contain pace maker cells.
ii.	Shows lack of activity in the absence of nerve stimulation.
iii.	Contracts when the actin and myosin filament shorten

b)	The sarcoplasmic  reticulum( a modified form of endoplasmic
reticulum):
i.	Is the site of protein synthesis.
ii.	Is present in skeletal and cardiac muscle but not in smooth
muscles.
iii.	Is the site of ATP synthesis in muscle cells.
please give references, thank you

Hello and thank you for your question:

a) Skeletal muscle: 

i. Contain pace maker cells. 
   FALSE: "[Only c]ardiac muscle tissue contracts without neural
stimulation. The timing of contraction is normally determined by
specialized muscle cells called pacemakers. Pacemakers have properties
of both neurons and muscle cells ie. they can produce action
potentials spontaneously and they can contract."
http://www.erin.utoronto.ca/~w3lange/BIO210/tutorials/tutorial%205.htm

ii. Shows lack of activity in the absence of nerve stimulation.
   TRUE: "A skeletal muscle must be activated by a nerve.  It will not
contract on its own."
http://www.geocities.com/andrearediske/1005_Chapter6_notes.rtf

iii. Contracts when the actin and myosin filament shorten 
   FALSE: "Myofibrils...are made up of two sets of filaments, thick
and thin, which slide past one another during a contraction causing
the myofibril to shorten (the filaments do not shorten during a
contraction)."
http://www.mrothery.co.uk/module4/Handout%20muscles.doc

b) The sarcoplasmic reticulum (a modified form of endoplasmic
reticulum):
i. Is the site of protein synthesis.
    FALSE:  The Rough Endoplasmic Reticulum (RER) is the site of
protein synthesis.  Sarcoplasmic reticulum is a special type of smooth
ER found in muscle cells.
http://ntri.tamuk.edu/cell/er.html
http://www-class.unl.edu/bios201a/spring97/group6/er.html
http://www.angelfire.com/band/teja/bio.htm

ii. Is present in skeletal and cardiac muscle but not in smooth
muscles.
   FALSE:  sarcoplasmic reticulum is important to the function of
heart (smooth) muscle.
http://216.239.53.100/search?q=cache:mt20BFN02YUC:www.nature.com/cgi-taf/DynaPage.taf%3Ffile%3D/nm/journal/v6/n9/full/nm0900_942a.html+%22sarcoplasmic+reticulum%22&hl=en&ie=UTF-8

iii. Is the site of ATP synthesis in muscle cells
   FALSE: ATP synthesis takes place in the mitochondrial space between
the inner and outer mitochondrial membrane/
http://www.gwu.edu/~mpb/oxidativephos.htm 


Search terms used:
Skeletal muscle Contain pacemaker cells
lack of activity in the absence of nerve stimulation "skeletal muscle"
actin and myosin filament shorten
sarcoplasmic reticulum smooth rough
site of ATP synthesis 

Good luck!
Google Answers Researcher
Richard-ga