The recent discovery of molecular switches that help ___(1)___ whether stem cells will become muscle cells or other cell types might ___(2)___ the way for effective treatments of Muscular Dystrophy (MD). Stem cells-primitive, self-replacing cells that ___(3)___ bodily tissues represent one of the most promising tools for replacing
muscle fibres (muscle cells) lost or damaged in MD. Although perhaps best known as the ___(4)___ force behind embryonic development, stem cells are also found in adult tissues, where they can promote regeneration.

In the embryo and – to the recent surprise of scientists – in a ___(5)___ of adult tissues, many stem cells are pluripotent, meaning they are able ___(6)___ give-rise to several different cell types, including those that make up bone, blood, fat, nerve and muscle. If scientists can ____(7)____ out how stem cells “choose” among these
“career” options, they might be able to direct them to become specific cell types and repair specific tissues.

A team ___(8)___ by MDA-funded scientist Michael Rudnicki at Canada’s Ottawa Hospital Research Institute identified a chemical switch that influences the choice made by stem cella found in skeletal muscle at switch is required ____(9)____ the cells to become satellite cells, which, in adult skeletal muscle, increase muscle mass
during normal growth, after exercise and in ____(10)____ to muscle trauma (injury).

1.
a) determine
b) determining
c) finding
d) knowing
e) knowledge

2.
a) paving
b) pave
c) have paved
d) save
e) destroy

3.
a) generates
b) creates
c) generate
d) germinate
e) originates

4.
a) dividing
b) drive
c) centrifugal
d) driving
e) divisive

5.
a) various
b) variety
c) kind
d) varieties
e) varied

6.
a) to
b) for
c) by
d) with
e) in

7.
a) find
b) figure
c) immerse
d) destroy
e) describe

8.
a) leading
b) captaining
c) led
d) heading
e) formed

9.
a) by
b) for
c) with
d) off
e) of

10.
a) resonance
b) effect
c) care
d) response
e) order