A.)1.)water flows from area of higher concentration to area of lower concentration.When air is sucked the pressure inside the straw is low...the atmospheric pressure thus pushes the water(applies force) and this causes the water to rise in the straw.
2.)Because of the blood pressure within our body.......the air we breathe circulates within our body(O∨2 mainly) in our body along with the blood stream.....thus creates a pressure in our body equivalent to the atmospheric pressure.
B.)1.)When the handle of the bicycle pump is pulled air gushes in from the area of higher concentration(atmosphere)to area of lower concentration(inside the pump)...and when we push it this air again follows the same principle and flows from the pump to the tube of the tire of the cycle.
All these are basically due to difference in pressure.....
C.) Androecium is the male reproductive part of a flower....consists of stamen,anthers,filaments.
hope i helped u:)