Answer to Question 1
First, stars are very far apart in relation to their sizes and their relative velocities, so they collide very infrequently. Only a tiny fraction of stars in our Galaxy have ever suffered a collision or close encounter with another star. Also, the gas pulled from the Sun and the star would be much too hot to condense to make planets, and it would have dispersed instead. Furthermore, even if planets did form from that gas, they would not have gone into stable orbits around the Sun.
Answer to Question 2
c
Pressure-flow hypothesis for phloem transport
Yellow Star Grass
Star Map Eastern Horizon
Testing a Simple Hypothesis
Under ideal conditions, a single cell of the bacterium E. coli would divide every 20 minutes to ...
One hypothesis for the evolution of the eukaryotes