Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

If a point $P$ moves such that its distances from the point $A(1,1)$ and the line $x+y+2=0$ are equal,then the locus of $P$ is

The cubic equation whose roots are the squares of the roots of $x^3-2x^2+10x-8=0$ is

The length of the tangent drawn to the circle $x^2+y^2-2x+4y-11=0$ from the point $(1,3)$ is:

The coordinate axes are rotated through an angle of $135^o$. If the coordinates of a point $P$ in the new system are $(4, -3)$,then the coordinates of $P$ in the original system are:

In the following reaction,$A$ and $B$ respectively are:
$A$ $\xrightarrow{HBr} C_2H_5Br$ $\xrightarrow{B} A$