In transgenics,the expression of a transgene in the target tissue is determined by:

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers: $(A)$ Duddell's thermo galvanometer is suitable to measure direct current only. $(B)$ Thermopile can measure temperature differences of the order of $10^{-3} {}^{\circ}C$.

Water flows in a streamlined manner through a capillary tube of radius $a$,the pressure difference being $P$ and the rate of flow $Q$. If the radius is reduced to $a/2$ and the pressure is increased to $2P$,the rate of flow becomes:

Tetrahalides of group $14$ elements (except that of carbon) act as:

In a meter bridge experiment,a resistance of $9 \Omega$ is connected in the left gap and an unknown resistance $x$ (where $x > 9 \Omega$) is connected in the right gap. If the resistances in the gaps are interchanged,the balancing point shifts by $10 \text{ cm}$. The value of the unknown resistance is: (in $Omega$)

If $R = \{ (x, y) | x, y \in Z, x^2 + y^2 \le 4 \}$ is a relation in $Z$,then the domain of $R$ is