What is the cause of embryo formation from pollen grains in tissue culture medium?

Which of the following is the weakest reducing agent?

$\frac{1}{e^{3x}}(e^x + e^{5x}) = a_0 + a_1x + a_2x^2 + \ldots$
$\Rightarrow 2a_1 + 2^3a_3 + 2^5a_5 + \ldots$ is equal to

$A$ group of species with a common ancestor is known as:

The compound$(s)$ with $P - H$ bond$(s)$ is$(are)$
$(A) \ H _3 PO _4$ $(B) \ H _3 PO _3$ $(C) \ H _4 P _2 O _7$ $(D) \ H _3 PO _2$

Carbon,silicon,and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $(Eg)_C$,$(Eg)_{Si}$,and $(Eg)_{Ge}$ respectively. Which one of the following relationships is true in their case?