What type of $p-n$ junction diode does not require forward bias to operate?

The given graph represents $V-I$ characteristic for a semiconductor device. Which of the following statements is correct?

$LED$ is constructed from $GaAsP$ semiconducting material. The energy gap of this $LED$ is $1.9\, eV$. Calculate the wavelength of light emitted and its colour.
$[h = 6.63 \times 10^{-34} \, Js$ and $c = 3 \times 10^{8} \, ms^{-1}]$

The bandgap of the material of a photodiode is $2.0 \ eV$. What is the minimum frequency of radiation that this material can absorb?

Which one of the following statements is '$WRONG$' regarding $LED$?

Statement $-I$: $A$ photodiode operates in reverse bias.
Statement $-II$: The fractional change due to the photo-effects on the minority carrier dominated reverse bias current is more easily measurable than the fractional change in the forward bias current.