Statement-1: A photodiode operates in reverse bias.
Statement-2 : 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.

A photodiode operates in reverse bias.
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.

When reverse biased, current will only flow through the photodiode with incident light creating photocurrent. The reverse bias causes the potential across the depletion region to increase and the width of the depletion region to increase. This is ideal for creating a large area to absorb the maximum amount of photons.