Paper 3 · June 2017 · gene banks, seed dormancy and biosensors
A reason for maintaining a gene bank is to
Araise the yield of a crop by selecting and sowing the largest seeds each season.
Bconserve alleles of wild relatives that plant breeders may need later.
Cincrease the rate at which new mutations arise in a crop species.
Dprovide a store of harvested grain to be sold when prices improve.
Explanation
Modern crop varieties are genetically narrow, and once a landrace or wild relative is lost the alleles it carried, for drought tolerance or disease resistance, are lost with it. A gene bank keeps that variation available so a breeder can draw on it when a new pest or a changed climate demands it. A gene bank is not a commercial grain store and it does not itself generate new variation.
Derived from ZIMSEC Biology Paper 3, Jun 2017, Q12