Paper 3 · June 2017 · gene banks, seed dormancy and biosensors
A seed sample in a seed bank falls short of 100 per cent germination because
Aseeds are only viable in the season in which they were collected.
Bsome seeds are dead, some are damaged and some are still dormant.
Call the seeds germinate but the seedlings die before they can be counted.
Dgermination testing destroys a fixed proportion of every sample by law.
Explanation
A sample is a population of individuals, not a uniform batch. Some seeds were never viable or have lost viability in store, some were damaged during collection, cleaning or drying, and some are alive but held in dormancy that the test conditions did not break. The count is therefore always short of the full number, which is why a viability standard is set at a figure such as 75 per cent rather than at 100.
Derived from ZIMSEC Biology Paper 3, Jun 2017, Q12