Gce Model Questions Vol1 2020 Biology Question 9

A tropical plant species X can reproduce both sexually (by seed) and asexually (by vegetative off‑shoots). Over a 12‑month period the following observations were recorded: - Seeds produced each month (Jan–Dec): 120, 150, 200, 180, 160, 140, 130, 110, 100, 90, 80, 70. - Germination rate of the seeds = 60 %. - Survival rate of germinated seedlings to maturity = 40 %. - Vegetative off‑shoots produced each month (Jan–Dec): 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85. - Survival rate of off‑shoots to maturity = 80 %. - The initial adult population at the start of January was 200 mature individuals. Using the data above, answer the following: a) Determine the total number of new mature individuals that arise from sexual reproduction and from asexual reproduction during the 12‑month period. b) Calculate the net increase in the mature population after one year and give the final population size. c) Discuss two ecological advantages for species X in maintaining both reproductive modes. Then explain how a prolonged drought that sharply reduces seed production but does not affect off‑shoot formation might alter the relative contributions of the two modes to population growth.