DP Biology (first assessment 2025)
Question 19M.2.SL.TZ2.16a
Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.2.SL.TZ2.16a |
Level | SL | Paper | 2 | Time zone | TZ2 |
Command term | Explain | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 3]
19M.2.SL.TZ2.16a
(a)
Explain the factors that can contribute to the exponential growth phase in a sigmoid population curve.
[3]
Markscheme
a. ideal environment/unlimited resources/below carrying capacity ✔
b. little disease/few predators ✔
c. high natality/birth rate AND immigration ✔ Both needed.
d. natality and immigration greater than mortality and emigration ✔
Examiners report
The vast majority of candidates could provide part of an explanation; most mentioned resources, but for many the effect of natality, mortality, immigration and emigration (both not well distinguished for some) was obscure.

