DP Biology (last assessment 2024)
Question 18M.3.HL.TZ1.14a
| Date | May 2018 | Marks available | [Maximum mark: 1] | Reference code | 18M.3.HL.TZ1.14a |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 1]
18M.3.HL.TZ1.14a
(a)
The sea star Pisaster ochraceus is identified as a keystone species in the Pacific Ocean.
Outline the characteristics of keystone species in an ecosystem.
[1]
Markscheme
a. keystone species has a strong/disproportionate effect on a community/food web/ecosystem
b. absence of keystone species would completely alter the ecosystem
