Question 18N.3.HL.TZ0.17
| Date | November 2018 | Marks available | [Maximum mark: 6] | Reference code | 18N.3.HL.TZ0.17 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 17 | Adapted from | N/A |
Explain how an ecological community structure could be affected by the removal of a keystone species.
[6]
a. «keystone species» have a main/disproportionate role in the maintenance of the structure of a community ✔
b. not necessarily top predator/most abundant species
OR
affect other organisms even if they have a small biomass/productivity ✔
c. may impact a top-down/bottom-up control ✔
d. «if removed» cause increase in populations of secondary consumers and decrease of primary consumers ✔
OWTTE
e. «if removed» may cause loss of balance in food chain/community ✔
f. «if removed» may cause «drastic» loss of biodiversity
OR
extinction of species ✔
g. example of named keystone species ✔
eg: honey bees
h. example of role in the environment where they are found ✔
eg: pollinate flowers
i. example of change if removed ✔
eg: plant reproduction is reduced
This question can be answered by referring to one specific species
