Question 18N.2.HL.TZ0.a
| Date | November 2018 | Marks available | [Maximum mark: 3] | Reference code | 18N.2.HL.TZ0.a |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Outline | Question number | a | Adapted from | N/A |
Calcium is absorbed from food in the human gut by both active and passive processes. Outline active transport, including the benefits of the process.
[3]
a. moved against a concentration gradient/lower to higher concentration ✔
b. energy/ATP required/used ✔
c. pump/carrier «protein» «carries out active transport» ✔
d. absorption «by active transport» into a cell is possible even if exterior concentrations are «very» low
OR
allows all/nearly all of/more of the substance/calcium to be absorbed «whereas diffusion can only even out concentrations»
OR
unidirectional/allows the direction of movement to be controlled
OR
allows a concentration gradient to be built up/potential energy to be stored/membrane potential to be generated/maintained
OR
allows a specific concentration to be maintained «in a cell» ✔
