| Date | May 2010 | Marks available | 1 | Reference code | 10M.1.HL.TZ2.32 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | State | Question number | 32 | Adapted from | N/A |
Question
How do mineral ions in the soil move into the root?
A. Osmosis
B. Mass flow of water
C. Translocation
D. Through phloem
Markscheme
B
Examiners report
This question contained an error, which a small number of G2 forms commented on. The question was intended to be based on AS 9.2.2, how mineral ions move to the root, not how they enter the root. The answer was therefore B. However the question actually asked how mineral ions move into the root. Perhaps surprisingly, this question proved to be the best discriminator on the paper. The most able candidates presumably answered it by eliminating the other answer, because they knew that mineral ions do not enter roots by osmosis, translocation or through phloem. There was some truth in the answer mass flow of water as mineral ions do pass through epidermis and cortex cell walls in the apoplastic flow of water, but this is certainly not expected knowledge for IB Biology candidates.
