Question 19M.1B.SL.TZ2.c
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.1B.SL.TZ2.c |
| Level | SL | Paper | 1B | Time zone | TZ2 |
| Command term | Suggest | Question number | c | Adapted from | N/A |
After fertilization, seeds of T. grandiflora form in a small pod. If you were provided with Petri dishes, absorbent cotton balls and seeds, suggest how one variable affecting germination of these seeds could be investigated.
[3]
a. different values for the named independent variable ✔ Name of the independent variable must be included, eg temperature.
b. large / equal number of seeds in each Petri dish ✔
c. control of other variables «than seeds» ✔
d. mentions how germination will be determined eg appearance of radicle.
OR
how germination rate/percentage will be measured ✔ eg number germinated over time/in a set time. Do not accept measurement of growth of stem/number of leaves.
e. includes a control giving seeds all factors needed ✔
Possible factors include water, oxygen, temperature, pH, light, salt concentration.
This question was an open opportunity for candidates to display their understanding of experimental processes. Although a certain number of well-structured answers were seen, this was probably the most poorly handled question of this paper. Although most had understood that only one variable could be changed at a time, it was expected they should have the basic knowledge that water is essential for germination and would go beyond experiments involving one seed with water and one with no water, as too many suggested. The majority could not understand that, to draw valid conclusions, many seeds should be used in many repeats and that controls should be used. They also had much difficulty at suggesting how results could be gathered, often confusing germination with seedling growth. One can therefore wonder about how the practical programme is delivered in many schools.
