Question 1
Paper 2Medium16 marksA student investigated the effect of water availability on seed germination. Five dishes were used for each treatment, with 20 seeds in each dish. Each dish contained filter paper and the same type of water. The dishes were kept at the same temperature and light conditions. After 72 hours, a seed was counted as germinated if its radicle had emerged. At 20 mL, the seeds were fully submerged; at the other volumes, the filter paper was moist but the seeds were not submerged.
| Water added / mL | Number of seeds germinated out of 100 |
|---|---|
| 0 | 0 |
| 2 | 38 |
| 5 | 82 |
| 10 | 86 |
| 20 | 42 |
Calculate the difference in germination percentage points between the 10 mL and 20 mL treatments.
Describe the relationship between water added and germination.
Explain why germination was absent without added water but high in the 5 mL and 10 mL treatments.
Explain how water acts as a transport medium from roots to leaves in a seedling, including one adaptation of xylem for this role.
The syllabus statement is that water is the medium for life. Using the results and your biological knowledge, explain how water can be essential as a medium without increasing water volume always increasing germination. Refer to the environment in which the first cells originated and to a role of water in present-day cells.