The table below shows the results of an investigation into seed dispersal by a coastal plant. A student placed equal numbers of its seeds in moving water an...
Question 1 Report
The table below shows the results of an investigation into seed dispersal by a coastal plant. A student placed equal numbers of its seeds in moving water and measured how far the seeds travelled before becoming trapped. The seeds have a waterproof outer layer and contain air spaces.
| water speed / cm s-1 | mean distance travelled before trapping / m |
|---|---|
| 5 | 1.8 |
| 10 | 4.7 |
| 15 | 8.9 |
| 20 | 13.6 |
(a) Describe the effect of water speed on distance travelled. [2]
(b) Explain how seed dispersal helps the survival of a plant species. [2]
(c) State the part of a flower that develops into a seed after fertilisation. [1]
(d) Design an improvement that would make the student's mean results more reliable. [3]
Answer Details
(a) Distance travelled increases as water speed increases. For example, seeds travel a mean of \(1.8\text{ m}\) at \(5\text{ cm s}^{-1}\), but \(13.6\text{ m}\) at \(20\text{ cm s}^{-1}\). [2]
(b) Dispersal allows seeds to grow away from the parent plant. This reduces competition for light, water, mineral ions or space, and can allow the species to colonise new areas. [2]
(c) The ovule develops into a seed after fertilisation. [1]
(d) Repeat trials at every water speed, use a larger number of seeds, and calculate a mean. Identify and ignore anomalous results when justified. Repeats reduce the effect of random variation, making the mean more reliable. [3]
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