Temperature (degrees Celsius) Number of seeds germinated (out of 50) Percentage germination (%) 10 4 8 20 21 42 25 36 72 30 44 88 45 15 30 A farmer carried ...
Question 1 Report
| Temperature (degrees Celsius) | Number of seeds germinated (out of 50) | Percentage germination (%) |
|---|---|---|
| 10 | 4 | 8 |
| 20 | 21 | 42 |
| 25 | 36 | 72 |
| 30 | 44 | 88 |
| 45 | 15 | 30 |
A farmer carried out an experiment to investigate the effect of temperature on seed germination. She placed 50 maize seeds at each of five different temperatures. All other conditions were kept the same. After 10 days she counted the number of seeds that had germinated. The results are shown in Table 1.
(a) State the temperature at which the highest percentage of seeds germinated. [1]
(b) Describe the effect of temperature on seed germination shown in Table 1. [3]
(c) Suggest one reason why very few seeds germinated at 10 degrees Celsius. [1]
(d) Name two conditions, other than a suitable temperature, that are needed for seed germination. [2]
[Total: 7]
Answer Details
(a) The highest percentage of seeds germinated at 30 degrees Celsius, where 88% (44 out of 50) germinated [1].
(b) The effect of temperature on seed germination shown in the data follows a clear pattern:
- As temperature increases from 10 to 30 degrees Celsius, the percentage of seeds that germinate increases steadily (from 8% to 88%) [1].
- Germination reaches its peak at 30 degrees Celsius with 88% [1].
- Above 30 degrees Celsius, germination decreases sharply: at 45 degrees Celsius only 30% of seeds germinated [1].
This pattern reflects an optimum temperature for germination, with both very low and very high temperatures being unfavourable.
(c) Very few seeds germinated at 10 degrees Celsius because at low temperatures, enzyme activity is very slow [1]. The metabolic reactions required for germination (such as the breakdown of stored food reserves in the endosperm and the synthesis of new proteins for growth) depend on enzymes, which function slowly at temperatures well below the optimum.
(d) Two conditions, other than suitable temperature, needed for seed germination (any two) [2]:
- Water (moisture) - needed to soften the seed coat, activate enzymes, and transport dissolved nutrients to the growing embryo.
- Oxygen (air) - needed for aerobic respiration, which provides the energy the embryo requires to grow.
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