An investigation was carried out to determine the conditions required for the germination of radish seeds.

Five boiling tubes were prepared, each containing 10 radish seeds placed on cotton wool and sealed with rubber bungs:

• Tube P contained dry cotton wool and was placed at a room temperature of 20°C in the light.
• Tube Q contained moist cotton wool and was placed at a room temperature of 20°C in the light.
• Tube R contained moist cotton wool and was placed in an incubator at 5°C in the dark.
• Tube S contained moist cotton wool and was placed at a room temperature of 20°C in the dark.
• Tube T contained moist cotton wool, was placed at a room temperature of 20°C in the light, and included a container of an oxygen-absorbing chemical.

The tubes were left for 5 days. The student then recorded how many seeds had germinated and measured the length of each shoot.

The observations were as follows:

• Tube P: no seeds germinated.
• Tube Q: 8 seeds germinated with the following shoot lengths: 1.4 cm, 2.5 cm, 1.9 cm, 2.2 cm, 1.7 cm, 2.0 cm, 2.4 cm, and 1.9 cm.
• Tube R: 3 seeds germinated with the following shoot lengths: 0.3 cm, 0.5 cm, and 0.4 cm.

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