A student wanted to investigate the conditions required for the germination of radish (Raphanus sativus) seeds.

She set up 5 petri dishes, each containing 12 radish seeds placed on filter paper, sealed in clear bags:

• Dish P contained dry filter paper and was placed in an incubator at 22°C in the light.
• Dish Q contained moist filter paper and was placed in an incubator at 22°C in the light.
• Dish R contained moist filter paper and was placed in a cold-room at 2°C in the dark.
• Dish S contained moist filter paper and was placed in an incubator at 22°C in the dark.
• Dish T contained moist filter paper and was placed in an incubator at 22°C in the light, but contained an oxygen-absorbing chemical inside the bag.

The student left the dishes for 5 days and then returned to observe the results. She measured the length of the shoots and recorded how many seeds had germinated.

Some of her results are shown below:

• Dish P: no seeds germinated.
• Dish Q: 9 seeds germinated with the following shoot lengths: $2.4cm$, $3.1cm$, $2.8cm$, $2.5cm$, $2.7cm$, $3.3cm$, $2.9cm$, $2.6cm$, and $2.9cm$.
• Dish R: 3 seeds germinated with the following shoot lengths: $0.3cm$, $0.6cm$, and $0.3cm$.

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