Required Practical: A student investigates germination. She places 50 cress seeds on damp cotton wool and counts how many have germinated (grown a root) each day for 7 days. Temperature and light are kept constant throughout.
(a)Identify one other variable, apart from temperature and light, that should be controlled in this investigation.(1)
(b)After 7 days, 42 of the 50 seeds had germinated. Calculate the percentage germination.(2)
(c)Calculate the mean number of seeds germinating per day over the 7 days.(2)
(d)Suggest why the student used 50 seeds rather than just 1 seed.(1)
(e)The student repeats the whole investigation and gets 88% germination the second time. Calculate the mean percentage germination for the two repeats.(2)
(f)Comment on how similar the two repeat results are and what this suggests about the reliability of the investigation.(1)