A researcher places germinating oat seedlings horizontally in an opaque growth chamber to investigate the response of the shoots to gravity. Light from the room enters from one side through an uncovered observation window.
Explain how leaving the observation window uncovered could weaken the researcher's conclusion that gravity caused any curvature of the shoots.
105 exam-style questions on Edexcel GCSE Biology 6.3 Plant hormones, covering 6.3.1 Plant hormones and tropisms and 6.3.2 Commercial uses of plant hormones. Each one has a worked solution and a mark scheme showing where the marks go.