A student investigated the effect of gravity on newly germinated seedlings. He pinned four germinating seedlings to a cork board so that each root pointed in a different direction. He put the board inside a light-proof box for 3 days. He set up a second board in the same way and fixed it to a clinostat, which turned the board round slowly all the time. The clinostat was also kept in the dark.
Explain why both boards were kept in the dark.
Describe the results the student should expect for the four roots on the board that did not turn.
Explain why the roots on the clinostat grew straight out instead.
59 exam-style questions on AQA GCSE Biology 5.4 Plant hormones, covering 5.4.1 Control and coordination and 5.4.2 Use of plant hormones (HT only). Each one has a worked solution and a mark scheme showing where the marks go.