A young root grows through transparent nutrient gel. Its left and right sides are labelled. The root receives light evenly, and a rotating holder prevents gravity from causing a directional response. A narrow gel strip releases auxin beside the right side of the root. At the concentration supplied by the strip, root cells elongate more slowly than untreated root cells.
Which prediction is correct?
the root curves away from the strip as its right side becomes longer
the root remains straight because its two sides elongate equally
the root curves towards the strip as its left side becomes longer
the root curves away from the strip as its left side becomes longer
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.