Selective weedkillers contain synthetic auxins. Farmers spray them on fields of wheat to kill broad-leaved weeds. Which statement explains how a selective weedkiller works?
It makes the wheat grow taller, so it shades out the weeds.
It makes broad-leaved weeds grow too fast, so they die.
It is absorbed by all plants, so every plant in the field dies.
It stops broad-leaved weeds absorbing light for photosynthesis.
84 exam-style questions on OCR GCSE Biology 3.2 Coordination and control – the endocrine system, covering 3.2.1 Principles of hormonal coordination and control, 3.2.2 Roles of thyroxine and adrenaline, 3.2.3 Hormones in human reproduction, 3.2.4 Interactions of reproductive hormones, 3.2.5 Hormones in contraception, 3.2.6 Hormones in reproductive technologies, 3.2.7 Plant hormones in growth and coordination, 3.2.8 Effects of plant hormones, and 3.2.9 Uses of plant hormones. Each one has a worked solution and a mark scheme showing where the marks go.