A student uses a potometer to estimate the rate of transpiration of a leafy shoot.
Which statement explains why the potometer may not give an accurate measure of the rate of transpiration?
The shoot is cut, so it can no longer take up any water through the xylem.
The air bubble shows the water lost from the leaves, not the water taken up.
Some water taken up is used by the shoot, for example in photosynthesis.
The capillary tube is too narrow to measure the volume of water accurately.
114 exam-style questions on OCR GCSE Biology 2.2 The challenges of size, covering 2.2.1 Exchange surfaces and surface area : volume ratio, 2.2.2 Substances transported in organisms, 2.2.3 The human circulatory system, 2.2.4 The heart and blood vessels, 2.2.5 Red blood cells and plasma, 2.2.6 Uptake of water and mineral ions by plants, 2.2.7 Transpiration and translocation, 2.2.8 Xylem and phloem, 2.2.9 Environmental factors and water uptake, and 2.2.10 Using a potometer. Each one has a worked solution and a mark scheme showing where the marks go.