At a tree nursery, a mesh windbreak reduces air movement around one row of young beech trees. A second row is exposed to faster-moving air.
The trees are well watered, and measurements are made at the same light intensity and leaf temperature.
Which statement explains why the sheltered trees have a lower rate of transpiration?
Water vapour accumulates beside the leaves, making the concentration gradient less steep.
The mesh reduces the area of each leaf through which water vapour can diffuse.
A lower air speed makes water move down the xylem from the leaves to the roots.
Less moving air means less energy is supplied to water molecules in the leaves.
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.