14. Homeostasis
A section of Biology, 9700
Listing 10 of 131 questions
Most of the water lost from plants passes out through the stomata of leaves. The distance between open guard cells is known as the stomatal aperture, as shown in . stomatal aperture Researchers investigated the effect of stomatal aperture on rates of transpiration in leaves of Tradescantia zebrina under two conditions: • air kept moving by a fan (moving air) • non-moving air. The results are shown in . stomatal aperture / +m rate of transpiration / g m–2 h–1 moving air non-moving air Compare the effect of stomatal aperture on the rate of transpiration in T. zebrina in the two conditions. Explain the effect of stomatal aperture on rates of transpiration in non-moving and moving air. Spruce trees and pine trees are adapted to dry conditions where water can be in limited supply. shows two stomata in a spruce leaf and shows a vertical section through a stoma from a pine leaf. Explain how the stomatal features shown in and give an advantage to plants such as spruce and pine. Some plants that live in very dry conditions close their stomata during the day and open them at night. State one disadvantage of this for these plants. State and explain two adaptations that plant leaves have for survival in dry conditions other than those involving number or structure of stomata. 1. 2.
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THEORY
2015
Paper 2, Variant 3
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