to its leaves. Xylem tissue is Define the term to take sections and observe Investigate the effect of coverslips, composed of hollow tubes the dye in the xylem vessels oxygen availability on microscopes. ‘transpiration’. strengthened by lignin under the microscope. the growth of plants. Explain why there are Prepared slides: of adapted for the transport of Observe results in later more stomata on the Observe and draw xylem, and phloem and water in the transpiration lessons. lower surface of a root hair cells. Estimate the root hair cells, stream from the to the leaf. size of the cells. Describe Nuffield - investigate microscopes, leaves. how they are adapted for their the effect of changing bioviewers. Describe the role of functions. conditions on the rate stomata and guard Water evaporates in the of transpiration using a cells to control water Recap diffusion and osmosis. leaves and the water photometer. loss and gas Compare them with active vapour escapes through tiny exchange. transport. Produce a Students predict then holes in the surface of comparison table. research the effect of leaves called stomata. The Stomata: Leaves Calculate stomatal humidity on the rate of stomata can open or close from privet and density. Introduce active transport as transpiration. Calculate as conditions change spider plants, kettle, absorption against the Describe and size of stomata given because the guard cells can beakers, nail concentration gradient. compare the images and scale bar. gain or lose water by varnish, slides, Discuss when this might be processes of osmosis. coverslips and useful. diffusion, osmosis microscopes. and active transport. Observe a video or pictures The rate of transpiration Demo: 2 cylindrical of plants growing in soil and Explain how factors varies with: balloons, sellotape. in hydroponic solutions. such as light, humidity light intensity, which • Suggest why farmers and affects the opening of and moving air affect gardeners turn the soil and stomata the rate of hydroponic solutions must be air movements, which • transpiration. kept aerated. affect the concentration of Rap: water vapour in the air Use the Nuffield activity. around leaves
to its leaves. Xylem tissue is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream from the to the leaves. Water evaporates in the leaves and the water vapour escapes through tiny holes in the surface of leaves called stomata. The stomata can open or close as conditions change because the guard cells can gain or lose water by osmosis. The rate of transpiration varies with: • light intensity, which affects the opening of stomata • air movements, which affect the concentration of water vapour in the air around leaves Define the term ‘transpiration’. Explain why there are more stomata on the lower surface of a leaf. Describe the role of stomata and guard cells to control water loss and gas exchange. Calculate stomatal density. Describe and compare the processes of diffusion, osmosis and active transport. Explain how factors such as light, humidity and moving air affect the rate of transpiration. to take sections and observe the dye in the xylem vessels under the microscope. Observe and draw xylem, and root hair cells. Estimate the size of the cells. Describe how they are adapted for their functions. Recap diffusion and osmosis. Compare them with active transport. Produce a comparison table. Introduce active transport as absorption against the concentration gradient. Discuss when this might be useful. Observe a video or pictures of plants growing in soil and in hydroponic solutions. Suggest why farmers and gardeners turn the soil and hydroponic solutions must be kept aerated. Use the Nuffield activity. Investigate the effect of oxygen availability on the growth of plants. Observe results in later lessons. Nuffield - investigate the effect of changing conditions on the rate of transpiration using a photometer. Students predict then research the effect of humidity on the rate of transpiration. Calculate size of stomata given images and scale bar. coverslips, microscopes. Prepared slides: of phloem and root hair cells, microscopes, bioviewers. Stomata: Leaves from privet and spider plants, kettle, beakers, nail varnish, slides, coverslips and microscopes. Demo: 2 cylindrical balloons, sellotape. Rap:
AQA-8465-SOW-TOLD.DOCX