Edexcel GCSE Plant structures and their functions Community and factors: Photosynthetic reaction: Discuss which organelle is more important to a plant - mitochondria or chloroplasts? Why is water not normally classed as a limiting factor of photosynthesis? Justify why oxygen is a waste product of photosynthesis. Why do conifers and pine trees grow in a cone shape? Core practical: Plan an experiment to investigate how different wavelengths of light affect photosynthesis in water plants. It has been suggested that LED lamps would be better to use for shining on the water plant than a normal light bulb lamp. Suggest why. How can you investigate the effect of light intensity on photosynthesis on a terrestrial plant? Use of glucose from photosynthesis: What percentage of a glucose molecule is made from carbon? How do seedlings grow underground before photosynthesis can happen? Design a method to extract oil from sunflower seeds. Why is oil present? How can we investigate that variegated leaves produce less glucose? Iodine solution turns black when dripped onto paper. Explain why. Transpiration experiment: A student took four leaves from a healthy well watered plant. He covered one leaf in vaseline on the top and bottom surface, one leaf was covered with vaseline on the top surface and one leaf was covered on the lower surface. One leaf was left untreated. He weighed each leaf and then suspended them on a washing line with pegs for 24 hours at room temperature. Suggest what he would find the next day when he reweighed each leaf and explain why. : Rate of photosynthesis: Discuss whether photosynthesis occurring on land or under water produces most oxygen. Do leaves in the middle of a tree photosynthesise as efficiently as those at the top and closer to the sun? Explain. If all the cells in a leaf contained chloroplasts wouldn’t photosynthesis be more effective? Can a plant photosynthesise in moonlight? Edexcel GCSE Plant structures and their functions ThinkIT! © Copyright The PiXL Club Ltd, 2017 Plant hormones (biology only): Explain why shoots grow away from gravity and roots grow towards gravity. In cold climates farmers soak seeds in gibberellins. Suggest why. Some people say that to ripen green tomatoes you can put them in a bag with a ripe banana. Explain why. A bean seedling is growing upright in soil. Suggest what would happen if it was laid on its side in the soil and the tips of the roots and shoots were cut off. : Plant tissues, organs and systems: Explain how plant tissues work together within a plant organism. Explain how phloem and xylem are adapted to their functions. Explain how a plants transport system is dependent on environmental conditions. Explain how gas exchange in plants is affected by the water content of leaves. If xylem is dead how does a plant grow taller? Commercial uses: How are seedless grapes produced and why is this necessary? Does this treatment affect food security? Explain your answer. Auxins promote growth so why are they also used as weedkillers? Research a plant that lives in extreme conditions. Explain how it is adapted to survive. : :