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Transcript of Photosynthesis
2012 This is a basic video to show what plants need to grow. Also know as "The Photosynthesis" song. What plants need to grow.. more detailed. Chlorophyll traps light energy
to make food.
Water is absorbed from the
roots. Along with some other
CO2 enters through the
stomata of the leaves.
Oxygen is released into the
atmosphere through the
stomata. Carbon Dioxide + Water ---------> Glucose + Oxygen Light energy Chlorophyll (Reactants) (Products) Word Equation: Balanced Symbol Equation: Feature of a leaf Waxy Cuticle- reduces water loss. Thicker upper surface because this layer is more exposed to sunlight. Testing a leaf for starch 1- Kill the leaf by placing in boiling water (destroys the cell membrane and makes the cells leaky) Upper Epidermis- One cell thick. Transparent which allows free passage of light. Palisade Mesophyll- Contain many Chloroplasts and the dense packing of these cells allows the maximum absorbtion of light energy. Vein- the transport system in and out of the leaf. Xylem: delivers water and mineral salts.
Phloem: carry away the organic products of photosynthesis (glucose) Spongy mesophyll- Air spaces between these cells aid the diffusion of gases through the leaf. Stomata- the pores allow the entry of carbon dioxide and the exit of oxygen. Mainly present in the lower epidermis. Less water evaporation due to the fact the surface is less exposed to sunlight. 2- Remove chlorophyll (place test tube with ethanol and leaf in a beaker of hot water) ethanol will turn green. 3 - Soften the leaf (pick up the leaf using forceps and dip into hot water to soften to allow penetration of iodine solution) 4- Stain with iodine (spread leaf on white tile and cover with iodine) Result: * If starch present leaf will change from yellow/brown to a dark blue/black (the darker the colour the more starch present). (Experiment) Raw materials required for photosynthesis 1-Light: cover area of leaf with black paper clipped onto both sides. Plant Minerals 2-Place leaf in sealed air tight bag with soda lime (removes CO2) . 3-Place leave in air tight bag with Hydrogen Carbonate solution (releases CO2) The leaf in the bag with the soda lime will not produce starch and therefore will remain yellow/light brown (no starch detected). The leaf in the bag with the Hydrogn Carbonate solution will be completely black/dark blue (starch has been detected). *Leaves must be destarched before beginning experiment by placing in a dark place (48 hours). LIMITING FACTOR : A factor that controls how quickly photosynthesis occurs/rate of photosynthesis. Increasing the light intensity will boost the speed of photosynthesis. Light is essential for plant growth. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide. CO2 is also essential for plant growth. If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot (enzymes are dentatured). * magnesium ions are required to make the protein chlorophyll. *magnesium deficiency - upper leaves are pale green and lower leaves pale yellow. * nitrate deficiency - reduced/stunted growth, upper leaves pale green and bottom leaves pale yellow or dead and weaker stem or roots. Yield of Commercial Crop Using fertilisers (organic or inorganic material containing minerals). We insure that the plants recieve the required minerals (magnesium/nitrogen) for growth. By not using fertilisers we decrease the chances of healthy plant growth hence lower crop yield. light intensity, temperature and carbon dioxide levels could increase the yield of commercial crops. HOW? The more light absorbed the more food made because chlorophyll traps light energy. Temperature affects enzyme activity. Very high temperatures will dentature the enzymes and too low temperatures will slow the enzyme activity. Carbon Dioxide is needed for photosynthesis and plant growth.With these factors controlled the rate of growth increases as the plants are recieving optimum conditions and therefore the yield of commercial crop increases. Measuring the rate of photosynthesis Light- *Nitrates are required to make amino acids/proteins. One of these proteins is chlorophyll.
1- Gradually move the light further away from the
2-Count the number of Oxygen bubbles produced
per minute at each distance.
Temperature- 1- Count the number of oxygen bubbles produced per
minute at different surrounding temperatures (20 - 50 degrees celicius). *water temperature, concentration of Hydrogen in vessel, wave length of light, species of plant used and number of leaves on plant must be controlled to remain a fair test. As you move the light source away from the water plant less bubbles/oxygen will be produced due to the fact that lower light intensity means a lower rate of photosynthesis. As the temperature increases more oxygen/bubbes will be produced but after it has reached the optimum temperature the rate of the oxygen bubbles produced will slow down as the enzymes of the plant are begining to denature (as high temperatures are dangerous for plants).