Energy Transfer through Living Systems Intro to Boiled Leaf Lab

Transfer of Energy Photosynthesis: How plants make food 6CO2 + 6H2O + light energy C6H12O6 + 6 O2 Cellular Respiration: How plants use stored food C6H12O6 + 6 O2 6 CO2 + 6H2O + energy chlorophyll

6CO2 + 6H2O + light energy C6H12O6 + 6 O2 six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen Chlorophyll

Photosynthesis in plain language Carbon Dioxide + Water (in the presence of light/chlorophyll) produce glucose (sugar) + oxygen.

What’s the big deal about chlorophyll? Sunlight Energy (can’t use this!) (thanks to chlorophyll) Chemical Energy (can use this) Chlorophyll is the green pigment that converts sunlight energy into something usable! It is a green pigment that absorbs light)

Respiration The process by which a plant uses up its stored food for energy.

Examples of Energy Transfer in the cell Photosynthesis in chloroplast inside of a mesophyll cell. “Photo”. Energy from the sun is harnessed into a chemical energy. Synthesis” Calvin Cycle and little help from carbon fixation, the actual sugar glucose is made. Cellular Respiration. This process is basically how energy transfers from the chemical energy in food to energy our body can use (ATP) (Campbell, 160-162).

Some Questions 1. The molecule produced directly by photosynthesis is: lipids; b) sugar; c) amino acids; d) DNA 2. Carbon dioxide enters the leaf through ____. a) chloroplasts; b) stomata: c) cuticle; d) mesophyll cells; e) leaf veins

New Lab! Scientific Question: Leaves are the most important photosynthetic organs of the plant. 1. What does the color of the leaf mean to you? 2. What would happen to this geranium plant if we deprived it of light? 3. How could you test this? Think about chlorophyll. Chlorophyll is a green pigment that absorbs unusable sunlight and converts it into usable chemical energy.

Boiled Leaf Lab

Preparation: Cut 2 one inch square pieces of thick cardboard (like cereal box) Clip the two pieces of cardboard to a leaf still growing and attached to a plant Label your squares Write down a prediction about what you will find under the cardboard squares

A day or two later… Pick the leaf Sketch the leaf with the cardboard on it Take off the cardboard Sketch the leaf noting any color changes

Saga continues… Boil the leaf in water for 5 minutes Sketch the leaf noting any color changes Note the change of color in the water Boil in alcohol for 5 minutes MUST WEAR GOGGLES! AVOID INHALATION! Sketch leaf noting any color changes

Lastly… Place iodine on the leaf Sketch the leaf noting changes in color Questions: Explain the reasons for each step. Write a paragraph explaining the results and make reference to photosynthesis, diffusion, starch and sugar.

Interpreting the test results Observe color change of the three leaves. The darker the color (purple), the more starch. The lighter the color, the less starch.