Short Questions
1. How does transpiration assist the photosynthetic process?
Transpiration aids the photosynthetic process in two ways. First, it creates a transpiration pull (transport chain) that helps move water, minerals and other substances from roots, where they are absorbed, to leaves, where they are used. Secondly, it produces an evaporative cooling effect that prevents leaves from heating to temperatures that could inhibit or even denature the enzymes that catalyze the reaction of photosynthesis.
2. Why do plants appear green?
Plants appear green, because chlorophyll absorbs only the wavelengths in a certain spectrum, leaving or reflecting the wavelengths between about 500nm and 600nm which appears green to our eyes.
3. What is an accessory pigment?
An accessory pigment is a molecule that absorbs photons that Chlorophyll a absorbs poorly or not at all.
4. Describe and explain Priestley's experiment.
Priestley studied 2 scenarios. 1, was a lit candle inside an air tight bell jar. It eventually ran out of oxygen and died. 2, was a lit candle with a plant, the candle stayed lit a little longer, but eventually it died again. However, with the second scenario, the candle could be re-lit with a magnifying glass after a few days. This proved that the plant had to be creating oxygen for the candle to use to burn.
5. Why do plants change from green to red-orange-yellow in the fall?
The accessory pigments contained in the leaves of plants are not as numerous as the chlorophyll molecules. So the other colors are drowned out by the green reflected by the chlorophyll. In the autumn when it begins to get cooler, the plant stops creating chlorophyll and starts to disassemble the already existing ones, leaving the accessory pigments to reflect their color.
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