Four students each describe an experiment…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Four students each describe an experiment. (a) Mia says: "I put a mint plant in a closed jar with a burning candle, and the candle did not go out." (b) Omar says: "I split light with a prism and found where bacteria collected along an alga." (c) Lena says: "I showed that a green leaf kept in light stores starch." (d) Kofi says: "I showed that only green parts of a water plant give off bubbles, and only in light." Match each student's experiment with the scientist, and give what it showed.
Need a reminder? The key ideaShow
Priestley (1770): a mint plant restores the air that a burning candle or an animal makes unfit. Ingenhousz (1779): sunlight is needed and only green parts release oxygen. Sachs (1854): glucose is made in green parts and stored as starch. Engelmann: bacteria gather in the blue and red regions of a prism spectrum, the first action spectrum. Van Niel: bacteria using H2S give out sulphur; in green plants the donor is water, so the oxygen comes from water. Overall: . Water is oxidised, carbon dioxide is reduced.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Mia. The mint plant and the candle are Priestley's experiment. It showed that plants restore the air that a candle or an animal makes unfit.
Step 2. Omar. The prism and the bacteria are Engelmann's experiment. It showed that the blue and red regions work best, which was the first action spectrum.
Step 3. Lena. Starch stored in a green leaf is Sachs's result. Glucose is made in green parts and stored as starch.
Step 4. Kofi. Bubbles from green parts in light are Ingenhousz's result. Sunlight is needed, and only the green parts release the gas.
Answer: (a) Priestley; (b) Engelmann; (c) Sachs; (d) Ingenhousz.
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