Photosynthesis review questions

1) After Thanksgiving break you return to the HTHMA garden to find that your crops have not been watered in over two weeks. Most of your plants are dead and those that are alive are barely hanging on.  In relation to the process of photosynthesis, describe what has happened to your plants.

There was not enough H2O to assist the plant in making Glucose to sustain itself. H2O is the main ingredient in photosynthesis, and it enables the plant cells to break down Carbon dioxide and form the molecules into Glucose. Since H2O works in the light-dependent reactions, the Calvin cycle is shut off from utilizing ATP to work. What water left inside the plants that are still alive must have been stored in the plant prior to the event. Plant cells can retain water, although most cells when dehydrated shrink and die. The Cellulose walls of the plant cells keep the plant's form, but when a plant does not have enough water in its cells, than each of its cells shrink inside itself, creating a wilted look to the plant. If the plant is rehydrated, there could be a chance of reviving its cells back to health.

2) Upon microscopic inspection of the underside of your plant’s leaves, you notice that in an attempt to conserve water the stomata (aka stomates) are closed. Explain in detail how this impacts the light independent reactions of photosynthesis.

Light independent reactions can still go on as long as ATP powers them. A plant might have enough ATP to work its Light independent cycle, and some plants store and retain water. I have heard that this happens with grass at times when it gets dry (usually in the mid-day time when the sun is out). When it gets hot, and water begins to evaporate, the grass world close its stomata. When it senses water the plant allows its stomata to open again. A helpful tip related to grass is to never water plants while the sun is out and it is hot. The Stomata will open up and try to take in the water, but if the water evaporates faster than the Stomata can take in, the plant gains little to no water and might even lose H2O in the process, making it harder to keep its Light independent cycles running.