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Average ocean water has a salinity of 35g of dissolved salts.

This is because there is the more salt and other dissolved chemicals within the potato then the surrounding water.

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In photosynthesis, water splitting ..

The thawing of large icebergs (made of frozen fresh water and lacking any salt) will decrease the salinity while the actual freezing of seawater will increase the salinity temporarily.

This salinity measurement is a total of all the salts that are dissolved in the water.

If a marine osmotic conformer were put in super salty water (greater than 35 o/oo salt) then osmosis would cause the water inside the cells to move out, eventually causing the cells to dehydrate (plasmolyze).

the influences of salt stress on photosynthesis and ..

This means that 1000g of average seawater contains 965 grams of water and 35 grams of salts.

, ) showed that recovery after a severe drought was a two-stage process: a first stage occurred during the first days upon re-watering, and consisted basically in leaf re-watering and stomata re-opening; and a second stage lasted several days and was supposed to require de novo synthesis of photosynthetic proteins. Recently, have shown that recovery after water stress, determined 10 d after re-watering, was accompanied by increases in some photosynthetic proteins, particularly Rubisco activase and proteins of the water splitting complex, although increased proteins transcripts were not detected. In the cases where photosynthesis recovery is slow and/or incomplete, sustained photoprotection and/or oxidative stress have been suggested as possible causes (; ). The influence of previous water stress severity on the velocity and extent of photosynthesis recovery has been illustrated in kidney bean by and . On the other hand, have shown that the interaction of salt and water stress strongly reduces plant's capacity to recover photosynthesis after stress alleviation as compared with plants subjected to a single stress. However, in these studies, the physiological mechanisms limiting recovery were not assessed. Therefore, current knowledge about physiological limitations to photosynthetic recovery after different water- and salt-stress intensities, as well as under different environmental conditions, is scarce.

The carbon balance of a plant during a period of salt/water stress and recovery may depend as much on the velocity and degree of photosynthetic recovery, as it depends on the degree and velocity of photosynthesis decline during water depletion. Surprisingly, since early studies by , ), photosynthesis recovery after stress has been scarcely studied. In general, plants subjected to mild stress recover fast (within 1 or 2 d) after stress is alleviated, but plants subjected to severe water stress recover only 40–60 % of the maximum photosynthesis rate during the day after re-watering, and recovery continues during the next days, but maximum photosynthesis rates are not always recovered (, ; ; ; ; ; ).

I will then add 5 different salt-water solutions ranging from ..

Salinity is related to the concentration of dissolved salts in seawater.



Let us see now how protists and other little animals of ponds react to alteration to theirenvironment.
1 - Some microscopic algae, like the euglena, search out light (phototaxis) and to do thisthey use an organelle sensible to the light, named stigma. With a dark paper, cover thebottom part of a test tube holding a culture of euglena. The part of the test tube exposedto light should become green, rich with algae. Make the same experiment with othermicroscopic algae and with protozoa.
2 - Add two or three drop of distilled water to a little water drop collected in a pondand watch what happens to the protists. Very probably you will see them inflate and thenexplode. This occurs because of the different saline concentration inside and outside theprotists and the osmotic pressure which is produced inside their cells.
3 - Protists are sensitive to most chemicals and generally they react by running away; insome cases instead they approach them (chemotaxis). Prepare some microscope slides withprotists and observe through the microscope their behavior when you add acidic substances(i.e.: vinegar), basic substances (i.e.: backing soda), glucose, salt, sparkling water(rich of CO2), broth, milk, tiny grain of cheese, dyes, etc. At thebeginning use very low amounts of these substances, then increase their concentration.
4 - From a pond or an aquarium, collect a hydra and place it on a microscope slide with apair of water drops. Observing this tiny polyp through the microscope, probably you willsee some sucker shaped microorganisms (trichodina) moving on its body. Watch what happensafter adding a little drop of vinegar to their water! Trichodina will escape from thehydra and probably die. Hydra itself will have launched many of its harmful paralyzingdarts.
5 - Submit protists to different stimulus such as light, temperature, electric field(about 5 V in DC). In this last case, some protists will gather on the cathode (thenegative - pole). Also amebas are inclined to move towards the cathode. Change thepolarity of the current and observe the behavior of the protists.
Internet Keyword: phototaxis chemotaxis protists.



If placed in a suitable nutrient environment, cells and tissues of many organisms are ableto reproduce and form new plants or animals. Now, we will deal with vegetable tissues,whose culture is simpler than that of animal cellules and tissues. It is necessary toprepare a nutritive and sterilized culture medium for the piece of plant tissue. Keep theculture in the suitable conditions of light and temperature and which vary from plant toplant. Over many days, you will observe the growth of a callus or roots or shoots. In thisway you can obtain even whole plants (cloning). These experiments show that special cellskeep all the information necessary to generate the whole plant.
As we have mentioned, it is necessary avoid bacteria and moulds in the cultures. For thisyou will need sterilize tools, vials, tubes, and nutrient medium. Place each in anautoclave for a ten minutes or, lacking an autoclave, a pressure cooker. The tissues aswell have to be free from microorganisms and they have to be sterilized with bleach (40%solution for 15 min) or with alcohol.
The transfer of the tissues into the test tubes has to be made in aseptic conditions,using a sterile box. Lacking that, make your first trials in a quiet place, as devoid ofwind and dust as possible. The culture medium should contain water, vitamins (particularlythose of the B-complex. For this, use yeast extract), sugars, mineral salts. To enrich thewater with mineral salts, boil some water with a handful of soil, then let settle andfilter it. Usually, people also insert 0.5-0.8% of agar-agar to "solidify" themedium. As culture medium, coconut milk has been used. It contains mineral salts, sugars,vitamins and growth hormones.
1 - For yours first tests of micropropagation, use strawberries tissues.
2 - If this simple experiment interests you, you can continue on the way of the invitro culture of vegetable tissues. In fact you can propagate a lot of plants in thisway. Plants easy to culture are the following: tomato, potato, strawberry, chrysanthemum,geranium, sunflower, tobacco, carrot and onion. You can use tissues obtained from seeds,such as the embryo, but you can use also tissues taken from adult plants, such as tissuesof roots, stems, apical buds, shoots, leaves, even single cells. Each plant and tissue hasits own needs. They are different from each other. You can try the influence of thevegetable hormones, special nutrients, etc.
This field is very broad and complex so, if you are interested in continuing with theseexperiments, you can buy special books and you should build a sterile box.
Plant Tissue Culture for the Gardener
Basic Principle in Plant Tissue Culture Technique
Plant Tissue Culture Kit Manual
Plant Micropropagation Using African Violet Leaves
Plant Tissue Culture (links)
Internet keywords: in vitro culture plant tissue micropropagation.

Dissolved oxygen in water comes from two main sources: the atmosphere and photosynthesis.
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  • 2 teaspoons salt in a cup of water) Elodea;

    This allows the cells to accumulate a higher salt concentration than the salt concentration in the sea water.

  • this is the concentration of salt in sea-water).

    The fish is about 18 o/oo salt so in seawater it tends to dehydrate and constantly drinks the seawater.

  • Plants make their own food thru the process of photosynthesis

    18/11/2012 · In photosynthesis, the plant used water and ..

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Peek into a hot oven and a microwave and watch molecules dance.

In addition to reduced CO2 diffusion through the stomata, both stresses also result in an apparent reduced CO2 diffusion through the leaf mesophyll, i.e. in a reduced mesophyll conductance to CO2 (gm; reviewed in , ). Although not as straight forward as stomatal conductance measurements, estimations of gm seem appropriate despite many assumptions involved in the most common methods used (). This is supported by the fact that different methods involving totally different assumptions, result in very similar estimates, as demonstrated by and , ), among others. These changes in mesophyll conductance may be linked to physical alterations in the structure of the intercellular spaces due to leaf shrinkage () or to alterations in the biochemistry (bicarbonate to CO2 conversion) and/or membrane permeability (aquaporins). In an early work, already suggested that leaf internal diffusion conductance was depressed under water-stress conditions. However, the model used by Jones assumed that CO2 concentration in the chloroplast was close to zero or to the compensation point, which was later shown to be untrue (). Comparison of chlorophyll fluorescence with gas exchange measurements also revealed that Cc was lower than Ci, and that the difference increased under conditions of water stress or salinity (; ). That water stress specifically lowers Cc below Ci was independently confirmed by measuring leaf 18O () and 13C discrimination (). Still, in these early works, it was assumed that gm was largely unaffected by stress, and that discrepancies between Cc and Ci arose from invalid estimations of the latter due to either heterogeneous stomatal closure (; ) and/or interference of cuticular conductance (). It was assumed that most of the mesophyll resistance to diffusion was caused by morphological and anatomical leaf traits, which are unlikely to change in response to stress, particularly in the short term. However, showed that most of the internal resistance to CO2 diffusion was in the liquid phase inside cells instead of in intercellular air spaces, i.e. not so much dependent on leaf structure, and later studies specifically suggested that gm was depressed under both salt (; ) and water stress (; ; Galmés et al., 2007a).

Photosynthesis: Science Lesson | TV411

Stomata close in response to leaf turgor decline, to high vapour pressure deficit in the atmosphere or to root-generated chemical signals, the latter being common to both drought and salinity. Supply of CO2 to Rubisco is therefore impaired, what predisposes the photosynthetic apparatus to increased energy dissipation and down-regulation of photosynthesis when plants are subjected to high light and temperature. Under mild stress, a small decline in stomatal conductance may have protective effects against stress, by allowing plant water saving and improving plant water-use efficiency by the plant.

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