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.
Contrary to what people think, lungs do not have muscles of their own, but they are dilated or compressed by means of the movements of chest and diaphragm. The device of figure 19 shows how a diaphragm causes air to enter and leave the lungs. In the phase A, the balloons have to be as empty as possible. If you are a teacher, ask to your pupils what would happen if there was a hole in the bottle. Then make a hole, so everybody will see that, even if the diaphragm is lowered, the lungs will not fill with air. Yet it is easy to close the hole and restore the functioning of the lungs. To prove this, seal the hole of the bottle with some sticking tape and move the diaphragm again. This simple experiment shows how a hole in the chest could be fatal. Also how you could save a person by simply plugging the hole. If you have difficulties in finding the Y tube to build the model of the lungs, just use a tube. You will only have one lung, but the principle is the same and you know that in reality there are two.
Do-It-Yourself Lung Model
Mesophyll cells in a leaf are the principal centers of photosynthesis. Carbon dioxide from the atmosphere enters the leaf by diffusion through the stomata. Water from the soil is taken up by the roots, sent up through the stem and finally to the leaves where it is distributed in the mesophyll tissue. During daytime, when sunlight falls on the leaf, the light energy is trapped by the chlorophyll of the upper layers of the mesophyll, specially the palisade cells. This energy is utilized in chemical processes involved in the manufacture of food (Glucose).
The initial process in photosynthesis is the decomposition of water (H2O) into oxygen (which is released) and hydrogen; direct light is required for this process. The hydrogen and the carbon and oxygen of carbon dioxide (CO2) are then converted into a series of increasingly complex compounds that result finally in a stable organic compound, glucose (C6H12O6), and water. This phase of photosynthesis utilizes stored energy and therefore can proceed in the dark.
Recent evidence suggests that a major enzyme of the Dark Reaction is indirectly stimulated by light, thus the term Dark Reaction is somewhat of a misnomer. The Light Reactions occur in the grana and the Dark Reactions take place in the stroma of the chloroplasts.
The Light Independent Process (or Dark Reactions) occurs when the products of the Light Reaction are used to form C-C covalent bonds of carbohydrates. The Dark Reactions can usually occur in the dark, if the energy carriers from the light process are present.
Photosynthesis occurs in two phases. The first phase is the Light Dependent Process (Light Reactions), requires the direct energy of light to make energy carrier molecules that are used in the second phase.
Keep your head up! So you didn't do as well as you had hoped. You can take this opportunity to continue your study of . To increase your knowledge of this subject, study up on , , and . Once you understand the photosynthesis process, look into the related process of , which explains how organisms use the oxygen produced in photosynthesis.
Keep your head up! So you didn't do as well as you had hoped. You can take this opportunity to continue your study of . To increase your knowledge of this subject, study up on , , and . Once you understand the photosynthesis process, look into the related process of , which explains how organisms use the oxygen produced in photosynthesis.I encourage you to investigate the fascinating world of plants by discovering the and how some plants . Have fun learning about and then test your knowledge of plant anatomy by taking the .
Hydroponics is a method of growing plants without soil. Plants are simply placed in water with the necessary chemicals. As plants are deprived of support from the ground, they will fall down. To support the plants, an inert material like expanded clay pebbles is used in a pot in the tank (figure 5). Before inserting a plant in a hydroponic system, you must carefully remove all soil from the roots otherwise bacteria will putrefy them.
For many houseplants you can use tap water. Though, particularly for vegetables, it is advised to add appropriate nutrients. This cultivation method has the advantages of both requiring less frequent waterings and using very little water. With this system you can grow nearly any houseplant or vegetable. Hydroponics is useful also to show what nutrition plants need.
1 - Place some houseplants in hydroponics.
2 - Try hydroponics with vegetables and find the suitable nutrients.
Hydroponics in the Classroom
Growing plants without soil
To teach orphaned children how to grow their own food with hydroponics (gardening that uses very little water).
Organic Greenhouse Vegetable Production
Internet keywords: hydroponics classroom.
Nice job! It is clear that you know a good deal about photosynthesis, but there is still room for improvement. To help strengthen your knowledge of photosynthesis, study up on , the process, and . You may also want to look into the related process of , which explains how organisms use the oxygen produced by photosynthesis.
Nice job! It is clear that you know a good deal about photosynthesis, but there is still room for improvement. To help strengthen your knowledge of photosynthesis, study up on , the process, and . You may also want to look into the related process of , which explains how organisms use the oxygen produced by photosynthesis.For additional information on the fascinating world of plants, learn about , , how some plants , and why some .