Laboratory Experience Units in Biology B. JOHN SYROCKI State University Teachers College Brockport, New York Radiant Energy and Food Production in Plants Principle to Be Developed cubic centimeters of water. Mix the sodi- The ultimate source of all energy is sun- um and potassium iodide thoroughly, and light and this energy is bound into food ma- add water to make a total of 250 cubic centimeters of solution]. Note the reaction terials during photosynthesis. Downloaded from http://online.ucpress.edu/abt/article-pdf/19/6/178/15158/4438913.pdf by guest on 01 October 2021 of the leaves to the iodine solution. Try iodine solution on some Activities in the Unit: some of this laundry starch, on a piece of potato, and A. Role of Sunlight in Photosynthesis on a piece of bread. Record the reaction of B. Storage of Food in Seed Leaves iodine with starch. C. Release of Stored Energy During Germ- B. Storage of Food in Seed Leaves.-Fill a ination of Seeds large drinking glass half-full with dry lima beans, and cover them with water over- Procedures night. The next day, split open the seeds, A. Role of Sunlight in Photosynthesis.-Ob- and put several drops of iodine solution tain two geranium, Coleus, or fuchsia on each half of the seed, as shown in Dia- plants and place them in a dark place for gram 7. Record the changes that take two days. The plants may be placed in a place and determine whether or not the closet, or under a paper box. After two change is prominent over all parts of the davs, put one plant in direct sunlight for surface of the lima bean seed leaves. several hours. Remove two leaves from the plant which has been placed in direct sunlight, and two leaves from the plant which has been in total darkness. Nick with a razor, or otherwise mark those leaves which had been in sunlight, and \~Iodine immerse the four leaves in boiling water ol iSolution for two minutes to kill the leaves. Remove (3 (10 Per cent) the leaves and put them into a Petri dish Inner side containing hot wood alcohol (rubbing of bean alcohol). Let the leaves remain in the alcohol for ten minutes, or until all traces DIAGRAM 7 of green coloring in the leaf have disap- peared. [Heat the wood alcohol in a nar- row-mouthed pyrex flask, then pour the C. Release of Stored Energy Dutring the alcohol into the Petri dish.] Cool ditto Germination of Seeds.-Fill a large drink- fluid has been found to be satisfactory for ing glass half-full with dry, packaged lima removing the chlorophyll, however the bean seeds, and cover them with water leaf has to remain in the fluid for a few overnight. Bore a hole one-quarter of an hours. inch into the center of a cork of a thermos Remove the leaves from the alcohol and bottle (one pint capacity). Insert a Fahren- put them into a solution of iodine in a heit thermometer into the cork so that the Petri dish [Iodine Solution: 1 gram of bulb of the thermometer reaches about potassium iodide and ?4 gram iodine in 10 halfway into the bottle. Put the seeds in- 178 Vol. 19, No. 6 LABORATORY EXPERIENCE UNITS IN BIOLOGY 179 to the thermos bottle, add about a third of What was the original source of this a cup of water, and replace the cork. Seal energy? the cork to the bottle with plastic clay, 5. Where does the plant get food material and seal around the thermometer in order during its growth from a seed to a seed- to prevent heat from escaping from the ling? bottle, as shown in Diagram 8. Outcomes Specific Understandings 1. Energy from the sun is necessary for Fahrenheit + or wax seal food production by a green leaf. thermometer Clay Air-tight seal 2. A seedling obtains its food supply from food stored in the seed leaves, or Downloaded from http://online.ucpress.edu/abt/article-pdf/19/6/178/15158/4438913.pdf by guest on 01 October 2021 cotyledons. 3. Heat energy is released during seed germination since the food is oxidized, thereby releasing bound heat energy. 4. The energy stored in a seed leaf has its TJ>e?os bottle origin in the sunlight used during food production. The Transportation System in the Human Body Principle to be developed In man, food and oxygen are carried to all DIAGRAM 8 parts of the body through a system of blood circulation. Keep the bottle out of direct sunlight or Activities in the Unit: other heat sources. Record the tempera- ture in the inside of the bottle, and repeat A. Viewing of the film The Heart and the reading after fifteen minutes to obtain Circulation a correct reading of the temperature in- B. Blood Circulation in Capillaries side the bottle. Repeat readings during the C. Pumping Action of the Heart in the second, third, and fourth days. Keep a Frog record of the temperature inside the bottle D. Study of a Beef Heart and Model of during the time from onset of germination the Human Heart until the fifth day, and construct a graph E. Heart Beat and Arterial Pulse (Human) to show the changes which have taken F. Effect of Exercise on the Rate of the place. Heart Beat Appended Questions Procedures 1. In the experiment on photosynthesis, of A. Viewing of the Film The Heart and Circu- what value was the "control plant"? lation.-To the instructor: Students will 2. What was the purpose of removing the be asked to observe the film on the heart green coloring matter in the leaves with and circulation. This film will be used to alcohol? introduce the subject of the transportation 3. What can be said with regard to the value system in the human body for the follow- of using iodine solution as an indicator of ing reasons: (1) Movement of the heart certain food materials? can be introduced at this time to all stu- 4. What are some probable reasons for the dents since the film captures motion [stu- results in the activity concerned with the dents will observe the beating of the heart release of energy during seed germination? of an animal in further study], (2) the 180 THE AMERICAN BIOLOGY TEACHER October, 1957 motion picture through its animated draw- web of the frog's leg over the aperture in ings can present a process which is diffi- the cardboard and superimpose this aper- cult to perceive about the human heart in ture over that in the stage, as shown in the laboratory, and (3) the film makes it Diagram 10. possible for the group as a whole to par- Clamp ticipate in a common experience which should prove helpful in further studies Tall is over \ about the human heart. aperture Prior to the showing of the film, the microscope instructor should discuss the general aspect Stage of the circulatory system, pointing out the principal functions of this system. The Downloaded from http://online.ucpress.edu/abt/article-pdf/19/6/178/15158/4438913.pdf by guest on 01 October 2021 action of the heart as a pumping station, and the meaning of a closed system of circulation should be emphasized. The stu- dents need to be oriented with respect to _ _ _ _ C) some of the content which they are to observe, hence the use of a model of the human heart, a chart, or reference to draw- ( Cotton cover ings during a brief talk about the circula- torv system should prove most helpful at Thin glass plate this time. Students should be instructed to pay special attention to the following DIAGRAM 9 during the showing of the film: Clamp 1. The rhythmic beating of the heart in the experimental animals. Pins 2. The function of the heart valves. 3. Path of blood through the heart. 4. The origin of the pulse beat. 5. The nature of the different kinds of blood vessels comprising the trans- portation system in man. Cardboard B. Blood Circulation in Capillaries-Wrap a smnall aquarium fish or tadpole in moist cotton, exposing the tail of the animal. Put the animal on a piece of glass about four by five inches, as shown in Diagram 9. Examine the thin end of the tail with a low power of a microscope, and look for tiny blood vessels through which blood is flowing. Keep in mind that both the size DIAGRAM 1 0 of the blood vessels and the speed of flow of blood in these vessels are exaggerated Examine the web for tiny blood vessels when viewed with a microscope. Look for in the thin membraneous portion of the blood vessels of different sizes and com- web. Compare the speed of flow of blood pare the flow of blood in these vessels. in the larger vessels in the web with that in In the event fish are not available, an the much smaller blood vessels. As in the anaesthetized frog can be used. Cut out a fishtail, both the speed of blood circula- hole equal to the size of the opening in the tion and the size of the blood vessels are stage of the microscope, in a piece of card- greatly exaggerated when observed by a board 4 x 8 inches. Pin the outstretched microscope. Vol. 19, No. 6 LABORATORYEXPERIENCE UNITS IN BIOLOGY 181 C. Pumping Action of the Heart in the Frog E. Heart Beat and Arterial Pulse (Human)- -Examine a demonstrationof an anaesthe- Find your pulse by placing your fore- tized or pitched frog showing an exposed finger and the two adjoining fingers on heart.