WWW.BOOK.DISLIB.INFO
FREE ELECTRONIC LIBRARY - Books, dissertations, abstract
 
<< HOME
CONTACTS



Pages:   || 2 |

«SIMPLE APPARATUS FOR THE QUANTITATIVE DETERMINATION OF PHOTOSYNTHETIC AND RESPIRATORY RATIOS' BERNARD S. MEYER AND DON S. RADER (WITH ONE FIGURE) ...»

-- [ Page 1 ] --

SIMPLE APPARATUS FOR THE QUANTITATIVE DETERMINATION OF PHOTOSYNTHETIC AND

RESPIRATORY RATIOS'

BERNARD S. MEYER AND DON S. RADER

(WITH ONE FIGURE)

Introduction

A relatively simple apparatus for determining respiratory and photosynthetic ratios quantitatively in a reasonably accurate manner is desirable

equipment for every plant physiology laboratory. The apparatus to be described, while not considered a precision instrument, has been found serviceable for this purpose. While designed primarily for student use in the laboratory work of plant physiology courses, it might also prove satisfactory for research if not too great accuracy of results is required. The apparatus depends, in principle, upon the measurement of changes in the volume of the CO2 gas present in the apparatus by absorption in a KOH solution, and upon the measurement of changes in a volume of the 02 gas present by manometric means. Results of sufficient quantitative exactness to demonstrate clearly the important principles regarding photosynthetic and respiratory ratios can easily be obtained with this apparatus.

Apparatus Figure 1 illustrates the arrangement of the apparatus, which consists

of the following essential parts:

A. Stationary 50-cc. burette equipped with a stopcock H at its upper end, and connected with a glass tube leading to the glass chamber C by a length of rubber tubing L.

B. Vertically adjustable 50-cc. burette. Burettes A and B are connected at their lower ends with a length of rubber tubing K.

C. Photosynthetic (or respiratory) chamber.

D. Separatory funnel provided with a stopcock I, and a side tube with a stopcock E.

F. Thermometer.

G. Three-way stopcock of the design indicated.

J. Heavy rubber stopper.

Details of the assembled apparatus are shown in figure 1. All of the parts are standard laboratory equipment except the modified separatory funnel, which must be made by a glass blower, and the photosynthetic chamber, which was improvised from a small glass tumbler about 11 cm.

Papers from the Department of Botany, Ohio State University, no. 367.

Downloaded from www.plantphysiol.org on June 18, 2016 - Published by www.plantphysiol.org Copyright © 1936 American Society of Plant Biologists. All rights reserved.

438 PLANT PHYSIOLOGY high and 6 cm. in top inside diameter. The rubber tubing used should be of seamless red rubber in order to minimize loss of CO2 gas by diffusion through the rubber. Impermeability of the rubber stopper to the gas can be assured by coating its lower surface with asphaltum which has been cut with turpentine. The glass parts can be of ordinary soft glass, although Pyrex glass would probably prove more serviceable in certain respects.

–  –  –

FiG. 1. Apparatus for the determination of photosynthetic and respiratory ratios.

Description in the text.

It is essential that the system be airtight, since attempted measurements in the absence of leakproof connections will be worthless. The apparatus can be tested for leaks by filling it completely with water, adjusting burette B so that the level of the water in it will be considerably lower than in the photosynthetic chamber, and allowing the entire set-up to stand for several hours. If no change occurs in the level of the water in burette B during this period, leakage in the apparatus may be considered negligible.

Downloaded from www.plantphysiol.org on June 18, 2016 - Published by www.plantphysiol.org Copyright © 1936 American Society of Plant Biologists. All rights reserved.

MEYER AND RADER: PHOTOSYNTHETIC AND RESPIRATORY RATIOS

Procedure for determination of photosynthetic ratios2 The aggregate volume of the photosynthetic chamber C, separatory funnel D, includingf the side tube E, connecting tube L, and burette A to the zero mark on that burette, must first be determined. This may be done by measuring the volume of water required to fill this part of the apparatus, or by determining its increase in weight after filling it with water. This measurement should be made as accurately as possible and the determined volume recorded.

Burettes A and B should each be about half full of water. A leaf of some suitable species should now be introduced into the photosynthetic chamber. The petiole of the leaf should dip into a small vial of water.

The volume of the leaf and the vial should first be determined by immersing in a graduated cylinder and noting the volume of water displaced. The total volume of leaf, vial, and water must be subtracted from the volume of the apparatus as determined above.

With the apparatus assembled, and stopcocks E and I closed, 30 cc. of a 25 per cent. KOH solution should now be poured into the separatory funnel D. The funnel should then be stoppered, stopcocks E and H opened, and burette B raised or lowered until water stands at the same level in both burettes. Stopcock E should then be closed. The volume of the photosynthetic chamber, after subtraction of the volume of the leaf, the vial, and the water should now be further corrected by subtracting the volume of the KOH solution. This final corrected volume will be designated as volume V.





The upper arm of stopcock G should now be connected to a simple type of gas-measuring burette which is in turn connected with a tank of pure CO2 gas. The CO2 should then be allowed to flow through the connecting rubber tube and out into the air through stopcock G until all of the other gases are swept out of the tube. Stopcock G should then be turned off, and the gas-measuring burette adjusted until it contains a known volume (usually approximately 25 cc.) of CO2 gas3 at atmospheric pressure. Stopcock 2 Since respiration also is occurring in the green parts of a plant, the apparent volume of CO2 consumed is less than the volume utilized in photosynthesis by the amount of the volume released in respiration, and similarly, the apparent volume of the 02 released is less than the actual amount liberated in photosynthesis by the amount of volume of 02 consumed in respiration. Hence the apparent photosynthetic ratio is a result of the differential effect between the two processes of photosynthesis and respiration. Since, in rapidly photosynthesizing leaves, the rate of photosynthesis is usually ten or miiore times as great as the rate of respiration, and the respiratory ratio of most leaves is usually almost unity, the simultianeous occurrence of respiration is not an appreciable source of error in determinations of the photosynthetic ratio in green leaves.

3 The gas in commercially furnished tanks of CO2 gas is not always 100 per cent.

pure. For precise work it may be desirable to analyze the sample of gas used, and to introduce the necessary correction in determining the volume of gas which has been added.

For demonstration purposes, however, this precaution can usually be neglected.

–  –  –

G should then be opened (stopcock H also being open), and the reservoir of the burette raised until the desired volume of CO2 gas has been delivered into the system. As the gas is driven into the photosynthetic chamber burette B should be gradually lowered so that the menisci are maintained at the same level in both burettes during the transference of the CO2 gas.

Stopcock G should now be closed and, after allowing the apparatus to stand for a few minutes, any final adjustment of burette B necessary to equalize the level of the menisci in the two burettes should be made. Stopcock H should then be closed. The exact position -of the water meniscus in burette A should now be recorded and the volume of the gas below the zero mark in the burette added to volume V. The sum of these two volumes will be designated as volume X.

The temperature of the photosynthetic chamber and the barometric pressure should also be recorded at the beginning of the determination.

The apparatus should be allowed to stand for six to eight hours in (preferably) a strong diffuse light. Any considerable heating of the gas mixture in the photosynthetic chamber above the temperature of the surrounding atmosphere should be avoided, since this makes it more difficult to secure satisfactory results. The intensity of the light can be reduced, if necessary, and the light diffused by shading the apparatus with one or more layers of cheesecloth.

At the end of this period stopcock H should be opened and the water menisci should be brought to the same level in both burettes by adjusting the position of burette B. Volume V plus the volume of gas below the zero mark in burette A at this reading will be designated as volume Y.

Stopcocks E and I should now be opened simultaneously and the KOH solution allowed to flow into the bottom of the photosynthetic chamber C.

It should not be allowed to come in contact with the leaf. About 15 minutes should be allowed for the absorption of the CO2 gas remaining in the apparatus. At the end of this period the water menisci should again be brought to the same level in the two burettes by adjusting the position of burette B.

Volume V plus the volume of gas below the zero mark on burette A at this reading will be designated as volume Z.

The temperature of the photosynthetic chamber and the barometric pressure must be recorded again at the end of the experiment. All three of the recorded gas volumes (X, Y, and Z) must be reduced to standard conditions and corrected for aqueous tension. The aqueous tension of the gas within the apparatus may be assumed to correspond to that of a saturated atmosphere at the temperature of the apparatus.

The significance of the several measured volumes is as follows:

X = atmospheric gases + added CO2 Y = atmospheric gases + unused C02 + 02 released in photosynthesis Z = atmospheric gases + 02 released in photosynthesis Downloaded from www.plantphysiol.org on June 18, 2016 - Published by www.plantphysiol.org Copyright © 1936 American Society of Plant Biologists. All rights reserved.

MEYER AND RADER: PHOTOSYNTHETIC AND RESPIRATORY RATIOS 441

–  –  –

Procedure for determination of respiratory ratios The aggregate volume of the respiratory chamber C, separatory funnel D +E, and connecting tube to the zero mark on burette A, must first be determined as previously described. Germinating seeds serve most satisfactorily as the respiratory material in this apparatus, but other material can also be used. The manipulations will be described on the assumption that seeds are used. About 10 gm. of germinating seeds should be inclosed in a small wire mesh basket which should be so suspended from the rubber stopper J that it swings free from the bottom of the chamber by several

–  –  –

centimeters. The volume of the basket and seeds must be determined before they are introduced into the respiratory chamber and subtracted from the volume as determined above. After the apparatus is assembled, 30 cc. of 25 per cent. KOH solution should be introduced into the separatory funnel.

The volume of the KOH solution must also be subtracted from the volume as determined above. The volume of the system, after subtraction of the volume of the seeds, basket, and KOH solution will be designated as volume V.

Each of the burettes should be about one-fifth full of water. After allowing the apparatus to stand for a few minutes, burette B (stopcock H open) should be raised or lowered until the water menisci stand at the same level in both burettes. The exact position of the water level in burette A should be recorded, and the volume of gas below the zero mark added to volume V. This will be designated as volume X. The temperature of the respiratory chamber and the barometric pressure must also be recorded at this time.

Stopcock H should now be closed and the apparatus allowed to stand for about two hours in the dark. At the end of this period the water in the two burettes should again be brought to the same level after opening stopcock H. Volume V plus the volume of gas below the zero mark on burette A at this reading will be designated as volume Y.



Pages:   || 2 |


Similar works:

«ÖROK Projekt ´ Periphere ländliche Räume´ Rahmenpapier – über das Projekt Februar 2009 Thomas Dax Eva Favry Luis Fidlschuster Theresia Oedl-Wieser Wolfgang Pfefferkorn ROSiNAK & PARTNER Ziviltechniker GmbH, Schloßgasse 11, 1050 Wien, Tel. (+431) 544 07 07, Fax (+431) 544 07 27, email: office@rosinak.at, http://www.rosinak.at Firmenbuchzahl FN 140466 v – UID: ATU39942201 Rosinak&Partner, Bundesanstalt für Bergbauernfragen, ÖAR Ausgangslage: Im Rahmen das „Mittelfristigen...»

«COMHAIRLE CATHRACH CHORCAI CORK CITY COUNCIL MINUTES OF ORDINARY MEETING OF CORK CITY COUNCIL HELD ON MONDAY 27th MAY 2002 PRESENT:An tArd-Mheara, Comhairleoir T. O’Driscoll in the chair. NORTH EAST Comhairleoiri T. Brosnan, L. Burke, B. Kelleher T.D., J. Kelleher. NORTH CENTRAL Seanoir N. O'Flynn T.D. Comhairleoir D. Wallace. NORTH WEST Seanoir D. McCarthy, Comhairleoiri, T. Falvey, C. Burke, M. O’Connell, J. O’Brien. SOUTH EAST Seanoir T. Shannon, Comhairleoiri D. Clune, J. Corr, J....»

«i Communicative Language Teaching in Georgia From Theory to Practice ii Published by LOT phone: +31 30 253 6111 Trans 10 3512 JK Utrecht e-mail: lot@uu.nl The Netherlands http://www.lotschool.nl Cover illustration: created specially for this dissertation by a Georgian painter and animator Dato Sikharulidze. The image captures the atmosphere of a communicative language lesson. ISBN: 978-94-6093-145-1 NUR 616 Copyright © 2014: Natalia Edisherashvili. All rights reserved. Communicative Language...»

«Identification of the mRNA-associated TOP3βTDRD3-FMRP (TTF) -complex and its implication for neurological disorders by Georg Stoll from Schweinfurt, Germany A thesis submitted to the Faculty of Pharmacy and Chemistry of the University of Würzburg, Germany, in fulfillment of the requirement for the degree of Doctor rerum naturalium (Dr. rer. nat.) Chair of Biochemistry Würzburg, Germany, 2015 Date of submission: 19 January 2015 PhD thesis examiners: 1st Examiner: Prof. Dr. Utz Fischer 2nd...»

«Cyber Essentials Scheme Summary June 2014 Cyber Essentials Scheme: Summary Introduction Background Scope Assurance Framework Next steps Questions about the scheme? Cyber Essentials Scheme: Summary Introduction The Cyber Essentials scheme has been developed by Government and industry to fulfil two functions. It provides a clear statement of the basic controls all organisations should implement to mitigate the risk from common internet based threats, within the context of the Government’s 10...»

«DAS INVESTITIONSPROFIL DER EUROREGION RUSE-GIURGIU 1. Vorwort Liebe Leser, Ich habe die Ehre, in dem Namen von über 200.000 Einwohnern der Euroregion Ruse-Giurgiu die echte und warme Einladung zu senden, um zusammen mit uns die Ressourcen und die Schönheit dieses Gebiets, das seit über 2000 Jahren ein Gastgeber für zwei Völker – Rumänisch und Bulgarisch ist, zu genießen. Ob in der Vergangenheit die Donau diejenige war, die beiden Gemeinden getrennt hat, ist in der Gegenwart der Fluss...»

«1 1 Problemstellung: Kreditrisiko im IFRS-Abschluss 1.1 Anwendungsbereiche Das Kreditrisiko hat sich in den letzten Jahren als zentrales und komplexes finanzielles 1000 Risiko herauskristallisiert. Anders als Marktrisiken lässt sich das Kreditrisiko schwer messen, weil Kreditereignisse selten auftreten. Kreditrisikoprämien werden regelmäßig bei Vertragsabschluss festgelegt, womit das Ertragspotential nach oben hin begrenzt ist. Dem steht ein seltenes und pro Instrument höchstens einmaliges...»

«Rating Action: Moody's concludes review on 14 UK banks' ratings; assigns CR Assessments to 17 UK banks Global Credit Research 05 Jun 2015 Actions conclude methodology-related reviews and revision of government support considerations London, 05 June 2015 Moody's Investors Service has today concluded its rating reviews on 14 banks in the UK (Aa1 stable). These reviews were initiated on 17 March 2015 following the publication of Moody's revised bank methodology (see Rating Methodology: Banks, 16...»

«Impulse Gemeindebrief der Lutherischen Kirche. Congregational Newsletter of the Lutheran Church. Hayfields. Jahrgang/ Year 42 October 2013 And do not forget to do good and to share with others, for with such sacrifices God is pleased. Hebrews 13v16 Gutes zu tun und mit andern zu teilen, vergesst nicht; denn solche Opfer gefallen Gott. Hebräer 13v16 Andacht Devotion 2 “And do not forget to do good and to share with others, for with such sacrifices God is pleased”. Hebrews 13:16 It is not...»

«Data Management System for Surface Drifters Bob Keeley1, Mayra Pazos2, Bruce Bradshaw1 1. Integrated Science Data Management, Department of Fisheries and Oceans, 200 Kent St., Ottawa, Canada, K1A 0E6.2. National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratory, 4301 Rickenbacker Causeway, Miami, FL 33149 Summary The large scale deployment of surface drifters has its origins in the FGGE programme in the late 1970s. Over the course of the next 25 years,...»





 
<<  HOME   |    CONTACTS
2016 www.book.dislib.info - Free e-library - Books, dissertations, abstract

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.