Experiment 6 Bio

Universiti Teknologi Teknologi Mara Sabah Faculty of Applied Science Diploma In Science BI !"#

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Date of Submission 8uly !"= !#+1

EXPERIMENT 5

1.

OBJECTIVE i. ii.

2.

To e:amine the anatomy of dry seeds and ;et seeds< To compare the chemical characteristics of dry seeds and ;et seeds<

INTRODUCTION

In the seeds of most plants the embryo is surrounded by a variable amount of  endosperm tissue= ;hich serves as a food supply during germination< In others= there is little or no endosperm tissue= food being supplied by the enlarged cotyledons< Flo;ering  plants are divided into monocotyledon and dicotyledons9 the former posses seeds ;ith only one cotyledon= the latter have t;o cotyledons< >hatever other factors are re?uired for germination= one essential factor is ;ater9 the first clearly observable event in germination is the imbibing of ;ater< As a result of this= the embryonic tissues s;ell and rupture the seed coat< The seed has lost most of its ;ater and carries on metabolism at a very slo; rate< This dormancy is maintained by the hormone abscisic acid< Some seeds ;ill be able to germinate under the right conditions and are viable< It is easy to test for metabolic activity in seeds by soaking them and observing the reduction of a dye by the living tissue< The dye is tetra@olium= ;hich is normally colourless= but turns pink ;hen it is reduced by living tissue< These e:periment study the different physical and chemical characteristics of t;o different samples< First sample is considered not active ;here seeds are not mi:ed ;ith ;ater< The second sample= seeds are soak ;ith ;ater as ready for germinations< 4omparing these t;o different samples can help students to understand the basis of seed germination<

3.

MATERIALS

i< ii<

Balance Forceps

iii< iv< v< vi< vii< viii< i:< :< :i< :ii<

Test tube Test tube rack   >ater bath Dish (a@or blade Benedicts (eagent*Food reserves test/ Iodine solution*Food reserves test/ #<" tetra@olium solution *Metabolic activity test/ Distilled ;ater   Broad bean seed*dry/ and Broad bean seed soaked for !CC.

:iii<

hours*dicotyledon/ 4orn grain *dry/ and 4orn grain soaked for !C hours*monocotyledon/

PROCEDURE

Seed Anatomy Test i<

The dry sample ;as compared ;ith one ;hich has been soaked in ;ater for !C E

ii<

C. hours by ;eighing the t;o seeds< The percentage of increase in mass ;as calculated< The result is recorded in Table

iii<

+< The structure ;as e:amine closely by dissecting a seed that has been soaked to

iv<

loosen skin and soften it< The seed ;as e:amined using a dissecting microscope< The seed ;as carefully split into t;o halves and the parts ;as identified as cotyloden= plumule or epicotyls= hypocotyls= radical and foliage leaves< (efer

v< vi< vii<

figure + as guidelines< The observation ;as recorded in Table +< A soaked corn kernel ;as cut in half as sho;n in Figure !< Identified 9 the single cotyledon= the endosperm= the hypocotyls= epicotyls and the

viii<

foliage leaves *plumule/ of the embryo< (eferring to Figure ! as guidelines< The observation ;as recorded in Table +<

4hemical 4haracteristic Test i<

The test for food reserves is carried out< The ;hole cotyledon ;as stained ;hole in iodine solution< Using a sharp ra@or blade ;e have cut a thin section of a cotyloden

ii<

The section ;as mounted in iodine solution and e:amine them under the

iii< iv< v<

microscope< The starch of the grains is visible< The result ;as recorded in Table !< Using a blender= ;e prepare the sample for reducing sugar test< The test tube ;as filled ;ith + cm! sample< ! cm! Benedicts reagent ;as added into the test tube and the initial colour ;as

vi< vii<

recorded< The test tube is then placed in a boiling ;ater bath for 1 minutes< The test tube ;as removed from the hot ;ater bath ;ith the test tubes holder and

viii<

 placed in the test tube rack< The colour changes ;as recorded in Table !< The contents of the test tube ;as discarded and rinse properly< >e have shake out

i:<

the e:cess ;ater from the test tube< The same procedure is carried out ;ith the other sample<

i< ii< iii< iv<

Metabolic activity test E ption ! Several of the soaked samples ;as cut in half and put into a test tube< #<" tetra@olium solution ;as added enough to cover the seed< The cut surface ;as observed from time to time for a production of a pink colour< After the pink colour is ;ell developed= the part ;hich the seed has the darkest colour ;as e:amine and therefore the greatest metabolic activity<

4.

RESULT

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TAB$6 !9 Analysis of Seed 4haracteristic Food reserve test *&resent or not present/ Sample

Treatment

Mass *g/

Increase in mass Starch

(educing sugar 

Dry

#
&resent

0ot present

*/

Soaked

+<# g

&resent

0ot present %#

Bean

Dry

#
&resent

&resent

Soaked

#<1 g

&resent

&resent

+#

4orn

5.

DISCUSSION

The advantages of a seed hat dried out is it gro; faster because a seed if ;et or moist= it can attract pathogen bacteria and fungi that can greedily devour it< A seed is necessary to absorb ;ater before germinated to active the en@yme= increases respiration and duplicating itself< The more ;ater it absorb= the faster the seed gro;< In our e:periment= the seed increase in si@e by ;eighing the t;o seeds< It represents the percentage in ;ater< In the test of present starch= both dried seed and soaked seed are contain starch< In the seed = the cotyledon contain more stored starch because ;hen cotyledon act as a food storage the endosperm totally disappear but if the endosperm act as a food storage= the cotyledon never disappear< The greatest metabolic activity in the seed occurs in hilum< The purpose of food reserve test is to investigate the presence of starch and producing sugar in both soaked and dry bean and corn kernel<

6.

CONCLUSION

The anatomies of dry and soaked seed of bean and corn kernel provide the inner structure of both seed< The comparison of chemical characteristic of the bean and corn kernel ;as investigated through the presence of starch and reducing sugar in it< 7.

REFERENCE

4ampbell 0 A< and (eece 8
San Francisco