ib biology extended essay

Candidate number: 000763-014

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OVERSEAS FAMILY SCHOOL (0763)

ASSESSMENT: Extended Essay

SUBJECT: Biology

TITLE: Can the seeds of tropical plants with soft

coats and a germination period of maximum 2 weeks

germinate in winter conditions?

WORD COUNT: 3988

CANDIDATE NAME: Claudia Antoinette Braganza

CANDIDATE NUMBER: 000763- (014)

EXAM SESSION: May 2012


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ABSTRACT

The aim of this essay was to try and answer the question Can the seeds of tropical

plants with soft coats and a germination period of maximum 2 weeks germinate in cold

and winter conditions?

The independent variable in this investigation was temperature, because I

manipulated 3 different temperatures (Room Temperature 26oC, cool conditions 3oC and

7oC and winter conditions -12oC) in order to find out about the germination process in

tropical seeds when subjected to different environmental conditions. I did this by

attempting to control the amount of water given and the oxygen levels the seeds are

subjected to; I then placed the seeds in egg trays filled with soil in their different locations

for them to start germinating. Of course, I watered them first; I watered them every two

days to keep the soil damp. I then recorded the amount of days taken by each seed to

germinate judging by the appearance of the first hooked hypocotyl above the soil. The seeds

I chose were garden plant seeds, in alphabetical order: Groundnuts, Green Field Peas,

Marigold Sierra Yellow, Tomato, Zinnia Dahlia Flora and Zinnia Lilliput. They all germinated

epigeally, which meant the hypocotyl emerges above the ground first to mark germination.

From the results of my experiment, I could quite safely conclude that these specific

seeds had entered into a period of dormancy due to the lack of suitable temperatures in

order to germinate. I also suggested that these seeds may have become quiescent because

they are ripe seeds that don’t germinate under harsh external conditions until suitable

germination requirements for the specific seed has been fulfilled. I termed them as

quiescent because compared to their normal germinating conditions, the temperatures I

subjected them to were quite harsh.

Word count: 290


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CONTENTS PAGE

1. INTRODUCTION AND HYPOTHESIS 4

2. APPARATUS AND METHODOLOGY 9

3. PICTURE OF EXPERIMENTS 11

4. DATA ANALYSIS 12

5. CONCLUSION AND EVALUATION 17

6. APPENDIX 19

7. WORKS CITED LIST AND BIBLIOGRAPHY 21


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INTRODUCTION AND HYPOTHESIS

The aim of this investigation is to find out Can the seeds of tropical plants with soft

coats and a germination period of maximum 2 weeks grow in cold and winter conditions?

I chose the topic of germination because not much is taught in the IB syllabus about

the process physically and chemically except for the factors of germination. My interest in

plants stems back to my younger days. My grandmother grew a variety of plants in her

garden and I remember watching her plant the seeds in soil and watching them grow over

the months and years. Up until Year 6, I just put the explanation down to magic, as most

ignorant young children would. One day, my science teacher assigned us to grow our own

plants for fun and record the variables and outcomes of the process, to get us used to

distinguishing between controlled and manipulated variables. There was no real theory to

be learned as a result of this, one could call it an initiation into the world of practical lab

work.

As the weeks passed, I manipulated different variables such as oxygen, amount of

moisture or water and temperature. What I didn’t realize at the time was that the three

factors I was manipulating were in fact the three important factors required for

germination. So when the time for deciding an EE topic, I immediately knew I wanted to

investigate germination in plants in detail. Since I’ve only lived in Southeast Asia, and the

weather consists of tropical dry and wet seasons, I decided to investigate germination in

tropical plants. I was also interested on whether tropical plants could germinate in cool or

winter conditions since they usually do not need a period of dormancy; I wanted to find out

exactly what happens and why it happens. So, would cold temperatures induce dormancy in

the seeds or slow down the process of germination?


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Germination is defined as the process in which a plant or a fungus emerges from a

seed or a spore, respectively, and begins growth (Wikipedia). A seed is a small package

produced in a fruit or cone after the union of the pollen from the anther and the ovules in

the ovary (Cactus-art.biz). All fully developed seeds will contain an embryo, and most plant

species will have foods reserves stored which are wrapped in by the testa. Some plants

produce a number of seeds that lack embryos called empty seeds, and they never germinate

(Buzzle.com).

Most seeds go through a period of quiescence, where no active growth of any kind is

recorded; during this time, seeds can be transported to a new location or survive adverse

climates until favourable circumstances of growth are met (Wikipedia). Quiescent seeds can

be defined as ripe seeds that don’t germinate because of being subject to harsh external

environmental conditions which prevent the initiation of metabolic processes and cell

growth (Dictionary.com, Wikipedia). Once the favourable conditions are met, the seeds will

then begin the process of germination. Essentially, germination is the resuming of growth of

the dormant embryonic plant inside the seed. Complex physical and chemical changes begin

as the embryo starts to develop into a young shoot and root. Then, the seed sends its first

radicle into the soil and its first stem and cotyledon into the sunlight. Mostly, the emergence

of a radical marks the end of germination.

Example structure of a seed (Allott 85)


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Seed germination is affected by both internal and external conditions. The most

important external conditions are temperature, water, oxygen and at times, light or

darkness (Clegg 322-323). Firstly, water is required for germination because mature seeds

are extremely dry. They need to take in a significant amount of water that is relative to the

dry weight of the seed in order for metabolic processes and growth to resume

(Plantphys.info). The seeds would need enough water to moisten them, but not enough to

soak. The process of uptake of water is called imbibition and this leads to the swelling and

breaking of the testa (Wikipedia). Most plants store a food reserve within the seed, such as

proteins, starch and oils, which provide nourishment to the growing embryo. When

imbibition occurs, hydrolytic enzymes are activated; they break down the food storage

resources and turn them into metabolically useful chemicals (Clegg 323).

Of course, they need the second factor oxygen, which must be available for aerobic

cell respiration. Some seeds respire anaerobically if oxygen isn’t available but the ethanol

produced in anaerobic respiration soon reaches toxic levels. Also, suitable temperatures are

needed for germination to occur. The process involves enzyme activity (such as the

hydrolytic enzymes) and the activity is too slow at very low or high temperatures

(Buzzle.com). Some seeds may remain dormant if temperatures are above or below a

particular point, and only germinate during certain times of the year. Lastly, light or

darkness can be an environmental trigger for germination to occur. This is a type of

physiological dormancy. Most seeds aren’t affected by light or dark, but some need light to

enable the process to begin (Wikipedia).

The metabolic events during germination are as follows; soon after absorbing water,

the plant growth hormone called gibberellin is produced in the cotyledons. Gibberellin

stimulates the production of amylase, which then catalyses the breakdown of starch into

maltose in the seed’s food reserves. The maltose is then transported to the growth regions

of the embryo, including the root and shoot, from the food reserves. This maltose is

converted into glucose, either for aerobic respiration or cellular growth (Wikipedia).

Some live seeds need more time or specific environmental conditions before they

will germinate. They are called dormant seeds. Dormancy-breaking involves changes in

membranes, initiated by dormancy-breaking signals, which generally only occurs in hydrated


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seeds (Wikipedia). Some factors that affect seed dormancy include the presence of abscisic

acid, which inhibits germination, and gibberellin, which ends seed dormancy (Clegg 323).

Dormancy occurs to seeds that have undergone incomplete seed development, which

causes the embryo to be immature, and this is overcome in time. It also occurs in seeds with

an impervious testa which is eventually made permeable either by abrasion with coarse soil

or by action of microorganisms. Seeds that have a requirement for pre-chilling under moist

conditions before they can germinate also have a dormancy period.

For this investigation, I decided to use dicotyledonous seeds because they are the

most commonly found ones in Singapore. There are two types of dicot germination: epigeal

germination, where the hypocotyl (section of shoot below cotyledon) elongates and forms a

hook, and once it reaches the surface it will straighten and pull the cotyledons and shoot tip

of growing seedlings into the air whereas hypogeal germination means that the epicotyl

(section of shoot below cotyledon) elongates and forms the hook while the cotyledons stay

underground where they eventually decompose (Theseedsite.co.uk). For control, all the

seeds I chose germinated epigeally, although groundnuts are an intermediate between

epigeal and hypogeal germination, but first germinated epigeally so it is mostly controlled.

Specifically, I decided to choose garden plants and vegetables because they take a shorter

time for germination. In lieu of my time limits, this was the best choice in order to ensure

multiple trials are possible.

The seeds that I chose were, in alphabetical order: Groundnuts (Peanut variety),

Marigold Sierra Yellow, Tomato, Green Field Peas, Zinnia Dahlia Flora and Zinnia Lilliput. I

chose 4 different temperatures to be manipulated: room temperature (26oC), cool

conditions (3oC and 7oC) and winter conditions (-12oC). The seeds that will be tested at 7oC

will also be put at room temperature afterward to make a conclusive assumption on

whether tropical seeds have a period of dormancy. To make this decision, I will judge by

seeing if the seeds germinate at room temperature after being left in cool conditions. It may

also help to decide whether some of the seeds can be classified as truly tropical as the

sources claim. This decision is made by seeing if the seeds germinate in cool conditions and

winter conditions, which they are not supposed to do if they are truly tropical seeds.

Usually, germination has first started when the first radicle pushes through the soil;

however for this investigation, the emergence of the first hooked hypocotyl will mark


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germination. This is because the seed will be covered in soil, and if the soil is disturbed

frequently to check whether the radicle has emerged it will cause anomalies. I conducted

this experiment entirely in my house so that I never missed any of the signs of germination,

and because it is easier to monitor.

I hypothesize that the seeds will have double the normal time taken for germination

when subjected to cool and winter conditions. Usually, tropical plants don’t have any period

of dormancy and so it will be interesting to know if these specific seeds have that

mechanism.

I.e. Cool conditions (3oC) and Winter conditions (-12oC)


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APPARATUS AND METHODOLOGY

MATERIALS

1) Horti-brand seeds (Groundnut, Marigold, Tomato, Field pea, Lilliput and Dahlia) x1

pack each

2) Soil (Horti Seed & Potting Mix, J Arthur Bower’s Seed & Cutting Compost) x1 pack

3) Empty egg tray (preferably different colours for easy distinguishing) x4

4) Digital refrigerator x1

5) Toothpicks and labels x24

6) Pen x1

7) Teaspoon x2

METHOD

1) Prepare all the materials. The seeds have been treated appropriately so no

imbibition is needed prior to planting the seeds.

2) Place out the four egg trays. If they are not different colours, make sure to label

them with their temperatures. Label 6 of the burrow sections with one seed name.

3) Using a teaspoon, first scoop out one spoon of soil. Even the soil out using the back

of the spoon. Do these to all 6 burrow sections in all the egg trays.

4) Take out 3 seeds from the groundnut packet and push them into the individually

labelled soil until they are fully covered. Do this to the other 3 egg trays.

5) Scoop out another teaspoon and spread evenly on top of the seeds. Repeat for the

other 3 egg trays.

6) Repeat step 4 for all the other seeds (Marigold, Tomato, Field pea, Lilliput and

Dahlia). Do this to all 4 trays.

7) Repeat step 5 for all 4 egg trays.

8) Take the other teaspoon, place 2 spoons of water into all of the seeds covered in

soil. Remember that the soil should never be wet, only damp, but not dry either.

Wait 15 minutes for the water to be fully absorbed before placing the trays in their

respective conditions.

9) Place the tray in room temperature (26oC) near a windowsill but position it away

from direct contact with sunlight. Direct contact may speed up germination too

much.


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10) Place the tray in cool conditions inside the main refrigerator. Set the temperature to

3oC.

11) Place the other tray in cool conditions inside the chiller. Set the temperature to 7oC.

12) Place the tray in winter conditions inside the freezer or other area in which

temperature can be adjusted. Set the temperature to -12oC.

13) Now, check periodically every 2 days and remember that the coiled hypocotyl marks

germination. Water the seeds every 2 days when the soil starts showing signs of

being dry; remember that the soil must always be damp.


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PICTURE OF EXPERIMENT READY TO GO

Temperature

i.e. 3oC

Egg tray

Toothpick

Label containing

seed name i.e.

Tomato

Soil i.e. JAB Seed

and Cutting

Compost

Seed i.e.

Groundnut


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DATA ANALYSIS

First, I will analyze the results of the seeds sown in room temperature i.e. normal

conditions, in order to understand the results of the seeds sown in cool conditions and

winter conditions. All the seeds sown in room temperature germinated within the

germination period prescribed on the packet. This means that the factors of germination

have been successfully met. Since the seeds have been treated, initial imbibition was not

required in order for the seeds to start their metabolic processes. The right conditions for

each seed differed slightly, but they all needed the three factors of germination in order to

start the process. For example, groundnuts had to be sown deeper (1 inch) than the other

seeds (6mm) to allow sufficient room for the first radicle to grasp the soil. Other than that, it

required enough water to dampen the soil every two days and oxygen was provided in the

air, as well as the temperature being in the right range. This information is displayed below:

When I first did some practice runs before the real trials, I found that the seeds

had to be watered every two days in order for the soil to stay continuously damp. At first, I

watered the seeds every day to stay safe; however, the soil then became too wet and soon

enough, maggots started appearing. After this, I then tried watering the seeds every 3 days

since watering every day lead to stagnation of water and every two days seemed too soon

at the time. I observed that by the 3rd day, the soil was too dry, which led me to conclude

that maybe 2 days was the right time. When I tested this out, it turned out to be just right

and the seeds germinated within the time period estimated on the packet. Oxygen was in

02468

10121416

Days

Plants

Mean germination time in 26oC (days)

Mean germination time in26oC (days)


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the air already; however, I had to make sure the air-conditioning was not turned on to

ensure that the air was not artificially cooled and the temperature wouldn’t be affected.

Seed Actual Germination Temperature (oC)

Groundnut 18

Marigold 21-27

Tomato 21-27

Field peas 21-30

Dahlia 21-27

Lilliput 21-26

The seeds in the cool and winter conditions never germinated at all. This showed

how important temperature was for a seed to germinate, even though other factors were

provided in the right conditions. The table above shows the actual temperature needed by

each seed to germinate, provided that oxygen and water is provided as needed. Oxygen was

one factor I couldn’t completely control, so this may be one of the many reasons behind the

seed not germinating. This result was a surprise as I thought that by continuing to provide

water as needed, the seeds would just take longer to germinate.

Since those seeds didn’t germinate, there must be a number of factors that would

have influenced them. After absorbing water, the plant growth hormone gibberellin is

produced; by watering the seeds before I put them into their respective conditions, it can be

assumed that gibberellin would have started to be produced by the seed before the

temperature had set in. Once this happened, the seed would have sensed that not all the

right conditions were provided in order for the germination process to occur, probably 10

minutes after being put into cool and winter conditions. At this point in time, since the right

conditions hadn’t been met yet, the seed would have started producing abscisic acid, which

would inhibit germination in the seed.

Gibberellin is now not being produced, which induces the seed into a period of

dormancy. After gibberellin is produced, it stimulates the production of amylase to break

down the starch in the food reserves to maltose so that it can be transported to the root

and tip of the seed to start growth. However, the gibberellin that may have been initially

produced would have been stopped immaturely and no germination would take place since

Table of Actual Germination Temperatures (Various sources)


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there wouldn’t be any food resources supplied. Hydrolytic enzymes are produced and work

when the temperature is in the right range; the enzymes may have been produced since

enough water had been soaked in for the 15-minute interval before placing the seeds in

their respective places, but enzymes denature at very high temperatures and work very

slowly at very low temperatures. Once the seed had sensed that the temperature was

below its working range, the enzymes’ activity would have slowed down significantly

because of the lack of optimum temperature.

I assume that the seeds entered into a period of dormancy because of the lack of the

factors stated above. It is quite a rare occurrence for tropical plants to have periods of

dormancy since the all factors needed for germination are in ample supply all year long,

except probably during the wet and monsoon seasons. To break this dormancy, the seed

would need to be hydrated before dormancy-breaking signals induce changes in the

membrane. At the same time, gibberellin would need to be produced to promote seed

germination while abscisic acid, which inhibits germination, would need to be stopped

producing.

However it is quite an assumption to make without further analysis, which is why the

experiment done at 7oC and then put into room temperature should be analyzed first. This

test was done to see if the seeds truly had entered into dormancy periods when tested in

the lower temperatures. There were two seeds that germinated in this temperature: field

peas and marigold, and I will consider them anomalies. The sources I have consulted state

that these seeds are tropical; however, one site states that field peas can be grown in

temperatures as low as 10oC. Though, since only one site can vouch for this, I will continue

on the knowledge that they germinate between temperatures of 21-30oC. It is very

interesting that field peas can germinate even in 7oC, but once the temperature was

lowered to 3oC there was no sign of germination. In accordance with my hypothesis

however, it did take double the time it took for the seeds to germinate in room

temperature.

An explanation that is relevant is that field peas are also grown in temperate zones

like the Upper Midwest states of Wisconsin and Minnesota in USA. Although known to be

cultivated extensively in the tropical regions of Southwest Asia in countries like India and


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China, the fact that they can be successfully grown in temperate zones too can mean an

evolutionary adaptation to lower temperatures than in the tropical region. Over the time

has led to a gradual separation of types: those grown for vegetable use, those grown for

seed and fodder, and the edible podded types which have evolved most recently (green

with yellow tinge used in this experiment). It is during this time that the field pea would

have evolved and changed its adaptations in accordance with the changing climates it was

put in.

As for the marigold, all sources that were actively sought state that it germinates

between the temperatures of 21-27oC, therefore making this result a surprise on my part.

The specific species that I chose is the Tagetes erecta which is native to countries in the

tropics such as Thailand and specific states in India that don’t have a winter season. The

temperatures in these areas rarely reach temperatures as low as 21oC so it should have

been impossible for the marigold seeds to germinate in temperatures of 7oC. Common

sources state however that marigold is known to be a tough plant, germinating even in

temperatures as high as 35oC. This explanation can be owed to the fact that Tagetes erecta

is known in English as African marigold, which explains the extreme adaptability of this

plant. It was also brought to France, a country with moderately cold temperatures, and the

dwarf species Tagetes patula evolved; during the travelling between different climates,

there must have been an evolution of the species along the way that made the marigold

such a flexible plant. In colder temperatures, it can be said that marigold do not grow as

magnificently tall as their counterparts in the normal germinating and growing

temperatures of 21-27oC.

The other seeds -which are the groundnut, tomato, dahlia and lilliput seeds- did not

show any signs of germination when they were put into room temperature after being

subjected to 7oC. This set of results disproves my hypothesis completely as it shows that

tropical seeds may indeed have the dormancy mechanism within them. The hydrolytic

enzymes produced during the germination process would not be working at their optimum

temperature thereby slowing down the process significantly. However, this still doesn’t

mean that the process may have been completely stopped until appropriate temperatures

for the seeds to germinate are provided; therefore it is necessary to classify when exactly

can the seeds can be assumed to have gone into a dormancy period. I would say that this


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assumption would be valid to make after triple the time taken for the seeds to germinate

under normal conditions. This is why I put the seeds in room temperature after subjecting

them to 7oC for an extra week to legitimize my deduction as much as possible.

I also assume that these seeds specifically, could be classified as quiescent seeds. A

period of quiescence is when no active growth is recorded, and during this time the seeds

can survive harsh environmental conditions and can be transported to an environment

where it is suitable for germination to occur in that particular seed. Quiescent seeds are

ripe, and these seeds are already ripe; therefore, it is possible that they are quiescent

because cool and winter conditions can be classified as harsh environmental conditions to

tropical seeds. There will be a prevention of the series of complicated chemical and

metabolic processes, due to the presence of abscisic acid as previously mentioned.

Germinated and Sprouted Seedlings


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CONCLUSION AND EVALUATION

In conclusion, my hypothesis was disproved completely as I have explained above in

the analysis.

This may be because the seeds have entered into a period of dormancy and became

quiescent due to being subject to harsh environmental conditions, considering that they are

tropical seeds. Complex chemical and metabolic processes have been inhibited just because

the temperature has been changed drastically, which conveys how important temperature

is as a factor of germination. In the process, the importance of water was also learned as a

factor of germination, and how it starts off a series of complicated chemical processes in

order for germination to occur.

I would definitely say that there is more to learn and understand about the topic of

germination because there are very few resources that guide you on the theory of

germination and its processes. It would be nice to find a book, article or website that fully

explains this interesting process. In future, I would love to learn more about germination

theories if possible because I like gardening and flora in general.

There are several ways in which I could improve my experiment. The main one is to

find a way in which I can provide oxygen to the plants in cool and winter conditions while

they are being stored in the refrigerator. This is one factor of germination, and it would be

good to find out if the seeds could germinate in cool conditions at least if oxygen was being

provided regularly along with water.

Secondly, I think a few more trials would have given me a chance to have a solid

analysis on the results that I procured. As always, the more trials there are, the better the

average and there would be minimal uncertainties, as much as can be avoided, to give

reliable results and lead to a good conclusion.

It would be good to find an environment that is perfectly suitable for investigating

normal germination conditions in order to lead to a more solidly-based analysis. A more

solid analysis may mean more data and theory that can be extensively used to explain how

the germination of tropical seeds is affected in cool and winter conditions. This investigation

yielded numerical data but which can’t exactly be examined through graphs since


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calculations are not necessary; possibly in the next experiment, rate of germination can be

investigated.

Also, the room temperature was in a range, which made it a little difficult to pinpoint

the exact germination temperature of a specific seed. I would need to conduct the

experiment in a room where temperature is can be kept under constant control, which can

improve the reliability of my data quite significantly.

One factor that I could possibly make sure of is the health of the seeds. If the seeds

aren’t healthy, the germination process would take longer than usual or not be in the right

condition to ever germinate. Also, seed age can interfere with the germination process;

garden plants usually have quite low shelf-lives (1-2 years). There was no way I could be

sure of the freshness of the seeds since they were externally packed. Next time, it would be

good if fresh seeds straight from the plants can be obtained.


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APPENDIX

DATA COLLECTION

Room temperature (26oC)

Name of Plant Estimated Germination Time (days)

Actual Germination Time (days) Mean Germination Time (days)+ 1 day Trial 1 Trial 2

Seed 1

Seed 2

Seed 3

Seed 1

Seed 2

Seed 3

Groundnut 10-15 15 15 15 14 14 14 15

Marigold 5-7 7 6 7 6 7 6 7

Tomato 10-15 12 12 11 10 11 11 11

Field pea 5-7 3 3 4 4 3 3 3

Dahlia 5-7 5 7 7 5 5 6 6

Lilliput 5-7 7 5 5 6 7 5 6

Cool conditions (3oC)



Seed 1

Seed 2

Seed 3

Seed 1

Seed 2

Seed 3

Groundnut 10-15 - - - - - - -

Marigold 10-14 - - - - - - -

Tomato 10-15 - - - - - - -

Field pea 5-7 - - - - - - -

Dahlia 5-7 - - - - - - -

Lilliput 5-7 - - - - - - -

Winter conditions (-12oC)



Seed 1

Seed 2

Seed 3

Seed 1

Seed 2

Seed 3

Groundnut 10-15 - - - - - - -

Marigold 10-14 - - - - - - -

Tomato 10-15 - - - - - - -

Field pea 5-7 - - - - - - -

Dahlia 5-7 - - - - - - -

Lilliput 5-7 - - - - - - -


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Cool conditions (7oC)



Seed 1

Seed 2

Seed 3

Seed 1

Seed 2

Seed 3

Groundnut 10-15 - - - - - - -

Marigold 10-14 14 14 14 14 14 14 14

Tomato 10-15 - - - - - - -

Field pea 5-7 7 7 7 7 7 7 7

Dahlia 5-7 - - - - - - -

Lilliput 5-7 - - - - - - -

And then to room temperature (26oC)



Seed 1

Seed 2

Seed 3

Seed 1

Seed 2

Seed 3

Groundnut 10-15 - - - - - - -

Marigold 10-14 Already germinated at 7oC -

Tomato 10-15 - - - - - - -

Field pea 5-7 Already germinated at 7oC -

Dahlia 5-7 - - - - - - -

Lilliput 5-7 - - - - - - -

Dependent variable: Germination Time (days)

Independent variable: Temperature

Controlled variables: Exposure to light, Amount of water given to seeds


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WORKS CITED LIST AND BIBLIOGRAPHY

Allott, Andrew. IB Study Guides Biology for the IB Diploma. Glasgow: Oxford University

Press, 2007.

Clegg, C.J. Biology for the IB Diploma. London: Hodder Education, 2007.

Field pea. Purdue. <http://www.hort.purdue.edu/newcrop/afcm/drypea.html> 25 Oct 2011. Web.

Gardening. Gardening. <http://gardening.wsu.edu/library/vege004/vege004.htm> 15 Sep

2011. Web.

Gardening. Plant care. <http://www.plantcare.com/gardening-guides/flower-seeds/seed-

germination-process.aspx> 20 Sep 2011. Web.

Germination. Wikipedia. <http://en.wikipedia.org/wiki/Germination> 15 Jul 2011. Web.

Germination. Cactus-Art. <http://www.cactus-art.biz/note-

book/Dictionary/Dictionary_G/dictionary_germination.htm> 15 Jul 2011. Web.

Germination. Plant-Phys. <http://plantphys.info/seedg/seed.html> 15 Jul 2011. Web.

Germination. Buzzle. <http://www.buzzle.com/articles/seed-germination-process.html> 15

Jul 2011. Web.

Germination. Gardening central.

<http://www.gardeningcentral.org/germination_process/germination_process.html> 25

Sep 2011. Web.

Germination. The Seed site. <http://theseedsite.co.uk/germinating.html> 25 Sep 2011. Web.

Marigold. Plant biology. <http://www.plant-biology.com/Tagetes-Marigold.php> 25 Oct 2011. Web.

http://www.hort.purdue.edu/newcrop/afcm/drypea.html

http://gardening.wsu.edu/library/vege004/vege004.htm

http://www.plantcare.com/gardening-guides/flower-seeds/seed-germination-process.aspx

http://www.plantcare.com/gardening-guides/flower-seeds/seed-germination-process.aspx

http://en.wikipedia.org/wiki/Germination

http://www.cactus-art.biz/note-book/Dictionary/Dictionary_G/dictionary_germination.htm

http://www.cactus-art.biz/note-book/Dictionary/Dictionary_G/dictionary_germination.htm

http://plantphys.info/seedg/seed.html

http://www.buzzle.com/articles/seed-germination-process.html

http://www.gardeningcentral.org/germination_process/germination_process.html

http://theseedsite.co.uk/germinating.html

http://www.plant-biology.com/Tagetes-Marigold.php

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