B11 - Hormonal Coordination Flashcards
How the body is controlled by chemicals called hormones .
The Endocrine system .
What is the endocrine system ?
-It contains a number of GLANDS , These glands secrete hormones directly into the BLOOD STREAM .
-The blood carries the hormones all around thebody .
-But ech hormone acts on specific traget organs where it produces an EFFECT .
ONE DIFFERENCE BETWEEN THE NERVOUS SYSTEM AND THE ENDOCRINE SYSTEM ?
-The nervous system uses electrical impusles which travel down neurones .
-Wheres the endocrine system uses hormones which are chemicals these are carried in the blood stream .
ANOTHER DIFFERENCE BETWEEN THE NERVOUS SYSTEM AND THE ENDOCRINE SYSTEM ?
-Whereas signalling in the nervous system is extremely fast .
-The endocrine tends to produce a much slower effect , which is also longer lasting .
ONE KEY GLAND IN THE ENDOCRINE SYSTEM - THE PANCREAS
-Releases hormones involved in controlling the concentration of glucose in the blood .
ANOTHER KEY GLAND IN THE ENDOCRINE SYSTEM - OVARIES AND TESTES
-Release hormones involved in puberty and in reproduction .
THIRD KEY GLAND IN THE ENDOCRINE SYSTEM - THE THYROID GLAND
-Produces hormones invovled in growth and regulating the body’s basal metabolic rate (how rapidly the bodies reactions take place ,)
FOURTH KEY GLAND IN THE ENDOCRINE SYSTEM - THE ADRENAL GLANDS
They release the hormone adrenline which is produced in times of fear or stress.
Final KEY GLAND IN THE ENDOCRINE SYSTEM - THE PITUITARY GLAND .
-Located in the BRAIN .
-It is extremely important , scientist ca;; the pituitary gland a MASTER GLAND as the pituitary gland releases a number of diferent hormones into hte blood depending on the conditions .
KEY POINT ABOUT PITUITAYR GLANDS .
-The pituitary hormones act on other glands causing other homes oto be released .
-By acting on other glands , the pituitary hormones can trigger a range of different effects in the body .
What is glucose needed for ?
-Glucose is needed by eveyr cells to release energy for respiration .
-So it is very important that the concentration of glucose is kept constant as possible . THIS IS PART OF HOMEOSTASIS .
WHAT HAPPENS WHEN YOU EAT A CARBOHHYDRATE RICH MEAL AND YOUR BLOOD GLCUOSE GOES UP .
-Blood glucose concentration is monitored by the pancres .
-After a meal rich in carbohydrates , the concnetraiton of glucose in the blood can rise.
-This is sensed by Tthe PANCREAS . the pancreas then produces the hromone INSULIN .
WHAT HAPPENS WHEN YOU EAT A CARBOHHYDRATE RICH MEAL AND YOUR BLOOD GLCUOSE GOES UP . Stage two
-Insulin travels in the bloodstream all around the body and it triggers the body cells to take up the glucose from the blood .
WHAT HAPPENS WHEN YOU EAT A CARBOHHYDRATE RICH MEAL AND YOUR BLOOD GLCUOSE GOES UP . STAGE THREE
Insulin also triggers liver and muscles cells to store excess glucose as a stroage moelcule called glycogen .
WHAT HAPPENS WHEN YOU EAT A CARBOHHYDRATE RICH MEAL AND YOUR BLOOD GLCUOSE GOES UP . Stage four
-As glucose is being taken out of the blood +stored the concentration of glusoe in the blood returns to is normal level . AKA HOMESTASIS HAS TKAEN PLACE .
In some people , their blood glucose control does not work effectively .
These people have diabetes .
WHAT HAPPENS IN TYPE 1 DIABETES
The pancreas doe snot produce enough insulin .
WHAT HAPPENS IN TYPE 1 DIABETES
The pancreas does not produce enough insulin .
What does the graph show ?
-Graph shows blood glucose in a person with type 1 , diabetes as a person who does not have diabetes .
-At the start of the experiment , both people ate a meal containing the same amount of carbohydrate .
What does star one show
-In both cases , the concentration of glucose in the blood rises .
-In ther person WITHOUT DIABETES , the blood glucose concenrations rapidly returns to its normal level . Due to the effect to Insulin .
Star one (2)
-However , with a perosn with type 1a high level .
* diabetes . the blood glucsoe conentrations rises and then stays at a high level .
-That is because the pancreas cannot produce a sufficent amount of insulin .
How do people with type 1 diabetes treat their condition
-They monitortheir blood glucose concentration and inject themselves with insulin if the blood glucose rises too much example after A CARB HIGH MEAL .
WHat does star two on the graph show ?
-When the person with type 1 diabetes injects themseles with insulin , you can see that thier lood glucose concentration can fall .
Type 2 diabetes
-The body cells stop responding tto insulin produced by the pancreas .
-Again in these patients , blood glucose leevsl rise too ghigh .
How is type 2 diabetes treated
-It is often treated with a diet contraining a controlled level of carbohdyrates .
-THis is to preven blood glcuose levels from rising too high .
-People with type two diabetes are also advised to take exercise
MAJOR RISK FACTOR FOR TYPE TWO DIABETES .
-OBESITY .
-As obesity levels are increasing in the Uk , we are seeing more type 2 diabetes int he U .
WHAT HAPPENS IF THE BOOD GLUCOSE CONCENTRATION FALLS .
-If it is too low , then the pancreas releases the hormone GLUCAGON , into the bloodstream
What does glucagon do ?
-Glucagon triggers liver cells to convert glycogen stores back to glucose . This glucose is then released back into the blood .
-This causes the blood glucose concentration to return to normal .
Check the grpah , what does it show ?
-A persons blood glcuose concentration . T
-this persond oes not have diabates .
-Blood glucose concenration rises slightly and falls slightly over the course of the day . AS YOU CAN SEE .
-That is because blood glucose concentrations is controlled by a balance between insulina nd glucagon .
What does star one of the triple graph show ?
-If the glucose concentration is rises , the pancreas releases insulin ,a nd this cuases the glucose conentration to fall .
bhWhat does stat two show of the triple graph ?
-However , when the glucose concentrationf alls to certain level , the pancreas releases glcuagon . Causing the glucose conentration to rise again . y
What is a negaitve feedback cycle
-Becuase INSULIN and glucagon can have opposite effects on the blood glucose concentration . SO scientits say that they form a NEGATIVE FEEDBACK CYCLE .
Where are the adrenal glands locted ,a nd what are there effect ?
-The adrenal glands are located at the top of the kidneys .
-During times of fer and stress , the adrenal glands produce the hormone adrenaline . aDRENALINE IS RELEASED into the blood .
What is the EFFECT of adrenaline ?
-O ne of the main effects of adrenaline is to increse HEARTRATE . As he heart is beating faster , more oxygen and glucose are delievered into the body to the brain and muscles .
-Both oxygen and glucose are needed for aerobic respiation . This prepares the body to either fighrt or runaway . Scientists call this FIGHT OR FLIGHT .
Where is the thyroid glands located ?
Thyroid glands are located in the back of the neck and this releases the hormone THYROXINE .
One effect of THYROXINE
-Firstly , thyroixine stimulates the body’s basal metabolism .
(Metabolism is the sum of all the chemical reactions in the body 0
-AKA , thyroxine makes the body;s chemical reactions take place at a FASTER RATE ./
Second effect of THYROXINE
-Thyroixien plays an important role in GROWTH + DEVELOPMENT .
-the level of thyroxine in the blood is controlled by NEGATIVE FEEDBACK .
EXAM NOTE - dont need to know any specifc negative feedbac cycles even THYROXINE , but hsould have a general idea .
…
Thyroxine negative feedback cycle p1
-Level of thyroxine in the blood is monitored by the brain .
-When thyroxine lvels fall , the pituitary gland releases the hormone TSH into the bloodstream .
Thyroxine negative feedback cycle p2
-TSH triggers the thyroid glands to release mroe thyroxine into the blood .
-The increasing level of thyroxine is now detected by the brain .
-This now prevents the pituitary gland from releasinng tsh .
-The TSH levels falls . The thyroid glands release less thryoixine .
A genereal understanding ont hyroxine negative feedback cycle
-If the level of thyroxine falls , events are triggered causing the levels of thyroxine to increase .
-If it gets too high ,e veents are triggered to bring it back down .
-THIS IS A NEGATIVE FEEDBACK CYCLE .
Other negtiave feedback systems ;
-Blood glucose
-Menustral cycle
What is a really important role of the endocrine hrome ?
-In the human reproductive sytem .
-During puberty , reproductive hormones cause SECONDARY SEXUAL CHARCATERSTICS TO DEVELOP , e.g ppubic hair .
IN MEN THE TESTES
-Produce the hormone testosterone .
-Tesosterone stimulates the testes to produce sperm .
IN WOMAN , THE OVARIES
produce the hormone oestrogen .
-Once puberty begins , eggs in the ovaries stsart to mature .
-Eevery 28 days an egg is rleased this is called OVULATION .
-The reelase of an egg eveyr 28 days is part of the menustual cycle . .
S1 - what happens during the menustral cycle ?
-Before we look at the hormones invovled , every 28 days , ovlation takes place (the ovaryies relese an egg ) .
S2 what happens during the menustral cyle ?
-In prepartion for this , the utereus lining becomes thick and spogy .
s3 what happens during the menustral cyle ?
-The egg now makes its way down the uterus .
S4 what happens during the menustral cyle ?
-iF THE SPERM IS PRESENT , THE EGG CAN BE FERTILISED.
-If this happens it can implant the uterus all and develop into a baby .
-
S5 what happens during the menustral cyle ?
-However , if the g does not get fertilised then btoh the gga nd the ueterus lining are released . We call this a PERIOD .
Four key homrones in the menustral Cycle (1)
-Follicle stimulaitng hormones (FSH) - CASES THE EGG TO MATURE IN THE OVARIES .
Four key hormones in the menustral cycle (2)
Lutenisng hormone (LH) causes this egg to be released in other words OVULATION .
what happens during the menustral cyle ? (3)
Oestrogen (produced by the ovary 0) and progesterone is invovled in maintaning the uterus lining , incase the egg is fertilised and implants .
How the hormones of the menustral cycle interact (1)
-In the first tsage (FSH) is released by the pituitary gland . FSH travels into the blood to the OVARIES ,w here it causes an egg to marture .
How the hormones of the menustral cycle interact (2)
-FSH travels in the blood to the ovaries where it causes an eggt o mature .
How the hormones of the menustral cycle interact (3)
-At the same time , FSH triggerds the ovaries to make oestrogen .
How the hormones of the menustral cycle interact (4)
Oestrogen causes the lining of the uterus to become thick .
How the hormones of the menustral cycle interact (5)
-Oestrogen also stops the pitruitary gland from releasing any more FSH .
How the hormones of the menustral cycle interact (6)
-Instead , the pitruiary gland now releases (LH) , LH CAUSES OVULATION .
-oNCE THE OVARY HAS RELEASED THE EGG THE OVARY PRODUCES THE HROMONE PROGESTERONE WHICH HAS two effects .
What is one effect of progesterone ;
-It stops the pituitary gland from releasing FSH and LH , tht is to prevent any more eggs from maturing or being released .
What is another effect of progesterone ;
-Progesterone keeps the lining of the uterus thick incase a fertilised egg implants .
-If fertilition DOES NOT take place , then the levels of progesteerone FALLS .
How the hormones of the menustral cycle interact (7)
-The uterus lining and the egg are now released and the woman has a period .
In the exam , we could be asked to interpet graphs of these hormones during the menustral cycle .
check sheet .
What does star one show ?
-The level of FSH rises , and this triggers the ovaries to release oestrogen .
What does star two show ?
-As the levels of the oestrogen increas e, this inhibits the production of FSH , SO THE LEVELS OF FSH FALLS .
wHAT DOES STAR three show ?
wHAT DOES STAR FOUR SHOW ?
-Lh triggers ovulation , and once thishappens , the ovaryes release porgesterone . So the progestorone levels now rise .
what does star five show ?
However , if fertilistion deos not happen , then progestrone levels falls againa nd the women has her period .
-MANY PEOPLE WITH SRUGGLE WITH INFERTILITY -
some men can have reduced sperm count .
-Sqome women find it diccult to cocneiceive .
-Many of these people undergo fertiilty treatment .
First type of fertility teatment;
-FSH and Lh are given to a women , scientists call this combinaiton “fertility drug” , .
-This causes the women to ovullate more than usual .
-Increasing her chcances of becoming pregnant through sexual inercourse .
sECOND TYPE OF FERTILITY TREATMENT ;
-iN VITRO FERTILISAITON OR ivf ,
-hERE FERTILISATION TAKES PLACE OUTSIDE THE BODY .
sTAGE ONE OF ivf
-During iVF , the mother is first treated with FSH +LH , causing several eggs to mature .
Stage two of IVF
-These eggsa re then collected from the mother .
Stage Three of IVF
-At this point , sperm from the father is collected and is used to fertilise the egg in the laboratory .
Stage four of ivf
-The fertlised egg then develops into embryos .
Stage five of ivf
-Once the embryos are tiny balls of cells , these are inserted into the mother’s uterus (womb)
Stage six of IVF
-tHESE EMBRYOS THEN DEVELOp inside the mother in the usual way ..
Stage six of IVF
-tHESE EMBRYOS THEN DEVELOp inside the mother in the usual way ..
Stage six of IVF
-tHESE EMBRYOS THEN DEVELOp inside the mother in the usual way ..
BENEFIT OF ivf
-iT GIVES THE MOTHER A CHANCE TO HAVE a aby of her own .
PROBLEMS WITH ivf (1)
-Sucess rates are not high .
-IVF is emotionally very stressful for both parents .
Problems of ivf (2)
-Also physically demanding on the mother (in the tretment with fertility drugs and collection of eggs ) .
-It can also lead to multiple births , this is risky for both the babies and mother .
Problems of ivf (2)
-Also physically demanding on the mother (in the tretment with fertility drugs and collection of eggs ) .
-It can also lead to multiple births , this is risky for both the babies and mother .
Ethical issues with IVF (1)
-Not all the embros that are created willbe transferred into the mother .
-This means that many embryos are destroyed and some people find tht unethical .
Ethical issues with IVF (2)
-IVF is also expensive .
-Some peoplebelieve this moeny can be spent on other medical issues like treatments ofr cancer .
Ethical issues with IVF (2)
-IVF is also expensive .
-Some peoplebelieve this moeny can be spent on other medical issues like treatments ofr cancer .
Artifical FSh how does it help woman conceive natrually who have infertility .
-I stimulated the gg to mature and oestrogen production in ovsires so uterus lining builds up .
-Artdial Lh can also trigger ovulation if necesary /
How does artifical fsh help women ocnceive through IVF , who have infertility .
Artifical FSh can be usd to stimulte the mturaion of manyeggs in the ovares .
-Artificl lh can then be used to brign them to the point of ovulation .
Advanatges of using artificial of using artifical hormones to control female fertility .
-People have the right to have children whenevr ageism .
-Career demands make it diffcult for women to have children early .
-mnay ot meet the right person until later in life .
-people still cosndiered young at 40 , life expectancies have increased .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
isadvantages of using artifical treatemnts (hormones) to control female fertility .
-chcances of succesful pregnancy are low .
-Cosrltty
-Older parents will be old s child grows .
Wha is contraception
-Ways to prevent fertilisation .
An example of hormonal contraception . The pill
-It is oral contrcpetion .
-These contrain hormones which prevent htebpdy from producing the hormone FSH .
-As FSH , causes the egg to mature .
-So taking the contracepivepill prevents any eggs from maturing .
Advantages of the pill.
-Esy to start an dstop .
-very effective if tken regularly .
-NOn invasive .
Disadvantages of the pill
-Must be taken every day .
-If a owmen forgets tot ake it , tthereis a risk o prgenany .
-Also there is a risk of breat cancer and bloot clots (although these riskss re low ) .
-Can take a long time to get pregnant fter the pill .
-mood swings (like on a period .)
Anothere hormonal contraceptin - using an impalnt , skin patch , or injection
-for implant - ainty tube is insergted under your skin and ptch jus stick on and it slwoly releases progesterone same a spill effect .
advanatges of implant etc
More convenient - dont need to remebet o take evry day . anf like implan alst thre years.
-It is 99.95 perecentge effecitve .
disadvanatge of implant etc
-same as pill
-it is an invasive porcedut .
-patch must be remebered to be replaced .
disadvanatge of implant etc
-same as pill
-it is an invasive porcedut .
-patch must be remebered to be replaced .
disadvanatge of implant etc
-same as pill
-it is an invasive porcedut .
-patch must be remebered to be replaced .
disadvanatge of implant etc
-same as pill
-it is an invasive porcedut .
-patch must be remebered to be replaced .
disadvanatge of implant etc
-same as pill
-it is an invasive porcedut .
-patch must be remebered to be replaced .
Another diadvanatge of hormonal contraception
-not RELATED TO PREGNANCY BUT
-does not protect agaisnt sexuall transmited disses stti like hiv .
Another diadvanatge of hormonal contraception
-not RELATED TO PREGNANCY BUT
-does not protect agaisnt sexuall transmited disses stti like hiv .
Another form of contracpetioni s the BARRIER METHOD .
-Like a condom or diaphragm .
-these prevent the sperm from releasing na gg .
-They are effective form of contraception if sued correclty .
-they dont use hormones os no side efects .
HOWEVR - a condom can break or slip off
-also it does reduce the risk of sti .
Another form of contraception is CHEMICAL METHODS - spermicide .
-Both condoms and diaphragm are more effective if theya re used with a spermicide gel .
Spermicides ill or disable sperm and reduce the chances of fertilistion
Inauternide devidcded - woemn use htis also known as Iud or coil
-Prevent an merbyo fromimpalnting .
-SOME COILS ,a lso release hromones to reduce the chances of fertilisation .
Advanatge highlye fective can prevent pregncny for u p to ten eats , very few side effects .
-disadvantages - dosent affect agaisnt stis .
Some people use contracpetion - sugricla methods called sterilisation .
-In women it prevent the egg from reaching the ueterus .
-In men tit prevents the perm from leaving the penis .
advanatege highly effective .
DISADVANATAG - veryd ifficult to reverse , needs ot be certain dont want children .
-also dont protect agaisnt stis .
Final form of contracrption ;
-Abstaining rom sexual intercourse during the time after ovulation .
-IT is a nutral fom of contracpetion .
Disadcanatge - hard to tell a omn has ovulaged , making natural contracpetio nd ifficlt ,and dont presvent sti .
-No side effects advanatge .
Strong opinions on contrception
-Catholic church reaches contraception to be unethical - and to only use natural methods .
-ohers belive it is apersons rights to choose what contracpetion is the best
-actuallyg ood condoms for exmpale prevent sti soo benefit .
plants growing towards the light ?
phototropism (positive)
if we shine light from one side only
shoots grow toward the light .
-ThERE ARE A NUMBER OF EAYS SCIENISTS TRIED TO FIND THE CUAE OF THIS .
One way
-scientists removed the very tips of the shoots .
-they foundthat the shoots did not grow toards the light .
-Scientists then suggested that the shoot tips produce a plant hormone , this hormone is called AUXIN .
Another way .
-scieniss then covered the tips of the shoots with foil to BLOCKOUT the lgiht .
-the shoots did not grow toards the lkight . This tells us the tips are SENSITIVE to light .
Final way
-scientists then used foil to cover the lower parts of the shoots .
-In this case , the shootsgrew towards the light as nromal .
-This tells us that the lower parts of the shoot ARE NOT sensitive to light .
How shoots use the hormmone auxin to grow towards the light . S1
-Auxin porduced at the very tip of the shoot .
-In shoots auxin triggers cell growth .
How shoots use the hormmone auxin to grow towards the light . S2
-Light causes auxin to concentrate on the darker side of the shoot tp .
How shoots use the hormmone auxin to grow towards the light . S3
-Auxin now spreads down the shoot .
-This means the cells on the darker side grow FASTER than cells on the lighter side .
How shoots use the hormmone auxin to grow towards the light . S3
-Auxin now spreads down the shoot .
-This means the cells on the darker side grow FASTER than cells on the lighter side .
How shoots use the hormmone auxin to grow towards the light . S4
-This cuases the shoots to grow towards the light .
Plant roots grow TOWARDS THE FORCE OF GRAVITY .
-This si called gravitropism /geotropism .
-This also invovles auxin .
geotropism
-auxin is porduced int he root , but graivty causes the auxin to concentrate ont he lower side .
KEY - in roots auxin INHIBITS the cell growth .
-SO the llowersidegrows more slowly then the upperside .
-Causing the roots gorw TOWARDS the force of gravity /
Plants also use other chemicals to regulate their behaviour (need to knwo 2 )
-Giberellins - are important in starting the germination of seeds .
-Ethene - controls cell division and the ripening of fruits .
What is the rqp about
-How plants use he homron eauxin to control teir growht .
What is the rqp about
-How plants use he homron eauxin to control teir growht .
Investigtion of first rqp
-investigting the effect of light intenisty ont he height of the seedlings .
Investigtion of first rqp
-investigting the effect of light intenisty ont he height of the seedlings .
What is the independant varibale .
Light intenisty
What is the dependant variable
height of the seedlings .
What is the control varibale
volvue of water , type of seend,
S1 of rqp
-Put cotton wool in three petridishes and soak them with equal volumes of water.
S2 of rqp
place 10 mustard seeds in each petridish .
S3 of rqp
leave the petridishes ina warm place nad allow the seeds to germinte .
S4 of rqp
we need to water the seeds everyday with the same volume of water .
s5 of rqp
afer a few days th seeds will germinate.
s6 of rqp
at this point , we need to make sure the three petridishes have the same umber of seedings . (as the number of seedlings is the ocntrol varibale .) (if there are more seeds in one petridish than the others , take seeds out ,)
s7 of rqp
use a ruler to measure the height of each seedling . We need to make sure the stems are striagt . But e careful not ot DAMAGE the seeldings .
s7 of rqp
use a ruler to measure the height of each seedling . We need to make sure the stems are striagt . But e careful not ot DAMAGE the seeldings .
s8 of rqp
place hte petridhses in different ocnditons .
1.in full sunglight - bright windowsill .
2.one in partial light - back of the lab .
3.last petridsh palced in darkness in a cupbboard.
s9 of rqp
theen emasure hte hgieght of each seedling everyday for 7 consecutive dyas , and record the results in a table .
s10 of rqp
when the experiment is finsihed ,w e cauclate the mean seedling height for eachdya .
-Also draw diagrmas to show the effects of different light intensities on the seedlings .
obersavtion one of seeldiings in light .
-the hieight of the seelding sis similar in both full sunlight and in partial sunlight .
-As CHOLORPHYL is a very effeicent at absorbing light energy ,s o plants DO NOT Nneed FULL SUNGOILHT TOGROW .
obersavtion one of seeldiings in light .
-the hieight of the seelding sis similar in both full sunlight and in partial sunlight .
-As CHOLORPHYL is a very effeicent at absorbing light energy ,s o plants DO NOT Nneed FULL SUNGOILHT TOGROW .
obersavtion one of seeldiings in light .
-the hieight of the seelding sis similar in both full sunlight and in partial sunlight .
-As CHOLORPHYL is a very effeicent at absorbing light energy ,s o plants DO NOT Nneed FULL SUNGOILHT TOGROW .
obersavtion one of seeldiings in light .
-the hieight of the seelding sis similar in both full sunlight and in partial sunlight .
-As CHOLORPHYL is a very effeicent at absorbing light energy ,s o plants DO NOT Nneed FULL SUNGOILHT TOGROW .
oBSERVATION TWO OF SEEDLINGS IN LIGHT .
HOWEVER , SEEDLING SHAVE GOWN towards THE LIGHT OSURCE DUE TO photoropism (AUXIN CONCENTRATE ON THE DARKER SIE SO THAT SIDE GROWS FASTER)
oBSERVATION one of seedlings in the dark
-they have grown the longest , as seeds usually germinate undergournd , and they grw rapidly to reach the light .
-Keep seedlings in the dark , t hey continue to grow rapidly to reach usnlight .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect two of seedlings in the dark
-the seeds ae smalla nd eywllow .
-as once hte seedligns hae used up all their energys tores , they cannot carryo ut photosynthesi sin the dark .
effect of gravity on the seeldings .
-petridish is placed on its side in the dark .
-The shoots will rgow upwards agasjnt the direction of graivty .
-thr ROOTS hve gorwn downawrds towards the direction of gravity .
(AS AUXIN INHIBITS THE CELL GROWTH IN ROOTS , gravityc uses the auxin to build up on thr lowerside of the root .)
-This now grows more slow y and makes the roots grow in the direction of gravity .
Auxins have three main uses
1.auxins ae used as weed killers (In gardens ) .
2.Auxins are used in rooting powders (saw than in the plan hormones topics when TAKING CUTTINGS.)
-Auxin is used fo rporomtoing growth in tissue cultures (Saw in cloning plnts topic .)
gibberelins are anohter type of plant hormones they have three different uses
-gibberelins can be used to end seed dormancy (they can ofrce a seed to germinate early then it normally would .)
-gibberelins can aslo be used to encoruage plants to flower .
-gibberleins can be used to mke fruit gro larger .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
ethene (bananas(
-Banans are usually harvested before they are ripe .
-These are then tranported long distances and can be stored before they are needed .
-Ethene is then used to trigger bananas to ripent , just before they are sold in the uk .
