Potometer Experiment : Measuring the rate of transpiration. A-level Biology Experiment

Learn how a potometer shows the rate of transpiration and the associated calculation. Learn how to set up the equipment, collect the data and try some common exam questions linked to this A-level biology topic.
**** Corrections at 7.57mins. The units should be mm^3 min^1
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[@MissEstruchBiology]

Hello! I hope this video helps you with your Biology A-level😊 For more STUDY TIPS and biology help, follow me on Instagram @MissEstruchBiology instagram.com/missestruchbiology/?hl=en OR if you want to get your hands on some A-level NOTES READY MADE by me with key marking points, keywords, and essay links, make your way to missestruch.com/ (this will be available from July 2021 - Can't wait?? email [e-mail] to get your hands on a copy before then).

[@Schmingle38]

The photometer practical is the worst thing in the world. I hate it with a passion. If I could remove one thing from the syllabus it would be this stupid waste of time. Try and get it set up for an hour then wait 30 mins for the stupid air bubble to move 1mm I HATE IT

[@shreyalapsia9438]

thank you for taking the time to make a powerpoint and explain it fully :)

[@MissEstruchBiology]

you're welcome, hope it helps 😊

[@izzy8506]

Thanl you so much! I am on study leave right now and panicked when I couldn't remember how to set up a photometer. This was super useful and I can confirm I officially understand!

[@dijasoar]

You make every thing so easy thank you so much 🥺❤️

[@MissEstruchBiology]

awww thank you. So glad the videos are helping you

[@drwai3157]

so valuable & helpful lecture

[@heeralchauhan1128]

I love your explanations. Thank you!

[@MissEstruchBiology]

Thank you! Glad its helping you

[@elianahanstater6359]

Thank you so much!! You really helped me understand this experiment

[@MissEstruchBiology]

You're welcome 😊 So pleased it helped you!!

[@leannegillingham4460]

Amazing!! Answered lots of my questions : )

[@MissEstruchBiology]

So glad it helped 😊

[@murriammurtaza339]

thankyou soooo much for this video. I didn't understand it in class but you explained it so well and now I'm confident with it

[@MissEstruchBiology]

I'm so pleased 😀 ☺️ That's great

[@sepilepi9908]

thank u so much for explaining, i understood the whole thing

[@MissEstruchBiology]

Hello, That's great ☺ So glad its helped you fully understand .

[@yashvisinghvi5564]

Thankyou sm for your help ❤️

[@MissEstruchBiology]

You're welcome!😊

[@hainguyenanghoang3131]

wow, thanks for your experiment. I very like it

[@MissEstruchBiology]

You are welcome

[@Nethmi3]

Thank you 💜

[@MissEstruchBiology]

You're welcome, hope it's helped you 😊

[@chiranthipoornima4793]

It was very useful.thank you very much

[@MissEstruchBiology]

That's great to hear you found it helpful 😀

[@elliebrunton3821]

I’ve got a practice paper and I’m stuck on a question : suggest how the student moved the air bubble back to 0mm. Please help love your vids x

[@MissEstruchBiology]

Hello, To reset, or in other words, move the air bubble back you need to open the tap connected to the water reservoir. This allows water from the reservoir to enter the capillary tube and therefore moves the air bubble back.

[@fadelgunawan4605]

Thank youuuuuuuuu

[@MissEstruchBiology]

you're welcome 😊

[@tsoanelomotai3]

This is perfect💕

[@MissEstruchBiology]

aww thank you ☺

[@arrybababecool]

Excellent

[@MissEstruchBiology]

Thank you 😊

[@EmmaMungolo]

Didnt have a clue on how this thing worked 😂 Thank you

[@MissEstruchBiology]

yay glad it helped

[@lucasmurray7504]

great for revision this

[@MissEstruchBiology]

thank you!

[@garvinodhiambo6134]

Thank

[@arrybababecool]

Very nice mam good work keep it up so lovely

[@MissEstruchBiology]

Thank you so much!

[@isarkar302]

Thank You Mam

[@MissEstruchBiology]

Most welcome 😊

[@chloesalloux7267]

if you do aqa a level biology do you need to memorise the volume of a cylinder or will they give you the equation in the exam ?

[@aggelikichrisomalli9]

Thank you! The video was really helpfull! What if, instead of water inside the potometer we put 0,4 M NaCl solution?

[@MissEstruchBiology]

You're welcome. I have only ever seen this experiment conducted with water, but as it is to due with evaporation and pressure changes I imagine it would work the same. That concentration of NaCl may have been used to represent the concentration or NaCl naturally occurring in the xylem.

[@mikeoxlong2077]

wow....... have an exam ina few days for biology and am literally sturggling. this videos of yours really helped me :)

[@MissEstruchBiology]

Best of luck for your exam! Really pleased it's helped you prepare 😀

[@nazish47]

Hello Miss Estruch, for the last question on what variables would have to be controlled, could you mention the length of the plants or the mass?

[@MissEstruchBiology]

Hello, Yes, the leaf surface area does have an effect, as this determines the number of stomata. Length or mass probably isn't specific enough, it would be size and number of leaves.

[@nazish47]

Miss Estruch thank you very much!

[@kuendennorbu308]

Tqsm for the best explanation la

[@MissEstruchBiology]

Thank you! So glad you found it clear to understand

[@gloriastefanus4613]

May God keep you for me. Safe and sound

[@rusherrusher6797]

Hi, your videos are very helpful! Will the practical (the Potometer one) be in the AS level paper (2022) ? It would be great if you could reply tomorrow since my exam is the day after. Thank you

[@Yousif_Tareq]

Did it come up>?

[@Anna-pt4uf]

Im so glad i found your videos, they will definitely help with my upcoming year 12 exams :) Thank you 😊

[@MissEstruchBiology]

Best of luck for your exams! Really glad they are helping you 😊

[@mohid0786]

Hey, I'm really confused at 05:30. How do I calculate vol. of water that has moved from the volume of the cylinder?

[@MissEstruchBiology]

hey it would be pi r squared x the distance the liquid had moved. Basically the volume of a cylinder, but the length is the distance the air bubble moved.

[@thephenomenalone2196]

For AS Paper 1 Biology - Does this video for all under paper 1 topics. Is this under mass transport or gas exchange? Thank you for everything.

[@MissEstruchBiology]

Hey. transpiration falls under mass transport as its linked to cohesion tension theory

[@karishmakaur3578]

Why isn’t the unit mm^3 min^-1?

[@MissEstruchBiology]

Hey, Good spot! They should be, as it is a volume measurement. I have added this correction in the description, thank you.

[@angelahalton8827]

Hi Miss Estruch, why is it important not to get water on the leaves when setting up the equipment?

[@MissEstruchBiology]

Water on the leaves will make the surrounding air more humid, and therefore can reduce transpiration and affect your results.

[@angelahalton8827]

Miss Estruch thank you!

[@asheeqahadams5737]

A combination of which conditions will yield the maximum /fastest rate of transpiration?

[@MissEstruchBiology]

Hello, High light intensity High temperature Low humidity High air movement These would give the fastest rate 😊

[@zombietron6080]

why does cohesion tension create a negative pressure in the xylem?

[@MissEstruchBiology]

as water evaporates out of the stomata that is what creates the negative pressure. Hope that helps.

[@alishahussain1431]

Hi! Is the rate of water uptake and rate of transpiration different? As I’m doing a question for water uptake and I had to do rate = speed of air bubble x cross section of tube. I tried to do rate = volume of water / time taken but the answer came up as wrong And help really appreciated thank you!

[@alishahussain1431]

It is from question 8a for the topic 3 assessments on your website!

[@MissEstruchBiology]

Hello, the rate of water uptake and rate of transpiration are proportional. The potometer actually measures water uptake, but we use this as the value for transpiration also.

[@amirabdullah2975]

Is the pressure inside the tube is lesser than air?

[@MissEstruchBiology]

The pressure inside the tube is dependent on how quickly transpiration occurs. If it is occurring quickly then lots of water is evaporation, which reduces the pressure and this is why more water is pulled up the tube.

[@user-nd2zs2ic6k]

when calculating the rate, you said to divide by the time taken, but in the example you didn't divide just multiplied, why is that? Thanks for the vids btw!

[@MissEstruchBiology]

Hello, you would divide by the time taken, but in this example the time taken was 1 minute. So divided by 1 would give the same answer, which is why I didn't include this step in the calculation. I hope that helps :)

[@sigmamale918]

Could you name the equipment of the setup please

[@MissEstruchBiology]

The set up is called a potometer

[@youmnaelsharaky7467]

hi thankyou so much but can i say keep temp /humidity/light /air the same as an answer for the last question?

[@MissEstruchBiology]

one of those may be the independent variable, but also it is not easy to accurately control those variables, around the plant. You may monitor them to see if they are consistent instead

[@keepinthefaith.5406]

On biology csec

[@garvinodhiambo6134]

Hi

[@garvinodhiambo6134]

Where are you know please mum

[@muskanshah1735]

Thia black band is irritating ...unable tk visualise a few lines

[@MissEstruchBiology]

The wiggly one? That's removed on my recent videos.