Translocation in the Phloem (New AQA AS/A Level)
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- Опубліковано 6 сер 2024
- First video exclusively for the new specification!
This is quite a tricky topic, so it may take a couple of watches to really understand whats's going on...I don't think the textbooks are brilliant for this one!
We look at:
- Structure of the phloem
- Translocation
- Mass Flow Hypothesis
- Experimental Evidence
Hope you enjoy!
got the exam in 3 hours hopefully this'll save me
How did it go?
what grade u get?
corinna leng f
What did ya get?
this video clearly failed to save her, RIP corinna
I've been looking for a you tube channel for detailed notes on topics since the start of the year. glad i found your channel. your videos are amazing very helpfull. thank you!
you're really good at explaining stuff, wish you were my teacher :( this video works for students doing ocr as well!
Why did I do a level bio 😫
Sam Ways same
same... bio is by far the hardest sub out of the 6 im currently taking ( ≧Д≦)
@@tabarnakdecalisse man said 6. Is everything okay at home ?
I think the same also. But play some relaxing music and you'll want to do more of it!
thankyou!! please upload as many as possible before the exam in 3 weeks, find your videos really helpful
I really struggled with this topic at school, even with my tutor as well. Your video has really helped me understand it. Thanks! :)
Dicovered your channel tonight! These videos are so helpful! Thank you!
There's plenty of stuff on the channel that related to new spec; keep exploring!
+Mr Pollock cheers
best video, covers everything. thank you so much!!
Haven't seen any of your other videos but this one really makes this topic easy to understand, I'll definitely be checking out your other ones, Thank you!
I just have one question, Why is it that at the Source, there is co-transport with the H+ ions to move the sucrose into the sieve tube elements whereas at the sink it seems to be just active transport?
Still need these videos. Thanks Mr Pollock!
Your vids are great! Thank you for making new spec videos it helps loads
this is amazing, you have no idea how grateful i am
Glad you're enjoying :)
thank you soooo much for this video.....your explanation was very helpful.
thanks, it is a really helpful video..very clear explanation.
I promise you this is some of the best A-level biology videos that you can ever find on UA-cam
THANKS, GREAT EXPLANATION
I'm interested in to know more about how sucrose transforms from the companion cell to the phloem.
Please link me to the better vision ;)
Thank you, God bless you!
This was so helpful! I feel like I've got a much better understanding of this topic as I found it so difficult before, thank you for all the effort you put in to it because it's certainly helping me and lots of others in the comment section too! :)
You explain it AWESOME!!!
LOVE YAAA
THANK YAA
I completed 2 chapters just because of you, thank you for existing Mr Pollock.
GOOD!! Thanks for this, just in time for exams.
I kept reading the textbook and it didn't quite make sense, had to come here, thank you.
Life saver, thank you!
Please could you put a link up to explain that the movement of molecules from the companion cell into the sieve elements and why it's not exactly active transport. Thank you, this was very helpful :)
your videos are amazing, it helps a lot. Could you please make videos on all the topics for the new spec?
very nice explanation Sir thank you
thank you SO MUCH for this video, i have difficulty understanding the textbook, and this video saved me :D
THIS IS AMAZING. THANK YOU SO MUCH!
Glad you like :)
My biology aqa student book contains information on the co-transport of hydrogen ions and the teacher has told us we need to know this. Please maybe make an updated video, including this section as it is the bit i am most unsure of.
This is so helpful! Thank you :)
wonderful presentation
Simply great !
I have a question about phisiology I was reading today from campbell biology,It said that medulla ablongata controls breathing and pons balances!I wanna what it means by balancing and how it's done
super helpful, thank you!!
Will definitely recommend this channel to everyone in my school.
Can you please add a link which explains the loading process further? Thanks!
sucrose doesn't move into the sieve tube element by facilitated diffusion because facilitated diffusion doesn't involve the use of ATP (as it's passive transport) and also facilitated diffusion is the movement of substances from an area of high to low concentration. So it moves by active transport.
I'm sat in the library in college cramming for my B2 exam tomorrow and i fell asleep because your voice is that soft hahahahaha
thank you very much
Great explanation
Great explanation!
Amazing video!
Nicely explained...
I was just lying in the Park, thinking about a procedural algorithm to let digital plants for Virtual Reality in real time depending on how much light each leave gets and wondered how the energy flows back down the plant. Your Videos answered it concise, I got it the first time. Thank you.
PS: How do plants defend against parasites? I know about poison, but to the have some like an immun system that detects cell infected by bacteria or viruses?
That's some deep thinking Tristan!
This article from nature details the plants immune response...www.nature.com/nature/journal/v444/n7117/full/nature05286.html
thank you so much
Really great videos- needed something like this so badly. I was just wondering why the they videos in the new spec playlist are in private?
Informative great thanks
is active transport is use when sucrose from palisade cells to companion cells? pleas answer! thank you
Hi...explanation is quite interesting
i have a question regarding xylem and phloem do they have different shapes according to the plants type?
Really helpful!!
About to sit two papers so this is perfect last minute revision
you are a god..... I vvish i discovered you earlier damnnnn
What about active loading ?
Thank you so much for doing the new spec. Will you do more new spec videos?
Will try and do a few more...more likely exam technique soon though. Most of my old spec videos still apply though; if in doubt, refer to the specification!
+Mr Pollock Thanks
Just one question, how is Sucrose transported to the companion cells through channel protein, i thought channel proteins are used for water soluble ions, shouldn't it be through a carrier protein
In the first part from source to companion cell it is by facilitated diffusion which can be with protien channels since sucrose is still soluble however in the second part at the sink cell it is through active transport so yes will only be via carrier proteins.
RHYSE TV 5
THANKS!!!!
Do you need to know about the co transport part for the new AS level?
very informative video!
Hi Mr Pollock. Thanks for the great video.
Just one small issue. At 8:28 you say that some water moves out of the phloem back into xylem.
I am unsure of why this is the case since the water potential of the xylem is higher than that of the phloem. Why would the water move against the concentration gradient.
Don't worry too much about it. In reality, the plant actively transports some mineral ions into the xylem in the roots to enable water to move in...but that's not on your spec :)
Thanks for the amazing explanation but I had a small confusion. How does the phkoem already have a concentrated solution of sucrose. I mean where does it come from
From the leaves that make glucose in photosynthesis(water + carbon dioxide -> oxygen + glucose). This is then turned in to sucrose which travels via the phloem.
Hello, I really like your videos, thank you.
Could you please go through some of the Experimental questions in AQA Biol-1 to Biol5 please (e.g. say from the June 2015 papers)? I really want to understand how to tackle them. If you have time to do a few then please could you go through some of the BIOL4/5 papers ( mainly the experimental questions which are usually towards the end). I have seen some of the other videos that you have done but could you please do a few more particularity explaining how to do the How science works and all the data questions, please.
E.g. questions which tell you to 'evaluate' 'explain the graph' 'use the table/graph and explain why this happens' ' suggest why this was done in the experiment' etc...
I would really appreciate it :)
TheOneWhoKnowsEverything yeah! That would be very helpful
Hi, are you doing the old spec retakes? If so which exams are you retaking?
Very cool Mr Pollock
Thanks for the video it was really useful. Im unsure however why at the sink end of the phloem, why are the solutes removed out from the phloem into the companion cells by active diffusion. Why would the solutes be going against their concentration gradient as it thought the phloem had more solutes in than the companion cells anyway (esspecially at the sink end??
Sucrose is actively transported out to avoid an equilibrium being reached.
+Mr Pollock thank youu!
My understanding is that H+ is actively transported from companion cells into the space within cell walls. The solute (eg, sucrose) is then co-transported from the companion cell into the sieve tube elemnt along with the H+. My quesiton is, if the H+ is in the cell wall, and the solute is in the companion cell, how can they interact to be co-transported together?
Thank you so much :)
Thank you so much, will you be uploading anymore videos within the run up to the biology exams?
Will try; probably more examination technique ones though
Also, when the sucrose moves down the phloem is that due to the different hydrostatic pressure or due to the difference in concentration on the sink and source end of the phloem ??? URGENT
I have a question for u when the sucrose is unloaded from phloem to companion cell it is from high to low concentration , isn`t it ? then why active transpot using atp it should be faciliated diffusion.
Prajwal Khadka i don’t understand this either help
@@GabijaS18 water is a smaller molecule and can pass through channel protein(aquaporins)no atp is required or directly through the phospholipid bilayer , whereas sucrose is a big molecule and should pass through carrier protein and it requires energy(from atp) so this is an active process
@@souhaylahabdoolraheem5301 but the thing he pointed out was why isnt it the same(facilitated diffusion through protein pump) when the sucrose is unloaded from phloem to companion cell(high to low concentration) as it is when sucrose is downloaded into companion cell from the palisade cell(which, is again, high to low concentration and still uses facilitated diffusion). So the size of the molecule shouldnt matter? because it is the same context just the solution with which the plant came is different and i dont understand why.
Alex G your question does not make sense
@@sea5205 I put that specific question in order for someone who does know the answer to point it out for me, or to explain how it does nt make sense. You just telling me it makes no sense, without showing me where, does not help anybody with anything.
Another great video! Thank you :)
Thanks :)
Why it has such low views!!!! Your way of explaining and animations are amazing....Thank you...
It sounds like active transport to me the movement of sucrose into the phloem. If you could quickly message me with some detail of why it is not active transport that would be great. To allow me to get a better picture of the process.
Good stuff Bruv !
thank u very much
That’s what she said
Sieve plates are to maintain the gradient between the source and the sink. Without the sieve plate to provide resistance and obstruct the flow of sucrose by translocation,sucrose will be transported too fast and this will cause the high hydrostatic pressure at the source to disappear. Its like there must be a "balance" between for the rate of translocation.It cant be too fast or too slow
Hi, at 7:56 you say sucrose moves out of the phloem into the companion cell by active transport? I don't get how, as there is a lower solute conc in the companion cell and a higher sucrose conc in the phloem? Surely thats high to low? Thank you!!
Hajra Batt active transport works against the gradient to transport the remaining 50% of the sucrose that's left once equilibrium has been reached, idk if that answers your question but hope it helps a bit
yehh, i get that!! Thank you x
are the sieves like locks on a canal? to regulate flow, which in the end does not hinder it
Sir ,thank you so much. I have a confusion. I had read that food made at the mesophyll cell then it's move to bundle sheath cell then pholem parenchyma then companion cell and then seive tube .so where is palisade cell . Is mesophyll cell is palisade cell. Or what I had read is wrong.
Great content
I drop kicked my dick when i saw this video!
I actually love you
Glad you appreciate my work :)
Hi. I'm just curious you say that sucrose moves into companion cells by facilitated diffusion but everywhere else I've look says active transport?
Exactlyyy
Yah...... I'm really not sure about that
@@katharinetayxinyi9919 it moves into the companion cells by active transport, i've confirmed it now :)
great video! could you please explain the mass flow theory using sieve tube and elements
you're amazing!
Thanks
if possible, can you please try to make a few more videos before the exams. These videos are extremely helpful. Thank you!
Will try; might just be exam technique ones though
For low levels of Oxygen medulla oblongata effects only rate,but for high Co2 both rate and depth! in page 1160 of campbell biology it didn't say only!but it hasn't written whether for low levels of O2 has an effect on depth too?!
if not Why
Very good
Amazing leaning
Amazing!!
Why is sucrose actively transported from the sieve tube elements into sink cells when the sucrose concentration in the sink cells are lower? Would they diffuse down the concentration gradient?
In my textbook it says the phloem load through hydrogen ions in active transport and unloaded with diffusion
Just did my exam
There was a 5 marker on this
I aced it! Thank you so much!
Exam tomorrow this is a god send
What about sieve tube elements???
what role do they have?
no one knows lol
THIS IS AMAZING ❤️❤️❤️❤️❤️
amazing video ... my all doubt is clear.. ur way is superb .. nice .. thanx
so useful!
This is quality, could you do one of these for the xylem pls??
+Dan Ghafoor /watch?v=t14KGGWtn4M
+Utopic I'm assuming that's for the old spec tho
Dan Ghafoor yeah, but this is a topic that is similar between the two syllabuses
+Utopic its got quite a few differences (apoplast/symplast pathway, root pressure, casparian strip) and I'm not sure what exactly I need to know for my spec
Dan Ghafoor oh okay, well I didn't watch the video myself as the stuff required for that topic in the new spec is quite simple, but the things you mentioned are definitely not required this year
is there any difference between active loading and phloem loading ???
Same thing. There are difference places where active loading is used for a different purpose, but here active loading results in the loading of the phloem so we can use the terms interchangeably.
Cheers
cheers for this! :)
You are most welcome
Thanks! I'm assuming the AQA spec doesn't require them to know about H+ ions and the role they play in translocation?
Hunger_C the knowledge required is only to the extent that they assist with co-transport of sugars into the phloem ^_^
Kαi Oh, I'm with OCR A where you need to know it in a bit more detail.
Hunger_C oh, that's rather unfortunate :p
Correct me if I'm wrong, but from what i understand sucrose is transported to the companion cells from the source by co-transport (via facilitated diffusion) using a co-transport carrier protein and down a conc gradient, created by actively transporting H+ ions out for the companion cell. Sucrose then is transported into the phloem sieve cell by co-transport again with H+ ions and while sucrose is going against its conc gradient the H+ ions are going down its conc gradient because there's a higher conc of H+ ions in the companion cell than there are in the sieve element?
I get the rest, but could you clarify this part please^?
Hiya, here are the steps:
1) sucrose in source moves down conc grad from source to companion cell by FACILITATED DIFFUSION.
2) H+ ACTIVELY TRANSPORT against conc grad from companion cells into spaces within cell wall using ATP.
3) H+ and sucrose diffuse down conc grad by CO-TRANSPORT.
Hope that helps :)
+Zoey M Thank you it makes sense now :D
Sorry, let me just clarify point 3:
Sucrose and H+ co-transported into sieve tube
+Zoey M yh thanks. Question: is there a different between facilitated diffusion and Co transport aren't the two the same thing because facilitated diffusion involves carried and channel protein and Co transport uses Co transport carrier protein to transport the H+ ions and sucrose into the sieve element?
+Aaron Owusu no, they aren't the same. Similarly, active transport also requires a carrier protein.
Co-transport (specific to translocation) is when the sucrose is drawn out to the cells along with H+ that have been actively transported out. This is also know as an indirect form of active transport. It is the H+ conc gradient that powers the movement of the sucrose into the sieve tube.
I would recommend looking at the sodium-potassium pump (especially since its on the spec), it will really help you in understanding co-transport :)