The Biology AS-level Thread

Reply 700

fs1996

Anyone got any tips for the evaluative coursework on species richness? Or in general?

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Reply 701

phaseshift

12

Original post by fs1996

x

I can't give you specific advice, because that would give you an unfair advantage over other students. However, the best thing to do with these ISAs is treat the marker as if they were 5 years old, walk through your points sequentially and in sufficient enough detail.

You can't really revise for the ISAs and they are just awful (in my opinion), but you only have two years of them at A-Level, they disappear at degree level.

Reply 702

~amethyst~

4

Hey guys

Does anyone have any revision material/resources that could be helpful for biology Aqa unit 1 and unit 2?

I have been researching for key terms too, because apparently they might come up in the exam, however i couldn't find any, so if anyone has a big list of all the key words and definitions that would be a massive help!

Any other helpful comments or tips are welcome

Thanks xx

Reply 703

dw1996

4

Does anyone have any revision material for WJEC BY4 and BY5? My teacher said I'm gonna do crap and I'm determined to get an A and prove her wrong.

Reply 704

Astudent100

Hi everyone :biggrin:

does anyone know any good revision sites or youtube channels for Edexcel as biology ????

and what is the difference between totipotent, pluripotent and multipotent ????

Reply 705

L'Evil Fish

18

Original post by Astudent100

Hi everyone :biggrin:

does anyone know any good revision sites or youtube channels for Edexcel as biology ????

and what is the difference between totipotent, pluripotent and multipotent ????

Haven't learnt but I know that:

totipotent = stem cell that can specialise into all other types

pluripotent = restricted to certain types of cells to differentiate into

Reply 706

Astudent100

Original post by L'Evil Fish

Haven't learnt but I know that:

totipotent = stem cell that can specialise into all other types

pluripotent = restricted to certain types of cells to differentiate into

aha thank you i think that i understand it now.

Reply 707

Nora R. Chloe

4

Hi everyone! :smile:

Can anyone give me some advice regarding Edexcel biology unit-3 written practical (6BIO7) ?? Like what books to read, what experiments to carry out, etc...

Reply 708

Astudent100

Original post by Nora R. Chloe

Hi everyone! :smile:

Can anyone give me some advice regarding Edexcel biology unit-3 written practical (6BIO7) ?? Like what books to read, what experiments to carry out, etc...

Hi, i'm taking edexcel biology unit-3 writtren practical too.
there is 4 experiments that you have to know :

1) Describe the stages of mitosis and how to prepare and stain a root tip squash in order to observethem practically.
2) Describe how totipotency can be demonstrated practically using plant tissue culture techniques.
3) Describe how to determine the tensile strength of plant fibres practically.
4) Describe how to investigate plant mineral deficiencies practically.

i have a PDF with these experiments procedure and example of questions i cant attach it on this forum because it exceeds the limit of attachments i can send it in an email if you want. I hope that this helped :biggrin:

and good luck in the exams :smile:

Reply 709

Nora R. Chloe

4

Original post by Astudent100

Hi, i'm taking edexcel biology unit-3 writtren practical too.
there is 4 experiments that you have to know :

1) Describe the stages of mitosis and how to prepare and stain a root tip squash in order to observethem practically.
2) Describe how totipotency can be demonstrated practically using plant tissue culture techniques.
3) Describe how to determine the tensile strength of plant fibres practically.
4) Describe how to investigate plant mineral deficiencies practically.

i have a PDF with these experiments procedure and example of questions i cant attach it on this forum because it exceeds the limit of attachments i can send it in an email if you want. I hope that this helped :biggrin:

and good luck in the exams :smile:

Thanks a lot for your suggestion! I'll keep them on my mind.
If I need the pdf I'll let you know.. :smile:

Good luck to you too!!

Reply 710

hamzahdsi

1

Just had my empa task 1 today, don't know what to expect from task 2. Any tips? :smile:

Reply 711

username1142080

8

Has anybody got a link to a thread for the AQA Biology ISAs taking place in the next couple of weeks? Thanks

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Reply 712

pinkgorilla

5

Hey guys and girls

how would you answer this question to get the full 6 marks ?
'The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.' (6 marks)

I do AQA AS if that helps.
Thanks :smile:

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Reply 713

RoyalBlue7

19

Original post by pinkgorilla

Hey guys and girls

how would you answer this question to get the full 6 marks ?
'The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.' (6 marks)

I do AQA AS if that helps.
Thanks :smile:

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Well do you want a model answer or help to make one?

I would go about giving the structure of this layer (possible by a labeled diagram) and then go onto describe the process of absorption that is by active uptake and the factors that affect the rate and quantity of glucose intake.

I'm not doing AQA. Is the digestive system in the specs? The question is more about your knowledge of transport. Maybe the structure and method (active uptake) carries two marks then you could describe two adaptations and how each increases the rate of uptake or the quantity for the rest of the marks. (The markscheme would surely specify the marking points).

The important thing is they might ask similar questions of transport adaptations (how gas exchange surfaces are adapted, how the roots of a plant is adapted for active uptake of mineral ions, how the kidney nephrones are adapted for reabsorption etc) which all tests your knowledge of the factors that affect transportation of molecules through a membrane.

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(edited 10 years ago)

Reply 714

DCMed96

16

Original post by pinkgorilla

Hey guys and girls

how would you answer this question to get the full 6 marks ?
'The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.' (6 marks)

I do AQA AS if that helps.
Thanks :smile:

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you need to mention co-transport of sodium and glucose via the carrier protein, you need to mention sodium ions are actively pumped out by the sodium-potassium pump to create diffusion gradient. Sodium ions diffuse into the epithelial cells together with glucose down the concentration gradient.
I suppose you can also mention facilitated diffusion just to be safe and perhaps hit some points? you can also mention the 'one cell thick' for short diffusion pathway..

Reply 715

ellilou13

Any one get any EMPA advice for a private candidate?

Reply 716

ps1265A

14

I'm struggling to make sense of cohesion and tension, can someone help me out?

I understand cohesion (water molecules moving in a bulk due to the property of water to firm hydrogen bonding) but what EXACTLY is pressure?

my book keeps stating that transpiration leads to a negative pressure in the xylem which causes tension

Doesn't transportation increase the pressure in the xylem as a result of pressure created by root pressure? And what exactly do they mean by "tension"? The establishment of a water potential gradient?

Reply 717

Hype en Ecosse

20

Original post by ps1265A

I'm struggling to make sense of cohesion and tension, can someone help me out?

I understand cohesion (water molecules moving in a bulk due to the property of water to firm hydrogen bonding) but what EXACTLY is pressure?

my book keeps stating that transpiration leads to a negative pressure in the xylem which causes tension

Doesn't transportation increase the pressure in the xylem as a result of pressure created by root pressure? And what exactly do they mean by "tension"? The establishment of a water potential gradient?

Pressure is the force-exerting attribute of an object (if you study physics: pressure is a force distributed over an area). In physiology, when we talk about a negative pressure, we mean that the pressure in our area of interest is lower than the pressure in our surroundings (the stuff outside is pushing harder than the stuff inside), thus creating a suction effect. This is how things move into vacuums, and how breathing works. In the case of the xylem given in your book, the pressure inside the xylem is lower than the pressure in its surroundings (presumably the root system that it's receiving water from). This creates tension (a pulling force) on the water, and thanks to cohesion and adhesion, our water can move up the xylem in response to this tension.

As for what actually happens in the xylem, I can't tell you. I don't know anything about plants. :tongue: