AQA AS Unit 1 Biology Exam 21st May 2015

Original post by benjenstark

Correct me if I'm wrong:
- Co-transport utilises the established concentration gradient of one molecule to move another againsts its through a channel protein

- active transport uses the Na/Ka+ pump, in which ATP - ADP + Pi, using it to change the shape and move something against its concentration gradient

Yeah?

Damn I'm stressed

Hi it's not a channel protein the protein itself is called a co-transporter which is a type of carrier protein
Active transport is not always the sodium potassium pump but it requires ATP uses a carrier protein and its against the concentration gradient

Reply 1582

OP

Original post by hum1

do u have a mark scheme for the specimen paper

Go onto freeexampapers.com

You'll find it there

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Reply 1583

OP

Original post by samwillettsxxx

Thanks for posting these! Might pick up something I may have missed/not known :smile:

That's okay :smile:

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Reply 1584

benjenstark

6

Original post by samwillettsxxx

Hi it's not a channel protein the protein itself is called a co-transporter which is a type of carrier protein
Active transport is not always the sodium potassium pump but it requires ATP uses a carrier protein and its against the concentration gradient

Ah, so, a channel protein is just used for facilitated diffusion?

And thanks :smile:

Reply 1585

OP

Original post by benjenstark

Ah, so, a channel protein is just used for facilitated diffusion?

And thanks :smile:

Yep

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Reply 1586

The-olden-days

Original post by benjenstark

Correct me if I'm wrong:
- Co-transport utilises the established concentration gradient of one molecule to move another againsts its through a channel protein

- active transport uses the Na/Ka+ pump, in which ATP - ADP + Pi, using it to change the shape and move something against its concentration gradient

Yeah?

Damn I'm stressed

I think that's right. And the movement of glucose with sodium ions is an example of co-transport

Reply 1587

sami.k

2

Any predictions on what's gnna be in today's paper??

I have a feeling immunity is gnna be a big one Wbu all??

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Reply 1588

Original post by benjenstark

Ah, so, a channel protein is just used for facilitated diffusion?

And thanks :smile:

Yes that's right :smile:

facilitated diffusion uses channel proteins and carrier proteins for large/water soluble/charged molecules

Reply 1589

Original post by sami.k

Any predictions on what's gnna be in today's paper??

I have a feeling immunity is gnna be a big one Wbu all??

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Could be anything tbh. Ain't even gonna try guess it is what it is and always prepare for the worst lol

Reply 1590

OP

Difference between t-cells and b-cells

T cells mature in the thymus gland
B cells mature in the bone marrow
T cells are involved in cell mediated immunity
B cells are involved in humoral immunity

Similarities

Both involved in immunity
Both are white blood cells
Both produced from stem cells

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Thanks guys :smile:

OP

The difference between cell mediated immunity and humoral immunity

Cell mediated immunity
Involves t-cells
No antibodies
First stage if immune response
Effective through cells
How thy respond? - t killer cells produce chemicals which result in the pathogen being killed

Humoral immunity
Involved b-cells
Antibodies produced
Second stage of immune response
Effective through the body fluids
How does it response? - b plasma cells produce antibodies, the antibodies attach to the pathogen leading to phagocytosis of pathogen

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Reply 1593

OP

Lol I'm done now
That was just revision

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Reply 1594

All chemical tests

The biuret test for proteins
1) add NaOH to make it alkaline
2) Add copper (II) sulfate
If it turns purple - positive result
If it stays blue - negative result

The emulsion test for lipids
1) add sample to ethanol
2) then to water
Milky emulsion should appear for positive result

Benedicts test for reducing sugars (all monosaccharides with exceptions of lactose and maltose)
1.) heat sample with Benedicts reagent
2.) turns brick red --> positive result
If the test is negative it may mean non-reducing sugars are still present

Non-reducing sugar (all disaccharides) test (Benedicts test)
Get a NEW SAMPLE
1.) boil with dilute HCl to break glycosidic bond between disaccharide
2.) neutralise with hydrogen sodium carbonate
3.) do Benedicts test as normal

The test for starch
1) add iodine in potassium iodide solution
2) if turns blue/black positive
If goes orange - negative
**MAKE SURE U SAY IODINE IS IN POTASSIUM IODIDE SOLUTION, NOT JUST IODINE***

(edited 8 years ago)

Reply 1595

username1533709

5

Original post by sami.k

Any predictions on what's gnna be in today's paper??

I have a feeling immunity is gnna be a big one Wbu all??

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I have a feeling we might get three five markers.

Reply 1596

cilla_e

Hi

What is the test for starch?

Reply 1597

OP