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AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

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Reply 580

Rickesh

Original post by DoaaK

does hydrolysis require atp? i know condensation does?

No, I dont think so?

Reply 581

Rickesh

Original post by reaperguy

Yeah starch.

I saw it in a paper eariler today.

Salivary amylase is secreted to partially break down the starch into maltose.
Then once the food gets into the duodenum, pancreatic juices contain maltase enzymes which hydrolyse the glycosidic linkages in maltose to for monomers of alpha glucose

Nice answer !

Reply 582

BeejTheone

Original post by reaperguy

Ok starch is a carbohydrate i kinda forgot that :P

MS answer:

Amylase;

(Starch) to maltose:
Maltase;
Maltose to glucose;
Hydrolysis;
(Of) glycosidic bond;

Reply 583

Spongebobu

Original post by Rickesh

To prevent osmotic processes occurring, so cells do not become flaccid or turgid

How do you test for lipids?

AHHH you fell into the trap, its ORGANELLES not cells, the dont accept cells.

Test for lipids, emulsion test= ethanol+water = white ppt

Reply 584

Rickesh

Original post by BeejTheone

Ok starch is a carbohydrate i kinda forgot that :P

MS answer:

Amylase;

(Starch) to maltose:
Maltase;
Maltose to glucose;
Hydrolysis;
(Of) glycosidic bond;

Damn, I would of got 3...forgot the hydrolysis and glycosidic bonds ! oopsy !

Reply 585

BeejTheone

Ok anyone explain function of Cell membrane, 5 marker!!

Reply 586

Rickesh

Original post by reaperguy

AHHH you fell into the trap, its ORGANELLES not cells, the dont accept cells.

Test for lipids, emulsion test= ethanol+water = white ppt

arrgghh !! lol Thanks....yepp thats the one !

Reply 587

Sparkly-Star

Original post by Tericon

Can anyone help me with this, from Jan 2010

Calculate the ratio of the mass at the start to the mass at the end for the disc
placed in the 0.60 moldm–3 sodium chloride solution.

Start: 23.7 end: 21.9

I know what the answer is, but how'd you get to it? And also, i really don't get ratios full stop, is this always how you'd tackle a ratio question?

The answer is 1.08 and just be taking 21.9 from 23.7, you get 1.8....is that just a coincidence? Or is that what you do with ratio question, take smaller from larger?

Thanks :smile:

Oh this also boggled my mind but then I realised it was a flipping ratio they were on about! So basically if you look at the two masses and divide them by each other, this should give you 1.08 if you do the others you'll see it works out. :smile:

(edited 12 years ago)

Reply 588

liviaaa

Original post by BeejTheone

Would they ask this sort of question? I thought they would only ask it for starch? What's your model answer for it?

Starch is a carbohydrate...

Reply 589

Tericon

Original post by BeejTheone

the distance is about 20um and rate of blood flow is about 200um in 1 second.
Therefore it will flow through there in 0.1 second

Excuse the stupidity, but I still don't understand that, ok, distance is 20....how did you work out rate of blood flow?

Reply 590

Spongebobu

how do the SAN and AVN control the cardiac cycle?
5 marks

Reply 591

301lw

Original post by BeejTheone

Ok anyone explain function of Cell membrane, 5 marker!!

FIVE?! D:

Reply 592

Rickesh

Original post by BeejTheone

Ok anyone explain function of Cell membrane, 5 marker!!

Cell membranes prevent large molecules that do not fit through the phospholipid layer, from entering. They also do not allow charged molecules, or molecules that are no lipid soluble. They allow larger molecules such as Sodium to enter through channel proteins, by facilitated diffusion. With the use of ATP molecules that are going against their concentration gradient (low to high) are also allowed to go through the proteins. Gosh i'm really struggling here ! urmm what else is there?

Reply 593

BeejTheone

Original post by liviaaa

Starch is a carbohydrate...

Yeah i realised a tad after replying xD

Reply 594

BeejTheone

Original post by Tericon

Excuse the stupidity, but I still don't understand that, ok, distance is 20....how did you work out rate of blood flow?

Convert all measurements into Um and u get 200um s-1 for blood flow and 20um as distance. Now just divide distance by blood flow = 0.1

Reply 595

liviaaa

5 markers that have been:

-Eukaryotic vs Prokaryotic cells
-TEM +/-
-SAN and AVN in cardiac cycle
-Digestion of starch (enzymes)
-Absorption of starch
-Substances across a plasma membrane
-Lungs adapted to gas exchange
-Atheroma linking to aneurium (specimen)
-Smoking/ diet high in sat fat - myocardial infarcation (specimen)

So I'm guessing we will get one if these:

-Cholera / ORS
-Mechanism of breathing
-Cardiac cycle
-Asthma
-Fibrosis
-Humoural / cell mediated response

Any others? :smile:

Reply 596

??????????????????

Original post by reaperguy

how do the SAN and AVN control the cardiac cycle?
5 marks

SAN is myogenic? So produces it's own impulse. This electrical impulse stimulates the atria causing it to contract so blood enters the ventrciles duh to an increase in perssure. It also stimulates the AVN where there is a slight delay to allow the ventricles to fill up up with blood. When the AVN is stimulated it relays the impulse to the bundle of His and punkjibe (sp?) fibres which contract the venctricles from the bottom, upwards to cause the ventricles to contract so decrease pressure so blood enters the pulmonary arteries/aorta.

Reply 597

BeejTheone

Original post by Rickesh

Most of that is good but I was looking for other functions aswell such as Cell recognition, Cell communication etc etc..

Reply 598

liviaaa

Original post by BeejTheone

Yeah i realised a tad after replying xD

Haha

Reply 599

Rickesh

Original post by reaperguy

how do the SAN and AVN control the cardiac cycle?
5 marks

The SAN sends electrical impulses to the atria, it then sends electrical impulses down the bundle of his avoiding the non-conductive tissue seperating the atria and the ventricles, to the purkyne fibres allowing contraction to take place from base upwards. The AVN allows for a short delay before the contractioon takes place, this allows the ventricles to fill up with blood, so they can contract with a full supply of blood. Without this delay less blood would be able to be pumped around the body as the ventricles would not have enough time to fill up. How many marks would I have got?? That was a toughy to get 5?!?