biology paper 1 doubts

[Irfan1995]

and does tissue fluid have protein ???

Yes, it does. But here's what you have to be very careful about:

The protein found inside tissue fluid does not come from blood (capillaries). This is because proteins are extremely large molecules and are too big to fit through the pores of the capillaries to diffuse to the tissue fluid.
However, normal body cells produce proteins as part of their life cycle, and those proteins are taken out by exocytosis (by the Golgi Apparatus). So the proteins that came from the cells is found in tissue fluid (and eventually drained to the lymph), not the proteins from the blood.

 

[NouranAyman]

Pressure potential actually increases the water potential, so it is positive and not negative.
The greater the pressure exerted, the higher the pressure potential.
So the more turgid a cell is, the more positive is the pressure potential (and the higher the water potential).

and am so sorry! I have one more question! its question 20 in the same paper http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_s06_qp_1.pdf

 

[Irfan1995]

Thanks alottt and btw a higher water potential is (less negative ) right?

Yes. That's right.

Think of it this way. Lets say that cell A has a water potential of -100kPa and cell B has a waer potential of -200kPa.
Cell A has a higher water potential because -100 is greater than -200. And cell A has a less negative water potential.
So less negative = higher water potential = more purer water.

 

[♥Яαηõõşḧ♥]

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
can someone please help with question 24, the answer is A but doesnt the volume of the ventricle decrease when it contracts ?????

 

[Irfan1995]

and am so sorry! I have one more question! its question 20 in the same paper http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s06_qp_1.pdf

Don't worry, ask as many questions as you like

You have to know that DNA replicates during interphase (before cell division). So DNA replicates during part A.

 

[Jevin Sanoo]

Lymph has the exact same content as tissue fluid. It only has a different name because it is in a different vessel, that's all.

Can u tell me the answer?

 

[railey]

Because each chromatid holds a replicated part of a DNA

Thank you soo much

 

[railey]

There are 46 chromosomes just before prophase.
Every chromosome is made up of 2 chromatids.
So you have a total of 46 x 2 = 92 chromatids just before prophase.

Every chromatid contains one DNA molecule.

There is no spindle present just before prophase. It starts forming by late prophase and continues until the end of metaphase.

Thanks mate.

 

[♥Яαηõõşḧ♥]

Yes, it does. But here's what you have to be very careful about:

The protein found inside tissue fluid does not come from blood (capillaries). This is because proteins are extremely large molecules and are too big to fit through the pores of the capillaries to diffuse to the tissue fluid.
However, normal body cells produce proteins as part of their life cycle, and those proteins are taken out by exocytosis (by the Golgi Apparatus). So the proteins that came from the cells is found in tissue fluid (and eventually drained to the lymph), not the proteins from the blood.

ok thank u sooooooo much..... u really helped a lot!!!!

 

[Irfan1995]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf
can someone please help with question 24, the answer is A but doesnt the volume of the ventricle decrease when it contracts ?????

Volume of the ventricle stays constant. Volume of the blood in the ventricle decreases, but the amount of cardiac muscle in the ventricle stays the same.

Take it this way, lets say you have a 8x2 rectangle. The area is 16 square units. When it "contracts", it becomes 4x4. The area is still 16 square units, but you've "shortened" the shape. Just like cardiac muscle, it gets shorter, but it also gets thicker so that volume is always constant.

 

[NouranAyman]

Can u tell me the answer?
View attachment 18202

answer is D?

 

[Jevin Sanoo]

answer is D?

Yes it's D. Can u explain?

 

[railey]

answer is D?

I say D aswell

 

[♥Яαηõõşḧ♥]

Volume of the ventricle stays constant. Volume of the blood in the ventricle decreases, but the amount of cardiac muscle in the ventricle stays the same.

Take it this way, lets say you have a 8x2 rectangle. The area is 16 square units. When it "contracts", it becomes 4x4. The area is still 16 square units, but you've "shortened" the shape. Just like cardiac muscle, it gets shorter, but it also gets thicker so that volume is always constant.

ahaaaa yeah i get it now, thanks !!

 

[xtremeforums]

Can someone please make a list of organelles that can be viewed with a light microscope?

 

[Irfan1995]

Thank you soo much

W does not have any plasma proteins (i.e. proteins coming from blood capillaries). So you can immediately eliminate answers A and B
X is at a lower pressure than Y. This means that X is at the venule end and Y is at the arteriole end. So X is blood entering capillaries and Y is blood leaving capillaries.
Z is at a lower pressure than Y and lacks red blood cells. Since it lacks red blood cells, it can only be tissue fluid or lymph. (Eliminate C).

The only answer you have left is D.

As for the water potential of W, here's what you have to know:
Proteins are not filtered from the blood to the tissue fluid, so it stays in the blood. This decreases the water potential of the blood (compared to tissue fluid). Yes, I know I said that tissue fluid contains proteins, but it is in a slightly lower concentration than blood.

 

[ZohaibAsad]

Anything greater than 200nm

 

[yashi30]

No, what you're talking about is a peptide bond.
Hydrogen bond is formed when a partially positive hydrogen atom in one molecule is bounded to a partially negative nitrogen, oxygen, or fluorine atom in another. This happens with a partially positive hydrogen atom in one amino acid binding with an oxygen atom in a fifth amino acid. This makes the structure coil into an alpha helix.

EDIT: The tertiary structure is mainly formed by amino acids with polar (hydrophilic) R groups on the outside and with other amino acids with non-polar (hydrophobic) R groups on the inside. This makes the protein like a ball (polar aa's on the outside surface and non-polar aa's on the inside surface)

http://www.google.mu/imgres?hl=en&c...&ndsp=18&ved=1t:429,r:0,s:0,i:68&tx=123&ty=99
that's what i'm talking about...check it out. you'll see..

 

[NouranAyman]

Yes it's D. Can u explain?

alright lisn! W is tissue fluid cuz they said that W has no plasma protein and no red blood cells while for Y and X blood pressure of blood entering the capillary should be higher than that leaving capillary and also blood entering capillary has a pressure higher than that of tissue fluid while Z is lymph as they said it lacks red blood cells but they didnt say about plasma protein as lymph has less plasma protein but it only lacks in RBCs so the answer is D

 

[♥Яαηõõşḧ♥]

Can someone please make a list of organelles that can be viewed with a light microscope?

At low power, u can see the cytoplasm with many dense granular bodies (refer to june 2012 question 2.)
At high power u can see, chloroplasts, nucleus, starch grains, vacuoles. u cant see the ER, ribosomes, mitochondria, lysosomes or cell membrane