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AQA A-level Biology Unit 1 26th May 2016

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Original post by Bennyab
I put the same as you :smile: triglyceride is limiting factor or ph would have continued to decrease


There seem to be two correct answers for this one....... That triglyceride is the limiting factor and that the enzyme denatured so the enzyme became the limiting factor....
Reply 201
Original post by mordin1428
So, DRAFT unofficial mark scheme (only what I remember, feel free to add and/or correct) Q 1. a) White blood cell has a cell membrane and a nucleus, no cell wallBacterial cell has a cell wall and cell membrane, no nucleusb) I A M , so actual size = image size/magnification, so (image size in mm)x10^3/30000, mine was 2.86 c) evidence for mitochondria - its own looped molecule of DNA, looks similar to bacterial cell d) advantage of mitochondria - aerobic respiration? produces ATP for metabolic processes in the cell, cell growth and repair, active transport etc. Q2a) oxygenated blood away from the heart - aorta, Cdeoxygenated blood to the heart - vena cava, A b) Ventricle has a thicker wall, so a thicker muscle layer. Thicker muscle layer means more forceful contraction and higher blood pressure c) hole between two ventricles - deoxygenated and oxygenated blood mixes, stroke remains the same volume, so instead of a full stroke of oxygenated blood, a mixture of deox. and ox. is pumped into the body --> less oxygen to cellsQ3 a) Ph meter gives a precise value, ph indicator gives a tame b) triglycerides get broken down into glycerol and fatty acids by lipase. Fatty acids lower the ph. c) ph is constant because all triglycerides have been broken down so no more fatty acids formed, so their conversation remains constant --> no change in phd) curve's gotta start from the same ph and decease less rapidly, taking no longer to reach the same ph level as the first curve in the end Q4a) rough endoplasmic reticulum/ribosomeb) not active inside the cell: trypsin is a protease - many vital proteins present within the cell, like channel proteins, that facilitate active transport, structural support etc. - if protease activates within the cell, it can break them down c) peptide bond breaks d) competitive inhibitor=shape similar to substrate - binds to active site - doesn't get broken down, so stays there - enzyme can no longer form E-S complexes - rendered uselessQ5a) Diaphragm relaxes and curves upwards - thorax and lungs collapse inwards and down - less volume in lungs so air pressure rises (above atmospheric) - air moves from area of high pressure to area of low pressure, which is outside of the body b) FEV1 of non-smokers went up by 0.05 after a year, whereas FEV1 of smokers went down by 0.05 after a year. Then FEV1 of non-smokers decreased by 0.12 after the increase and FEV1 of smokers decreased by 0.25 after the first decrease. c) scar tissue formation - loss of lung elasticity tar in cigarettes causes release of proteases - digests elastin, so less recoil and breakdown of alveoli Q6 a) milk treated with lactase to break down lactose b) first thing in the morning - nothing else in digestive tract, so provides a benchmark OR in the morning, not before sleep - can consciously become aware of the symptoms and record them c) dietary guidelines - don't eat any other dairy, foods that will cause bloating or any other symptoms (beans/peas), or lactase supplements the part about conclusions from results I put none of the symptoms are severe or even moderately severe, all of them scoring less than 2, so it may be safe for lactose intolerant people to drink small quantities of milk. Then bloating was more likely to be experienced when drinking untreated milk, whereas diarrhoea - when drinking lactose-free milk. Both untreated and lactose-free milk scored roughly equally on stomach ache. results may be unreliable because the respondents may have been biased about symptoms, not answered truthfully, not a quantitative analysis and no long-term effects studied Q7 a) No receptor protein - virus can't enter cell, so can't replicate and its RNA can't be transcribed, so it can't start harming the cells or make cells produce harmful substances and also is quickly destroyed by white blood cells (phagocytes) if it remains in the blood b) increase in plasma cells: a macrophage presenting antigens meets T-helper cell with a complimentary receptor to that antigen, cytokines activate, among others, B-cells (their proliferation and speciation) and after clonal selection many clone B-plasma cells are produced to produce antibodies to combat the viruses c) plasma transfusion: people who have been recently infected still have specific plasma cells active (that produce antibodies specific to Ebola antigen) and soluble antigens, so a transfusion will introduce those into the sufferer's blood, so that the antigens can bind to Ebola viruses d) high mutation rate=high antigen variability. A vaccine exposes a person to one set of Ebola virus antigens - highly specific antibodies and memory cells formed will only respond/are complementary to the same set of antigens. A new strain of Ebola virus can have completely different antigens, rendering the memory cells useless - primary immune response all over again Q8 a) glucose enters small intestine epithelial cells via facilitated diffusion through a carrier protein by co-transport with sodium. 1 Na+ and 1 glucose have to bind for carrier protein to change shape and release Na+ and glucose inside the cell. A concentration gradient of Na+ has to be maintained since it's facilitated diffusion (passive process). This is achieved by Na+/K+ pump that actively pumps Na+ out of cell (K+ into the cell), so there is always a higher concentration of Na+ outside of the cell, so it binds to a carrier protein again and glucose can enter the cell. b) Plasma membrane=phospholipid bilayer arranged in a fluid mosaic (fluid mosaic makes diffusion possible). Only lipid soluble or very small molecules/atoms (that can be polar) can diffuse across. Oxygen is a small non-charged molecule, so can diffuse down its conc. gradient. Chloride is strongly (negatively) charged and not lipid-soluble, so needs a channel/carrier protein.


holy **** son
Original post by Kira Yagami
For the question about drawing the curve:

It started the same as other curve but it went straight for a bit longer than decreased a bit later until it is similar level as other curve?


It didn't go straight for a bit longer as the enzyme was added at the same stage rather the triglyceride was broken down at a slower rate. It is the q10 rule... That for every 10 degrees lowered the time taken doubles....
Original post by A9M4D
holy **** son


Ikr
Original post by Kira Yagami
It can have about 3 answers, that one makes sense.

I put it has ribosomes ( and so do eukaroytes)

It' basically saying what is similar about both


I never saw a diagram lol, I just guessed and put it has a matrix -_-
Original post by A9M4D
holy **** son


wow. thanks alot
That is exactly what I said!
Reply 207
Would I be punished for referencing glycoproteins rather than antigens? .... as they were referring to glycoproteins on the HIV surface.
Original post by EmmaHarvard
Can someone please make up MS?


Butt
Original post by merlin444
70 Ribosomes for Mitochnodria as a reason for prokaryote ? even though everyone else put double membrane!

I read up on a website this morning that had a paragraph about something like this and I just put prokaryotic cells do not have mitochondria yet they are still able to respire aerobically.
(I thought that was enough to imply that prokaryotes could do what a mitochondria does. The website says 'Mitochondria are very similar to bacteria and are thought to have originated from bacteria. This points you to the answer: bacteria produce ATPs the same way mitochondria do, with the oxidation machinery place in their plasma membrane (analogous to the mitochondrial membrane).' )

Original post by merlin444
With giving blood from those who suffered ebola, I put that it contains high proportion of antigens complentary to the antigen?
Ye same so they would bind onto the antigens on the virus and kill them? I also said it acted as a serum that provided the correct antibodies. I didn't talk about memory cells as I thought it was more about the urgent need to save the patient rather than helping him/her to develop immunity towards it?
Original post by merlin444
Wasn't sure on Trysin inactive, so it can't hydrolyse proteins in the pancreas, destruction or pancreas??
Do you mean the pancreatic cells rather than the actual pancreas? I put it could be packaged, stored and transported in the cell. I also said that the inactive Trypsin wouldn't be able to break down any proteins (since Trysin is a protease) in the cell itself?
Original post by merlin444
Enzyme question, surely the answer was that substrate was limiting, if enzyme was limiting ph would still be falling?
Ye that's what I thought. Surely if the concentration of enzymes was the limiting factor, the rate of decrease in pH would remain constant and therefore the pH would continue to drop?I put all the triglycerides have been hydrolysed and therefore no further hydrolysis of triglycerides could take place hence the pH remained constant.

What do you guys think about my answers to these questions?
(edited 7 years ago)
Original post by Kira Yagami
For the one about what the people should not eat/drink I said they shouldn't consume anything containing lactose.


I also said there will be high metabolism in the morning ☺️ I hope that's right
Reply 211
For the ebola question: stating something along the lines of why some people where not infected by the diesie...

I said because they may have been vaccinated, this the dead antigens help the immune system produce memory cells thus they did not obtain the dieses
Original post by Kira Yagami
For the ph meter I said it gives an quanititative reading.

whereas using indiciator means you need to see colour change which is subjective.

The one about the why results of the lactose intoelrance thing be unreliable, I said because the severity of symoptoms is subjective, will vary from person to person.


Yep👍🏽 how many marks was that question ?
Original post by ShayShay97
Yep👍🏽 how many marks was that question ?

1 for each one.
for the one about why plasma cells were produced?

I put the pathogens antigens trigger an immune response which causes the production of memory cells and antibodies

Did you have to talk about how the antigens are taken up by the pathogen and t-helper cells? I dunno
Reply 215
I wrote that pH stayed constant after that point because enzymes denatured as enzymes have an optimum pH that they work at, so no more fatty acids were being produced, so pH stayed the same.
Reply 216
Original post by FraserK
Would I be punished for referencing glycoproteins rather than antigens? .... as they were referring to glycoproteins on the HIV surface.


Did I f up?

Would they accept the use of glycoprotein in place of antigen?
Reply 217
For the increase in plasma cells and antibodies qs i put: B cells detect the antigens and the specific antibody on the b-cell binds to the antigens released by virus and this activates it to clone by mitosis into plasma cells which secrete antibodies which are released leading to increase in both
Reply 218
Original post by srkd
I wrote that pH stayed constant after that point because enzymes denatured as enzymes have an optimum pH that they work at, so no more fatty acids were being produced, so pH stayed the same.


same here! - it messes up the ionic bonding and changes tertiary structure
Original post by A2LEVELSHELPME
I also put down they cant rate their symptoms throughout the day since theyll be asleep? ?


I said this aswell, and because their symptoms may take time to develop

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