Competition - post a photo you've taken of nature >>

Official AQA Biology Unit 3 14th May 2013 NEW SPEC

Scroll to see replies

1 (b) During exercise, the heart rate increases.
Explain, as fully as you can, why this increase is necessary.
.............................................................................................................................................
........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
.............................................................................................................................................

(4 marks)

Reply 701

cookiesncream123

Helppp!!! are nephrons the same as tubules?

Reply 702

grammar12

Original post by HarryRiley88

DOuble circulatory system means more blood flowing around the body to muscles therefore more oxygen can be taken round the body when needed? idk it was just an educated guess

Double circulation system ensures an efficient blood supply to the body. Deoxygenated blood is not mixed with oxygenated blood which maintains a steep concentration gradient when oxygen diffuses into the blood in the lungs, it then goes back into the heart via the pulmonary vein and out the aorta around the body. The double circulation system is extremely effective because of its adaptations etc.

Posted from TSR Mobile

Reply 703

Quantaˌ

Original post by bbadonde2

For most patients a kidney transplant is better than continued treatment by dialysis.Give two advantages of having a kidney transplant rather than treatment by dialysis.
1 .........................................................................................................................................
............................................................................................................................................
2 .........................................................................................................................................
............................................................................................................................................
(2 marks)
Give two possible disadvantages of having a kidney transplant.
1 .........................................................................................................................................
............................................................................................................................................
2 .........................................................................................................................................
............................................................................................................................................
(2 marks)

Advantages are no diet restrictions and no need to go to the hospital for dialysis.
Disadvantages are need for immosuppressant drugs and risk of rejection.

Reply 704

DecantedOrange

Original post by bbadonde2

For most patients a kidney transplant is better than continued treatment by dialysis.Give two advantages of having a kidney transplant rather than treatment by dialysis.
1. Less or no need to control diet.
2. More freedom
(2 m)
Give two possible disadvantages of having a kidney transplant.
1. You need to take immuno-suppressant drugs to stop your bodies antibodies attacking the "foreign" kidneys antigent
2.Not readily availiable, need to wait for a donor to be availiable
(2 marks)

I changed the persons original quote by accident.. woops im new here..

(edited 10 years ago)

Reply 705

cmorga1

Guys my revision guide has nothing on artificial blood help! Can someone quickly summarise the topic or link me some notes etc? Thanks!

Reply 706

cookiesncream123

Original post by bbadonde2

1)-less time consuming on the large scale
-cheaper

1)can reject the kidney
need to take immonosurpresant drugs for rest of life which increases the chances of other illnesses.

Reply 707

ShadowHawk

Can some A*/A students share some exam tips? I desperately need to get 83% minimum to secure an A grade :s-smilie:

Reply 708

C-king

Original post by bbadonde2

this is necessary as during exercise, energy is required through respiration. the ingredients for respiration are all supplied in the blood. so as a result more blood is needed as more energy is required; so the hart rate increases

Reply 709

ABC05

Original post by cmorga1

Guys my revision guide has nothing on artificial blood help! Can someone quickly summarise the topic or link me some notes etc? Thanks!

Artificial blood is used a blood substitute when someone loses a lot of blood. It's often in the form of saline solution which is used to replace the lost volume of blood. It can keep the patient alive until they get a blood transfusion. Hope that helps a little, sure someone else will be able to explain in a little more detail. People, what are the advantages/disadvantages of it?

Reply 710

bbadonde2

Artificial blood consists of saline solution. It does not contain platelets, red or white blood cells. Although it can carry substances like Urea, it is often used as a temporary solution until the patient starts making blood cells again or gets a blood transfusion. It is an option if you have lost up to 2/3 of your blood. It's basically a substitute to keep the blood volume up.

Reply 711

Unknown505

You guys good luck for the exam tomorrow, hope you get the grades you want. :smile:

Reply 712

DecantedOrange

Can someone tell me if this is right?
Explain how the kidney works.

Unfiltered blood enters the kidney and the blood gets passed through into the kidney tubules where urea, water and ions are filtered out. All of the glucose in the blood is reabsorbed and only ions and water that is needed fr the body is reabsorbed, this is called selective reabsorbtion, filtered blood then leaves the kidney

Reply 713

augustbaby

Anybody got any tips for in the exam?

Reply 714

Kill3er

I NEVER have enough space to write down my full answer on the lines provided for the 6 mark question. It is okay, to just write in the space below the lines, right? The examiners will still mark it..?

Reply 715

DecantedOrange

Original post by augustbaby

Anybody got any tips for in the exam?

Read every question fully and highlight keywords in the question e.g Evaluate, describe, the sample size. Things like that

Reply 716

Mrkingpenguin

Original post by cmorga1

Guys my revision guide has nothing on artificial blood help! Can someone quickly summarise the topic or link me some notes etc? Thanks!

"People who suffer from kidney failure may be treated either by using a kidney dialysis machine or by having a healthy kidney transplanted. If the kidneys doesn’t function properly then waste products build up in the body's bloodstream and the body's ability to control the water content and ion concentrations is lost, a situation that can be fatal - kidney failure is a bad situation - a major lack of this aspect of homeostasis control. Though uncommon, kidney failure can be caused by infection, severe poisoning, and an injury with severe loss of blood or very high blood pressure
Treatment by dialysis restores the concentrations of dissolved substances in the blood to normal levels and has to be carried out at regular intervals.
In particular, keeping the ion concentrations at the right level and removing waste products is essential and a dialysis machine can perform some of the functions of a real kidney. In a dialysis machine a person’s blood flows between partially permeable membranes (selectively permeable membrane).
The dialyser is connected to a patient's arm - blood is pumped from an artery to the dialysis machine and the 'cleaned' blood pumped back into a vein. In a dialysis machine there is a selectively permeable membrane where the patient's blood flows on one side and the dialysis fluid on the other.
The membrane allows substances like ions and urea to pass through the membrane from the blood to the dialysing fluid, but, does not allow larger molecules like proteins through. The dialysis fluid contains the same concentration of useful substances i.e. ions and glucose as the blood to ensure that glucose and useful mineral ions are not lost in the dialysis process. Waste substances such as urea and excess ions pass out from the blood through the membrane into the dialysis fluid.
This will naturally happen by diffusion because the dialysis fluid contains no urea, so, the diffusion gradient is from blood to dialysis solution. The levels of ions and glucose in the dialysis fluid are set at approximately those required in the patient's blood so that diffusion may occur in either direction to maintain the correct concentrations in the blood.
For people with poorly functioning kidneys, dialysis might be required several times a week with each session lasting several hours.
In kidney transplants a diseased kidney is replaced with a healthy one from a donor. Kidney transplants are one of the most common organ transplant operations done in our modern health service (i.e. the NHS of the UK).The only cure for serious kidney disease is to have a kidney transplant, hopefully from a suitable matching donor. The donor can be a relative donating one of their kidneys or a fatal accident victim. However, the donor kidney may be rejected by the immune system unless precautions are taken. There are also problems with availability of kidneys, i.e. a long waiting list and the cheaper dialysis is often used as an interim treatment.
Antigens are proteins on the surface of cells. The recipient’s anti-bodies may attack antigens on the donor organ as the body doesn’t recognise it as a part of the recipient’s body, hence rejecting the organ.
To prevent this rejection, a donor kidney can be found – that has a similar tissue match to the receipting’s i.e. a relative. The person is also treated with immune-suppressant drugs to suppress the response of the immune system.
"

Reply 717

Quantaˌ

What did everyone get in the Specimen Paper? And what grade are they aiming for?