ALL CIE BIOLOGY DOUBTS HERE !!!

[elemis]

Please post all doubts here.

[ruby92]

what is the difference between electron acceptors and electron carriers?
And the difference between oxidative and photophosphorylation?
also any notes on the reactions of photosynthesis .

[Deadly_king]

what is the difference between electron acceptors and electron carriers?
And the difference between oxidative and photophosphorylation?
also any notes on the reactions of photosynthesis .

Sorry......won't be able to help you much now because am very busy.
Anyway try this and see if it helps..........ask any question and i'll attend to them later

http://www.s-cool.co.uk/alevel/biology/respiration.html

http://www.biologymad.com/ -----> A2 Biology -----> Photosynthesis and Respiration

[Dania]

Hi, does anyone know where I can get thorough notes on Malaria?

[Deadly_king]

Hi, does anyone know where I can get thorough notes on Malaria?

Try this for now :

http://www.biology-questions-and-answers.com/malaria.html

I'll keep on adding new sites as I find them

[Dania]

Explain why it has proved difficult to develop a vaccine for malaria. [4 marks]

[elemis]

P. falciparum has demonstrated the capability, through the development of multiple drug-resistance parasites, of evolutionary change. The Plasmodium species has a very high rate of replication, much higher than that actually needed to ensure transmission in the parasite’s life cycle. This enables pharmaceutical treatments that are effective at reducing the reproduction rate, but not halting it, to exert a high selection pressure, thus favoring the development of resistance. The process of evolutionary change is one of the key considerations necessary when considering potential vaccine candidates. The development of resistance could cause a significant reduction in efficacy of any potential vaccine thus rendering useless a carefully developed and effective treatment.

From wikipedia : http://en.wikipedia.org/wiki/Malaria_vaccine#The_diversity_of_the_parasite

[**RoRo**]

Okay, this is one the points I came across while going through the syllabus under 'Infectious Diseases':

Describe the roles of social, economic and biological factors in the prevention and control of cholera, malaria, TB and HIV/AIDS.

Can anyone explain what is meant by that and what do we need to know?

Thank you in advance!!

[Deadly_king]

Okay, this is one the points I came across while going through the syllabus under 'Infectious Diseases':

Describe the roles of social, economic and biological factors in the prevention and control of cholera, malaria, TB and HIV/AIDS.

Can anyone explain what is meant by that and what do we need to know?

Thank you in advance!!

These are not specifically found in the syllabus but you're supposed to know how and where these particular diseases are transmitted. This will help you to answer this question.

I'll take one by one, and i'll try to elaborate a bit.

1. Cholera
You should know that this disease is transmitted by fecal-oral route and the main mode of transmission is ingestion of contaminated water or food. It is most prevalent in places that lack adequate sanitary conditions.

Social factors : Sensitisation programmes must be launched through out the whole society so as to educate the inhabitants about the mode of transmission and cure of this disease in order that each one of them take precautions.

Economic : The states should provide money to afford the drugs or vaccine required to combat the disease.

Biological : The person should be in good health so that his immune system is effective against the disease.

2. Malaria
You must know the main preventive measures against malaria are the elimination of the vector mosquito, treatment of infected people, avoidance of the mosquito bite, information for travelers to endemic areas and the use of preventive medicines.

Social factors : Wear long sleeved shirts, take precautionary measures against mosquitoes.

Economic : Funds from the states.

Biological : Effective immune system.

3. Tuberculosis
You should be aware that tuberculosis is highly contagious, transmitted by air route through sneezes and coughs from a person with the active disease. Transmission is common between members of the same family or even in work environments. The disease today has treatment with efficient antibiotics. Generally, the patient receives three different drugs for several months until healing is complete. There are however some strains of multi-resistant TB-bacteria that emerged by mutation and natural selection due to the intense use of antibiotic drugs mainly in hospitals and treatment facilities; in these cases the treatment is more difficult.

Social factors : Again sensitisation programmes to isolate persons affected as the disease is highly contagious by air.

Economic : Funds should be provided by the governement.

Biological : Everyone should be in good health in order to contain e very effective immune system.

4. HIV/AIDS
You must be aware that HIV (human immunodeficiency virus) is supposed to be transmitted through blood, semen, vaginal secretions and maternal milk.

Social factors : Avoid from having various sex partners.

Economic : Condoms or pills should be readily available.

Biological : Do not risk the life of a baby.

As you can note, most of the factors resemble for most diseases but still you can opt for more appropriate ones according to the diseases' mode of transmission.

[**RoRo**]

These are not specifically found in the syllabus but you're supposed to know how and where these particular diseases are transmitted. This will help you to answer this question.

I'll take one by one, and i'll try to elaborate a bit.

1. Cholera
You should know that this disease is transmitted by fecal-oral route and the main mode of transmission is ingestion of contaminated water or food. It is most prevalent in places that lack adequate sanitary conditions.

Social factors : Sensitisation programmes must be launched through out the whole society so as to educate the inhabitants about the mode of transmission and cure of this disease in order that each one of them take precautions.

Economic : The states should provide money to afford the drugs or vaccine required to combat the disease.

Biological : The person should be in good health so that his immune system is effective against the disease.

2. Malaria
You must know the main preventive measures against malaria are the elimination of the vector mosquito, treatment of infected people, avoidance of the mosquito bite, information for travelers to endemic areas and the use of preventive medicines.

Social factors : Wear long sleeved shirts, take precautionary measures against mosquitoes.

Economic : Funds from the states.

Biological : Effective immune system.

3. Tuberculosis
You should be aware that tuberculosis is highly contagious, transmitted by air route through sneezes and coughs from a person with the active disease. Transmission is common between members of the same family or even in work environments. The disease today has treatment with efficient antibiotics. Generally, the patient receives three different drugs for several months until healing is complete. There are however some strains of multi-resistant TB-bacteria that emerged by mutation and natural selection due to the intense use of antibiotic drugs mainly in hospitals and treatment facilities; in these cases the treatment is more difficult.

Social factors : Again sensitisation programmes to isolate persons affected as the disease is highly contagious by air.

Economic : Funds should be provided by the governement.

Biological : Everyone should be in good health in order to contain e very effective immune system.

4. HIV/AIDS
You must be aware that HIV (human immunodeficiency virus) is supposed to be transmitted through blood, semen, vaginal secretions and maternal milk.

Social factors : Avoid from having various sex partners.

Economic : Condoms or pills should be readily available.

Biological : Do not risk the life of a baby.

As you can note, most of the factors resemble for most diseases but still you can opt for more appropriate ones according to the diseases' mode of transmission.

So this point in the syllabus just means that we suggest a social, economical and a biological preventive measure to combat these diseases?

Thank you VERY VERY MUCH for your help!!

[Deadly_king]

So this point in the syllabus just means that we suggest a social, economical and a biological preventive measure to combat these diseases?

Thank you VERY VERY MUCH for your help!!

Yupz.......you need to use all the theory you learnt on the specific disease to suggest a preventive measure.

Anytime

[Dania]

1.Please explain why cell membranes are described as having "fluid mosaic" structure.

2. Explain, in terms of protein structure, how it is possible for each type of T cell receptor to
bind specifically to one type of antigen. [Ref: May/June 2002, Paper 2, Question 3 (b)]


Thanks in advance.

[ashish]

1.Please explain why cell membranes are described as having "fluid mosaic" structure.

2. Explain, in terms of protein structure, how it is possible for each type of T cell receptor to
bind specifically to one type of antigen. [Ref: May/June 2002, Paper 2, Question 3 (b)]


Thanks in advance.

it is fluid because there is lateral diffusion of the fatty acid chains which make it looks like a fluid moving !
it is mosaic because there is protein molecules which has been scattered around the surface!

2)in each T cell receptor there is sequence of amino acids which bind to form a tertiary structure, this means that each T cell receptor has a different variable region. different receptors will bind with complementary antigens .

[Deadly_king]

it is fluid because there is lateral diffusion of the fatty acid chains which make it looks like a fluid moving !
it is mosaic because there is protein molecules which has been scattered around the surface!

2)in each T cell receptor there is sequence of amino acids which bind to form a tertiary structure, this means that each T cell receptor has a different variable region. different receptors will bind with complementary antigens .

Your answers are good but I would just like to add some precision, if you don't mind.

1. Membranes are described as fluid mosaic structure since they consisit of proteins which are scattered among the phospholipid bi-layer giving rise to a mosaic appearance. Moreover the phospholipid within the bi-layer is always on the move rendering it fluid.

2. A T-cell contains a globular protein with a precise conformation showing tertiary structure. The amino acids are arranged in a specific sequence so that there is a variable region that allows only specific antigen with a complementary shape to bind.

[Dania]

Thank You, DK!
Oh, I was doing a past paper this morning and there were questions on drug tolerance and caffeine and what not? I don't think that's in the 2010 CIE syllabus, right?